[Neal Becker]
> >>I don't know to what extent these kind of optimizations are
available to
> >>cpython. For example, are constant calculations removed from loops?
[Brett Cannon]
> > If you mean ``2+3``, then yes.
[Greg Ewing]
> Actually, no. Constant folding *could* be done, but it currently
isn't:
>
> >>> def f():
> ... return 2+3
> ...
> >>> import dis
> >>> dis.dis(f)
> 2 0 LOAD_CONST 1 (2)
> 3 LOAD_CONST 2 (3)
> 6 BINARY_ADD
> 7 RETURN_VALUE
> 8 LOAD_CONST 0 (None)
> 11 RETURN_VALUE
That looks like a disassembly from the ancient and primitive Py2.3 ;-)
It looks a little different in the ahead-of-its-time Py2.5 alpha:
Python 2.5a0 (#46, Sep 15 2005, 00:51:34) [MSC v.1200 32 bit (Intel)] on
win32
Type "copyright", "credits" or "license()" for more information.
>>> def f():
return 2+3
>>> import dis
>>> dis.dis(f)
2 0 LOAD_CONST 3 (5)
3 RETURN_VALUE
Raymond
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