Error: need this for method of type

[Márcio Martins via Digitalmars-d-learn]

Hi!

Consider this simplified program:
```
import std.stdio;

struct X {
void method(int x) {
writeln("method called");
}
}


void main() {
X x;

foreach (member; __traits(allMembers, X)) {
alias method = __traits(getMember, x, member);
method(1);
}
}
```

Output:
test.d(15): Error: need this for method of type void(int x)



This one as well:
```
import std.stdio;

struct X {
void method(int x) {
writeln("method(int) called");
}
}


struct Y {
void method(ref X x) {
foreach (member; __traits(allMembers, X)) {
alias method = __traits(getMember, x, member);
method(1);
}
}
}


void main() {
Y y;
X x;
y.method(x);
}
```

Output:
```test.d(14): Error: this for method needs to be type X not type 
Y```



This is a bug, right? If not, why, and how can I get around it 
and call `method`?

Re: Error: need this for method of type

[Dennis via Digitalmars-d-learn]

On Wednesday, 23 October 2019 at 11:40:09 UTC, Márcio Martins 
wrote:
This is a bug, right? If not, why, and how can I get around it 
and call `method`?


An alias refers just to a symbol, in this case a member function 
of struct X.
The fact that you polled it on instance 'x' is not something an 
alias keeps track of.

You can change `method(1)` into `x.method(1)` and it should work.

Re: Error: need this for method of type

[Dennis via Digitalmars-d-learn]

On Wednesday, 23 October 2019 at 11:48:29 UTC, Dennis wrote:
You can change `method(1)` into `x.method(1)` and it should 
work.


Wait, but that's only because the local alias and member function 
have the same name 'method'.
I think you just have to keep the method name as a string instead 
of an alias and use ` __traits(getMember, x, member)(3);` the 
moment you want to call it.