w*s
发帖数: 7227 | 1 in c code i can do this
func(struct aaa *)
{
aaa->f1 = 1;
aaa->f2 = "abc";
}
how to do this in python pls ? |
d**o
发帖数: 864 | 2 create a class aaa
if you give an instance of aaa as a parameter to a function, the reference
is passed.
You don't need to do anything special.
class aaa:
def __init__(self):
self.a=1
def treat(aaa):
aaa.a=2
ins=aaa()
print ins.a
treat(ins)
print ins.a
【在 w*s 的大作中提到】
: in c code i can do this
: func(struct aaa *)
: {
: aaa->f1 = 1;
: aaa->f2 = "abc";
: }
: how to do this in python pls ?
|
w*s
发帖数: 7227 | 3 good to know.
any limitations that c++ can do, but python cannot,
for structure, passing buffer, passing by reference ?
thx !
【在 d**o 的大作中提到】
: create a class aaa
: if you give an instance of aaa as a parameter to a function, the reference
: is passed.
: You don't need to do anything special.
: class aaa:
: def __init__(self):
: self.a=1
: def treat(aaa):
: aaa.a=2
: ins=aaa()
|
s*s
发帖数: 100 | 4 agreed. Just remember do not reassign the passed parameter.
def treat_surprise(p_a):
b=aaa()
b.a=3
p_a=b # surprise for a C++ programmer!
treat_surprise(ins)
【在 d**o 的大作中提到】
: create a class aaa
: if you give an instance of aaa as a parameter to a function, the reference
: is passed.
: You don't need to do anything special.
: class aaa:
: def __init__(self):
: self.a=1
: def treat(aaa):
: aaa.a=2
: ins=aaa()
|
f*******n
发帖数: 12623 | 5 Why is it a surprise? It's the same in C++:
void treat_surprise(aaa *p_a) {
aaa *b = new aaa;
b->a = 3;
p_a = b;
}
【在 s*s 的大作中提到】
: agreed. Just remember do not reassign the passed parameter.
: def treat_surprise(p_a):
: b=aaa()
: b.a=3
: p_a=b # surprise for a C++ programmer!
:
: treat_surprise(ins)
|
d**o
发帖数: 864 | 6 If you want to copy an object, normally do a copy explicitly.
Cite from Stackoverflow:
"passing by value" and "passing by reference" are not concepts that are
relevant in Python. The relevant concepts are instead "mutable object" and "
immutable object".
【在 w*s 的大作中提到】
: good to know.
: any limitations that c++ can do, but python cannot,
: for structure, passing buffer, passing by reference ?
: thx !
|
s*s
发帖数: 100 | 7 I am thinking this:
void treat_surprise(aaa & p_a) {
.......
.......
}
If you pass by reference, p_a=b will call the copy constructor.
【在 f*******n 的大作中提到】
: Why is it a surprise? It's the same in C++:
: void treat_surprise(aaa *p_a) {
: aaa *b = new aaa;
: b->a = 3;
: p_a = b;
: }
|
p***o
发帖数: 1252 | 8 Reference in languages like java and python means pointer in C/C++.
【在 s*s 的大作中提到】
: I am thinking this:
: void treat_surprise(aaa & p_a) {
: .......
: .......
: }
: If you pass by reference, p_a=b will call the copy constructor.
|
