I need to use a lambda expression to bind some extra contextual data
(should be constant after it's computed) to a call to a function. I had
originally thought I could use something like this demo (but useless) code:
funcs=[]
def testfunc(a,b):
print "%d, %d" % (a,b)
for x in xrange(10):
funcs.append(lambda p: testfunc(x+2,p))
Now what I'd like is to call, for example, funcs[0](4) and it should
print out "2,4". In other words I'd like the value of x+2 be encoded
into the lambda somehow, for funcs[x]. However the disassembly shows
this, which is reasonable, but not what I need:
>>> dis.dis(funcs[0])
2 0 LOAD_GLOBAL 0 (testfunc)
3 LOAD_GLOBAL 1 (x)
6 LOAD_CONST 0 (2)
9 BINARY_ADD
10 LOAD_FAST 0 (p)
13 CALL_FUNCTION 2
16 RETURN_VALUE
The LOAD_GLOBAL 1 (x) line is definitely a problem. For one it refers
to a variable that won't be in scope, should this lambda be called from
some stack frame not descended from the one where I defined it.
So how can I create a lambda expression that calculates a constant based
on an expression, rather than referring to the object itself? Can it be
done?
Michael
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