Hi,
"Steven Bethard" <[EMAIL PROTECTED]> a écrit dans le message de news:
[EMAIL PROTECTED]
> houbahop wrote:
>> Thank you everyone, but I still not understand why such a comon feature
>> like passing parameters byref that is present in most serious programming
>> languages is not possible in a clean way,here in python.
>
> I understand from this statement that Java is not a serious programming
> language? ;)
;) I didn't want to say that.
In fact, python is the first language I use that is like java 100% oriented
object.
I didn't realise that the main function, was an object too ! (and I don't
really knew that self.something was meaning that it was a class attribute..
just grabed this in a code found on the net :) )
My habit in VB was to start a new project with a module (that is not an
object and doesn't have class functions) and then calling object functions
and passing them local to the main objects.
like this :
class a()
blabla
class b()
blabla
main()
create a instance
create b instance
b()
a(b)
end main
But in the very small script that I'm coding, I don't really need OOP and I
will not use it even if I really like that.
> I don't see why lack of pass-by-reference would force you to use
> globals...
> Or by globals do you mean instance variables? If you don't want any
> instance variables (which means you don't really want OO), you can still
> clear your list as long as you have any name bound to the list object:
You're right.
> >>> def clear(lst):
> ... while lst:
> ... lst.pop()
> ...
> >>> x = [pow(x, 7, 19) for x in range(10)]
> >>> x
> [0, 1, 14, 2, 6, 16, 9, 7, 8, 4]
> >>> clear(x)
> >>> x
> []
>
> or alternatively:
>
> >>> def clear(lst):
> ... lst[:] = []
> ...
> >>> x = [pow(x, 7, 19) for x in range(10)]
> >>> x
> [0, 1, 14, 2, 6, 16, 9, 7, 8, 4]
> >>> clear(x)
> >>> x
> []
>
> Note that neither of these functions requires pass-by-reference; the lst
> local in the function is not the same name as the x local outside the
> function. But since you're basically just passing a "pointer" by value,
> both "variables" still "point" to the same object
Passing a pointer by value appears to me as passing a var by reference.
(or in Python terms,
> both "names" are "bound" to the same object). To apply an affect that is
> visible to all names bound to an object, you simply need to mutate the
> object. In the cases above, this is just a matter of using the
> appropriate object method (list.pop or list.__setslice__ respectively
> above).
Thanks I will try all of that, but what does really means mutating in
python? It's the first time I hear this word in programming :))
Dominique
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