[Tutor] Still Trying to Understand GAE
Hi All, i've started earning python sone months ago (on Google App Engine unfortunately). I have some doubts reagrding "import", and have asked a similar question here months ago, but without finding a solution. So: with import i can import modules or single functions. And this is ok. Then: as i have understood from all the books i readm in each package directory i have the __init__.py file that decides what import with it. In other words if my package skel is like: /gg/ /gg/sub1/ /gg/sub1/file.py /gg/sub2/ /gg/sub2/file.py and i use "import gg", nothing is imported. To import sub1 and sub2, i can: - Put in /gg/ a __init__.py file that tells to import them - Use "from gg import sub1" Ok now the $1 Billion question: google app engine has the same schema than my "gg" package, an empty __init__.py file, but if i use "import google" it also imports all subdirectories. And i can't understand wiìhy it does so. Can you help me? Thankyou Giorgio ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] Still Trying to Understand GAE
Hi Wesley! Thankyou very much for your mail (and i'd like to thankyou in a special way for your corrections :) ). > it imports all sub*packages*. don't think directories because the > import mechanism doesn't work this way. this is likely because there > are __init__.py files in those subdirectories. another possibility is > that there are non-empty __init__.py files that do the imports of > things that you're not expecting. Ok, i've checked all those files, because in a standard python evinronment the __init__.py is the only file that can decide what to import. If you want to check directly, here you can find the SDK. Just open the "google" directory. http://googleappengine.googlecode.com/files/google_appengine_1.2.5.zip As i've said, this simple script: --- #!/usr/bin/python import google print "Content-Type: text/html" print "" print "" print "" print "" print "google",dir(google) print "" print "" print "" --- Gives this output: "google ['__builtins__', '__doc__', '__file__', '__name__', '__package__', '__path__', 'appengine', 'net', 'pyglib']" The "google" directoy has an empty __init__.py file (well, if we want to be completely correct it contains some commented -#- lines). Same for "appengine", "net" and "pyglib". As they all have an __init__.py file, they should be consiedered as modules from the python interpreter. So, if i run "import google" it imports all google's submodules. Well, now, the problem: if i create another directory (module) in the google dir, it doesn't get imported. Of course i've put in it some .py files and an empty __init__.py file. Thankyou again! Giorgio 2009/9/13 wesley chun : > hi Giorgio, > > welcome to Python (whether directly or from GAE!) :-) my comments below. > > >> with import i can import modules or single functions. And this is ok. > > not quite true. regardless of whether you use import or from-import, > you're *always* importing (and loading) modules or packages in their > entirety. > > now, whether you have *access* to "entire" modules/packages or > individual attributes (functions, classes, or standard data), is > another matter -- usually this is a result of using from-import. > > also, the difference between importing and loading is that loading > only happens the first time you import a module/package. (if you do it > more than once, e.g., module A imports B and C and module B also > imports C, the import of C happens twice but the loading happens only > once. > > >> if i use "import >> google" it also imports all subdirectories. And i can't understand >> wiìhy it does so. > > it imports all sub*packages*. don't think directories because the > import mechanism doesn't work this way. this is likely because there > are __init__.py files in those subdirectories. another possibility is > that there are non-empty __init__.py files that do the imports of > things that you're not expecting. > > hope this helps! > -- wesley > - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - > "Core Python Programming", Prentice Hall, (c)2007,2001 > "Python Fundamentals", Prentice Hall, (c)2009 > http://corepython.com > > wesley.j.chun :: wescpy-at-gmail.com > python training and technical consulting > cyberweb.consulting : silicon valley, ca > http://cyberwebconsulting.com > ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] Still Trying to Understand GAE
Thankyou all, you're very precious for me. yeah it seems the development webserver (and the production one) are importing modules in a non-standard way. I absolutely don't understand this choice. Why import everything everytime? Don't you think it makes scripts much more slow? Giorgio 2009/9/16 Kent Johnson : > On Sun, Sep 13, 2009 at 9:59 AM, ad...@gg-lab.net wrote: >> Hi All, >> >> i've started earning python sone months ago (on Google App Engine >> unfortunately). >> >> I have some doubts reagrding "import", and have asked a similar >> question here months ago, but without finding a solution. >> >> So: >> >> with import i can import modules or single functions. And this is ok. >> Then: as i have understood from all the books i readm in each package >> directory i have the __init__.py file that decides what import with >> it. In other words if my package skel is like: >> >> /gg/ >> /gg/sub1/ >> /gg/sub1/file.py >> /gg/sub2/ >> /gg/sub2/file.py >> >> and i use "import gg", nothing is imported. To import sub1 and sub2, i can: >> >> - Put in /gg/ a __init__.py file that tells to import them >> - Use "from gg import sub1" >> >> Ok now the $1 Billion question: google app engine has the same schema >> than my "gg" package, an empty __init__.py file, but if i use "import >> google" it also imports all subdirectories. And i can't understand >> wiìhy it does so. > > In general, > import foo > does not import subpackages of foo unless they are specifically > imported in foo/__init__.py, so dir(foo) will not show the > subpackages. > > However if you > import foo > import foo.bar > then dir(foo) will include 'bar'. Here is an example from the std lib: > > In [1]: import distutils > > In [2]: dir(distutils) > Out[2]: > ['__builtins__', > '__doc__', > '__file__', > '__name__', > '__package__', > '__path__', > '__revision__', > '__version__'] > > In [3]: import distutils.cmd > > In [4]: dir(distutils) > Out[4]: > ['__builtins__', > '__doc__', > '__file__', > '__name__', > '__package__', > '__path__', > '__revision__', > '__version__', > 'archive_util', > 'cmd', > 'dep_util', > 'dir_util', > 'errors', > 'file_util', > 'log', > 'spawn', > 'util'] > > My guess is that the startup for GAE is importing the subpackages so > they then appear as imported modules. To access your sub-package, just > import it normally. > > Kent > ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] Still Trying to Understand GAE
Yes Kent, i'm not worrying about it, i was just trying to find the reason why they're doing so. Anyway, i'm a newbye, but the GAE Evinronment is very very difficult to understand. The only thing is thas in common with the real python is the sintax. Thankyou again 2009/9/17 Kent Johnson : > On Thu, Sep 17, 2009 at 8:38 AM, ad...@gg-lab.net wrote: >> Thankyou all, you're very precious for me. >> >> yeah it seems the development webserver (and the production one) are >> importing modules in a non-standard way. >> >> I absolutely don't understand this choice. Why import everything >> everytime? Don't you think it makes scripts much more slow? > > My guess is that they are importing what they need. It does impact > startup but hey, if you need it, you need it. > > Try this for comparison: Start Python from a command line, then > In [5]: import sys > > In [6]: len(sys.modules) > Out[6]: 323 > > I have IPython loaded so this number may be larger than yours. In > Python 3, with no IPython, I get >>>> import sys >>>> len(sys.modules) > 47 > > So my advice is, don't worry about it. > > Kent > ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
[Tutor] Determine Filetype
Hi, i'm putting file in a DB as BLOB entries. To serve them, i need to take Content-Type headers. So, i'm looking for a function that returnes the filetype, given a data str. I've found many other topics like this in python mail-archive, but any of them contains the solution. Can you help me, please? Thankyou! ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] Determine Filetype
Hi Emile,
that functions requires a filename/path. Just like this one (for images)
http://docs.python.org/library/imghdr.html
Ok, i don't have a filename. I get the file from a BLOB in a db. Any idea?
Thankyou for your precious help.
2009/9/18 Emile van Sebille :
> On 9/18/2009 10:05 AM ad...@gg-lab.net said...
>>
>> Hi,
>>
>> i'm putting file in a DB as BLOB entries. To serve them, i need to
>> take Content-Type headers.
>>
>> So, i'm looking for a function that returnes the filetype, given a data
>> str.
>>
>> I've found many other topics like this in python mail-archive, but any
>> of them contains the solution.
>>
>> Can you help me, please?
>
> I'd take a look at python-magic at
> http://hupp.org/adam/hg/python-magic/file/d3cd83e5a773 where the example
> shows that you can do:
>
> # For MIME types
>>>> mime = magic.Magic(mime=True)
>>>> mime.from_file("testdata/test.pdf")
> 'application/pdf'
>
>
> HTH,
>
> Emile
>
>
>
>
>
>>
>> Thankyou!
>> ___
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Re: [Tutor] Determine Filetype
Oh, i'm sorry.
I've read the README, but haven't noticed that
m.from_buffer(open("testdata/test.pdf").read(1024))
was exactly what i was looking for.
Ok, i'll try it and let you know :D
2009/9/18 Kent Johnson :
> On Fri, Sep 18, 2009 at 2:21 PM, ad...@gg-lab.net wrote:
>> Hi Emile,
>>
>> that functions requires a filename/path.
>
> Did you even look at the link? There is a from_buffer() method also.
>
> Kent
>
>> 2009/9/18 Emile van Sebille :
>
>>> I'd take a look at python-magic at
>>> http://hupp.org/adam/hg/python-magic/file/d3cd83e5a773 where the example
>>> shows that you can do:
>>>
>>> # For MIME types
>>>>>> mime = magic.Magic(mime=True)
>>>>>> mime.from_file("testdata/test.pdf")
>>> 'application/pdf'
>
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Re: [Tutor] Determine Filetype
Ok, a good news for me:
i've modified my script, adding a:
import magic
line at the top of it. But I got this error:
No module named magic
Ok, so magic is not installed on GAE. I've then uploaded it and it
loaded succesfully. New error:
No module named _ctypes
And, reading the full debug i got this:
File "/base/python_dist/lib/python2.5/ctypes/__init__.py", line 10, in
from _ctypes import Union, Structure, Array
So, the __init__.py file of the GAE evinronment's ctypes library is
broken, as it's importing from a package that doesn't exist. Right?
Maybe i'm doing something wrong.
Thankyou
2009/9/18 ad...@gg-lab.net :
> Oh, i'm sorry.
>
> I've read the README, but haven't noticed that
>
> m.from_buffer(open("testdata/test.pdf").read(1024))
>
> was exactly what i was looking for.
>
> Ok, i'll try it and let you know :D
>
> 2009/9/18 Kent Johnson :
>> On Fri, Sep 18, 2009 at 2:21 PM, ad...@gg-lab.net wrote:
>>> Hi Emile,
>>>
>>> that functions requires a filename/path.
>>
>> Did you even look at the link? There is a from_buffer() method also.
>>
>> Kent
>>
>>> 2009/9/18 Emile van Sebille :
>>
>>>> I'd take a look at python-magic at
>>>> http://hupp.org/adam/hg/python-magic/file/d3cd83e5a773 where the example
>>>> shows that you can do:
>>>>
>>>> # For MIME types
>>>>>>> mime = magic.Magic(mime=True)
>>>>>>> mime.from_file("testdata/test.pdf")
>>>> 'application/pdf'
>>
>
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Re: [Tutor] Determine Filetype
Hi All,
the solution was in the link i've posted before. If i use:
type = imghdr.what('img.test', image.data)
The imghdr modules ignore the filename (first argument) and takes the
second as a data stream assumed to contain the filetype.
The solution only works for images, but that's what i need. I think
that right now is not possible to generally determine the mimetype for
all types of files on GAE, because some libraries are missing. Anyway,
i'll send a mail to the gae mailing list, and if find a solution i'll
post it here.
Thankyou all guys.
2009/9/19 Sander Sweers :
> On Fri, 2009-09-18 at 16:48 -0400, Kent Johnson wrote:
>> > So, the __init__.py file of the GAE evinronment's ctypes library is
>> > broken, as it's importing from a package that doesn't exist. Right?
>>
>> Probably ctypes is not supported in GAE, that would be a pretty big
>> security hole.
>
> There is a pure python implementation on pypi [1]. It states it is in
> alpha and missing some features. Never used it myself though...
>
> Greets
> Sander
>
> [1] http://pypi.python.org/pypi/pymagic/0.1
>
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Re: [Tutor] Determine Filetype
Ops, i have another question, it seems very simple.
I want to check the extension of an uploaded file. So i've created a
list with allowed extensions:
enabled_ext = ['gif', 'jpeg', 'png', 'bmp', 'tiff']
How can i create a simple if that check if the file ext (file_ext) is
in the list?
I've searched in the python tutorial, but have not been able to find
any example that uses an if statement combined with a list.
Thankyou again
2009/9/19 ad...@gg-lab.net :
> Hi All,
>
> the solution was in the link i've posted before. If i use:
>
> type = imghdr.what('img.test', image.data)
>
> The imghdr modules ignore the filename (first argument) and takes the
> second as a data stream assumed to contain the filetype.
>
> The solution only works for images, but that's what i need. I think
> that right now is not possible to generally determine the mimetype for
> all types of files on GAE, because some libraries are missing. Anyway,
> i'll send a mail to the gae mailing list, and if find a solution i'll
> post it here.
>
> Thankyou all guys.
>
> 2009/9/19 Sander Sweers :
>> On Fri, 2009-09-18 at 16:48 -0400, Kent Johnson wrote:
>>> > So, the __init__.py file of the GAE evinronment's ctypes library is
>>> > broken, as it's importing from a package that doesn't exist. Right?
>>>
>>> Probably ctypes is not supported in GAE, that would be a pretty big
>>> security hole.
>>
>> There is a pure python implementation on pypi [1]. It states it is in
>> alpha and missing some features. Never used it myself though...
>>
>> Greets
>> Sander
>>
>> [1] http://pypi.python.org/pypi/pymagic/0.1
>>
>> ___
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Re: [Tutor] Determine Filetype
if file_ext in enabled_ext
Found an example some seconds ago in another mailing lists. I'm not
able to find the python tutorial that describes this statement. Can
you help me please?
2009/9/19 ad...@gg-lab.net :
> Ops, i have another question, it seems very simple.
>
> I want to check the extension of an uploaded file. So i've created a
> list with allowed extensions:
>
> enabled_ext = ['gif', 'jpeg', 'png', 'bmp', 'tiff']
>
> How can i create a simple if that check if the file ext (file_ext) is
> in the list?
>
> I've searched in the python tutorial, but have not been able to find
> any example that uses an if statement combined with a list.
>
> Thankyou again
>
> 2009/9/19 ad...@gg-lab.net :
>> Hi All,
>>
>> the solution was in the link i've posted before. If i use:
>>
>> type = imghdr.what('img.test', image.data)
>>
>> The imghdr modules ignore the filename (first argument) and takes the
>> second as a data stream assumed to contain the filetype.
>>
>> The solution only works for images, but that's what i need. I think
>> that right now is not possible to generally determine the mimetype for
>> all types of files on GAE, because some libraries are missing. Anyway,
>> i'll send a mail to the gae mailing list, and if find a solution i'll
>> post it here.
>>
>> Thankyou all guys.
>>
>> 2009/9/19 Sander Sweers :
>>> On Fri, 2009-09-18 at 16:48 -0400, Kent Johnson wrote:
>>>> > So, the __init__.py file of the GAE evinronment's ctypes library is
>>>> > broken, as it's importing from a package that doesn't exist. Right?
>>>>
>>>> Probably ctypes is not supported in GAE, that would be a pretty big
>>>> security hole.
>>>
>>> There is a pure python implementation on pypi [1]. It states it is in
>>> alpha and missing some features. Never used it myself though...
>>>
>>> Greets
>>> Sander
>>>
>>> [1] http://pypi.python.org/pypi/pymagic/0.1
>>>
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>>>
>>
>
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Re: [Tutor] Determine Filetype
2009/9/19 Sander Sweers :
> On Sat, 2009-09-19 at 17:20 +0200, ad...@gg-lab.net wrote:
>> I want to check the extension of an uploaded file. So i've created a
>> list with allowed extensions:
>>
>> enabled_ext = ['gif', 'jpeg', 'png', 'bmp', 'tiff']
>
> If this does not change make it s tuple. It does not change what is
> written below.
>
>> How can i create a simple if that check if the file ext (file_ext) is
>> in the list?
>
> The below idle session should help you figure it out.
>
>>>> enabled_ext = ('gif', 'jpeg', 'png', 'bmp', 'tiff')
>>>> 'gif' in enabled_ext
> True
>
> Greets
> Sander
>
> A: Because it messes up the order in which people normally read text.
> Q: Why is top-posting such a bad thing?
> A: Top-posting.
> Q: What is the most annoying thing in e-mail?
>
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Sander, sorry for the top-posting, it's the default in GMail. This is
one of my first times in a mailing list, so it's possible i'm doing
something wrong. Sorry again for it.
I've replied to my mail, as i've found what i was looking for:
if OBJECT in LIST:
Well, but i'd like to read the page of the python tutorial regarding
this. I'm not able to locate it. Can you help me?
Thankyou
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Re: [Tutor] Determine Filetype
Thankyou guys.
> The search feature of the web site is quite effective! :-)
Alan, i know that every site has a search function, but they're not so
simple to be used if you're looking for a very common word ("in") and
don't know other keys to find it.
Regards,
Giorgio
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