• Andrej Mitrovic <andrej.mitrovich gmail.com> Sep 26 2011
• David Nadlinger <see klickverbot.at> Sep 26 2011
• travert phare.normalesup.org (Christophe) Sep 28 2011
• bearophile <bearophileHUGS lycos.com> Sep 28 2011
• Andrej Mitrovic <andrej.mitrovich gmail.com> Sep 27 2011
• Andrej Mitrovic <andrej.mitrovich gmail.com> Sep 28 2011

Andrej Mitrovic <andrej.mitrovich gmail.com> writes:

import std.typetuple;
import std.traits;

alias TypeTuple!(int, float) MyTypes;
template isCompatible(T)
{
    enum bool isCompatible = allSatisfy!(isImplicitlyConvertible!T, MyTypes);
}

This won't work since the compiler tries to instantiate
isImplicitlyConvertible with a single type (it takes two types).

The reason I'm doing this is to catch bad arguments inside of a static
assert so I can give out better error messages and optionally provide
a tip (based on a version switch). The above won't work, so do you
know of a workaround?

David Nadlinger <see klickverbot.at> writes:

On 9/26/11 9:32 PM, Andrej Mitrovic wrote:
 alias TypeTuple!(int, float) MyTypes;
 template isCompatible(T)
 {
      enum bool isCompatible = allSatisfy!(isImplicitlyConvertible!T, MyTypes);
 }


template PApply(alias Target, T...) {
   template PApply(U...) {
     alias Target!(T, U) PApply;
   }
}

…

enum isCompatible = allSatisfy!(PApply!(isImplicitlyConvertible, T), 
MyTypes);

David

travert phare.normalesup.org (Christophe) writes:

Andrej Mitrovic , dans le message (digitalmars.D.learn:29825), a écrit :
 Thanks for the tips guys. I have another similar issue now, I want to
 check whether a type passes any of the predicates I list. This would
 be similar to anySatisfy, however anySatisfy takes one predicate and
 multiple types, and what I need is one type and multiple predicates,
 e.g.:
 
 anyPredicateSatisfy!(int, isNumeric, isIntegral);
 
 I've tried copying anySatisfy's code and modifying it to work:
 
 template anyPredicateSatisfy(T, F...)
 {
     static if (F.length == 0)
     {
         enum bool anySatisfy = false;
     }
     else static if (F.length == 1)
     {
         enum bool anySatisfy = (F[0])!T;
     }
     else
     {
         enum bool anySatisfy = (F[0])!T) || anySatisfy!(T, F[1 .. $]);


     }
 }
 
 But the compiler thinks I'm doing C-style casts so this doesn't work. Any
clues?

bearophile <bearophileHUGS lycos.com> writes:

Andrej Mitrovic:

 But the compiler thinks I'm doing C-style casts so this doesn't work. Any
clues?


This seems to work (eye the base of the recursion):

template satisfies(T, alias P) { enum satisfies = P!T; }
 
template anyPredicateSatisfy(T, Preds...) {
    static if (Preds.length)
        //enum bool anyPredicateSatisfy = (Preds[0]!T) ||
anyPredicateSatisfy!(T, Preds[1 .. $]);
        enum bool anyPredicateSatisfy = satisfies!(T, Preds[0]) ||
anyPredicateSatisfy!(T, Preds[1 .. $]);
    else
        enum bool anyPredicateSatisfy = false;
}
 
template is4(T) { enum is4 = T.sizeof == 4; }
template signed(T) { enum signed = T.min != 0; }
 
static assert(anyPredicateSatisfy!(int, is4, signed));
 
void main() {}


Maybe the error on (Preds[0]!T) is fodder for Bugzilla.

Bye,
bearophile

Andrej Mitrovic <andrej.mitrovich gmail.com> writes:

Thanks for the tips guys. I have another similar issue now, I want to
check whether a type passes any of the predicates I list. This would
be similar to anySatisfy, however anySatisfy takes one predicate and
multiple types, and what I need is one type and multiple predicates,
e.g.:

anyPredicateSatisfy!(int, isNumeric, isIntegral);

I've tried copying anySatisfy's code and modifying it to work:

template anyPredicateSatisfy(T, F...)
{
    static if (F.length == 0)
    {
        enum bool anySatisfy = false;
    }
    else static if (F.length == 1)
    {
        enum bool anySatisfy = (F[0])!T;
    }
    else
    {
        enum bool anySatisfy = (F[0])!T) || anySatisfy!(T, F[1 .. $]);
    }
}

But the compiler thinks I'm doing C-style casts so this doesn't work. Any clues?

Andrej Mitrovic <andrej.mitrovich gmail.com> writes:

Thanks, that works. I'll report the bug as well.