digitalmars.D.learn - static foreach and inline if

JS (25/25) Jul 27 2013 I'd like to have foreach and inline if in templates:

JS (2/2) Jul 27 2013 BTW, it works with static if's, I'm trying to use an inline if to

monarch_dodra (19/21) Jul 27 2013 I don't really understand, since you didn't really explain *what*

anonymous (4/8) Jul 27 2013 Lower case 'f' here, ...

JS (4/12) Jul 27 2013 Thanks... I'm glad someone can see the tree's from the forest. (I

QAston (2/3) Jul 28 2013 inline if is available as std.traits.Select

JS (4/7) Jul 28 2013 This doesn't work for variadic args...

JS (2/10) Jul 28 2013 Obviously I mean Select!

JS (31/31) Jul 28 2013 The following works but is somewhat of a hack...
anonymous (3/15) Jul 28 2013 template Wrap(Stuff ...) {alias unwrap = Stuff;}

JS (3/19) Jul 28 2013 I tried to do that with tuple which is identical to your wrap but

monarch_dodra (3/6) Jul 28 2013 It should work. You can expand the *types* with Types, and the
anonymous (6/14) Jul 28 2013 If you're refering to that implementation of tuple:

"JS" <js.mdnq gmail.com> writes:

I'd like to have foreach and inline if in templates:


The tIf doesn't work properly but I'm not sure why


template tuple(args...) { alias tuple = args; }

template tIf(bool cond) { alias tIf = tuple!(); }
template tIf(bool cond, alias T)
{
	static if (cond) alias tIF = T; else alias tIF = tuple!();
}

template tForEach(alias func, args...)
{
	pragma(msg, args);
	static if (args.length == 0)
		alias tForEach = tuple!();
	else
	{
		static assert(is(typeof(func(args[0]))), "tForEach: function 
not valid for argument : "~typeof(args[0]).stringof);
		pragma(msg, "1"~typeof(args[0]).stringof);
		alias tForEach = tuple!(func(args[0]), tIf!(args.length > 1, 
tForEach!(func, args[1..$])));
	}
}


e.g.,

writeln(tForEach((string x) => x ~ ";", "a", "b"));

should print a;b;

Jul 27 2013

"JS" <js.mdnq gmail.com> writes:

BTW, it works with static if's, I'm trying to use an inline if to 
reduce redundant code.... since there is no static ?:.

Jul 27 2013

"monarch_dodra" <monarchdodra gmail.com> writes:

On Saturday, 27 July 2013 at 17:15:54 UTC, JS wrote:
 BTW, it works with static if's, I'm trying to use an inline if 
 to reduce redundant code.... since there is no static ?:.

I don't really understand, since you didn't really explain *what* 
you were trying to do before pasting that code, but for what it's 
worth, there *is* static foreach is supported in D, via 
typetuples. Once you are inside a static you can evaluate the arg 
statically.

import std.typetuple, std.stdio;
void main()
{
   foreach(I; TypeTuple!(0, 1, 2))
   {
     static if (I == 1)
       writeln(I);
   }
}

As you can see, this compiles, meaning the if is evaluated at 
compile time. Does this help you?

I'm currently working on a static Iota. Details here:
http://d.puremagic.com/issues/show_bug.cgi?id=4085

Jul 27 2013

"anonymous" <anonymous example.com> writes:

On Saturday, 27 July 2013 at 17:14:35 UTC, JS wrote:
 The tIf doesn't work properly but I'm not sure why

[...]
 template tIf(bool cond, alias T)

Lower case 'f' here, ...

 {
 	static if (cond) alias tIF = T; else alias tIF = tuple!();

... upper case 'F's here.

Jul 27 2013

"JS" <js.mdnq gmail.com> writes:

On Saturday, 27 July 2013 at 19:06:48 UTC, anonymous wrote:
 On Saturday, 27 July 2013 at 17:14:35 UTC, JS wrote:
 The tIf doesn't work properly but I'm not sure why

 [...]
 template tIf(bool cond, alias T)

 Lower case 'f' here, ...

 {
 	static if (cond) alias tIF = T; else alias tIF = tuple!();

 ... upper case 'F's here.

Thanks... I'm glad someone can see the tree's from the forest. (I 
originally was going to use all caps but changed it at the last 
minute.

Jul 27 2013

"QAston" <qaston gmail.com> writes:

On Saturday, 27 July 2013 at 17:14:35 UTC, JS wrote:
 I'd like to have foreach and inline if in templates:

inline if is available as std.traits.Select

Jul 28 2013

"JS" <js.mdnq gmail.com> writes:

On Sunday, 28 July 2013 at 08:30:17 UTC, QAston wrote:
 On Saturday, 27 July 2013 at 17:14:35 UTC, JS wrote:
 I'd like to have foreach and inline if in templates:

 inline if is available as std.traits.Select

This doesn't work for variadic args...

Something Split!(Cond, targ..., split, fargs) is what I need... 
where split somehow signals the split between the two.

Jul 28 2013

"JS" <js.mdnq gmail.com> writes:

On Sunday, 28 July 2013 at 08:38:01 UTC, JS wrote:
 On Sunday, 28 July 2013 at 08:30:17 UTC, QAston wrote:
 On Saturday, 27 July 2013 at 17:14:35 UTC, JS wrote:
 I'd like to have foreach and inline if in templates:

 inline if is available as std.traits.Select

 This doesn't work for variadic args...

 Something Split!(Cond, targ..., split, fargs) is what I need... 
 where split somehow signals the split between the two.

Obviously I mean Select!

Jul 28 2013

"JS" <js.mdnq gmail.com> writes:

The following works but is somewhat of a hack...

module main;

import std.stdio, std.typetuple;

struct tTupleSplit
{

}

template tIndexOf(T, args...)
{
	static if (staticIndexOf!(T, args) < 0) enum tIndexOf = 
args.length;
	else enum tIndexOf = staticIndexOf!(T, args);
}
template tMin(alias a, alias b)
{
	static if (a < b) alias tMin = a; else alias tMin = b;
}
template tIf(alias cond, args...)
{
	enum sp = tIndexOf!(tTupleSplit, args);
     static if (cond)
	    alias tIf = args[0..tMin!($,sp)];
	else
		alias tIf = args[tMin!($,sp+1)..$];
}

int main(string[] argv)
{

	alias x = tIf!(false, "a", tTupleSplit, "b");
    writeln(x);
    readln();
    return 0;
}

Jul 28 2013

"anonymous" <anonymous example.com> writes:

On Sunday, 28 July 2013 at 08:38:40 UTC, JS wrote:
 On Sunday, 28 July 2013 at 08:38:01 UTC, JS wrote:
 On Sunday, 28 July 2013 at 08:30:17 UTC, QAston wrote:
 On Saturday, 27 July 2013 at 17:14:35 UTC, JS wrote:
 I'd like to have foreach and inline if in templates:

 inline if is available as std.traits.Select

 This doesn't work for variadic args...

 Something Split!(Cond, targ..., split, fargs) is what I 
 need... where split somehow signals the split between the two.

 Obviously I mean Select!

template Wrap(Stuff ...) {alias unwrap = Stuff;}
Select!(cond, Wrap!targs, Wrap!fargs).unwrap

Jul 28 2013

"JS" <js.mdnq gmail.com> writes:

On Sunday, 28 July 2013 at 09:11:55 UTC, anonymous wrote:
 On Sunday, 28 July 2013 at 08:38:40 UTC, JS wrote:
 On Sunday, 28 July 2013 at 08:38:01 UTC, JS wrote:
 On Sunday, 28 July 2013 at 08:30:17 UTC, QAston wrote:
 On Saturday, 27 July 2013 at 17:14:35 UTC, JS wrote:
 I'd like to have foreach and inline if in templates:

 inline if is available as std.traits.Select

 This doesn't work for variadic args...

 Something Split!(Cond, targ..., split, fargs) is what I 
 need... where split somehow signals the split between the two.

 Obviously I mean Select!

 template Wrap(Stuff ...) {alias unwrap = Stuff;}
 Select!(cond, Wrap!targs, Wrap!fargs).unwrap

I tried to do that with tuple which is identical to your wrap but 
was not successful... possibly because I did not unwrap it...

Jul 28 2013

"monarch_dodra" <monarchdodra gmail.com> writes:

On Sunday, 28 July 2013 at 15:33:48 UTC, JS wrote:
 I tried to do that with tuple which is identical to your wrap 
 but was not successful... possibly because I did not unwrap 
 it...

It should work. You can expand the *types* with Types, and the 
*values* with expand.

Jul 28 2013

"anonymous" <anonymous example.com> writes:

On Sunday, 28 July 2013 at 15:33:48 UTC, JS wrote:
 On Sunday, 28 July 2013 at 09:11:55 UTC, anonymous wrote:
 On Sunday, 28 July 2013 at 08:38:40 UTC, JS wrote:


[...]
 template Wrap(Stuff ...) {alias unwrap = Stuff;}
 Select!(cond, Wrap!targs, Wrap!fargs).unwrap

 I tried to do that with tuple which is identical to your wrap 
 but was not successful... possibly because I did not unwrap 
 it...

If you're refering to that implementation of tuple:

On Saturday, 27 July 2013 at 17:14:35 UTC, JS wrote:
 template tuple(args...) { alias tuple = args; }

That's not exactly the same. It really must not be an eponymous 
template.

Jul 28 2013

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digitalmars.D.learn - static foreach and inline if