Re: Getting a template parameter list
On Tue, Jul 24, 2012 at 11:08 AM, Simen Kjaeraas wrote: >> Sigh... I'll go back to parsing a .stringof representation. > > > I went ahead and filed a new bug[1], and (90) minutes after, Kenji Hara > responded > this is already implemented for 2.060. > > [1]: http://d.puremagic.com/issues/show_bug.cgi?id=8420 I'm getting used to being kenji'ed on a regular basis. Thanks Kenji! Geez, I guess I didn't thank you this week, that was a long time without yet another miraculous and instantaneous bug correction :) Philippe
Re: Getting a template parameter list
On Tue, 24 Jul 2012 08:08:19 +0200, Philippe Sigaud
wrote:
class C(T,U) {}
// does not work on class C
template dissect1(T : Name!(Params), alias Name, Params...) {}
// works on class C
template dissect2(T : Name!(Param1, Param2), alias Name, Param1, Param2)
{}
No ambiguity. But hell, a lot less power also.
Sigh... I'll go back to parsing a .stringof representation.
I went ahead and filed a new bug[1], and (90) minutes after, Kenji Hara
responded
this is already implemented for 2.060.
[1]: http://d.puremagic.com/issues/show_bug.cgi?id=8420
--
Simen
Re: Getting a template parameter list
On Mon, Jul 23, 2012 at 4:08 PM, Simen Kjaeraas wrote:
> This was filed as bug 3608[1], but that report was insufficiently specific,
> and so T... matching both a TemplateParameterList and a variadic
> TemplateParameter apparently did not make it into the patch.
>
> I'm unsure if I should mark the old bug report as reopened, or file a new
> one.
In a sense, it's cleaner that way: is() trailing params (or template
specializations, as you used in the bug report) are exactly the ones
present in the template.
class C(T,U) {}
// does not work on class C
template dissect1(T : Name!(Params), alias Name, Params...) {}
// works on class C
template dissect2(T : Name!(Param1, Param2), alias Name, Param1, Param2) {}
No ambiguity. But hell, a lot less power also.
Sigh... I'll go back to parsing a .stringof representation.
Philippe
Re: Getting a template parameter list
On Mon, 23 Jul 2012 15:46:37 +0200, Philippe Sigaud wrote: Can someone offer me some advice on this? My old version that cheated with the type .stringof suddenly seems so much better. This was filed as bug 3608[1], but that report was insufficiently specific, and so T... matching both a TemplateParameterList and a variadic TemplateParameter apparently did not make it into the patch. I'm unsure if I should mark the old bug report as reopened, or file a new one. [1]: http://d.puremagic.com/issues/show_bug.cgi?id=3608 -- Simen
Re: Getting a template parameter list
On Monday, 23 July 2012 at 13:32:54 UTC, Philippe Sigaud wrote:
As an aside to a reflection-related train of thought, I tired
again to get a templated type's parameter list.
I mean, given
class C(T) { T t; }
Drat, 'tab' is dangerous with the forum interface, sorry for that.
So given C above and
auto c = new C!(int)();
I want a template that, given typeof(c), gives me back 'C' and
'int'.
is() is our friend here, notably the new T... extension:
import std.typetuple;
template Composition(T) if (isComposite!T)
{
static if (is(T comp == Name!(U), alias Name, U) || is (T
comp == Name!(U), alias Name, U...))
alias TypeTuple!(Name, U) Composition;
}
(isComposite!T is the same check with is())
Works beautifully:
auto t = tuple(1,"abc", 'c');
writeln(Composition!(typeof(t)).stringof); // ("Tuple(Specs...)",
int, string, char)
So, I get "Tuple(Specs...)" (the template name) and the
arguments. Nice!
Except, this does not work for 2-args templates. I thought the
U... branch would get them, but apparently, U... means 'with a
template param tuple' very strictly. No problem, I'll just add
the 2, 3 and 4-args cases, that should be enough.
template Composition(T) if (isComposite!T)
{
static if (is(T comp == Name!(U), alias Name, U) || is (T
comp == Name!(U), alias Name, U...))
alias TypeTuple!(Name, U) Composition;
else static if (is(T comp == Name!(U,V), alias Name, U, V))
alias TypeTuple!(Name, U,V) Composition;
else static if (is(T comp == Name!(U,V,W), alias Name, U, V,
W))
alias TypeTuple!(Name, U,V,W) Composition;
...
}
(and isComposite accordingly).
Right. Except, this only gets template instantiations with pure
types as parameters. Things like std.algorithm.map which take a
function by name are out.
OK... So, I'll add also alias overloads. Hmm, Pure Type / Alias :
2 possibilities, so for 3 args that's 8 different tests to do + 4
for 2-params, + 2 for the single param and the tuple...
Except, you can have a tuple also in 2-params and 3-params
templates.
Also, what about value template parameters? I tested, this does
not work when passed strings or ints, or whatever. I should test
for them also.
Argh, so it's more 10 different possibilities per slot, the n-th
power for n args.
No way am I generating a template with more than a thousand(!)
is() tests in it!
Can someone offer me some advice on this? My old version that
cheated with the type .stringof suddenly seems so much better.
Philippe
Getting a template parameter list
As an aside to a reflection-related train of thought, I tired
again to get a templated type's parameter list.
I mean, given
class C(T) { T t; }
