tmp/tmpkprqb4yk/{from.md → to.md}
RENAMED
|
@@ -0,0 +1,52 @@
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
| 1 |
+
#### Simple assignment <a id="over.assign">[[over.assign]]</a>
|
| 2 |
+
|
| 3 |
+
A *simple assignment operator function* is a binary operator function
|
| 4 |
+
named `operator=`. A simple assignment operator function shall be a
|
| 5 |
+
non-static member function.
|
| 6 |
+
|
| 7 |
+
[*Note 1*: Because only standard conversion sequences are considered
|
| 8 |
+
when converting to the left operand of an assignment operation
|
| 9 |
+
[[over.best.ics]], an expression `x = y` with a subexpression x of class
|
| 10 |
+
type is always interpreted as `x.operator=(y)`. — *end note*]
|
| 11 |
+
|
| 12 |
+
[*Note 2*: Since a copy assignment operator is implicitly declared for
|
| 13 |
+
a class if not declared by the user [[class.copy.assign]], a base class
|
| 14 |
+
assignment operator function is always hidden by the copy assignment
|
| 15 |
+
operator function of the derived class. — *end note*]
|
| 16 |
+
|
| 17 |
+
[*Note 3*:
|
| 18 |
+
|
| 19 |
+
Any assignment operator function, even the copy and move assignment
|
| 20 |
+
operators, can be virtual. For a derived class `D` with a base class `B`
|
| 21 |
+
for which a virtual copy/move assignment has been declared, the
|
| 22 |
+
copy/move assignment operator in `D` does not override `B`’s virtual
|
| 23 |
+
copy/move assignment operator.
|
| 24 |
+
|
| 25 |
+
[*Example 1*:
|
| 26 |
+
|
| 27 |
+
``` cpp
|
| 28 |
+
struct B {
|
| 29 |
+
virtual int operator= (int);
|
| 30 |
+
virtual B& operator= (const B&);
|
| 31 |
+
};
|
| 32 |
+
struct D : B {
|
| 33 |
+
virtual int operator= (int);
|
| 34 |
+
virtual D& operator= (const B&);
|
| 35 |
+
};
|
| 36 |
+
|
| 37 |
+
D dobj1;
|
| 38 |
+
D dobj2;
|
| 39 |
+
B* bptr = &dobj1;
|
| 40 |
+
void f() {
|
| 41 |
+
bptr->operator=(99); // calls D::operator=(int)
|
| 42 |
+
*bptr = 99; // ditto
|
| 43 |
+
bptr->operator=(dobj2); // calls D::operator=(const B&)
|
| 44 |
+
*bptr = dobj2; // ditto
|
| 45 |
+
dobj1 = dobj2; // calls implicitly-declared D::operator=(const D&)
|
| 46 |
+
}
|
| 47 |
+
```
|
| 48 |
+
|
| 49 |
+
— *end example*]
|
| 50 |
+
|
| 51 |
+
— *end note*]
|
| 52 |
+
|