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September 23, 2010
Re: foreach over enums?
%u <e@ee.com> wrote:

>> I'm not sure what you're getting at here. In what way that you don't  
>> like
>> it is it enum-unlike?
>
> These two have distinctly different outputs ;P
>
> alias defineEnum!( "A", "B", "C" ) Bar;
> writefln( typeof(Bar.A).stringof );
>
> enum Foo { A, B, C }
> writefln( typeof(Foo.A).stringof );

They do. There are ways around that - mostly by using string mixins
on this form:

    template defineEnum( string name, T... ) {
        string defineEnum = "struct " ~ name ~ " {"
            // Stuff from other implementation goes here.
        "}"
    }

    mixin( defineEnum!( "EnumName", "A","B","C" ) );

This pattern is one of the reasons I have been lobbying for automatic
mixin templates in D2 - it should look only like this:

    defineEnum!( "EnumName", "A","B","C" )


> Won't the compiler even choke on the type size when feeding defineEnum a  
> hundred
> elements or so?

Types are limited to 64K of memory, I think. That should be enough for 16K
elements in this case. If you're thinking of the horribly long names,
I believe identifiers are hashed rather than being stored wholesale, once
they move past 16K.

-- 
Simen
September 24, 2010
Re: foreach over enums?
== Quote from Simen kjaeraas (simen.kjaras@gmail.com)'s article
> %u <e@ee.com> wrote:
> >> I'm not sure what you're getting at here. In what way that you don't
> >> like
> >> it is it enum-unlike?
> >
> > These two have distinctly different outputs ;P
> >
> > alias defineEnum!( "A", "B", "C" ) Bar;
> > writefln( typeof(Bar.A).stringof );
> >
> > enum Foo { A, B, C }
> > writefln( typeof(Foo.A).stringof );
> They do. There are ways around that - mostly by using string mixins
> on this form:
>      template defineEnum( string name, T... ) {
>          string defineEnum = "struct " ~ name ~ " {"
>              // Stuff from other implementation goes here.
>          "}"
>      }
Of course! The encapsulation only needs to string mixin the struct signature.

>      mixin( defineEnum!( "EnumName", "A","B","C" ) );
> This pattern is one of the reasons I have been lobbying for automatic
> mixin templates in D2 - it should look only like this:
>      defineEnum!( "EnumName", "A","B","C" )

Looking more and more like typecons's defineEnum :)
though, supporting a non-continues range of values (which I don't need) will be
annoying in this setup, I think..
but, I think typecons uses the slow if version..

> > Won't the compiler even choke on the type size when feeding defineEnum a
> > hundred
> > elements or so?
> Types are limited to 64K of memory, I think. That should be enough for 16K
> elements in this case. If you're thinking of the horribly long names,
> I believe identifiers are hashed rather than being stored wholesale, once
> they move past 16K.
Good to know.

All this makes for a nice freachable D1 defineEnum, thanks!
September 24, 2010
Re: foreach over enums?
%u <e@ee.com> wrote:

> though, supporting a non-continues range of values (which I don't need)  
> will be
> annoying in this setup, I think..

Impossible in the current version, unless you accept having a bunch of
dummy fields. It is not hard to implement:

template defineStaticImpl( T, int value, string name ) {
    // Do as below, no recursion.
}

template defineStaticImpl( T, int value, string name, string next, args...  
) {
    // Mostly as before.
}


template defineStaticImpl( T, int value, string name, int actualValue,  
args... ) {
    mixin defineStaticImpl!( T, actualValue, name, args );
}

>> > Won't the compiler even choke on the type size when feeding  
>> defineEnum a
>> > hundred
>> > elements or so?
>> Types are limited to 64K of memory, I think. That should be enough for  
>> 16K
>> elements in this case. If you're thinking of the horribly long names,
>> I believe identifiers are hashed rather than being stored wholesale,  
>> once
>> they move past 16K.
> Good to know.
>
> All this makes for a nice freachable D1 defineEnum, thanks!

My pleasure. Was a fun challenge.

-- 
Simen
October 05, 2010
Re: foreach over enums?
Simen kjaeraas napisał:

> enum X { A=3, B=1, C }
> 
> void main( ) {
> foreach( e;  __traits(allMembers, X) ) {
> writeln( "X.", e, " = ", mixin( "X."~e ) );
> }
> }

mixin("X."~e)  =>  __traits(getMember, X, e)
For mixin-allergics.

-- 
Tomek
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