[EMAIL PROTECTED] wrote:
Neal> I noticed in some profiling, that it seems that:
Neal> def Func ():
Neal> def something():
Neal> ...
Neal> It appears that if Func is called many times, this nested func
Neal> definition will cause significant overhead. Is this true? I
Neal> guess I've become accustomed to decent compilers performing
Neal> reasonable transformations and so have tended to write code for
Neal> clarity.
It could. OTOH, the code object which implements the something body is
stored as a local var (or a constant, can't remember off the top of my
head), so it's not compiled over and over again.
Constant. With 3.0...
>>> def f():
def g():
pass
>>> import dis
>>> dis.dis(f)
2 0 LOAD_CONST 1 (<code object g at
0x0137D920, file "<pyshell#4>", line 2>)
3 MAKE_FUNCTION 0
6 STORE_FAST 0 (g)
9 LOAD_CONST 0 (None)
12 RETURN_VALUE
If the inner function is constant and does not directly access outer
function locals, and if every last tick of speed is a concern, then it
can be move out and given a name like _outer_helper.
I would go for clarity and correctness first, but I would also wonder
whether an inner function that is independent of its setting and
therefore movable might be turned into something of more general use and
usefully moved out for purposes other than just speed.
Terry Jan Reedy
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