Re: Using custom attribute for a general parser. Is possible in D ?

[Ali Çehreli via Digitalmars-d-learn]

On 05/23/2014 09:09 AM, bioinfornatics wrote:

> struct A {
>           @section( ( word ) =>  word[0] == '@', ( word ) =>
> word[0] == '\n')
>           int a;
> }

I was able to make that work if I used function instead of delegate:

import std.stdio;

struct attribute { }

alias MatchFunc = bool function( string );

@attribute
struct section {
     MatchFunc start;
     MatchFunc end;

     this( in MatchFunc start,
           in MatchFunc end)
     {
         this.start  = start,
         this.end    = end;
     }
}

struct A {
    @section((string word) => word[0] == '@',
             (string word) => word[0] == '\n')
    int a;
}

import std.traits;

void main()
{
    auto aa = A();
    auto t = __traits(getAttributes, A.a);

    foreach (sect; t) {
        auto start_result = sect.start("@test");
        auto end_result = sect.end("\n");

        writefln("Results: %s and %s", start_result, end_result);
    }
}

Ali