no side effects

[holger krekel]

"Martin v. L?wis" wrote:
> holger krekel wrote:
> > 'i' might not be local but usually it is.  When answering 
> > newcomer questions i try to refrain from talking in language
> > lawyer details (as much as possible).  I only tried to explain the 
> > for-loop from the viewpoint of names bound to objects.  I didn't 
> > want to compare iteration protocols between python and C++ just 
> > to explain that. 
> 
> I'm uncertain though whether an actually incorrect explanation helps the 
> newcomer.

Of course, it shouldn't be incorrect.  I don't think i actually was. 

> Namespaces are totally irrelevant for this feature of the for loop.

Depends on your background.  *If* somebody e.g. thinks that 

    for i in range(3):
        print i
        i = 3

is somewhat equivalent to C's

    int i;
    for (i=0 ; i<3 ; i++) {
        printf("%d\n", i);
        i = 3;
    }

then IMHO my explanation serves well and talking about underlying 
iterator protocols wouldn't help too much.  

Why is the way the python for-loop gets to the next *value* 
more important than understanding that python works with 
name-object bindings everywhere?  And what is so wrong 
about this (*)? 

slightly irritated,

    holger


(*) see http://www.python.org/dev/doc/devel/ref/naming.html
    for further details.