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Re: python 2.5 and ast

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  Re: python 2.5 and ast Andrea Crotti <andrea.crotti.0@gmail.com> - 2011-11-29 09:51 +0000
    Re: python 2.5 and ast Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2011-11-29 11:32 +0000
      Re: python 2.5 and ast Andrea Crotti <andrea.crotti.0@gmail.com> - 2011-11-29 13:51 +0000
      Re: python 2.5 and ast Andrea Crotti <andrea.crotti.0@gmail.com> - 2011-11-30 18:03 +0000
        Re: python 2.5 and ast DevPlayer <devplayer@gmail.com> - 2011-12-02 07:18 -0800
          Re: python 2.5 and ast Andrea Crotti <andrea.crotti.0@gmail.com> - 2011-12-02 16:54 +0000
          Re: python 2.5 and ast Andrea Crotti <andrea.crotti.0@gmail.com> - 2011-12-02 17:01 +0000

#16385 — Re: python 2.5 and ast

On 11/29/2011 03:55 AM, Dave Angel wrote:
>
> But don't forget to tag it as version specific, so it gets removed 
> when the later version of the library is available.  There are various 
> ways of doing that, but the easiest is probably to put a test in the 
> acceptance suite that fails if this code is used in 2.6 or later.
>

Ok thanks,
something like this is ok?
(or maybe I can use a try/catch and export my own if is not found in the 
standard library?)

from sys import version_info

if version_info[1] == 5:
     from psi.devsonly.ast import parse, NodeVisitor
else:
     from ast import parse, NodeVisitor

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#16387

On Tue, 29 Nov 2011 09:51:24 +0000, Andrea Crotti wrote:

> On 11/29/2011 03:55 AM, Dave Angel wrote:
>>
>> But don't forget to tag it as version specific, so it gets removed when
>> the later version of the library is available.  There are various ways
>> of doing that, but the easiest is probably to put a test in the
>> acceptance suite that fails if this code is used in 2.6 or later.
>>
>>
> Ok thanks,
> something like this is ok?
> (or maybe I can use a try/catch and export my own if is not found in the
> standard library?)
> 
> from sys import version_info
> 
> if version_info[1] == 5:
>      from psi.devsonly.ast import parse, NodeVisitor
> else:
>      from ast import parse, NodeVisitor


I prefer to check against sys.version.

import sys
if sys.version <= '2.5':
    from psi.devsonly.ast import parse, NodeVisitor
else:
    from ast import parse, NodeVisitor



Or even:


try:
    from ast import parse, NodeVisitor
except ImportError:
    from ast import parse, NodeVisitor



-- 
Steven

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#16391

On 11/29/2011 11:32 AM, Steven D'Aprano wrote:
>
> I prefer to check against sys.version.
>
> import sys
> if sys.version<= '2.5':
>      from psi.devsonly.ast import parse, NodeVisitor
> else:
>      from ast import parse, NodeVisitor
>
>
>
> Or even:
>
>
> try:
>      from ast import parse, NodeVisitor
> except ImportError:
>      from ast import parse, NodeVisitor
>
>
>

The try/except is probably the nicest...
I've seen in other places using sys.version <=, but is it a good idea to 
rely
on the fact that the <= on strings has the right semantic?
After all that's just a string, version_info looks more correct to me..

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#16443

Another thing about the AST, I am having fun trying to for example list 
out all
the unused imports.

I have already a visitor which works quite nicely I think, but now I 
would like
to get a way to find all the unused imports, so I need more visitors that
find out all the used names.

I didn't find too much documentation about these kind of things, so any
suggestions on how to approach?

Pylint and snakefood have similar code, but they use the old "compiler" 
module,
so it's not really helpful.

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#16545

On Nov 30, 1:03 pm, Andrea Crotti <andrea.crott...@gmail.com> wrote:
> Another thing about the AST, I am having fun trying to for example list
> out all
> the unused imports.
>
> I have already a visitor which works quite nicely I think, but now I
> would like
> to get a way to find all the unused imports, so I need more visitors that
> find out all the used names.
>
> I didn't find too much documentation about these kind of things, so any
> suggestions on how to approach?
>
> Pylint and snakefood have similar code, but they use the old "compiler"
> module,
> so it's not really helpful.

There was another topic in these forums recently about "un-importing"
modules (and how you can not do that reliably without restarting
python). There was various ways mentioned of keeping track of what was
imported. And there was mentioned reasonable ways of finding all
possible imports on a computer.

By "unused imports" I assume you mean "all unused imports in the
application's source code" as opposed to meaning "all unused modules/
packages/libraries on that computer."

Personally I'd love to see more tutorials on the AST module; An AST
for Dummies. Pretty much the tutorials talk about parsing an
expression like "1+2=3". But I'd like to see how blocks are compiled/
managed by the indent/dedent tokens and how the complete algorithm for
finding qouted strings is implimented (using really simple
explanations).

Some google buzzwords to help with your search for your question:  sys
import cache, import hook, pydoc walkpackages().

And I just found this little tool; never knew about it: C:\PythonXX
\Tools\Scripts\pydocui.pyw

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#16555

On 12/02/2011 03:18 PM, DevPlayer wrote:
> There was another topic in these forums recently about "un-importing"
> modules (and how you can not do that reliably without restarting
> python). There was various ways mentioned of keeping track of what was
> imported. And there was mentioned reasonable ways of finding all
> possible imports on a computer.
>
> By "unused imports" I assume you mean "all unused imports in the
> application's source code" as opposed to meaning "all unused modules/
> packages/libraries on that computer."
>
> Personally I'd love to see more tutorials on the AST module; An AST
> for Dummies. Pretty much the tutorials talk about parsing an
> expression like "1+2=3". But I'd like to see how blocks are compiled/
> managed by the indent/dedent tokens and how the complete algorithm for
> finding qouted strings is implimented (using really simple
> explanations).
>
> Some google buzzwords to help with your search for your question:  sys
> import cache, import hook, pydoc walkpackages().
>
> And I just found this little tool; never knew about it: C:\PythonXX
> \Tools\Scripts\pydocui.pyw
>

Yes I meant unused imports in each of the modules actually...
The problem for me is to actually understand what are all the possible
AST node that can involve the use of an actual import, and I didn't
find anything helpful aboupt that.

The ASDL definition says everything in theory but without some examples
is a bit hard.

I got something nice however:
http://stackoverflow.com/questions/8340567/python-ast-to-dot-graph/8342383#8342383

But on windows and Python 2.5 nothing is working :/, even if I blandly 
copied the
ast.py from the python 2.7 code file..

   File "h:\long\path\devsonly\ast.py", line 166, in iter_fields
     for field in node._fields:
TypeError: 'NoneType' object is not iterable

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#16557

And on a related topic, how can I actually detect other types of 
imports, for example
__import__

Doing a dump I get this:

In [113]: ast.dump(ast.parse('__import__("module")'))
Out[113]: "Module(body=[Expr(value=Call(func=Name(id='__import__', 
ctx=Load()), args=[Str(s='module')], keywords=[], starargs=None, 
kwargs=None))])"

So the visitor should be quite smart, and the string passed can't be 
always be done.
I think the easiest way is just to use regexp and look for them warning 
the user that there might be other
stupid imports, the harder way is to try to detect it and if the string 
passed is actually known at compile-time
use it, otherwise warn the user.

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