Re: [Tutor] Django Read

[Huy Ton That]

I've went through the djangobook myself, and found it quite readable. This
would be my recommendation as well.

Be sure to read the sidebar comments; if you ever feel stuck, someone else
may have addressed the question/answer for you!

-Lee

On Thu, Jul 8, 2010 at 9:31 AM, Jeff Johnson  wrote:

> On 07/08/2010 06:06 AM, Nick Raptis wrote:
>
>> There actually aren't that many books on django around yet which is a
>> pity.
>> You should definitely read "The django book":
>> http://www.djangobook.com/en/2.0/
>> either on the online version on that link, or it's printed counterpart
>> (yes, it's really the same book):
>> http://www.amazon.com/Definitive-Guide-Django-Development-Second/dp/143021936X/
>>
>> The printed one is a bit more updated (1.1) and pays off it's money
>> because of it's great reference section :)
>>
>> Nick
>>
>> On 07/08/2010 03:48 PM, Dipo Elegbede wrote:
>>
>>> Hi all,
>>>
>>> I have done a little basic on python and have to start working on a
>>> major django platform.
>>> I'm starting new and would like recommendations on books I can read.
>>>
>>> Kindly help me out. I want to get my hands dirty as fast as I can so
>>> that I can be part of the project.
>>>
>>> Thanks and Best regards,
>>>
>>>
>>  I have six books on my bookshelf for Django.  There are others I don't
> have.  Django 1.0 Template Development is my favorite.  Many of them walk
> you through building apps step by step.  Do a search on Amazon.  That is
> where I got most of them.
>
> --
> Jeff
>
> ---
>
> Jeff Johnson
> j...@dcsoftware.com
>
>
>
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[Tutor] Python Documentation Clarification

[Huy Ton That]

This is going to sound silly, but I realized there are some areas within the
documentation that do not make absolute sense to me.

e.g.

compile(source, filename, mode[, flags[, dont_inherit]])

I see within this built in function, the first argument can be what they
define as source, the second argument as the filename and the third as the
mode.

But what confuses me is sometimes I see a bracket, above as [, flags[,
dont_inherit]]. Is this an optional argument like flags=dont_inherit?

Just not grokking it correctly and I can't seem to track down where the
documentation formatting is defined within the python.org documentation...
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Re: [Tutor] Python Documentation Clarification

[Huy Ton That]

Proverbial Ah-ha moment all. This clarifies things greatly (:

Thanks you all!!

On Mon, Jul 12, 2010 at 11:29 AM, Nick Raptis  wrote:

>
>
>> compile(source, filename, mode[, flags[, dont_inherit]])
>>
>> I see within this built in function, the first argument can be what they
>> define as source, the second argument as the filename and the third as the
>> mode.
>>
>> But what confuses me is sometimes I see a bracket, above as [, flags[,
>> dont_inherit]]. Is this an optional argument like flags=dont_inherit?
>>
>>
>>  Brackets do indeed mean optional arguments.
> So you can do
> compile(source, filename, mode, flags=whatever, dont_inherit=True)
> or something.
>
> The nested brackets most likely show that (in your example), dont_inherit
> is optional, but can be used only if you (optionally) also provide the flags
> argument.
>
> Of course, don't take my word for it and read the rest of the description
> in the documentation.
>
> Also read here:
> 
> http://docs.python.org/reference/introduction.html?highlight=brackets#notation
>
> Nick
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Re: [Tutor] django help....

[Huy Ton That]

I highly recommend www.djangobook.com

The continuity is very good, and along the side of the book are comment
boxes with further insight from users.

After getting to about chapter 4, you should be able to toggle between
djangoproject.com's documentation and the rest of the djangobook for further
insight.

On Mon, Jul 26, 2010 at 9:03 AM, Dipo Elegbede wrote:

> hi,
>
> I am doing reading on django
>
> what ook would you recommend for a beginner?
>
> I have been trying to work with the documentations but get stock in between
> and totally become lost.
>
> this continous break is giving me too much headache to move on and i am
> getting discouraged.
>
> Please recommend a book for starters.
>
> Thanks.
>
> --
> Elegbede Muhammed Oladipupo
> OCA
> +2348077682428
> +2347042171716
> www.dudupay.com
> Mobile Banking Solutions | Transaction Processing | Enterprise Application
> Development
>
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Re: [Tutor] Problem with input() and unicode string

[Huy Ton That]

You can do:

input(unicode('Introduce el año:', 'latin-1').encode('latin-1'))

Maybe someone could explain it better than I can.

HTH,

Huy

On Wed, Jul 28, 2010 at 12:05 PM, Alex  wrote:

> Hello, I have a problem with this code:
>
> # -*- coding: latin-1 -*-
> year = u'año, ò, ó, ç'
> print year
> year = input(u'Introduce el año:')
> print year
> raw_input()
>
> The first print statement works as expected, both in IDLE and when
> double-clicking the file for a console view.
> The second one works in IDLE, but just flashes by when double-clicking the
> file, due to an error report I can't see.
> I believe the problem is that input prompt doesn't support unicode strings,
> which means I can't use my language for prompts?
> Could someone please tell me how to fix it or provide a workaround?
> Thanx.
>
> Using Python 2.7 under win32.
>
>
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[Tutor] Where to start with Unit Testing

[Huy Ton That]

Hi all,

Do any of you have any feedback, strategies and best practices related to
unit testing within Python. This is a relatively new topic for me. I was
thinking of starting with reading the documentation associate with the
unittest module.

-Huy
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Re: [Tutor] Where to start with Unit Testing

[Huy Ton That]

All these responses are incredible, I will go through them on my venture to
bring unit testing under my belt.

I have never done formal unit testing in my programming career, I've just
gone through way of general debugging and utilizing version control such as
Mercurial.

On Sun, Aug 1, 2010 at 9:42 PM, David Hutto  wrote:

> On Sun, Aug 1, 2010 at 9:39 PM, David Hutto  wrote:
> > On Sun, Aug 1, 2010 at 9:31 PM, David Hutto 
> wrote:
> >> On Sun, Aug 1, 2010 at 9:11 PM, Che M  wrote:
> >>>
> >>>
>  > The idea of unit testing/test driven development has remained
>  > foreign to me throughout my time trying to learn Python--by choice.
>  > I want to make desktop GUI applications and I don't use MVC, so
>  > the idea of writing tests strikes me as far more work--and a major
>  > delayer of getting to an application that actually does something--
>  > than simply using the software myself and noting problems.  It
>  > sounds like TDD is probably the most proper way to go about things,
>  > but, in the interest of getting something out of Python to warrant
> the
>  > time I've put into it, I favor a "good enough" approach for now.
> 
>  Writers just call this a rough draft. Perfection is in the revisions
>  that come after a little thought.
> >>>
> >>> Well, I don't see what I'm doing as a rough draft, as I am attempting
> >>> to hone it to "perfection" (that is, a working app)--just without unit
> >>> testing.
> >>
> >> Every time you try to perfect is a revision of your initial 'written'
> >> algorithm. From concept forward is your revisions. Notice that svn and
> >> cvs are called revisions. How quickly is a different story. To you,
> >> your writing and rewriting, but each rewrite is a revision of the
> >> initial concept. And as far as i can tell, if you want to be the unit
> >> test yourself, it's fine, but unit testing might be inappropriate for
> >> something like this. But basically unit testing would be a script that
> >> inputs the possible combinations of requests to the original script,
> >> which should be tested like chefs do soups-intermittently as you
> >> design it. So the tests are really what you put or type as input given
> >> directly to the script , right?.
> >>
> >>
> >>
> >>>
> >>> A different analogy comes to my mind; I once saw two different sets of
> >>> people analyze data.  One did it "by hand":  visually inspecting
> thousands
> >>> of signals herself and typing Y or N to accept or reject each signal.
> The
> >>> other did it with an automated system that accepted or rejected signals
> >>> based on fuzzy logic.
> >>
> >> This depends on your need for control, do you need to manually accept,
> >> or can you just detect the signal, and let the program proceedl. Do
> >> you want the local nuclear plant to have their system throw an error,
> >> without a human response?
> >>
> >> In an important interpretation, the automated system
> >>> was far better, and yet the first scientist was done with her analysis
> and
> >>> accepted for publication before the second team even had the bugs
> worked
> >>> out of the automated system!
> >>
> >> Like you state below, the automated system used, evolved from manually
> >> designed systems, so automation is the easy way, but sometimes not the
> >> best, depending on the circumstance and priority level of the
> >> information being received.
> >>
> >> Yes, I think the slow-but-more-proper team
> >>> did the more correct thing, but there is something to be said for "good
> >>> enough", too (it works for evolution, for example).
> >>
> >>
> >>>
> >>>
> >>>
> >>>
> >>> ___
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> >>>
> >>
> >
> > Disclaimer: I have no clue what unit testing is, nor have I had to use it
> yet.
> >
>
> But it would be a series of function instances from a module, right?
> Not to butt in on the OP.
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Re: [Tutor] Where to start with Unit Testing

[Huy Ton That]

Thanks additionally for your insight gems.

Without reading too much into it, it was quite simple to create a series of
test classes which just run some expected assertion values on a small
scenario of inputs and what's expected.

I usually find that I learn best by dabbling around in source code, then
writing some code to test what I think I know.

I'll try to integrate this and commit this to memory with time where I won't
have to look back as much (:


On Sun, Aug 1, 2010 at 9:25 AM, Mac Ryan  wrote:

> On Sun, 2010-08-01 at 03:30 -0400, Huy Ton That wrote:
> > Hi all,
> >
> > Do any of you have any feedback, strategies and best practices related
> > to unit testing within Python. This is a relatively new topic for me.
> > I was thinking of starting with reading the documentation associate
> > with the unittest module.
>
> My answer falls in the category "feedback" (I was also going to mention
> the diveintopython page, but somebody else has done that already!), so
> you should be aware what follows is highly subjective...
>
> JUST THINK... IN PYTHON!
>   IMO, unit testing is really easy to pick up. It really does not
> amount to much more than taking note (in python) of what you are
> thinking when you are coding.
>   If you are anything like me, when you code you keep on formulating
> "rules" in your head, in the line of "when everything works as expected,
> if the methods iterates four times, then this method must return X" or
> "when everything works as expected, if a user enter a value over 212
> then the script must throw this exception", etc...
>   * the "when everything works as expected" translates in "this test
> pass when..."
>   * the "if X" translates in your test case (i.e. the scenario you are
> testing for)
>  * the "then Y" translates in "the outcome of my test case must be Y"
>
> TESTING IS VALUABLE IN THE LONG RUN
>   At times, designing and coding a test is a time-consuming activity,
> and if the code is particularly straightforward you might be tempted to
> skip the unit testing altogether. In my experience - however - unit
> testing is never as useful on the spot as it is three months from now,
> when you will have/want/choose to modify a little bit of your old code,
> and all of a sudden everything will break. In the latter scenario, your
> test suite will be an invaluable asset.
>
> FUNCTIONAL PROGRAMMING WINS
>   The most difficult thing in writing a test, is replicating the state
> of the environment needed for the test to happen. This is especially
> (but not uniquely) true for DB-driven applications, when you might wish
> to perform test on methods that interact with the DB. In that case you
> have to create a test DB, populate it with ~credible data, etc...
>   The most "functional" (as in functional programming, i.e.
> machine-state independent) is your code, the easiest is to write a test.
> Example: if you need to check a method that validate the postal code of
> an address based on the name of the city, it is easier to test a method
> that is invoked with "validate_postal_code(code, city)" rather than one
> that is invoked with "validate_postal_address(user)" and that will have
> to retrieve the full address of a user from a DB, and extract the city
> and postal address from it.
>
> MVC WINS
>   I never test UI's. I know it is bad... but it is simply too
> time-consuming for me (I'll be very glad if somebody reading this will
> show me how one can make it snappier!). This means - at least for me -
> that writing tests become extremely easier for me if I keep separated
> the presentation layer from all the rest of the stuff.
>
> EVERY BUG IS A TEST YET NOT WRITTEN
>   A program that passes all its tests is not necessarily a bug-free
> program. But once you find a new bug, try to make a point of writing a
> new test that check for that particular scenario in which said bug is
> happening.
>
> TEST-DRIVEN IS BETTER
>   What I find useful (although not always applicable) is to start my
> programming session by writing the tests before I write the code to be
> tested. This somehow reconnect to my previously articulated "just
> think... in python!" point: you are however *already doing a list of
> rules* in your head, before writing code, so you could well write it
> down directly in code. All you need is to create a mock method/function
> in your code with the same signature you are using in your test. For
> example. You could write tests in the form:
>
>assertEqual(better_square_root(9), 3)
>assertRaises(ValueError, better_square_root, -4)
>
> an

Re: [Tutor] Where to start with Unit Testing

[Huy Ton That]

One final note, that I thought might be useful to others.

I've just discovered doctest, which allows you to run tests on your embedded
function/class documentation.

Check it out here:
http://docs.python.org/tutorial/stdlib.html#quality-control

On Sun, Aug 1, 2010 at 3:30 AM, Huy Ton That  wrote:

> Hi all,
>
> Do any of you have any feedback, strategies and best practices related to
> unit testing within Python. This is a relatively new topic for me. I was
> thinking of starting with reading the documentation associate with the
> unittest module.
>
> -Huy
>
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Re: [Tutor] how to get str() to use my function?

[Huy Ton That]

You could write __str__ function

>>> class card(object):
... def __init__(self, card1, card2):
... self.card1, self.card2 = card1, card2
... def __str__(self):
... return str(str(self.card1)+','+str(self.card2))
...
>>> a = card(0,0)
>>> str(a)
'0,0'

On Wed, Aug 4, 2010 at 10:37 AM, Alex Hall  wrote:

> Hi all,
> I have a card class. A card object simply consists of a pair of
> numbers; 0,0 might be the ace of clubs, for example. I have a toString
> method in my card class. Is there a way to just say str(card) instead
> of card.toString()? Maybe some sort of basic, built-in function to
> override? TIA. Oh, what about doing the same with operators? For
> example, could I get the program to call my own math functions when it
> sees a card object in a math expression, like
> if(card1==card2)
>
> --
> Have a great day,
> Alex (msg sent from GMail website)
> mehg...@gmail.com; http://www.facebook.com/mehgcap
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Re: [Tutor] how to get str() to use my function?

[Huy Ton That]

These are special method names.

View section 3.4 and below here

http://docs.python.org/reference/datamodel.html

On Wed, Aug 4, 2010 at 11:37 AM, Alex Hall  wrote:

> It worked, thanks. Is there a list of these functions somewhere? That
> is, the functions that map implicitly to operators or implied uses?
> For example, printing will call __str__, as will a cal to str(). What
> about math or comparison operators? I have heard of __eq__, __gt__,
> and so on, but I tried to implement one and I got an error saying that
> it required three arguments. It did, but only because the first was
> self. I put the function inside my card class:
>  def __eq__(self, card1, card2):
>  return(card1.rank==card2.rank)
>  #end def __eq__
> For some reason it is still looking for three arguments...
>
>
> On 8/4/10, Huy Ton That  wrote:
> > You could write __str__ function
> >
> >>>> class card(object):
> > ... def __init__(self, card1, card2):
> > ... self.card1, self.card2 = card1, card2
> > ... def __str__(self):
> > ... return str(str(self.card1)+','+str(self.card2))
> > ...
> >>>> a = card(0,0)
> >>>> str(a)
> > '0,0'
> >
> > On Wed, Aug 4, 2010 at 10:37 AM, Alex Hall  wrote:
> >
> >> Hi all,
> >> I have a card class. A card object simply consists of a pair of
> >> numbers; 0,0 might be the ace of clubs, for example. I have a toString
> >> method in my card class. Is there a way to just say str(card) instead
> >> of card.toString()? Maybe some sort of basic, built-in function to
> >> override? TIA. Oh, what about doing the same with operators? For
> >> example, could I get the program to call my own math functions when it
> >> sees a card object in a math expression, like
> >> if(card1==card2)
> >>
> >> --
> >> Have a great day,
> >> Alex (msg sent from GMail website)
> >> mehg...@gmail.com; http://www.facebook.com/mehgcap
> >> ___
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> >>
> >
>
>
> --
> Have a great day,
> Alex (msg sent from GMail website)
> mehg...@gmail.com; http://www.facebook.com/mehgcap
>
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Re: [Tutor] getattr()

[Huy Ton That]

*You can do like below Pete. Where globals has a reference to all
functions in this space.*

def output(data, format="text"):

output_function = getattr(globals()['FUNCTION'], "output_%s" %
format, statsout.output_text)
return output_function(data)


On Wed, Aug 4, 2010 at 3:18 PM, Pete  wrote:

> Hey Huy,
>
> thanks. But what is the first parameter in this case? (Note there is
> nothing here I'm trying to accomplish except understand).
>
> In the original example, 'statsout' is the name of the module. In this case
> there is no module so why can you substitute 'output_text'?
>
> thanks,
>
> Pete
>
> On 2010-08-04, at 3:09 PM, Huy Ton That wrote:
>
> If it is in the same code, and the namespace isn't a module or another
> class you could do this:
>
> def output_text(data):
> return_value = "This is text: " + data
> return return_value
>
> def output(data, format="text"):
> output_function = getattr(output_text, "output_%s" % format,
> output_text)
> return output_function(data)
>
> -HTH
>
> Huy
>
> On Wed, Aug 4, 2010 at 1:23 PM, Pete  wrote:
>
>> Hi,
>>
>> I'm trying to understand the syntax for reflection in python. I was
>> wondering about this.
>>
>> From the example on diveintopython:
>>
>>http://diveintopython.org/power_of_introspection/index.html
>>
>> import statsout
>> def output(data, format="text"):
>> output_function = getattr(statsout, "output_%s" % format, 
>> statsout.output_text)
>> return output_function(data)
>>
>>
>> I was wondering about how to make this work if the function that you are
>> trying to call is not in a module. Is that possible?
>>
>> Something like this:
>>
>>  def output_text(data):
>>
>>
>> return_value = "This is text: " + data
>> return return_value
>>
>>
>> def output(data, format="text"):
>> output_function = getattr(*, "output_%s" % format, 
>> statsout.output_text)
>> return output_function(data)
>>
>>
>> What I can't figure out is what to put in place of *. I've tried
>> globals()['__name__'], in various forms, to no avail.
>>
>> Any pointers would be appreciated.
>>
>> thanks,
>>
>> Pete
>>
>>
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Re: [Tutor] getattr()

[Huy Ton That]

Oh, that's right, I should have tried to example in the interpreter instead
of in my head:P

Say Bob,

Is that the preferred method over something like:

>>> import __main__ as main

On Wed, Aug 4, 2010 at 3:32 PM, bob gailer  wrote:

>  On 8/4/2010 1:23 PM, Pete wrote:
>
> Hi,
>
>  I'm trying to understand the syntax for reflection in python. I was
> wondering about this.
>
>  From the example on diveintopython:
>
> http://diveintopython.org/power_of_introspection/index.html
>
>  import statsout
> def output(data, format="text"):
> output_function = getattr(statsout, "output_%s" % format, 
> statsout.output_text)
> return output_function(data)
>
>I was wondering about how to make this work if the function that you
> are trying to call is not in a module.
>
>
> Everything in Python is in a module. I suspect you mean not in an imported
> module, e.g. in the main module. Whose __name__ is '__main__'. A reference
> to the main module can be found:
>
> import sys
> main = sys.modules['__main__']
>
>  Is that possible?
>
>  Something like this:
>
>  def output_text(data):
>
> return_value = "This is text: " + data
> return return_value
>
>   def output(data, format="text"):
> output_function = getattr(*, "output_%s" % format, 
> statsout.output_text)
> return output_function(data)
>
>
>  What I can't figure out is what to put in place of *. I've tried
> globals()['__name__'], in various forms, to no avail.
>
>
> Replace those stars with main as derived above.
>
> globals()['output_text'] will also give you a reference to the function.
>
> --
> Bob Gailer
> 919-636-4239
> Chapel Hill NC
>
>
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Re: [Tutor] getattr()

[Huy Ton That]

I have a side question,

I am using python 2.7.

Why do you use class A: instead of class A(object): ?

-Huy

On Wed, Aug 4, 2010 at 4:08 PM, bob gailer  wrote:

> On 8/4/2010 4:04 PM, bob gailer wrote:
>
>> On 8/4/2010 3:44 PM, Huy Ton That wrote:
>>
>>> Oh, that's right, I should have tried to example in the interpreter
>>> instead of in my head:P
>>>
>>> Say Bob,
>>>
>>> Is that the preferred method over something like:
>>>
>>
>> I would prefer to create a class and make these functions class methods.
>>
>> class A:
>>  def output_text(self, data):return data
>>  def output_hex(self, data):return '\\x' + data
>>  def __getattr__(self, name):
>>return self.output_text
>> a = A()
>> data='bar'
>> print a.output_text(data)
>> print a.output_hex(data)
>> print a.foo(data)
>>
>>  I just realized my answer does not accomodate your looking for the
> function by name. Please stand by
>
>
> --
> Bob Gailer
> 919-636-4239
> Chapel Hill NC
>
>
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Re: [Tutor] string to list

[Huy Ton That]

Speaking of which, is there some place you or anyone can recommend on
picking up all the constructs for list comprehension & generator
comprehension. I've perused the python.org documents and have just been
building them according to example.

How can I pick up more advanced usage?

I mostly catch myself using it to return a list of functions like:

>>> class foo(object):
... def __init__(self, bar):
... self.bar = bar
...
>>> [(foo(i)) for i in range(0,10)]
[<__main__.foo object at 0x00C54FD0>, <__main__.foo object at 0x00C54FF0>,
<__ma
in__.foo object at 0x00C54F50>, <__main__.foo object at 0x00C54F30>,
<__main__.f
oo object at 0x00C59050>, <__main__.foo object at 0x00C59070>, <__main__.foo
obj
ect at 0x00C590B0>, <__main__.foo object at 0x00C590D0>, <__main__.foo
object at
 0x00C59110>, <__main__.foo object at 0x00C59130>]

On Thu, Aug 5, 2010 at 3:25 AM, James Mills wrote:

> On Thu, Aug 5, 2010 at 2:38 PM, Vikram K  wrote:
> > Suppose i have this string:
> > z = 'AT/CG'
> >
> > How do i get this list:
> >
> > zlist = ['A','T/C','G']
>
> >>> import re
> >>> z = 'AT/CG'
> >>> [x for x in re.split("([A-Z]\/[A-Z])|([A-Z])", z) if x]
> ['A', 'T/C', 'G']
> >>>
>
> cheers
> James
>
> --
> -- James Mills
> --
> -- "Problems are solved by method"
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Re: [Tutor] Question about Dictionaries

[Huy Ton That]

What do you mean by subclass?

On Aug 16, 2010 3:26 PM, "Emile van Sebille"  wrote:

On 8/16/2010 10:44 AM Chorn, Guillaume said...


>
> Hi All,
>
> I know that I can look up the value for a particular key in a
> dictionary, but can...
Yes.  But you'll need to implement it.  There are likely modules out there
that'll do this, but it'd take more time to look up and evaluate than to
simply write and implement exactly what you need.



> I understand that this could be problematic from the standpoint
> of multiple keys having the sa...
So, in untested code you'd have a function something like:

result = []

for ky, val in dict.items():
 if val == targetval:
 result.append(ky)
return result

If you need repeated access such that iterating over a large dict frequently
impacts performance, you could subclass dict and maintain a second index
allowing instant access to the keys associated with a specific value.

HTH,

Emile



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[Tutor] classmethod, staticmethod functions (decorator related)

[Huy Ton That]

I am reading the decorator section within Expert Python Programming and I am
very confused in the first example, of a method that was done before
decorators. It reads:

class WhatFor(object):
def it(cls):
print 'work with %s' % cls
it = classmethod(it)
def uncommon():
print 'I could be a global function'
uncommon = staticmethod(uncommon)

But I can't seem to understand the above. Under what circumstance would
staticmethod be useful? I am just deriving that you are not passing self.
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Re: [Tutor] classmethod, staticmethod functions (decorator related)

[Huy Ton That]

Hm, thanks guys; I just had to verify I was thinking sanely about it. I am
going to pick up classmethods next. Do any of you have common design
patterns for the usage. They are just items I haven't integrated in my
coding, and I want to be certain I'm off on the right foot (:


On Sun, Sep 12, 2010 at 9:01 PM, Alan Gauld wrote:

> "Steven D'Aprano"  wrote
>
>
>  A little more information... static methods are quite common[1] in Java
>> and C++, where people feel the need (or in the case of Java, are forced
>> by the language) to make every function a method.
>>
>
> static methods in C++ are normally reserved for use as class
> methods (although with the "pollution" from Java that is slowly
> changing). Java OTOH has made them much more common but
> as substitutes for functions as well as true class methods - yeck!
>
> They are also found in a slightly different guise in Delphi.
>
> Python classmethods are more powerful and useful than either.
>
> Alan G.
>
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Re: [Tutor] classmethod, staticmethod functions (decorator related)

[Huy Ton That]

Thank you all,

I was taking a look at the module decimal.py as you cited, and it makes
sense now. Looks very useful to make tools without having to instantiate
anything.

On Mon, Sep 13, 2010 at 7:05 AM, Steven D'Aprano wrote:

> On Mon, 13 Sep 2010 12:29:07 pm Huy Ton That wrote:
> > Hm, thanks guys; I just had to verify I was thinking sanely about it.
> > I am going to pick up classmethods next. Do any of you have common
> > design patterns for the usage. They are just items I haven't
> > integrated in my coding, and I want to be certain I'm off on the
> > right foot (:
>
> The most common use for classmethods is to implement alternative
> constructors. For example, in the Decimal class starting in version 2.7
> and 3.1, you have two constructors:
>
> >>> from decimal import Decimal
> >>> Decimal("1.2345")
> Decimal('1.2345')
> >>> Decimal.from_float(1.2345)
> Decimal('1.2344307220832633902318775653839111328125')
>
> from_float is a class method.
>
>
> --
> Steven D'Aprano
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