On Apr 29, 3:39 pm, "Diez B. Roggisch" <[EMAIL PROTECTED]> wrote:
> Danny Shevitz schrieb:
>
>
>
> > Simple question here:
>
> > I have a multiline string representing the body of a function. I have
> > control
> > over the string, so I can use either of the following:
>
> > str = '''
> > print state
> > return True
> > '''
>
> > str = '''
> > def f(state):
> > print state
> > return True
> > '''
>
> > and I want to convert this into the function:
>
> > def f(state):
> > print state
> > return True
>
> > but return an anonmyous version of it, a la 'return f' so I can assign it
> > independently. The body is multiline so lambda doesn't work.
>
> > I sort of need something like:
>
> > def function_constructor(str):
> > f = eval(str) # What should this be
> > return f
>
> > functions = {}
> > for node in nodes:
> > function[node] = function_constructor(node.text)
>
> > I'm getting stuck because 'def' doesn't seem to work in an eval function,
> > and exec actually modifies the namespace, so I run into collisions if I use
> > the function more than once.
>
> > I know I'm missing something stupid here, but I'm stuck just the same...
>
> The "stupid" thing is that you can pass your own dictionary as globals
> to exec. Then you can get a reference to the function under the name "f"
> in the globals, and store that under whatever name you need.
>
> Beware of recursion though! If that happens, you need to create unique
> names for your functions, but as you know these beforehand I don't see
> any problem with that - just enumerate them, like f1, f2, f3....
>
> Diez
In other words:
>>> d = {}
>>>
>>> # don't use str, that is the name of the built-in string type
>>> text = '''
... def f(state):
... print state
... return True
... '''
>>>
>>> exec text in d
>>>
>>> f('state')
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
NameError: name 'f' is not defined
>>>
>>> f = d['f']
>>> f('state')
state
True
Matt
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