[lttng-dev] [PATCH lttng-ust] Fix: Corrected python version assumptions in lttng-gen-tp

[Jesper Derehag]

> Date: Tue, 25 Mar 2014 14:16:02 +0000
> From: mathieu.desnoyers at efficios.com
> To: jderehag at hotmail.com
> CC: lttng-dev at lists.lttng.org
> Subject: Re: [lttng-dev] [PATCH lttng-ust] Fix: Corrected python version	assumptions in lttng-gen-tp
> 
> ----- Original Message -----
>> From: jderehag at hotmail.com
>> To: lttng-dev at lists.lttng.org
>> Cc: "Jesper Derehag" <jderehag at hotmail.com>
>> Sent: Monday, March 24, 2014 10:29:44 AM
>> Subject: [lttng-dev] [PATCH lttng-ust] Fix: Corrected python version	assumptions in lttng-gen-tp
>> 
>> From: Jesper Derehag <jderehag at hotmail.com>
>> 
>> This modification calls the interpreter through env instead of
>> directly, which should be more portable for those distros which do not
>> install
>> python into /usr/bin/.
>> 
>> Also, since lttng-gen-tp is not python2 compatible, I changed it to strictly
>> call python3 which is the recommended way.
>> See PEP 394.
>> http://legacy.python.org/dev/peps/pep-0394/
> 
> Hi Jesper,
> 
> I somehow thought that lttng-gen-tp was meant to work with
> Python 2.7 and Python 3. But maybe I'm missing something.
> Where have you seen the dependency of this script on python
> 3 in our docs ?
> 
> Thanks,
> 
> Mathieu

Hmm... The reason for why I changed into python3 was due to that I got syntax error when trying to run it:
-----
./lttng-gen-tp 
  File "./lttng-gen-tp", line 100
    except OSError as msg:
                    ^
SyntaxError: invalid syntax
------
I *thought* I was running on python2.7 but as it turns out I was not. 
When resolving "python" I get python2.7 but when I check the explicit version laying at /usr/bin/python its actually a 2.4 version so no wonder it was failing. 

Checking the PEP for when "except XX as yy" was introduced points to that it was introduced in python 2.6 so entirely my mistake.
Reran it now with the a 2.7 version and it works as intended.

However, I still think you should run it through env as proposed in the patch and not use the explicit path to python.

If you agree, do you want me to send you another patch removing the "3"?

Otherwise, I apologize for my blunder.

Regards,
Jesper

> 
> 
>> ---
>> tools/lttng-gen-tp | 2 +-
>> 1 file changed, 1 insertion(+), 1 deletion(-)
>> 
>> diff --git a/tools/lttng-gen-tp b/tools/lttng-gen-tp
>> index c49e8a5..c7bf295 100755
>> --- a/tools/lttng-gen-tp
>> +++ b/tools/lttng-gen-tp
>> @@ -1,4 +1,4 @@
>> -#!/usr/bin/python
>> +#!/usr/bin/env python3
>> #
>> # Copyright (c) 2012 Yannick Brosseau <yannick.brosseau at gmail.com>
>> #
>> --
>> 1.7.9.5
>> 
>> 
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>> 
> 
> -- 
> Mathieu Desnoyers
> EfficiOS Inc.
> http://www.efficios.com