Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > comp.lang.python > #36530 > unrolled thread

pylint or similar to test version-specific language constructs?

Back to article view | Back to comp.lang.python

Contents

  pylint or similar to test version-specific language constructs? jkn <jkn_gg@nicorp.f9.co.uk> - 2013-01-09 15:45 -0800
    Re: pylint or similar to test version-specific language constructs? Gisle Vanem <gvanem@broadpark.no> - 2013-01-10 01:07 +0100
      Re: pylint or similar to test version-specific language constructs? The Night Tripper <jkn+gg@nicorp.co.uk> - 2013-01-11 08:29 +0000
        Re: pylint or similar to test version-specific language constructs? Terry Reedy <tjreedy@udel.edu> - 2013-01-11 08:38 -0500
        Re: pylint or similar to test version-specific language constructs? Dave Angel <d@davea.name> - 2013-01-11 10:06 -0500
          Re: pylint or similar to test version-specific language constructs? Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-01-11 15:37 +0000
            Re: pylint or similar to test version-specific language constructs? Dave Angel <d@davea.name> - 2013-01-11 11:09 -0500
          Re: pylint or similar to test version-specific language constructs? jkn <jkn_gg@nicorp.f9.co.uk> - 2013-01-13 09:56 -0800
            Re: pylint or similar to test version-specific language constructs? Chris Angelico <rosuav@gmail.com> - 2013-01-14 07:59 +1100
    Re: pylint or similar to test version-specific language constructs? thenault@gmail.com - 2013-01-11 00:35 -0800

#36530 — pylint or similar to test version-specific language constructs?

Hi all
    I have to write python code which must run on an old version of
python (v2.4) as well as a newer (v2.7). I am using pylint and would
like to check if is possible to check with pylint the use of operators
etc. which are not present in 2.4; the ternary operator springs to
mind.

I haven't found anything in pylint which indicates it can do this sort
of check; am I missing anything? Other suggestions for this kind of
checking welcome.

    Thanks
    Jon N

[toc] | [next] | [standalone]

#36535

"jkn" <jkn_gg@nicorp.f9.co.uk> wrote:

>    I have to write python code which must run on an old version of
> python (v2.4) as well as a newer (v2.7). I am using pylint and would
> like to check if is possible to check with pylint the use of operators
> etc. which are not present in 2.4; the ternary operator springs to
> mind.

No idea about PyLint. Why not install Python 2.4 and test
with that? Sounds safer IMHO.

-gv

[toc] | [prev] | [next] | [standalone]

#36608

Gisle Vanem wrote:

> "jkn" <jkn_gg@nicorp.f9.co.uk> wrote:
> 
>>    I have to write python code which must run on an old version of
>> python (v2.4) as well as a newer (v2.7). I am using pylint and would
>> like to check if is possible to check with pylint the use of operators
>> etc. which are not present in 2.4; the ternary operator springs to
>> mind.
> 
> No idea about PyLint. Why not install Python 2.4 and test
> with that? Sounds safer IMHO.

I do have Python 2.4 installed; but I would like a checker that warned me 
beforehand about trying to use constructs (like the ternary operator, 
decorators) which are version-specific.

    J^n

[toc] | [prev] | [next] | [standalone]

#36621

On 1/11/2013 3:29 AM, The Night Tripper wrote:
> Gisle Vanem wrote:
>
>> "jkn" <jkn_gg@nicorp.f9.co.uk> wrote:
>>
>>>     I have to write python code which must run on an old version of
>>> python (v2.4) as well as a newer (v2.7). I am using pylint and would
>>> like to check if is possible to check with pylint the use of operators
>>> etc. which are not present in 2.4; the ternary operator springs to
>>> mind.
>>
>> No idea about PyLint. Why not install Python 2.4 and test
>> with that? Sounds safer IMHO.
>
> I do have Python 2.4 installed; but I would like a checker that warned me
> beforehand about trying to use constructs (like the ternary operator,
> decorators) which are version-specific.

Search each chapter of the reference manual (about 7) for 'version changed'.

-- 
Terry Jan Reedy

[toc] | [prev] | [next] | [standalone]

#36626

On 01/11/2013 03:29 AM, The Night Tripper wrote:
> Gisle Vanem wrote:
>
>> "jkn" <jkn_gg@nicorp.f9.co.uk> wrote:
>>
>>>    I have to write python code which must run on an old version of
>>> python (v2.4) as well as a newer (v2.7). I am using pylint and would
>>> like to check if is possible to check with pylint the use of operators
>>> etc. which are not present in 2.4; the ternary operator springs to
>>> mind.
>> No idea about PyLint. Why not install Python 2.4 and test
>> with that? Sounds safer IMHO.
> I do have Python 2.4 installed; but I would like a checker that warned me 
> beforehand about trying to use constructs (like the ternary operator, 
> decorators) which are version-specific.
>
>     J^n
>

Not sure what you mean by beforehand.  Don't you run all your unit tests
before putting each revision of your code into production?  So run those
tests twice, once on 2.7, and once on 2.4.  A unit test that's testing
code with a ternary operator will fail, without any need for a separate
test.

if it doesn't, then you've got some coverage gaps in your unit tests.



-- 

DaveA

[toc] | [prev] | [next] | [standalone]

#36628

On Fri, 11 Jan 2013 10:06:30 -0500, Dave Angel wrote:

> On 01/11/2013 03:29 AM, The Night Tripper wrote:
>> Gisle Vanem wrote:
>>
>>> "jkn" <jkn_gg@nicorp.f9.co.uk> wrote:
>>>
>>>>    I have to write python code which must run on an old version of
>>>> python (v2.4) as well as a newer (v2.7). I am using pylint and would
>>>> like to check if is possible to check with pylint the use of
>>>> operators etc. which are not present in 2.4; the ternary operator
>>>> springs to mind.
>>> No idea about PyLint. Why not install Python 2.4 and test with that?
>>> Sounds safer IMHO.
>> I do have Python 2.4 installed; but I would like a checker that warned
>> me beforehand about trying to use constructs (like the ternary
>> operator, decorators) which are version-specific.

Decorators work fine in Python 2.4.


> Not sure what you mean by beforehand.  Don't you run all your unit tests
> before putting each revision of your code into production?  So run those
> tests twice, once on 2.7, and once on 2.4.  A unit test that's testing
> code with a ternary operator will fail, without any need for a separate
> test.

You don't even need tests for the code that includes the ternary 
operator. The module simply won't compile in Python 2.4, you get a 
SyntaxError when you try to import it or run it.

You don't need PyLint to check for *illegal syntax*. Python already does 
that.


-- 
Steven

[toc] | [prev] | [next] | [standalone]

#36631

On 01/11/2013 10:37 AM, Steven D'Aprano wrote:
> On Fri, 11 Jan 2013 10:06:30 -0500, Dave Angel wrote:
>
>> <snip>
>
>> Not sure what you mean by beforehand.  Don't you run all your unit tests
>> before putting each revision of your code into production?  So run those
>> tests twice, once on 2.7, and once on 2.4.  A unit test that's testing
>> code with a ternary operator will fail, without any need for a separate
>> test.
> You don't even need tests for the code that includes the ternary 
> operator. The module simply won't compile in Python 2.4, you get a 
> SyntaxError when you try to import it or run it.
>
> You don't need PyLint to check for *illegal syntax*. Python already does 
> that.
>

You're right of course.  But I can weasel out of it by saying that
Python will only check it if the particular module is imported.  I've
seen equivalent bugs in real projects, where a release went out with one
of its dynamic libraries not even present.

Another thing that can stop Python from checking is if some naive
programmer uses a bare except in production code.

Both of these would show up in the simplest of unit testing code.



-- 

DaveA

[toc] | [prev] | [next] | [standalone]

#36744

Hi Dave

On 11 Jan, 15:06, Dave Angel <d...@davea.name> wrote:
>
> Not sure what you mean by beforehand.  Don't you run all your unit tests
> before putting each revision of your code into production?  So run those
> tests twice, once on 2.7, and once on 2.4.  A unit test that's testing
> code with a ternary operator will fail, without any need for a separate
> test.
>
> if it doesn't, then you've got some coverage gaps in your unit tests.

By 'beforehand' I meant 'before testing on my target 2.4 system;
perhaps I should have been clearer in that I am running 2.7 on my
'development' platform, and 2.4 on my target. It would be painful to
put 2.4 on my target system (although I continue to wonder about
that...). So I was looking to catch such errors before migrating to
the target.

[Steven D'Aprano]
> Decorators work fine in Python 2.4.

Yes, I was just coming up with another example of a language construct
which didn't exist at one point.

> You don't even need tests for the code that includes the ternary
> operator. The module simply won't compile in Python 2.4, you get a
> SyntaxError when you try to import it or run it.

In fact I had a misapprehension about this; for some reason (I thought
I'd tried it) I thought such an error only got caught at runtime, not
'compile-time'. I now see that this is not the case, which means the
athe problem is less of a concern than I thought.

Thanks for the comments.

    Jon N

[toc] | [prev] | [next] | [standalone]

#36753

On Mon, Jan 14, 2013 at 4:56 AM, jkn <jkn_gg@nicorp.f9.co.uk> wrote:
> Hi Dave
>
> On 11 Jan, 15:06, Dave Angel <d...@davea.name> wrote:
>>
>> Not sure what you mean by beforehand.  Don't you run all your unit tests
>> before putting each revision of your code into production?  So run those
>> tests twice, once on 2.7, and once on 2.4.  A unit test that's testing
>> code with a ternary operator will fail, without any need for a separate
>> test.
>>
>> if it doesn't, then you've got some coverage gaps in your unit tests.
>
> By 'beforehand' I meant 'before testing on my target 2.4 system;
> perhaps I should have been clearer in that I am running 2.7 on my
> 'development' platform, and 2.4 on my target. It would be painful to
> put 2.4 on my target system (although I continue to wonder about
> that...). So I was looking to catch such errors before migrating to
> the target.

Painful to put 2.4 on your dev, you mean? I've never done it, but I
would expect that the old sources will compile against newer libraries
with no problems.

That's likely to be the easiest option. It's the language-level
equivalent of watching for a thrown exception rather than asking
forgiveness beforehand :)

ChrisA

[toc] | [prev] | [next] | [standalone]

#36609

On Thursday, January 10, 2013 12:45:32 AM UTC+1, jkn wrote:
> Hi all
> 
>     I have to write python code which must run on an old version of
> 
> python (v2.4) as well as a newer (v2.7). I am using pylint and would
> 
> like to check if is possible to check with pylint the use of operators
> 
> etc. which are not present in 2.4; the ternary operator springs to
> 
> mind.
> 
> 
> 
> I haven't found anything in pylint which indicates it can do this sort
> 
> of check; am I missing anything? Other suggestions for this kind of
> 
> checking welcome.


Hi,

there is no such checker in pylint yet, though it should be fairly easy to build one. The longer part being to identify all constructs that should be detected and their representation in the ast. Then pylint checkers are simple visitors. You'll get some help from the project mailing list (python-projects@lists.logilab.org) if you go that way.

Regards,

-- 
Sylvain

[toc] | [prev] | [standalone]

Back to top | Article view | comp.lang.python

csiph-web