[Tutor] Help with packages and namespaces please
Hi all, I'm new to the list and relatively new to python, and very new to the use and creation of packages. Let's say I have these files in one directory: PrintBase.py PrintHello.py PrintBye.py PrintBase defines a very simple base class PrintBase, whose __init__ method initializes a member to an optionally provided string (otherwise the string is empty) and whose PrintMe method prints the string given (or empty string otherwise). PrintHello defines a class that inherits from PrintBase and whose PrintMe method prepends a 'Hello, ' to the provided string. PrintBye defines a class that inherits from PrintBase and whose PrintMe method prepends a 'Good-bye' to the provided string. Since all the files are in the same directory, I can use import statements like from PrintHello import PrintHello ... I'd like to reorganize the files so they're like the Sound example in the Python tutorial: PrintMe/ PrintMe/PrintBase/PrintBase.py PrintMe/PrintHello/PrintHello.py PrintMe/PrintBye/PrintBye.py I've created empty __init__.py files in each of the subdirectories. Here I run into a number of problems and get confused - my goal is to keep the import statements as they are (the actual files I'd be editing are many and I'd rather avoid having to edit them all) - is there something I can put in the __init__.py files so that the modules are brought into namespace w/o having to use absolute module notation? As simple tests, I've tried running different import commands in the python interpreter: I've tried adding the absolute directory paths to __path__ in each __init__.py per subdirectory, and adding the paths to sys.path. When I do that and run the python intepreter and try 'from PrintMe.PrintHello import PrintHello' I get an error saying 'Error when calling the metaclass bases, module.__init__() takes at most 2 arguments (3 given)'. The same code functioned fine when all the files were in the same directory, so I'm confused about why the interpreter thinks I'm passing 3 arguments along. W/o those directories in sys.path I get an import error (there is no module named 'PrintBase'). Also, if I'm in one of the subdirectories I get a similar error when attempting to import the toplevel (PrintMe) package. (Essentially I would like to structure the directories (er package?) so that files in one subdirectory can subclass base classes from a sibling (not parent) directory, ideally in a way that doesn't require each file to state something like 'from 'PrintMe.PrintHello ... import ...' but instead 'from PrintHello import ...'. Is this possible, and if so how can I go about doing it?) Many Thanks! Andrew ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] Help with packages and namespaces please
Hmmm ... thank you very much for the detailed explanations. This is a very simplified version of some actual code I'm currently using and attempting to rework on each individual file (about 60+ of them). If it's not feasible then I guess I'm stuck with the rework. =( More comments inline ... On 10/13/07, Kent Johnson <[EMAIL PROTECTED]> wrote: > > Andrew Wu wrote: > > > Let's say I have these files in one directory: > > > > PrintBase.py > > PrintHello.py > > PrintBye.py > > > I'd like to reorganize the files so they're like the Sound example in > > the Python tutorial: > > > > PrintMe/ > > PrintMe/PrintBase/PrintBase.py > > PrintMe/PrintHello/PrintHello.py > > PrintMe/PrintBye/PrintBye.py > > Will there be more modules in each subdirectory? I'm not sure if this is > just for learning or if it is a simplification of a real problem, but > from your description of the classes it sounds like they belong in the > same package. Yes - there will be more modules in each subdirectory (I only had one in the example for my own testing purposes and for simplification). > I've created empty __init__.py files in each of the subdirectories. > > Here I run into a number of problems and get confused - my goal is to > > keep the import statements as they are (the actual files I'd be editing > > are many and I'd rather avoid having to edit them all) - is there > > something I can put in the __init__.py files so that the modules are > > brought into namespace w/o having to use absolute module notation? > > You can bring names into the package namespace, but the actual code will > still run in the module where it is defined. For example, in > PrintMe/PrintBase/__init__.py you can say >from PrintBase import Printbase > > Hmm. I'm not sure if this will work the way you want because of the name > collisions. Using the sound example where the names are unique, suppose > wavread.py includes a function read_wav(). Then in Formats/__init__.py > you can say >from wavread import read_wav This imports the name read_wav into the Formats package namespace so > other code will be able to say >from Sound.Formats import read_wav > > In your example, *without* the import in PrintBase/__init__.py it is > already valid to say >from PrintMe.PrintBase import PrintBase > which will access the *module* PrintBase. When you add the line >from PrintBase import Printbase > to __init__.py then there are two possible meanings for > PrintMe.PrintBase.PrintBase and I don't know which one will have > priority. My guess is that the module import will win but I don't know. > > At best this seems like a recipe for endless confusion - you have three > entities named PrintBase - a package, a module and a class. Hmmm ... this could be due to the poor naming convention (which also afflicts the actual code I'm modeling - the use of the same name for the class and file) ... If the import in __init__ promotes the class as you want, it still won't > help with the imports in PrintHello.py - it will still have to say at > least >from PrintMe.PrintBase import PrintBase > > Why do you want to do this? It looks like a confusing mess to me. > > > > As simple tests, I've tried running different import commands in the > > python interpreter: > > > > I've tried adding the absolute directory paths to __path__ in each > > __init__.py per subdirectory, and adding the paths to sys.path. > > Yuck. What is the point of the directories and packages if you are going > to put every thing on sys.path anyway? But I think it should work if you > put each of the subdirectories of PrintMe on sys.path. My hope was to avoid having to edit the individual files but if that leads to a gobbled mess then I'd rather do it more correctly. > When I > > do that and run the python intepreter and try 'from PrintMe.PrintHello > > import PrintHello' I get an error saying 'Error when calling the > > metaclass bases, module.__init__() takes at most 2 arguments (3 > > given)'. The same code functioned fine when all the files were in the > > same directory, so I'm confused about why the interpreter thinks I'm > > passing 3 arguments along. > > You get an error on the import? Please show the traceback. It could be I'm doing it all wrong. Hmmm ... I can't get it to happen again. If / when I do I'll post the traceback. Thanks! Andrew Kent > ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] Help with packages and namespaces please
After a more careful perusing and sifting of your response, I discovered this helped my understanding a lot better: > > You can bring names into the package namespace, but the actual code will > still run in the module where it is defined. For example, in > PrintMe/PrintBase/__init__.py you can say >from PrintBase import Printbase > > Hmm. I'm not sure if this will work the way you want because of the name > collisions. Using the sound example where the names are unique, suppose > wavread.py includes a function read_wav(). Then in Formats/__init__.py > you can say >from wavread import read_wav > > This imports the name read_wav into the Formats package namespace so > other code will be able to say >from Sound.Formats import read_wav This above seems to be closest to what I'm hoping to achieve ... I will try this out and see how it goes. Thanks again! Andrew ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] Help with packages and namespaces please
Thanks again for your help. I guess I should ask a more basic question about hierarchical directory structures and packages. If I have a bunch of files in a flat (single) directory structure that I want to reorganize into a hierarchical directory structure, do I necessarily have to turn them into package files (i.e. add the __init__.py files, or can I simply place them into a subdirectory structure and do something else so python can find the modules? Or is it better practice whenever a hierarchical directory structure exists to treat it as a package? Thanks! Andrew ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
[Tutor] Regular Expression help - parsing AppleScript Lists as Strings
Hi,
I'm writing utilities to handle return values from AppleScript in python and
one of the steps is recognizing when a returned value from an AppleScript
execution (via popen and osascript) represents a list (in AppleScript) or
not. For the most part I think I have the correct matching pattern, but I
am hung up on one of the sample strings I was using to test it - AppleScript
allows for one level of nested lists (I believe) and I get tripped up with
attempting to match lists with nested lists.
My second question is, once I have a pattern matching correctly, I need to
convert the AppleScript list into a Python list - I've read a bit about the
findall() method of the re module and was wondering if that would work in
this instance (there's also split() but I've been having issues with that,
probably b/c my pattern matching isn't correct).
Thank you!
Andrew
(source code below)
#!/usr/bin/env python
# Sample script to test if a string represented an AppleScript List or not
import re
import os
def IsASList(thestr=''):
# AppleScript lists are bracked by curly braces with items separate by
commas
# Each item is an alphanumeric label(?) or a string enclosed by
# double quotes or a list itself
# e.g. {2, True, "hello"}
#
# They differ from AppleScript records in that AS records have a key and
value:
# {name: "Buffy", field: "Slaying", job: true, age: 21}
#
# Now the question is how to make the distinction?
pattern = '''
^{# Must start with a curly brace
(
\s*? # Group to repeat; clear the whitespace after commas first
( # Start of group of alternating match possibilities
".+?" # Match a string
| \d+? # Match a number
| true|false # Match 'true' or 'false' label
) # End of group of alternating match possibilities
,?)* # Items are comma-delimited, except for the last item
}$# Must end with a closing curly brace
'''
pattern2 = '''
(
\s*? # Group to repeat; clear the whitespace after commas first
( # Start of group of alternating match possibilities
".+?" # Match a string
| \d+? # Match a number
| true|false # Match 'true' or 'false' label
) # End of group of alternating match possibilities
,?)* # Items are comma-delimited, except for the last item
'''
pattern3 = '''
^{
(
%s
| {%s} # Possible to have 1 level of nested lists
,?)* # Items are comma-delimited, except for the last item
}$
''' % (pattern2, pattern2)
regex = re.compile(pattern3, re.VERBOSE)
result = regex.match(thestr)
# print 'Result: ',
# try:
# print result.groups()
# except AttributeError:
# pass
if result:
return True
else:
return False
# main()
sample_strs = [
'{}', # Empty list
'{a}', # Should not match
'{a, b, c}', # Should not match
'{"hello"}',
'{"hello", "kitty"}',
'{true}',
'{false}',
'{true, false}',
'{9}',
'{9,10, 11}',
'{93214, true, false, "hello", "kitty"}',
'{{1, 2, 3}}', # This matches
'{{1, 2, "cat"}, 1}', # This matches
# These don't match:
'{{1,2,3},1,{4,5,6},2}',
'{1, {2, 3, 4}, 3}',
'{{1, 2, 3}, {4, 5, 6}, 1}',
'{1, {1, 2, 3}}', # Should match but doesn't
'{93214, true, false, "hello", "kitty", {1, 2, 3}}', # Should match but
doesn't
'{label: "hello", value: false, num: 2}', # AppleScript dictionary -
should not match
]
for sample in sample_strs:
print 'Is AppleScript List: %s; String: %s' % (str(IsASList(sample)),
sample)
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Re: [Tutor] Regular Expression help - parsing AppleScript Lists as Strings
Ah - thanks for the correction! I missed the extra grouping and the
extra spacing ... doh! Sorry about the HTML-formatted e-mail ...
Thanks also for the pyparsing variant as well - I didn't know the
module existed before!
Andrew
On 11/1/07, Kent Johnson <[EMAIL PROTECTED]> wrote:
> Andrew Wu wrote:
>
> >pattern3 = '''
> > ^{
> > (
> > %s
> > | {%s} # Possible to have 1 level of nested lists
> > ,?)* # Items are comma-delimited, except for the last item
> > }$
> >''' % (pattern2, pattern2)
>
> The above doesn't allow comma after the first instance of pattern2 and
> it doesn't allow space after either instance. Here is a version that
> passes your tests:
>
> pattern3 = '''
>^{
>(
>(%s
>| {%s}) # Possible to have 1 level of nested lists
>,?\s*)* # Items are comma-delimited, except for the last item
>}$
> ''' % (pattern2, pattern2)
>
> You might want to look at doing this with pyparsing, I think it will
> make it easier to get the data out vs just recognizing the correct pattern.
>
> Kent
>
> PS Please post in plain text, not HTML.
>
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