Re: [Tutor] how obsolete is 2.2, and a pickle question
c smith wrote:
> oh, and a question on 'pickle':
> can pickle deserialize things that were not serialized by python?
> can it convert data into a python data type regardless of it was
> originally a 'c array' or something else that python doesn't support?
As long as the file written by C is a valid pickle file and all classes used
are available to the Python interpreter you are fine:
$ cat pickledemo_struct.c
#include
typedef struct NAMEDPAIR {
char name[10];
int x;
int y;
} namedpair;
main()
{
FILE *f = fopen("tmp_struct.pickle", "wb");
int i;
namedpair *p, data[] = {{"Cube", 10, 20}, {"Pyramid", 30, 40}};
fprintf(f, "(lp0\n");
for (i = 0, p = data; i != 2; i++, p++) {
fprintf(f, "(S'%s'\nI%d\nI%d\ntp%d\na", p->name, p->x, p->y, i+1);
}
fprintf(f, ".");
}
$ gcc pickledemo_struct.c
$ ./a.out
$ python -c 'import pickle; print pickle.load(open("tmp_struct.pickle"))'
[('Cube', 10, 20), ('Pyramid', 30, 40)]
But remember that in C the information whether you have a 32 bit integer or
four characters is in the code, not in the data; if you just dump that data
to a file Python can still read it, but has no way of knowing what it's
meant to be.
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Re: [Tutor] how obsolete is 2.2?
On 08/09/11 04:26, c smith wrote: I found a book at the local library that covers python but it's 2.2. I already have been using 2.7 for basic stuff and would like to know if it's worth my time to read this book. That depends on your experience level and what you are looking to get out of it. The Python 2 series is very backwards compatible so virtually everything you read in the book will still work in Python 2.7. It's just that some new whizzy features have been added since 2.2 that it won't cover. But many of those features are not things the average programmer uses every day. The vast majority of the standard library modules haven't changed that much and any information about those will probably still be accurate. Given you get to read it for free from the library I'd say yes, its very worthwhile. But if you have been using Python for a while and want to dig deeper into its power features then it probably isn't worth reading because the changes in Python recently have focused on many of the more subtle things "under the covers" and 2.2 won't cover them, can pickle deserialize things that were not serialized by python? Not unless the thing that serialised them was deliberately copying Pythons serialisation format. can it convert data into a python data type regardless of it was originally a 'c array' or something else that python doesn't support? No, the nearest thing to that is the struct module. But there you have to know what you are reading and construct a format specifier to match. -- Alan G Author of the Learn to Program web site http://www.alan-g.me.uk/ ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] understanding **kwargs syntax
Following up on this...
Why does pylint seem to think it is a bad idea?
Description ResourcePathLocationType
ID:W0142 plot_ts_array_split_x: Used * or **
magic tsplot.py /research.plot line 299PyLint Problem
Thanks,
john
On Thu, Aug 25, 2011 at 10:44 AM, Alan Gauld wrote:
> On 25/08/11 09:27, John wrote:
>>
>> Just a quick question,
>>
>> is it wrong to use the *args and **kwargs ( the latter in particular)
>> when DEFINING a function?
>
> No, in fact it's essential if you don't know in advance what arguments are
> going to be passed to the function. This is very common if you are wrapping
> another function that itself takes variable arguments.
>
>> def fest(**kwargs):
>> """ a function test """
>> keys = sorted(kwargs.keys())
>>
>> print("You provided {0} keywords::\n".format(len(keys)))
>> for kw in keys:
>> print("{0} => {1}".format(kw, kwargs[kw]))
>>
>> Are there some good examples of when this would be a good idea to
>> implement?
>
> GUI frameworks like Tkinter often take variable numbers of configuration
> values. If you want to wrap that with a
> function of your own you can do something like(pseudocode):
>
> def myfunc(**kwargs):
> if some interesting arg exists
> do something with it
> return wrappedFunc(kwargs)
>
> There are plenty other cases, try grepping the standard library code
> for lines with def and **kwargs for some examples...
>
> --
> Alan G
> Author of the Learn to Program web site
> http://www.alan-g.me.uk/
>
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--
Configuration
``
Plone 2.5.3-final,
CMF-1.6.4,
Zope (Zope 2.9.7-final, python 2.4.4, linux2),
Python 2.6
PIL 1.1.6
Mailman 2.1.9
Postfix 2.4.5
Procmail v3.22 2001/09/10
Basemap: 1.0
Matplotlib: 1.0.0
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[Tutor] need advice about a dictionary ({})
I've succeeded in writing a dictionary ({}) that I can use as a small
personal phone book. The dictionary (very shortened and simplified)
looks like this in the script;
p = {}
p['bp1'] = 'xxx'
p['bp2'] = 'ooo'
p['ch'] = 'zzz'
p['me'] = 'aaa'
p['mg'] = 'vvv'
p['pu1'] = 'bbb'
p['pu2'] = 'ccc'
p['pw'] = 'kkk'
I have a function that enables the user to enter 'bp', for example,
and return both 'xxx' and 'ooo'.
(The keys are initials; I've disguised the values, each of which of
course are name, home number, mobile number, speed dial number,
etc.)
But I'd like to put the lines of the dictionary in a text file so that
I can add key/value items to it by writing to it with another script.
I think I can do that, but I need some hints about how to get the
script to access the text file in a way that lets the user look up a
phone number. I'm thinking that the script needs to recreate the
dictionary each time it's called, but I don't know how to do that.
Thanks,
Dick Moores
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Re: [Tutor] understanding **kwargs syntax
John wrote:
> Following up on this...
>
> Why does pylint seem to think it is a bad idea?
>
> Description ResourcePathLocationType
> ID:W0142 plot_ts_array_split_x: Used * or **
> magic tsplot.py /research.plot line 299PyLint Problem
I would guess it's a readability concern. Consider a simple function
def f(x, y=0):
print x + y
for a in [1], "ab", "abc":
f(*a)
Can you tell what will be printed immediately? For me
f(1)
f("a", "b")
f("a", "b", "c")
is much easier to predict.
That said, there are valid usecases for * and ** "magic", and of course
pylint cannot take the tradeoffs into account. Therefore don't take pylint's
warnings as gospel.
PS: the exception is intentional
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Re: [Tutor] need advice about a dictionary ({})
On 2011/09/08 12:58 PM, Richard D. Moores wrote:
I've succeeded in writing a dictionary ({}) that I can use as a small
personal phone book. The dictionary (very shortened and simplified)
looks like this in the script;
p = {}
p['bp1'] = 'xxx'
p['bp2'] = 'ooo'
p['ch'] = 'zzz'
p['me'] = 'aaa'
p['mg'] = 'vvv'
p['pu1'] = 'bbb'
p['pu2'] = 'ccc'
p['pw'] = 'kkk'
I have a function that enables the user to enter 'bp', for example,
and return both 'xxx' and 'ooo'.
(The keys are initials; I've disguised the values, each of which of
course are name, home number, mobile number, speed dial number,
etc.)
But I'd like to put the lines of the dictionary in a text file so that
I can add key/value items to it by writing to it with another script.
I think I can do that, but I need some hints about how to get the
script to access the text file in a way that lets the user look up a
phone number. I'm thinking that the script needs to recreate the
dictionary each time it's called, but I don't know how to do that.
Thanks,
Dick Moores
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You could pickle your dictionary object which will give you the
persistence and then when your script starts up you can unpickle the
file if it exists else create a new one. Of course if you make any
changes to your object you'll need to pickle it once your app finishes
otherwise new changes won't be written out.
With just a plain text file you can also just grep the info out
$ cat test.file
bp1:xxx|yyy
bp2:ooo|ppp
ch:zzz|asf
me:agkjh|agjh
$ grep -i ^bp* test.file
bp1:xxx|yyy
bp2:ooo|ppp
$ grep -i ^BP* test.file
bp1:xxx|yyy
bp2:ooo|ppp
--
Christian Witts
Python Developer
//
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Re: [Tutor] need advice about a dictionary ({})
On Thu, Sep 8, 2011 at 04:36, Christian Witts wrote:
> On 2011/09/08 12:58 PM, Richard D. Moores wrote:
>
> I've succeeded in writing a dictionary ({}) that I can use as a small
> personal phone book. The dictionary (very shortened and simplified)
> looks like this in the script;
>
> p = {}
>
> p['bp1'] = 'xxx'
> p['bp2'] = 'ooo'
> p['ch'] = 'zzz'
> p['me'] = 'aaa'
> p['mg'] = 'vvv'
> p['pu1'] = 'bbb'
> p['pu2'] = 'ccc'
> p['pw'] = 'kkk'
>
> I have a function that enables the user to enter 'bp', for example,
> and return both 'xxx' and 'ooo'.
>
> (The keys are initials; I've disguised the values, each of which of
> course are name, home number, mobile number, speed dial number,
> etc.)
>
> But I'd like to put the lines of the dictionary in a text file so that
> I can add key/value items to it by writing to it with another script.
> I think I can do that, but I need some hints about how to get the
> script to access the text file in a way that lets the user look up a
> phone number. I'm thinking that the script needs to recreate the
> dictionary each time it's called, but I don't know how to do that.
>
> Thanks,
>
> Dick Moores
> ___
> Tutor maillist - Tutor@python.org
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>
>
>
> You could pickle your dictionary object which will give you the persistence
> and then when your script starts up you can unpickle the file if it exists
> else create a new one. Of course if you make any changes to your object
> you'll need to pickle it once your app finishes otherwise new changes won't
> be written out.
>
> With just a plain text file you can also just grep the info out
> $ cat test.file
> bp1:xxx|yyy
> bp2:ooo|ppp
> ch:zzz|asf
> me:agkjh|agjh
> $ grep -i ^bp* test.file
> bp1:xxx|yyy
> bp2:ooo|ppp
> $ grep -i ^BP* test.file
> bp1:xxx|yyy
> bp2:ooo|ppp
I should have stated that I'm using Win 7, Python 3.2.1. No Unix.
Dick
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Re: [Tutor] need advice about a dictionary ({})
Richard D. Moores wrote:
> I've succeeded in writing a dictionary ({}) that I can use as a small
> personal phone book. The dictionary (very shortened and simplified)
> looks like this in the script;
>
> p = {}
>
> p['bp1'] = 'xxx'
> p['bp2'] = 'ooo'
> p['ch'] = 'zzz'
> p['me'] = 'aaa'
> p['mg'] = 'vvv'
> p['pu1'] = 'bbb'
> p['pu2'] = 'ccc'
> p['pw'] = 'kkk'
>
> I have a function that enables the user to enter 'bp', for example,
> and return both 'xxx' and 'ooo'.
>
> (The keys are initials; I've disguised the values, each of which of
> course are name, home number, mobile number, speed dial number,
> etc.)
>
> But I'd like to put the lines of the dictionary in a text file so that
> I can add key/value items to it by writing to it with another script.
> I think I can do that, but I need some hints about how to get the
> script to access the text file in a way that lets the user look up a
> phone number. I'm thinking that the script needs to recreate the
> dictionary each time it's called, but I don't know how to do that.
Start with a simple file format. If you don't allow "=" in the key and "\n"
in either key or value
bp1=xxx
bp2=ooo
...
pw=kkk
should do. I suppose you know how to read a file one line at a time? Before
you add the line into the dictionary you have to separate key and value
(str.partition() may help with that) and remove the trailing newline from
the value. If you need more flexibility look into the json module. This
makes reading and writing the file even easier, and while the format is a
bit more complex than key=value
>>> print json.dumps(p, indent=2)
{
"me": "aaa",
"mg": "vvv",
"ch": "zzz",
"pw": "kkk",
"bp1": "xxx",
"bp2": "ooo",
"pu1": "bbb",
"pu2": "ccc"
}
it can still be edited by a human.
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Re: [Tutor] how obsolete is 2.2?
c smith wrote: Also, am I correct in thinking that 3.0 will always be called 3.0 but will change over time and will always include experimental features, while 2.x will gradually increase the 'x' and the highest 'x' will indicate the most current, stable release? No, I'm afraid you are wrong. Python 2.7 is the last version in the 2.x series. It will continue to get bug fixes and security updates for the next few years, but no new features. 2.7 and 3.2 are the most up to date versions. As I said, 2.7 is the last of the 2.x line. 3.x is the future of Python, although 2.7 will be supported for quite some time. But all new features will be going into 3.x and 2.7 will only get bug fixes. Python 3.0 is no longer supported: to be frank, it was released too early, and it has too many bugs and is painfully slow. If you are using 3.0, you should update to 3.1 or 3.2, they are much, much better. -- Steven ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
[Tutor] a quick Q: built-in method pop of list object at 0x7f8221a22cb0>
Hi, what does the 0x7f8221a22cb0 mean here? the computer physical address. Thanks, -- Best Regards, lina ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
[Tutor] a quick Q: what does the "collapse" mean?
Hi, I failed to understand the "collpase" meaning in a string. can someone give me a simple example? Sorry, -- Best Regards, lina ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] need advice about a dictionary ({})
Richard D. Moores wrote: But I'd like to put the lines of the dictionary in a text file so that I can add key/value items to it by writing to it with another script. If you expect human beings (yourself, or possibly even the user) to edit the text file, then you should look at a human-writable format like these: Good ol' fashioned Windows INI files: import configparser JSON: import json PLIST: import plistlib YAML: download from http://pyyaml.org/wiki/PyYAML If the ability to edit the files isn't important, then I suggest using the pickle module instead. -- Steven ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] need advice about a dictionary ({})
On Thu, Sep 8, 2011 at 04:43, Peter Otten <__pete...@web.de> wrote:
> Richard D. Moores wrote:
>
>> I've succeeded in writing a dictionary ({}) that I can use as a small
>> personal phone book. The dictionary (very shortened and simplified)
>> looks like this in the script;
>>
>> p = {}
>>
>> p['bp1'] = 'xxx'
>> p['bp2'] = 'ooo'
>> p['ch'] = 'zzz'
>> p['me'] = 'aaa'
>> p['mg'] = 'vvv'
>> p['pu1'] = 'bbb'
>> p['pu2'] = 'ccc'
>> p['pw'] = 'kkk'
>>
>> I have a function that enables the user to enter 'bp', for example,
>> and return both 'xxx' and 'ooo'.
>>
>> (The keys are initials; I've disguised the values, each of which of
>> course are name, home number, mobile number, speed dial number,
>> etc.)
>>
>> But I'd like to put the lines of the dictionary in a text file so that
>> I can add key/value items to it by writing to it with another script.
>> I think I can do that, but I need some hints about how to get the
>> script to access the text file in a way that lets the user look up a
>> phone number. I'm thinking that the script needs to recreate the
>> dictionary each time it's called, but I don't know how to do that.
>
> Start with a simple file format. If you don't allow "=" in the key and "\n"
> in either key or value
>
> bp1=xxx
> bp2=ooo
> ...
> pw=kkk
>
> should do. I suppose you know how to read a file one line at a time? Before
> you add the line into the dictionary you have to separate key and value
> (str.partition() may help with that) and remove the trailing newline from
> the value. If you need more flexibility look into the json module. This
> makes reading and writing the file even easier, and while the format is a
> bit more complex than key=value
>
print json.dumps(p, indent=2)
> {
> "me": "aaa",
> "mg": "vvv",
> "ch": "zzz",
> "pw": "kkk",
> "bp1": "xxx",
> "bp2": "ooo",
> "pu1": "bbb",
> "pu2": "ccc"
> }
>
> it can still be edited by a human.
Thanks Peter!
You made it a lot easier than I thought it would be. Please see
for the script's current incarnation.
The text of the demo data file is quoted in the script, lines 6-13. It
doesn't seem I need to use the json module, though I want to learn it
eventually.
The data file very easily edited. However, as the number of lines gets
large (maybe 100?) I'll need a way to determine if the new key is
already in the file. So I'll be working on a script that I can use to
safely add lines to the the file, by keeping all the keys unique.
Dick
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Re: [Tutor] understanding **kwargs syntax
On 08/09/11 11:10, John wrote: Following up on this... Why does pylint seem to think it is a bad idea? Description ResourcePathLocationType ID:W0142 plot_ts_array_split_x: Used * or ** magic tsplot.py /research.plot line 299PyLint Problem I assume because it is a bad idea in most cases. If you know what the arguments are going to be then specify them. Otherwise you can get all sorts of rubbish being passed in that you have to figure out how to deal with. That's never a good place to be. But occasionally you have to do things that are less than ideal. And *args/**kwargs are useful in those situations, just don't use them unless you have to. -- Alan G Author of the Learn to Program web site http://www.alan-g.me.uk/ ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] need advice about a dictionary ({})
On Thu, Sep 8, 2011 at 04:43, Peter Otten <__pete...@web.de> wrote:
> Richard D. Moores wrote:
>
>> I've succeeded in writing a dictionary ({}) that I can use as a small
>> personal phone book. The dictionary (very shortened and simplified)
>> looks like this in the script;
>>
>> p = {}
>>
>> p['bp1'] = 'xxx'
>> p['bp2'] = 'ooo'
>> p['ch'] = 'zzz'
>> p['me'] = 'aaa'
>> p['mg'] = 'vvv'
>> p['pu1'] = 'bbb'
>> p['pu2'] = 'ccc'
>> p['pw'] = 'kkk'
>>
>> I have a function that enables the user to enter 'bp', for example,
>> and return both 'xxx' and 'ooo'.
>>
>> (The keys are initials; I've disguised the values, each of which of
>> course are name, home number, mobile number, speed dial number,
>> etc.)
>>
>> But I'd like to put the lines of the dictionary in a text file so that
>> I can add key/value items to it by writing to it with another script.
>> I think I can do that, but I need some hints about how to get the
>> script to access the text file in a way that lets the user look up a
>> phone number. I'm thinking that the script needs to recreate the
>> dictionary each time it's called, but I don't know how to do that.
>
> Start with a simple file format. If you don't allow "=" in the key and "\n"
> in either key or value
>
> bp1=xxx
> bp2=ooo
> ...
> pw=kkk
>
> should do. I suppose you know how to read a file one line at a time? Before
> you add the line into the dictionary you have to separate key and value
> (str.partition() may help with that) and remove the trailing newline from
> the value. If you need more flexibility look into the json module. This
> makes reading and writing the file even easier, and while the format is a
> bit more complex than key=value
>
print json.dumps(p, indent=2)
> {
> "me": "aaa",
> "mg": "vvv",
> "ch": "zzz",
> "pw": "kkk",
> "bp1": "xxx",
> "bp2": "ooo",
> "pu1": "bbb",
> "pu2": "ccc"
> }
>
> it can still be edited by a human.
Thanks Peter!
You made it a lot easier than I thought it would be. Please see
for the script's current incarnation.
The text of the demo data file is quoted in the script, lines 6-13. It
doesn't seem I need to use the json module, though I want to learn it
eventually.
The data file very easily edited. However, as the number of lines gets
large (maybe 100?) I'll need a way to determine if the new key is
already in the file. So I'll be working on a script that I can use to
safely add lines to the the file, by keeping all the keys unique.
Dick
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Re: [Tutor] a quick Q: built-in method pop of list object at 0x7f8221a22cb0>
lina wrote: Hi, what does the 0x7f8221a22cb0 mean here? the computer physical address. That's the ID of the list object, converted to hexadecimal. Every object in Python gets a unique (for the life of the object) ID. In CPython, the version you are using, that ID happens to be the memory address, and can be reused. For Jython and IronPython, the ID is an auto-incrementing counter, and will never be re-used: first object created gets ID 1 second object gets ID 2 third object gets ID 3 ... etc. -- Steven ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] a quick Q: what does the "collapse" mean?
lina wrote: Hi, I failed to understand the "collpase" meaning in a string. can someone give me a simple example? Sorry, I don't understand what you mean. Can you give context? -- Steven ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] a quick Q: what does the "collapse" mean?
On 08/09/11 14:02, lina wrote: Hi, I failed to understand the "collpase" meaning in a string. can someone give me a simple example? Can you give us some context? Its not a method of a string object so far as I can tell? Where did you read about it? -- Alan G Author of the Learn to Program web site http://www.alan-g.me.uk/ ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] a quick Q: built-in method pop of list object at 0x7f8221a22cb0>
On 08/09/11 13:59, lina wrote: what does the 0x7f8221a22cb0 mean here? the computer physical address. It's a unique identifier for the object which is implementation dependant. In practice you can consider it the memory address. But I wouldn't try using it as an address by passing it into a C function say. That's not guaranteed to work at all! -- Alan G Author of the Learn to Program web site http://www.alan-g.me.uk/ ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] need advice about a dictionary ({})
On 08/09/11 11:58, Richard D. Moores wrote:
I've succeeded in writing a dictionary ({}) that I can use as a small
personal phone book. The dictionary (very shortened and simplified)
looks like this in the script;
p = {}
p['bp1'] = 'xxx'
p['bp2'] = 'ooo'
p['ch'] = 'zzz'
p['me'] = 'aaa'
p['mg'] = 'vvv'
p['pu1'] = 'bbb'
p['pu2'] = 'ccc'
p['pw'] = 'kkk'
You could have done that in one line if you preferred:
> p = {
'bp1':'xxx',
'bp2':'ooo'
etc/...
'pw':'kkk'
}
But I'd like to put the lines of the dictionary in a text file so that
I can add key/value items to it by writing to it with another script.
Consider using a shelve (See the shelve module)
It is basically a file that you can treat as a dictionary...
Try:
>>> import shelve
>>> help(shelve)
For examples and info.
--
Alan G
Author of the Learn to Program web site
http://www.alan-g.me.uk/
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[Tutor] throwing exception across modules?
This is more a design question. One lesson C++ programmers might learn is that throwing exceptions from within library code is fraught with problems because the internals of exception handling were spelled out in the C++ standard. This manifests itself as problems when the library was compiled with one vendor's compiler, but the user of the library is using another compiler. While I understand that Python doesn't suffer from this exact problem, are there other reasons that raising exceptions in a module only be caught by consumers of the module a bad idea? Any insight which can be shared would be most appreciated. Thanks. Jim ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] a quick Q: built-in method pop of list object at 0x7f8221a22cb0>
Thanks, this is very informative. open some windows for me. On Thu, Sep 8, 2011 at 9:58 PM, Alan Gauld wrote: > On 08/09/11 13:59, lina wrote: >> >> >> >> what does the 0x7f8221a22cb0 mean here? the computer physical address. > > It's a unique identifier for the object which is implementation dependant. > In practice you can consider it the memory address. > > But I wouldn't try using it as an address by passing it into a > C function say. That's not guaranteed to work at all! > > > -- > Alan G > Author of the Learn to Program web site > http://www.alan-g.me.uk/ > > ___ > Tutor maillist - Tutor@python.org > To unsubscribe or change subscription options: > http://mail.python.org/mailman/listinfo/tutor > -- Best Regards, lina ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] a quick Q: what does the "collapse" mean?
On Thu, Sep 8, 2011 at 9:59 PM, Alan Gauld wrote: > On 08/09/11 14:02, lina wrote: >> >> Hi, >> >> I failed to understand the "collpase" meaning in a string. >> >> can someone give me a simple example? > > Can you give us some context? > Its not a method of a string object so far as I can tell? > Where did you read about it? >From "dive into python", http://diveintopython.org/ one example: def info(object, spacing=10, collapse=1): """Print methods and docs strings. Take modules, class, list, dictionary, or strong.""" methodList = [e for e in dir(object) if callable(getattr(object, e))] processFunc = collapse and (lambda s: " ".join(s.split())) or (lambda s: s) print "\n".join(["%s %s" % (method.ljust(spacing), processFunc(str(getattr(object, method).__doc__))) for method in methodList]) if __name__ == "__main__": print info.__doc__ I felt so hard to understand the collapse, Please don't discourage me telling me it's an old book, To me I started reading till 42 pages. let me finish it. I used to study python on and off, sometimes give a whole week, but due to not using it, so it's frustrating that when I really needed it, I barely could complete one. > > -- > Alan G > Author of the Learn to Program web site > http://www.alan-g.me.uk/ > > ___ > Tutor maillist - Tutor@python.org > To unsubscribe or change subscription options: > http://mail.python.org/mailman/listinfo/tutor > -- Best Regards, lina ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] throwing exception across modules?
James Hartley wrote: This is more a design question. One lesson C++ programmers might learn is that throwing exceptions from within library code is fraught with problems because the internals of exception handling were spelled out in the C++ standard. This manifests Do you mean "weren't spelled out"? itself as problems when the library was compiled with one vendor's compiler, but the user of the library is using another compiler. While I understand that Python doesn't suffer from this exact problem, are there other reasons that raising exceptions in a module only be caught by consumers of the module a bad idea? Not at all. Python is designed to use exceptions as the primary error mechanism. Nearly every module and function you will use in Python will use exceptions to signal errors. A few will also use exceptions to signal non-error exceptional cases, e.g. StopIteration is used by iterators when they run out of items. Exceptions in Python aren't bolted on the top, they are fundamental to the way the language works. Even things like for loops work by catching exceptions. Any insight which can be shared would be most appreciated. The only thing which sometimes catches out beginners is that they forget to use fully-qualified names for exceptions. E.g. you may need to do this: import socket try: ... except socket.error: ... instead of just "except error". If possible, document which exceptions your code might throw. At least, document which exceptions you expect to throw under normal circumstances. An exception in the top level of your module will be treated as fatal: it will prevent the module from being imported. (When I say fatal, I mean fatal for your module, not the caller: the caller can always catch the exception and skip the import.) Think carefully about what exceptions you should use. Try to integrate with the standard Python exception hierarchy. See the docs for further details. It's a matter of opinion whether you should use built-in exceptions as-is, or whether you subclass them. Subclassing can be as simple as: class StatsError(ValueError): pass or as complicated as you want. But in general, keep exceptions simple. Try not to raise private exceptions where the caller will see them. In other words, if you define a private exception type by flagging the name with a leading single underscore: class _InternalUseOnly(TypeError): # single underscore means "private" pass then never raise it unless you also catch it. -- Steven ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] a quick Q: what does the "collapse" mean?
On Thu, Sep 8, 2011 at 4:16 PM, lina wrote: > On Thu, Sep 8, 2011 at 9:59 PM, Alan Gauld > wrote: > > On 08/09/11 14:02, lina wrote: > >> > >> Hi, > >> > >> I failed to understand the "collpase" meaning in a string. > >> > >> can someone give me a simple example? > > > > Can you give us some context? > > Its not a method of a string object so far as I can tell? > > Where did you read about it? > > >From "dive into python", > > http://diveintopython.org/ > > one example: > > def info(object, spacing=10, collapse=1): >"""Print methods and docs strings. > >Take modules, class, list, dictionary, or strong.""" >methodList = [e for e in dir(object) if callable(getattr(object, e))] >processFunc = collapse and (lambda s: " ".join(s.split())) or (lambda s: > s) >print "\n".join(["%s %s" % >(method.ljust(spacing), >processFunc(str(getattr(object, method).__doc__))) >for method in methodList]) > > if __name__ == "__main__": >print info.__doc__ > > I felt so hard to understand the collapse, > > Please don't discourage me telling me it's an old book, > To me I started reading till 42 pages. let me finish it. > > I used to study python on and off, > sometimes give a whole week, but due to not using it, > so > it's frustrating that when I really needed it, I barely could complete one. > Reading this, it seems that 'collapse' is a variable defined somewhere else in the code. -- André Engels, andreeng...@gmail.com ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] a quick Q: what does the "collapse" mean?
On Thu, Sep 8, 2011 at 10:36 AM, Andre Engels wrote: > On Thu, Sep 8, 2011 at 4:16 PM, lina wrote: > >> On Thu, Sep 8, 2011 at 9:59 PM, Alan Gauld >> wrote: >> > On 08/09/11 14:02, lina wrote: >> >> >> >> Hi, >> >> >> >> I failed to understand the "collpase" meaning in a string. >> >> >> >> can someone give me a simple example? >> > >> > Can you give us some context? >> > Its not a method of a string object so far as I can tell? >> > Where did you read about it? >> >> >From "dive into python", >> >> http://diveintopython.org/ >> >> one example: >> >> def info(object, spacing=10, collapse=1): >>"""Print methods and docs strings. >> >>Take modules, class, list, dictionary, or strong.""" >>methodList = [e for e in dir(object) if callable(getattr(object, e))] >>processFunc = collapse and (lambda s: " ".join(s.split())) or (lambda >> s: s) >>print "\n".join(["%s %s" % >>(method.ljust(spacing), >>processFunc(str(getattr(object, method).__doc__))) >>for method in methodList]) >> >> if __name__ == "__main__": >>print info.__doc__ >> >> I felt so hard to understand the collapse, >> >> Please don't discourage me telling me it's an old book, >> To me I started reading till 42 pages. let me finish it. >> >> I used to study python on and off, >> sometimes give a whole week, but due to not using it, >> so >> it's frustrating that when I really needed it, I barely could complete >> one. >> > > Reading this, it seems that 'collapse' is a variable defined somewhere else > in the code. > > -- > André Engels, andreeng...@gmail.com > > > ___ > Tutor maillist - Tutor@python.org > To unsubscribe or change subscription options: > http://mail.python.org/mailman/listinfo/tutor > > collapse is a function that Mark must have described earlier in the chapter you are working on. Are you using the online version? which chapter -- Joel Goldstick ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] a quick Q: what does the "collapse" mean?
On Thu, Sep 8, 2011 at 10:48 AM, Joel Goldstick wrote: > > On Thu, Sep 8, 2011 at 10:36 AM, Andre Engels wrote: > >> On Thu, Sep 8, 2011 at 4:16 PM, lina wrote: >> >>> On Thu, Sep 8, 2011 at 9:59 PM, Alan Gauld >>> wrote: >>> > On 08/09/11 14:02, lina wrote: >>> >> >>> >> Hi, >>> >> >>> >> I failed to understand the "collpase" meaning in a string. >>> >> >>> >> can someone give me a simple example? >>> > >>> > Can you give us some context? >>> > Its not a method of a string object so far as I can tell? >>> > Where did you read about it? >>> >>> >From "dive into python", >>> >>> http://diveintopython.org/ >>> >>> one example: >>> >>> def info(object, spacing=10, collapse=1): >>>"""Print methods and docs strings. >>> >>>Take modules, class, list, dictionary, or strong.""" >>>methodList = [e for e in dir(object) if callable(getattr(object, e))] >>>processFunc = collapse and (lambda s: " ".join(s.split())) or (lambda >>> s: s) >>>print "\n".join(["%s %s" % >>>(method.ljust(spacing), >>>processFunc(str(getattr(object, method).__doc__))) >>>for method in methodList]) >>> >>> if __name__ == "__main__": >>>print info.__doc__ >>> >>> I felt so hard to understand the collapse, >>> >>> Please don't discourage me telling me it's an old book, >>> To me I started reading till 42 pages. let me finish it. >>> >>> I used to study python on and off, >>> sometimes give a whole week, but due to not using it, >>> so >>> it's frustrating that when I really needed it, I barely could complete >>> one. >>> >> >> Reading this, it seems that 'collapse' is a variable defined somewhere >> else in the code. >> >> -- >> André Engels, andreeng...@gmail.com >> >> >> ___ >> Tutor maillist - Tutor@python.org >> To unsubscribe or change subscription options: >> http://mail.python.org/mailman/listinfo/tutor >> >> collapse is a function that Mark must have described earlier in the > chapter you are working on. Are you using the online version? which chapter > > I spoke too soon. collapse is a boolean variable that you set if you want > to have the code in the lamda function collapse the text. If it is False > then the statement returns false instead of whatever is going on in the > Lambda > -- Joel Goldstick ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] a quick Q: what does the "collapse" mean?
lina wrote: one example: def info(object, spacing=10, collapse=1): """Print methods and docs strings. Take modules, class, list, dictionary, or strong.""" methodList = [e for e in dir(object) if callable(getattr(object, e))] processFunc = collapse and (lambda s: " ".join(s.split())) or (lambda s: s) print "\n".join(["%s %s" % (method.ljust(spacing), processFunc(str(getattr(object, method).__doc__))) for method in methodList]) In this example, "collapse" is used as the name of an argument which takes a true/false flag. If collapse is true, runs of whitespace is collapsed into a single space: "hello world" => "hello world" The above function would be much easier to understand if it was written like this: def info(object, spacing=10, collapse=1): """Print methods and docs strings. Take modules, class, list, dictionary, or string. """ method_names = [] doc_strings = [] for name in dir(object): attribute = getattr(object, name) if callable(attribute): method_names.append(name.ljust(spacing)) doc_strings.append(str(attribute.__doc__)) if collapse: doc_strings = [" ".join(doc.split()) for doc in doc_strings] parts = ["%s %s" % (n, d) for n,d in zip(method_names, doc_strings)] print "\n".join(parts) Much longer, but easier to follow for a beginner. -- Steven ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] a quick Q: what does the "collapse" mean?
<... ... > >> collapse is a function that Mark must have described earlier in the >> chapter you are working on. Are you using the online version? which chapter >> http://diveintopython.org/power_of_introspection/optional_arguments.html >> I spoke too soon. collapse is a boolean variable that you set if you want >> to have the code in the lamda function collapse the text. If it is False collapse the text means? destory the text? make it collapse? Thanks, >> then the statement returns false instead of whatever is going on in the >> Lambda > > > -- > Joel Goldstick > > > ___ > Tutor maillist - Tutor@python.org > To unsubscribe or change subscription options: > http://mail.python.org/mailman/listinfo/tutor > > -- Best Regards, lina ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] a quick Q: what does the "collapse" mean?
lina wrote: collapse the text means? destory the text? make it collapse? Collapse runs of spaces into a single space. -- Steven ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] a quick Q: what does the "collapse" mean?
On Thu, Sep 8, 2011 at 11:03 PM, Steven D'Aprano wrote: > lina wrote: > >> collapse the text means? destory the text? make it collapse? > > Collapse runs of spaces into a single space. That's what I want, thanks. ^_^ > > > > -- > Steven > ___ > Tutor maillist - Tutor@python.org > To unsubscribe or change subscription options: > http://mail.python.org/mailman/listinfo/tutor > -- Best Regards, lina ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] a quick Q: what does the "collapse" mean?
On Thu, Sep 8, 2011 at 8:08 AM, lina wrote: > On Thu, Sep 8, 2011 at 11:03 PM, Steven D'Aprano > wrote: > > lina wrote: > > > >> collapse the text means? destory the text? make it collapse? > > > > Collapse runs of spaces into a single space. > > That's what I want, thanks. ^_^ > Be aware that that meaning of "collapse" is not a standard Python term - it's just the word that the author chose to describe this function. ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] a quick Q: what does the "collapse" mean?
On Thu, Sep 8, 2011 at 11:17 PM, Marc Tompkins wrote: > On Thu, Sep 8, 2011 at 8:08 AM, lina wrote: >> >> On Thu, Sep 8, 2011 at 11:03 PM, Steven D'Aprano >> wrote: >> > lina wrote: >> > >> >> collapse the text means? destory the text? make it collapse? >> > >> > Collapse runs of spaces into a single space. >> >> That's what I want, thanks. ^_^ > > Be aware that that meaning of "collapse" is not a standard Python term - > it's just the word that the author chose to describe this function. Thanks for reminding. Sometimes it's not so easy to realize which part I should focus to understand well. > > ___ > Tutor maillist - Tutor@python.org > To unsubscribe or change subscription options: > http://mail.python.org/mailman/listinfo/tutor > > -- Best Regards, lina ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] a quick Q: what does the "collapse" mean?
Steven D'Aprano wrote: > lina wrote: > >> one example: >> >> def info(object, spacing=10, collapse=1): >> """Print methods and docs strings. >> >> Take modules, class, list, dictionary, or strong.""" >> methodList = [e for e in dir(object) if callable(getattr(object, e))] >> processFunc = collapse and (lambda s: " ".join(s.split())) or (lambda >> s: s) print "\n".join(["%s %s" % >> (method.ljust(spacing), >> processFunc(str(getattr(object, method).__doc__))) >> for method in methodList]) > > > In this example, "collapse" is used as the name of an argument which > takes a true/false flag. If collapse is true, runs of whitespace is > collapsed into a single space: > > "hello world" => "hello world" > > The above function would be much easier to understand if it was written > like this: > > def info(object, spacing=10, collapse=1): > """Print methods and docs strings. > > Take modules, class, list, dictionary, or string. > """ > method_names = [] > doc_strings = [] > for name in dir(object): > attribute = getattr(object, name) > if callable(attribute): > method_names.append(name.ljust(spacing)) > doc_strings.append(str(attribute.__doc__)) > if collapse: > doc_strings = [" ".join(doc.split()) for doc in doc_strings] > parts = ["%s %s" % (n, d) for n,d in zip(method_names, doc_strings)] > print "\n".join(parts) > > > > Much longer, but easier to follow for a beginner. Or even def info(object, spacing=10, collapse=True): for name in dir(object): attribute = getattr(object, name) if callable(attribute): doc = str(attribute.__doc__) if collapse: doc = " ".join(doc.split()) print name.ljust(spacing), doc ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] need advice about a dictionary ({})
On Thu, Sep 8, 2011 at 10:03 AM, Alan Gauld wrote:
> On 08/09/11 11:58, Richard D. Moores wrote:
>
>> I've succeeded in writing a dictionary ({}) that I can use as a small
>> personal phone book. The dictionary (very shortened and simplified)
>> looks like this in the script;
>>
>> p = {}
>>
>> p['bp1'] = 'xxx'
>> p['bp2'] = 'ooo'
>> p['ch'] = 'zzz'
>> p['me'] = 'aaa'
>> p['mg'] = 'vvv'
>> p['pu1'] = 'bbb'
>> p['pu2'] = 'ccc'
>> p['pw'] = 'kkk'
>>
>>
> You could have done that in one line if you preferred:
>
> > p = {
> 'bp1':'xxx',
> 'bp2':'ooo'
> etc/...
> 'pw':'kkk'
>
> }
>
>
> But I'd like to put the lines of the dictionary in a text file so that
>> I can add key/value items to it by writing to it with another script.
>>
>
> Consider using a shelve (See the shelve module)
> It is basically a file that you can treat as a dictionary...
>
> Try:
>
> >>> import shelve
> >>> help(shelve)
>
> For examples and info.
>
>
> --
> Alan G
> Author of the Learn to Program web site
> http://www.alan-g.me.uk/
>
>
> __**_
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>
Another option would be for you to use XML and base it off of a schema.
There's a really nifty tool called generate DS (just google it) that will
turn any valid schema into a python module.
I pasted an example schema that you might use here:
http://pastebin.com/AVgVGpgu
Once you install generateds, just cd to where it is installed and type:
python generateds.py -o pn.py PhoneNumber.xsd
This assumes you named the above schema as PhoneNumber.xsd
That will create a file called pn.py. For some reason it generated a bad
line on line 452, which I just commented out.
I then made a script in just a few lines to make a phonebook:
http://pastebin.com/h4JB0MkZ
This outputs XML that looks like this:
>
> aaa
>
> 1231231234
>
>
>
> bbb
>
> 1231231234
>
>
> 6789231234
>
>
>
> ccc
>
> 1231231234
>
>
>
> ddd
>
> 1231231234
>
>
>
The advantage is, you can immediately grab the generated xml and create
python instances using the build() method for further editing. You would of
course need to create a schema that fits your needs. Mine was just a quick
and dirty example of what you could do.
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[Tutor] Tkinter Entry field text
How do you display text in a Entry field and have it disappear when a
person clicks in it?
This is what I have so far:
from Tkinter import *
root = Tk()
root.title("Password Changer")
root.geometry("300x300+600+250")
label1 = Label(root, text="Enter you password: ")
label1.grid(sticky=W, row=0, column=0)
enter_data1 = Entry(root, bg = "pale green")
enter_data1.grid(row=0, column=1)
enter_data1.insert(0, "password")
root.mainloop()
To get text into this box the person must first delete what is already
in there.
Python 2.6.6
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[Tutor] Flat is better than Nested
Hello everyone,
I am still learning to program by writing this boxing game. I'm running into
a problem with how to organize data. My current setup looks something like
this:
"""This feels incredibly disgusting to me."""
self.behaviors = {
'offensive_combos': {
'combo1': {
1: { #time in seconds
'punch': {
'speed': 2,
'strength': 4,
'side': 'left'}
}
1.5: { #time in seconds
'punch': {
'speed': 4,
'strength': 8,
'side': 'right'}
}
}
}
}
By the time I write this all into a file, the end user will never even know
this crazy hierarchy exists, but I will, and I don't like it. Do I just need
to get over it and realize that sometimes nested is necessary, or is there a
better way I might consider?
Thanks for any help you can provide.
Best,
Ryan
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Re: [Tutor] Flat is better than Nested
Ryan Strunk wrote:
Hello everyone,
I am still learning to program by writing this boxing game. I'm running into
a problem with how to organize data. My current setup looks something like
this:
"""This feels incredibly disgusting to me."""
You might find it a little less disgusting with the application of some
helper classes and a slightly different data format.
Combos probably should be treated as a sequence of moves. For
simplicity, I'm going to assume each move takes the same time, and once
a combo is entered, the opponent can't interrupt it. You may want to
make it more complicated/realistic.
The hard part is deciding what fields you need. Here's my guess:
class Move:
def __init__(self, speed, strength, side, purpose, kind, foul=False):
self.speed = speed
self.strength = strength
self.side = side
self.purpose = purpose
self.kind = kind
self.foul = foul
CENTRE = NEUTRAL = ''
LEFT, RIGHT = 'left right'.split()
ATTACK, DEFENSE = 'attack defense'.split()
right_cross = Move(2, 3, RIGHT, ATTACK, 'punch')
left_lead = Move(3, 4, LEFT, ATTACK, 'punch')
left_jab = Move(1, 1, LEFT, ATTACK, 'punch')
headbutt = Move(1, 3, CENTRE, ATTACK, 'headbutt', True)
step_in = Move(2, 0, NEUTRAL, NEUTRAL, 'footwork')
weave = Move(1, 0, NEUTRAL, DEFENSE, 'footwork')
rabbit_punch = Move(1, 2, CENTRE, ATTACK, 'punch', True)
class Combo:
def __init__(self, *moves):
self.moves = moves
old_one_two = Combo(left_lead, right_cross)
liverpool_kiss = Combo(step_in, headbutt)
combos = {
1: old_one_two,
2: liverpool_kiss,
3: Combo(weave, weave, step_in, rabbit_punch),
4: Combo(left_jab, left_jab, left_jab, step_in, uppercut),
}
Does that help?
--
Steven
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