[Issue 1827] Uniform syntax for is(), static if, alias, template definition & static assert

[d-bugmail at puremagic.com]

http://d.puremagic.com/issues/show_bug.cgi?id=1827





------- Comment #3 from aarti at interia.pl  2008-02-12 06:52 -------
continuation for 'alias' thing...

Templates already currently can evaluate to one of two:
1. manifest constant
2. type (symbol)

---------------------

Template which evaluates to manifest constant:

template isRefType(T) {
    static if (is(T TYPE == TYPE*) || is(T == class))
        const isRefType = true; // or alias true isRefType;
    else
        const isRefType = false;  // or alias false isRefType;
}

Unfortunately syntax:

alias true isRefType;

is not very readable, so maybe it would be worth to introduce
inverted syntax when only one symbol is defined:

alias isRefType = true;

as alternative...

---------------------

It would be in pair with templates which evaluates to type:

Template which evaluates to type:

template arrayElementType(T) {
    static if( is( T U : U[] ) )
        alias U arrayElementType;
    else
        static assert(false, "'" ~ T.stringof ~ "' is not an array.");
}

BTW. with alias syntax above template will be not necessary at all, as it would
be probably easier to write:

alias T U : U[];


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