On Jan 24, 9:51 am, Peter Otten <__pete...@web.de> wrote: > iu2 wrote: > > I'm trying to convert functions - pass a few functions to a converting > > function, which change their behaviour and return the changed > > functions: > > > >>> def cfuncs(*funcs): > > n = [] > > for f in funcs: > > def ff(*args, **key): > > print 'Start!', f.func_name > > res = f(*args, **key) > > print 'End', f.func_name > > return res > > n.append(ff) > > return n > > > then I try it using two functions: > > > >>> def f1(): > > print 'hello' > > > >>> def f2(x): > > return 2 * x > > > Eventually: > > >>> newfuncs = cfuncs(f1, f2) > > > I would expect newfuncs to hold changed versions of f1 and f2, but > > what is actually contained in newfuncs is twice the changed version of > > f2. > > That is because the inner ff() references f which is a local variable of > cfuncs(). By the time you invoke your newly created functions cfuncs() and > thus the 'for f in funcs' loop has finished and the value of f is that of > the last item in the funcs tuple. You can avoid the problem with another > indirection > > def make_ff(f): > def ff(*args, **key): > print 'Start!', f.func_name > res = f(*args, **key) > print 'End', f.func_name > return res > return ff > > def cfuncs(*funcs): > return [make_ff(f) for f in funcs] > > Peter- Hide quoted text - > > - Show quoted text -
Thanks! I thought a function definition creates a closure around all used vars. As I understand now only variables that are passed as function arguments can participate in a closure. -- http://mail.python.org/mailman/listinfo/python-list
