Re: Pass by reference or by value?
- From: Thomas Jollans <thomas@xxxxxxxxxxx>
- Date: Fri, 17 Aug 2007 01:20:02 +0200
On Thursday 16 August 2007, Robert Dailey wrote:
Hi,
I previously created a topic named "Pass by reference or by value" where I
inquired on how python's function parameters work. I received a lot of nice
responses, however I'm still confused on the topic. Note that I come from a
C++ background to Python, so any comparisons to C++ would be very helpful.
Very short answer:
Think of normal objects as always-pointers. There are no references. param = 5
sets the local variable "param" (be that of imaginary type int* or int, I
don't care) to whatever 5 is. This does not call an operator=, this plain
overwrites the variable.
If you want to change arguments in that way, you can use a list as an ugly
hack:
def foo(param):
param[0] = 5
print param[0]
a = [4]
foo(a)
yeah, I said ugly. That hack makes sure that a method of the passed object is
called instead of of the local namespace dict. (please note that I'm throwing
around abstract concepts without caring about an implementation).
--
Regards, Thomas Jollans
GPG key: 0xF421434B may be found on various keyservers, eg pgp.mit.edu
Hacker key <http://hackerkey.com/>:
v4sw6+8Yhw4/5ln3pr5Ock2ma2u7Lw2Nl7Di2e2t3/4TMb6HOPTen5/6g5OPa1XsMr9p-7/-6
Attachment:
signature.asc
Description: This is a digitally signed message part.
- Prev by Date: Re: How to say $a=$b->{"A"} ||={} in Python?
- Next by Date: Re: How to say $a=$b->{"A"} ||={} in Python?
- Previous by thread: How to say $a=$b->{"A"} ||={} in Python?
- Next by thread: Re: Pass by reference or by value?
- Index(es):
Relevant Pages
|
