[Python-Dev] syntax warnings don't go through warnings.warn?

[Robert Kern]

On 2009-06-01 11:50, Dino Viehland wrote:
> I’m just a little surprised by this - Is there a reason why syntax
> warnings are special and untrappable via warnings.warn?
>
>  >>> import warnings
>
>  >>> def mywarn(*args): print 'xx', args
>
> ...
>
>  >>> warnings.warn = mywarn
>
>  >>> compile("def f():\n a = 1\n global a\n", "", "exec")
>
> :3: SyntaxWarning: name 'a' is assigned to before global declaration
>
> <code object <module> at 012DB410, file "", line 1>

symtable.c uses PyErr_WarnExplicit() to provide file and line number 
information. You need to stub warnings.warn_explicit().

 >>> import warnings
 >>> def mywarn_explicit(*args):
...     print 'xx', args
...
 >>> warnings.warn_explicit = mywarn_explicit
 >>> compile("def f():\n a = 1\n global a\n", "", "exec")
xx ("name 'a' is assigned to before global declaration", <type 
'exceptions.SyntaxWarning'>, '', 3, None, None)
<code object <module> at 0x39e9f8, file "", line 1>

-- 
Robert Kern

"I have come to believe that the whole world is an enigma, a harmless enigma
  that is made terrible by our own mad attempt to interpret it as though it had
  an underlying truth."
   -- Umberto Eco