digitalmars.D - alias this and opDot()
- Salih Dincer (29/29) Sep 27 2022 Ok, opDot() is deprecated in version 2.082. However, if we
- user1234 (26/55) Sep 27 2022 opdot is called two times so you reset the state of point members
- user1234 (22/84) Sep 27 2022 I realize that maybe you are aware of what's happening, in which
- Salih Dincer (15/17) Sep 28 2022 ```d
Ok, opDot() is deprecated in version 2.082. However, if we
simulate this situation with a function (opdot in our example),
we get unexpected results.
```d
struct Point { int x, y; }
struct S
{
Point point;
alias opdot this;
auto opdot()
{ // opDot() is deprecated in v2.082
//this.point = Point(100, 100);/* <-- also if you only use:
s == Point(100, 101)
point.x = 100;
point.y = 100;
point.x++;//*/
return &point;
}
}
void main()
{
S s;
s.x++; // as if this line doesn't exist!
s.y++;
//s.x++; // <-- also if you use: s == Point(102, 100)
assert(s.point == Point(101, 101));
}
```
SDB 79
Sep 27 2022
On Wednesday, 28 September 2022 at 03:45:59 UTC, Salih Dincer
wrote:
Ok, opDot() is deprecated in version 2.082. However, if we
simulate this situation with a function (opdot in our example),
we get unexpected results.
```d
struct Point { int x, y; }
struct S
{
Point point;
alias opdot this;
auto opdot()
{ // opDot() is deprecated in v2.082
//this.point = Point(100, 100);/* <-- also if you only
use: s == Point(100, 101)
point.x = 100;
point.y = 100;
point.x++;//*/
return &point;
}
}
void main()
{
S s;
s.x++; // as if this line doesn't exist!
s.y++;
//s.x++; // <-- also if you use: s == Point(102, 100)
assert(s.point == Point(101, 101));
}
```
SDB 79
opdot is called two times so you reset the state of point members
100
```d
struct Point { int x, y; }
struct S
{
Point point;
alias opdot this;
Point* opdot() return
{
this.point.x = 100;
this.point.y = 100;
return &this.point;
}
}
void main()
{
S s;
s.x += 1;
assert(s.point == Point(101, 100));
s.y += 1;
assert(s.point == Point(100, 101));
}
```
Sep 27 2022
user1234 <user1234 12.de> On Wednesday, 28 September 2022 at 06:39:30 UTC, user1234 wrote:On Wednesday, 28 September 2022 at 03:45:59 UTC, Salih Dincer wrote:I realize that maybe you are aware of what's happening, in which case you need to use opDispatch instead ```d struct Point { int x, y; } struct S { Point point; auto ref opDispatch(string member)() return { return __traits(getMember, point, member); } } void main() { S s; s.x += 1; assert(s.point == Point(1, 0)); s.y += 1; assert(s.point == Point(1, 1)); } ```Ok, opDot() is deprecated in version 2.082. However, if we simulate this situation with a function (opdot in our example), we get unexpected results. ```d struct Point { int x, y; } struct S { Point point; alias opdot this; auto opdot() { // opDot() is deprecated in v2.082 //this.point = Point(100, 100);/* <-- also if you only use: s == Point(100, 101) point.x = 100; point.y = 100; point.x++;//*/ return &point; } } void main() { S s; s.x++; // as if this line doesn't exist! s.y++; //s.x++; // <-- also if you use: s == Point(102, 100) assert(s.point == Point(101, 101)); } ``` SDB 79opdot is called two times so you reset the state of point members 100 ```d struct Point { int x, y; } struct S { Point point; alias opdot this; Point* opdot() return { this.point.x = 100; this.point.y = 100; return &this.point; } } void main() { S s; s.x += 1; assert(s.point == Point(101, 100)); s.y += 1; assert(s.point == Point(100, 101)); } ```
Sep 27 2022
On Wednesday, 28 September 2022 at 06:39:30 UTC, user1234 wrote:opdot is called two times so you reset the state of point members 100```d void main() { S s; s.x++; /* In this line, it's x = y = 100 firstly, then x = 101 and 102. */ s.y++; /* In this line, it's x = y = 100 again, then x = 101 and y = 101. */ assert(s.point == Point(101, 101)); // That's ok... } ``` Thank you... It seems that I'm as sharp as a tack. 😀 SDB 79
Sep 28 2022