Gregory Piñero wrote:
> Hey guys, would someone mind giving me a quick rundown of how
> references work in Python when passing arguments into functions? The
> code below should highlight my specific confusion:
All arguments are passed by reference, but in Python equality rebinds
the name.
>
> <code>
>
> bool1=True
> lst1=[1,2,3]
>
> def func1(arg1): arg1.append(4)
In C++, pretending it had dynamic typing, this would be equivalent to:
void func1( * arg1){
arg1->append(4);
}
>
> def func2(arg1): arg1=False
void func2 ( * arg2) {
arg2 = &(False);
> Why does my list variable get changed for the rest of the program, but
> my boolean variable doesn't. What am I not understanding?
In Python, "x = y" has a very definite meaning of "y is assigned to the
name of x." This change does not affect whatever was in x to start
with, and it certainly would not affect anything else which holds a
reference to the object formerly known as x.
In contrast, calling a function which mutates the object (like .append
on lists, or assignment by lst[index]=something) actually changes the
object itself, which is of course reflected by all other names that hold
a reference to the object.
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