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digitalmars.D - Need trait of isPod.

reply Yang Bo <pop.atry gmail.com> writes:
Because I really want to know whether a type is pod.
Oct 09 2007
parent reply Aarti_pl <aarti interia.pl> writes:
Yang Bo pisze:

 Because I really want to know whether a type is pod.


Simple template should be just enough.

See: http://dsource.org/projects/tango/browser/trunk/tango/core/Variant.d


template isAtomicType( T ) {
	static if( is( T == bool )
 		|| is( T == char )
 	        || is( T == wchar )
 	        || is( T == dchar )
 	        || is( T == byte )
 	        || is( T == short )
 	        || is( T == int )
 	        || is( T == long )
 	        || is( T == ubyte )
 	        || is( T == ushort )
 	        || is( T == uint )
 	        || is( T == ulong )
 	        || is( T == float )
 	        || is( T == double )
 	        || is( T == real )
 	        || is( T == ifloat )
 	        || is( T == idouble )
 	        || is( T == ireal ) )
 		const isAtomicType = true;
	else
 	        const isAtomicType = false;
}

BR
Marcin Kuszczak
(aarti_pl)
Oct 09 2007
parent reply Matti Niemenmaa <see_signature for.real.address> writes:
Aarti_pl wrote:

 Yang Bo pisze:

 Because I really want to know whether a type is pod.


 
 Simple template should be just enough.
 
 See: http://dsource.org/projects/tango/browser/trunk/tango/core/Variant.d
 
 
 template isAtomicType( T ) {
 	static if( is( T == bool )
  		|| is( T == char )
  	        || is( T == wchar )
  	        || is( T == dchar )
  	        || is( T == byte )
  	        || is( T == short )
  	        || is( T == int )
  	        || is( T == long )
  	        || is( T == ubyte )
  	        || is( T == ushort )
  	        || is( T == uint )
  	        || is( T == ulong )
  	        || is( T == float )
  	        || is( T == double )
  	        || is( T == real )
  	        || is( T == ifloat )
  	        || is( T == idouble )
  	        || is( T == ireal ) )
  		const isAtomicType = true;
 	else
  	        const isAtomicType = false;
 }


That misses structs, which are also POD.

-- 
E-mail address: matti.niemenmaa+news, domain is iki (DOT) fi
Oct 09 2007
next sibling parent reply Aarti_pl <aarti interia.pl> writes:
Matti Niemenmaa pisze:

 Aarti_pl wrote:

 Yang Bo pisze:

 Because I really want to know whether a type is pod.


 Simple template should be just enough.

 See: http://dsource.org/projects/tango/browser/trunk/tango/core/Variant.d


 template isAtomicType( T ) {
 	static if( is( T == bool )
  		|| is( T == char )
  	        || is( T == wchar )
  	        || is( T == dchar )
  	        || is( T == byte )
  	        || is( T == short )
  	        || is( T == int )
  	        || is( T == long )
  	        || is( T == ubyte )
  	        || is( T == ushort )
  	        || is( T == uint )
  	        || is( T == ulong )
  	        || is( T == float )
  	        || is( T == double )
  	        || is( T == real )
  	        || is( T == ifloat )
  	        || is( T == idouble )
  	        || is( T == ireal ) )
  		const isAtomicType = true;
 	else
  	        const isAtomicType = false;
 }


 
 That misses structs, which are also POD.
 


It should be just enough to add additional condition:

	(...)
	|| is( T == struct )
	(...)

and also probably union and enum.

More:
http://digitalmars.com/d/expression.html  (section: is expression)


BR
Marcin Kuszczak
(aarti_pl)
Oct 09 2007
next sibling parent reply Paolo Invernizzi <arathorn NO_SPAMfastwebnet.it> writes:
Not related... but what's the expression for testing an associative 
array? DMD 1.0 please...

Paolo

Aarti_pl wrote:

 Matti Niemenmaa pisze:

 Aarti_pl wrote:

 Yang Bo pisze:

 Because I really want to know whether a type is pod.


 Simple template should be just enough.

 See: 
 http://dsource.org/projects/tango/browser/trunk/tango/core/Variant.d


 template isAtomicType( T ) {
     static if( is( T == bool )
          || is( T == char )
              || is( T == wchar )
              || is( T == dchar )
              || is( T == byte )
              || is( T == short )
              || is( T == int )
              || is( T == long )
              || is( T == ubyte )
              || is( T == ushort )
              || is( T == uint )
              || is( T == ulong )
              || is( T == float )
              || is( T == double )
              || is( T == real )
              || is( T == ifloat )
              || is( T == idouble )
              || is( T == ireal ) )
          const isAtomicType = true;
     else
              const isAtomicType = false;
 }


 That misses structs, which are also POD.


 
 It should be just enough to add additional condition:
 
     (...)
     || is( T == struct )
     (...)
 
 and also probably union and enum.
 
 More:
 http://digitalmars.com/d/expression.html  (section: is expression)
 
 
 BR
 Marcin Kuszczak
 (aarti_pl)
Oct 08 2007
parent reply Marcin Kuszczak <aarti_nospam please_interia.pl> writes:
Paolo Invernizzi wrote:


 Not related... but what's the expression for testing an associative
 array? DMD 1.0 please...
 
 Paolo


I found following template in Tango core/Traits.d:

private template isAssocArrayType( T )
{
    const bool isAssocArrayType = is( typeof(T.init.values[0]
[typeof(T.init.keys[0])] == T );
}

I don't know if it really works (why is there private access qualifier???).

Probably better answer could give Tango people... and tests of course :-)

-- 
Regards
Marcin Kuszczak (Aarti_pl)
-------------------------------------
Ask me why... I believe in Jesus - http://www.zapytajmnie.com (en/pl)
Doost (port of few Boost libraries) - http://www.dsource.org/projects/doost/
-------------------------------------
Oct 09 2007
parent reply Paolo Invernizzi <arathorn NOSPAM_fastwebnet.it> writes:
This static assert is false under GDC 0.24...

template isAssocArrayType( T )
{
    const bool isAssocArrayType = is(
typeof(T.init.values[0][typeof(T.init.keys[0])]) == T );
}
static assert( isAssocArrayType!( int[char[]] ) );

Paolo


Marcin Kuszczak Wrote:


 Paolo Invernizzi wrote:
 

 Not related... but what's the expression for testing an associative
 array? DMD 1.0 please...
 
 Paolo


 
 I found following template in Tango core/Traits.d:
 
 private template isAssocArrayType( T )
 {
     const bool isAssocArrayType = is( typeof(T.init.values[0]
 [typeof(T.init.keys[0])] == T );
 }
 
 I don't know if it really works (why is there private access qualifier???).
 
 Probably better answer could give Tango people... and tests of course :-)
 
 -- 
 Regards
 Marcin Kuszczak (Aarti_pl)
 -------------------------------------
 Ask me why... I believe in Jesus - http://www.zapytajmnie.com (en/pl)
 Doost (port of few Boost libraries) - http://www.dsource.org/projects/doost/
 -------------------------------------
Oct 10 2007
parent reply Frits van Bommel <fvbommel REMwOVExCAPSs.nl> writes:
Paolo Invernizzi wrote:

 This static assert is false under GDC 0.24...
 
 template isAssocArrayType( T )
 {
     const bool isAssocArrayType = is(
typeof(T.init.values[0][typeof(T.init.keys[0])]) == T );
 }
 static assert( isAssocArrayType!( int[char[]] ) );


The closing bracket of the first typeof() is misplaced. The correct code is
---
template isAssocArrayType( T )
{
     const bool isAssocArrayType = is( 
typeof(T.init.values[0])[typeof(T.init.keys[0])] == T );

}

static assert( isAssocArrayType!( int[char[]] ) );
---

Which also seems to be how it appears in Tango. Maybe Marcin typed it 
over from Tango with a typo? (since the file hasn't changed for 7 months 
according to the svn repository, a copy-paste from an older buggier 
version seems unlikely)
Oct 10 2007
parent Aarti_pl <aarti interia.pl> writes:
Frits van Bommel pisze:
  > Which also seems to be how it appears in Tango. Maybe Marcin typed it

 over from Tango with a typo? (since the file hasn't changed for 7 months 
 according to the svn repository, a copy-paste from an older buggier 
 version seems unlikely)


Just for clarification: That's not my code. It's taken from Tango as I 
pointed out in my first post.

I copied it from dsource page, so during stripping line numbers I 
probably lost one closing bracket.

BR
Marcin Kuszczak
Oct 10 2007
prev sibling parent Lutger <lutger.blijdestijn gmail.com> writes:
Aarti_pl wrote:

 Matti Niemenmaa pisze:


...

 That misses structs, which are also POD.


 
 It should be just enough to add additional condition:
 
     (...)
     || is( T == struct )
     (...)
 
 and also probably union and enum.
 
 More:
 http://digitalmars.com/d/expression.html  (section: is expression)
 
 
 BR
 Marcin Kuszczak
 (aarti_pl)


Correct me if I'm wrong, but I thought POD requires members of a struct 
be public and also POD.
Here is a version (quick hack) that takes these criteria into account 
(D1.0 syntax):

template isAtomicType( T ) {
     static if( is( T == bool )
             || is( T == char )
             || is( T == wchar )
             || is( T == dchar )
             || is( T == byte )
             || is( T == short )
             || is( T == int )
             || is( T == long )
             || is( T == ubyte )
             || is( T == ushort )
             || is( T == uint )
             || is( T == ulong )
             || is( T == float )
             || is( T == double )
             || is( T == real )
             || is( T == ifloat )
             || is( T == idouble )
             || is( T == ireal ) )
         const isAtomicType = true;
     else static if (is(T == struct))
     {
         static if (is (typeof(T.tupleof))) // test for private members
         {
             static if (T.tupleof.length == 0)
                 const isAtomicType = true;
             else
                 const isAtomicType = areAtomicTypes!(typeof(T.tupleof));
         }
         else
             const isAtomicType = false;
     }
     else
        const isAtomicType = false;
}

// helper template
template areAtomicTypes(T...)
{
     static if (T.length == 1)
         const areAtomicTypes = isAtomicType!(T[0]);
     else
         const areAtomicTypes = isAtomicType!(T[0]) && 
areAtomicTypes!(T[1..$]);
}
Oct 09 2007
prev sibling parent "Janice Caron" <caron800 googlemail.com> writes:
On 10/9/07, Matti Niemenmaa <see_signature for.real.address> wrote:

 That misses structs, which are also POD.


So are fixed-size arrays of PODs.
Oct 09 2007