On Tue, 02 Nov 2010 12:32:54 -0400, kenji hara <[email protected]> wrote:
My first motivation is more easiness of writing meta-programming code.
For formatting output, I usually use writefln.
Quoted-string is very usuful, but interpolating variable is very
difficult.
----
string count = "10";
enum code = q{ enum msg = "I call you } ~ count ~ q{ times"; }
// I want to generate q{ enum msg = "I call you 10 times"; }, but can't.
The main issue is that q{} string respect D syntax, so the } inside the ""
is treated as text, not a terminator. There's lots of ways around this:
enum code = text(q{ enum msg = "I call you "}, count, q{" times"} );
enum code = text(` enum msg = "I call you `, count, ` times;` );
enum code = ` enum msg = "I call you ` ~ count ~ ` times;`
enum code = q{ enum msg = "I call you "} ~ count ~ q{" times"; }
----
With expand!, I can write code generating very easy.
Last, adaptTo contains following code:
----
// generates function definition
template generateFun(string n)
{
enum generateFun = mixin(expand!q{
mixin DeclareFunction!(
CoTypes[${n}], // covariant
NameOf!(TgtFuns[${n}]),
"return source." ~ NameOf!(TgtFuns[${n}]) ~ "(args);"
);
});
}
// mixin all generated function definitions here
mixin mixinAll!(
staticMap!(
generateFun,
staticMap!(StringOf, staticIota!(0,
TgtFuns.length))));
----
If expand! does not exist, it would be terribly ugly.
Kenji
Really?
template generateFun(string n)
{
enum generateFun = mixin(text(q{
mixin DeclareFunction!(
CoTypes[},n,q{], // covariant
NameOf!(TgtFuns[},n,q{]),
"return source." ~ NameOf!(TgtFuns[},n,q{]) ~ "(args);"
);
});
}
I admit ${n} is slightly better than },n,q{, but it's by no means ugly.
(And using `` instead of q{} makes it better: `,n,`)
_______________________________________________
phobos mailing list
[email protected]
http://lists.puremagic.com/mailman/listinfo/phobos
