Re: Can attributes trigger functionality?

[Adam D. Ruppe via Digitalmars-d-learn]

On Wednesday, 6 September 2017 at 02:43:20 UTC, Psychological 
Cleanup wrote:

I'm having to create a lot of boiler plate code that creates 
"events" and corresponding properties(getter and setter).

I'm curious if I can simplify this without a string mixin.


You certainly don't need a string mixin, but you do need some 
code to react to the attribute.

Here's one that generates a wrapper function on-demand:

---

import std.stdio;
import std.traits;

class Test {
        @cool void foo_() {
                writeln("cool function called");
        }

        mixin CoolFunctions;
}

// our UDA
enum cool;

// adds the decorator implementation
mixin template CoolFunctions() {
        template opDispatch(string name) 
if(hasUDA!(__traits(getMember, typeof(this), name ~ "_"), cool)) {
                auto opDispatch(Parameters!(__traits(getMember, 
typeof(this), name ~ "_")) params) {
                        writeln("cool before");
                        scope(success) {
                                writeln("cool after");
                        }
                        return __traits(getMember, this, name ~ 
"_")(params);
                }
        }
}

void main() {
        auto test = new Test();
        test.foo();
}

-----


No string mixin (uses a mixin template instead), and not even a 
loop over the functions - it does them on-demand when used via 
opDispatch.