how to dynamically create a function object (from a code object)?
antonmuhin.REMOVE.ME.FOR.REAL.MAIL at rambler.ru
Wed Jul 2 13:37:33 CEST 2003
Petri Savolainen wrote:
> After reading the manuals and googling around a bit, I thought I'd use
> the 'compile' built-in to create a code object. Then, using either
> new.function() or types.FunctionType(), create a function object out of
> the code object. The function object can then be turned into a method
> for example using types.MethodType(). Right? Well, on Windows 98, using
> python 2.2.2 (or 2.3b2):
> >>> c=compile('def a(msg): return msg','<nowhere>','exec')
> >>> f=types.FunctionType(c,globals(),'a')
> >>> f
> >>> <code object ? at 00F8A9E0, file "<nowhere>", line 1>
> >>> f('hello')
> Traceback (most recent call last):
> File "<pyshell#136>", line 1, in -toplevel-
> TypeError: ?() takes no arguments (1 given)
> >>> f()
> >>> a('hello')
> >>> 'hello'
> This is, well, not what I would have expected.
> After peeking around in the code object, I found out its 'co_const'
> instance variable also contains a code object - which, it seems, should
> really be fed to the function creation methods:
> >>> c.co_consts
> (<code object a at 00F8A960, file "<nowhere>", line 1>, None)
> >>> f=types.FunctionType(c.co_consts,globals(),'a')
> >>> f('hello')
> Which is the behaviour I would have expected in the first place!
> I would really like to know what I am doing wrong here, or any
> clarification regarding what is going on above... I dare not hope having
> found a bug :-P
Unfortunately, I didn't manage to do it the way you described above. But
if you just want to create a function there is much simplier way:
def _(s): return s
x = _()
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