Le samedi 03 mars 2012 à 19:18 +0100, Jacob Carlborg a écrit :
> On 2012-03-03 17:50, bioinfornatics wrote:
> > Le samedi 03 mars 2012 à 17:42 +0100, bioinfornatics a écrit :
> >> hi,
> >> In ruby we can delegate some method. by example:
> >> ---- Ruby ----
> >> class MineArray
> >> include Forwardable
> >> def_delegators: @array, :[], :[]=, :each_with_index, :length
> >>
> >> def initialize( array )
> >> @array = array
> >> end
> >> end
> >> -------------
> >>
> >> this code delegate opIndexAssign opIndex, length ... attribute to his
> >> member.
> >>
> >> This save time, bug and line. You do not to have to write a code as:
> >> void opIndexAssign( size_t index, T item){
> >> array[index] = item;
> >> }
> >>
> >> thanks
> >>
> > I miss the question ^^
> >
> > can w do same in D ?
> >
> > thanks
>
> I would say "yes", but not with the same pretty syntax. Something like this:
>
> class MineArray
> {
> mixin delegates!(array, "opIndexAssign", "opIndex");
> }
>
> Just implement "delegates" to generate the given functions and forward
> them to "array".
>
I have try to do a mixin template but i fail
------------------ D Code --------------------
import std.string;
import std.stdio;
import std.range;
mixin template arrayDelegator( alias instance, methods... ){
string result;
static if( methods.length > 0 ){
static if( "opIndexAssign" ){
result ~="
void opIndexAssign( size_t index, " ~
ElementEncodingType!(typeof(instance)) ~ " item ){
array[index] = item;
}
";
}
static else if( "opIndex" ){
result ~="
" ~ ElementEncodingType!(typeof(instance)) ~ " opIndex( size_t index
){
return instance[index];
}
";
}
static else if( "length" ){
result ~="
@property size_t length(){
return instance.length;
}
";
}
static else
throw new Exception( "Unknown methods: "~ method );
static if( methods.length > 2 )
arrayDelegator!( instance, methods[1 .. $ ] );
}
mixin(result);
}
class Container{
size_t[] array;
mixin arrayDelegator!(array, "opIndexAssign", "opIndex", "length");
this( size_t[] a ){
array = a:
}
}
void main( string[] args ){
Container c = new Container( [0u, 1u, 2u, 3u] );
writeln( c[2] );
c[2] = 4u;
writeln( c[2] );
}
---------------------------------------------------------
$ ldc2 delegator.d
delegator.d(9): no identifier for declarator result
delegator.d(9): semicolon expected, not '~='
delegator.d(9): Declaration expected, not '~='
delegator.d(15): Declaration expected, not 'else'
delegator.d(22): Declaration expected, not 'else'
delegator.d(29): Declaration expected, not 'else'
delegator.d(32): no identifier for declarator
arrayDelegator!(instance,methods[1 .. __dollar])
delegator.d(33): unrecognized declaration
