access to the namespace of a function from within its invocation

P

Poor Yorick

In the example below, the attribute "data" is added to a function
object. "me" can be used to get the function when it is invoked using
an identifier that matches the "co_name" attribute of function's code
object. Can anyone conjure an example of accessing fun2.data from
without prior knowledge of the value of fun2.f_code.co_name?

###code begin###
#!/bin/python

import sys

def me():
t = sys._getframe(0)
return t.f_back.f_globals[t.f_back.f_code.co_name]
def fun1():
m = me
print me().data

def makefun () :
def tmpfunc():
print 'need something like me().data'
return tmpfunc

fun1.s = fun1
fun1.data=['one', 'two', 'three']
fun1()
fun2 = makefun()
fun2.data=['four', 'five','six']
fun2()

###code end###
 
J

John Nagle

Poor said:
In the example below, the attribute "data" is added to a function
object.

There are these things called "classes" which might be useful
in this situation.

Python has some gratitious semantics that come with implementations
in which everything is a dictionary. Don't get carried away.

John Nagle
 
B

Bruno Desthuilliers

Poor Yorick a écrit :
In the example below, the attribute "data" is added to a function
object. "me" can be used to get the function when it is invoked using
an identifier that matches the "co_name" attribute of function's code
object. Can anyone conjure an example of accessing fun2.data from
without prior knowledge of the value of fun2.f_code.co_name?

###code begin###
#!/bin/python

import sys

def me():
t = sys._getframe(0)
return t.f_back.f_globals[t.f_back.f_code.co_name]
def fun1():
m = me
print me().data
def makefun () :
def tmpfunc():
print 'need something like me().data'
return tmpfunc

fun1.s = fun1
fun1.data=['one', 'two', 'three']
fun1()
fun2 = makefun()
fun2.data=['four', 'five','six']
fun2()

###code end###

Not a direct answer to your question, but anyway;

As soon as you want to bundle data with behaviour, OO comes to mind.
Good news is that Python is actually an OOPL which implements functions
as objects and let you define function-like ('callable') objects.

class DataFunc(object):
def __init__(self, data):
self.data = data

def __call__(self, *args, **kw):
print self.data

fun2 = DataFunc(['four', 'five', 'forty-two'])
fun2()

Note that you'll also have to correctly implement the __get__ method if
you want an instance of DataFunc to be usable as a method (look for the
descriptor protocol in the FineManual(tm) for more information on this
point).

HTH
 

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