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[Python-Dev] Issue #26204: compiler now emits a SyntaxWarning on constant statement

francismb francismb at email.de
Mon Feb 8 13:00:49 EST 2016 
Hi,

On 02/08/2016 06:44 PM, Victor Stinner wrote:
> Hi,
> 
> I changed the Python compiler to ignore any kind "constant
> expressions", whereas it only ignored strings and integers before:
> http://bugs.python.org/issue26204
> 
> The compiler now also emits a SyntaxWarning on such case. IMHO the
> warning can help to detect bugs for developers who just learnt Python.
> 
[...]
> New behaviour:
>
> haypo at smithers$ ./python
> Python 3.6.0a0 (default:759a975e1230, Feb  8 2016, 18:21:23)
>>>> def f():
> ...  False
> ...
> <stdin>:2: SyntaxWarning: ignore constant statement
>


Just for my understanding:

What would happen if someone has functions where some return
constant expressions and others not and then that functions
are used depending on some other context. E.g:


def behaviour2(ctx):
   return 1

def behaviour1(ctx):
   return some_calculation_with(ctx)


[...]

if ... :
  return behaviour1(ctx)
else :
  return behaviour2()


Is that going to raise a warning?


Thanks in advance!
francis
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