Scope

[Elliot Temple]

I want to write a function, foo, so the following works:

def main():
n = 4
foo(n)
print n

#it prints 7

if foo needs to take different arguments, that'd be alright.

Is this possible?

I already tried this (below), which doesn't work. foo only changes
the global n.
n = 3
def main():
def foo(var, context, c2):
exec var + " = 7" in context, c2

n = 4
foo("n", locals(), globals())
print n

if __name__ == '__main__': main()

print n
And of course I tried:

def inc(n): .... n += 3
.... a = 4
inc(a)
a

4

-- Elliot Temple
http://www.curi.us/
---
[This E-mail scanned for viruses by Declude Virus]

[Leif K-Brooks]

Elliot Temple wrote:

I want to write a function, foo, so the following works:

def main():
n = 4
foo(n)
print n

#it prints 7

What's wrong with:

def foo(n):
return 7

def main():
n = 4
n = foo(n)
print n

Anything else (including the tricks involving mutable objects that will
no doubt be posted) will result in ugly, hard to maintain code.

[Elliot Temple]

On Jun 4, 2005, at 2:13 AM, Leif K-Brooks wrote:

Elliot Temple wrote:

I want to write a function, foo, so the following works:

def main():
n = 4
foo(n)
print n

#it prints 7

What's wrong with:

def foo(n):
return 7

def main():
n = 4
n = foo(n)
print n

Anything else (including the tricks involving mutable objects that
will
no doubt be posted) will result in ugly, hard to maintain code.

Nothing is wrong with it in this case. I just want to know if Python
can do what I said.

-- Elliot Temple
http://www.curi.us/
---
[This E-mail scanned for viruses by Declude Virus]

[Robert Kern]

Elliot Temple wrote:

Nothing is wrong with it in this case. I just want to know if Python
can do what I said.

With a number of difficult hacks, yes. Passing around objects as
namespaces, however, is vastly easier and far superior.

--
Robert Kern
rk***@ucsd.edu

"In the fields of hell where the grass grows high
Are the graves of dreams allowed to die."
-- Richard Harter

[James Stroud]

On Friday 03 June 2005 07:17 pm, Elliot Temple wrote:

Nothing is wrong with it in this case. I just want to know if Python
can do what I said.

Read the python-list "working with pointers" thread from Tuesday. Good answers
were posted there.

James

--
James Stroud
UCLA-DOE Institute for Genomics and Proteomics
Box 951570
Los Angeles, CA 90095

http://www.jamesstroud.com/

[Ron Adam]

Elliot Temple wrote:

I want to write a function, foo, so the following works:

def main():
n = 4
foo(n)
print n

#it prints 7

if foo needs to take different arguments, that'd be alright.

Is this possible?

It is possible if you pass mutable objects to foo such as lists or
dictionaries.

Is this what you are looking for?

def main():
d = [3,]
foo(d)
print d[0]

def foo(var):
var[0] = 7

main()
Cheers,
_Ron