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From: Vladimir Grigoriev on 12 Jan 2010 11:00
Another question.

When I include std::rel_ops before the main() my code compiles. When I
include the operators inside the main the compiler issues errors. May I use

using std::rel_ops::operator !=;

using std::rel_ops::operator >;

using std::rel_ops::operator <=;

using std::rel_ops::operator >=;

statements inside a code block such a way that the compiler could deduce
template arguments?



Vladimir Grigoriev

c:\program files\microsoft visual studio 8\vc\include\functional(165) :
error C2784: 'bool std::operator <=(const std::reverse_iterator<_RanIt>
&,const std::reverse_iterator<_RanIt2> &)' : could not deduce template
argument for 'const std::reverse_iterator<_RanIt> &' from 'const element'
c:\program files\microsoft visual studio 8\vc\include\xutility(1858)
: see declaration of 'std::operator <='
c:\program files\microsoft visual studio
8\vc\include\functional(164) : while compiling class template member
function 'bool std::less_equal<_Ty>::operator ()(const _Ty &,const _Ty &)
const'
with
[
_Ty=element
]


From: Victor Bazarov on 12 Jan 2010 11:49
Vladimir Grigoriev wrote:
> Another question.
>
> When I include std::rel_ops before the main() my code compiles.

How do you "include" it? It's not like it's a header...

> When I
> include the operators inside the main the compiler issues errors. May I use
>
> using std::rel_ops::operator !=;
>
> using std::rel_ops::operator >;
>
> using std::rel_ops::operator <=;
>
> using std::rel_ops::operator >=;
>
> statements inside a code block such a way that the compiler could deduce
> template arguments?

Are those by any chance templates?

>
>
>
> Vladimir Grigoriev
>
> c:\program files\microsoft visual studio 8\vc\include\functional(165) :
> error C2784: 'bool std::operator <=(const std::reverse_iterator<_RanIt>
> &,const std::reverse_iterator<_RanIt2> &)' : could not deduce template
> argument for 'const std::reverse_iterator<_RanIt> &' from 'const element'
> c:\program files\microsoft visual studio 8\vc\include\xutility(1858)
> : see declaration of 'std::operator <='
> c:\program files\microsoft visual studio
> 8\vc\include\functional(164) : while compiling class template member
> function 'bool std::less_equal<_Ty>::operator ()(const _Ty &,const _Ty &)
> const'
> with
> [
> _Ty=element
> ]
>

And where is the code? Are we to divine it or read your mind (or,
better yet, the mind of your computer)? Please post the code when
asking a question about the code and the errors you get from compiling it.

V
--
Please remove capital 'A's when replying by e-mail
I do not respond to top-posted replies, please don't ask
From: zeromem on 12 Jan 2010 12:26
You probably need to move "#include <utility>" to before "#include
<map>" or whatever the master data type file is.

On 1/12/2010 8:00 AM, Vladimir Grigoriev wrote:
> Another question.
>
> When I include std::rel_ops before the main() my code compiles. When I
> include the operators inside the main the compiler issues errors. May I use
>
> using std::rel_ops::operator !=;
>
> using std::rel_ops::operator>;
>
> using std::rel_ops::operator<=;
>
> using std::rel_ops::operator>=;
>
> statements inside a code block such a way that the compiler could deduce
> template arguments?
>
>
>
> Vladimir Grigoriev
>
> c:\program files\microsoft visual studio 8\vc\include\functional(165) :
> error C2784: 'bool std::operator<=(const std::reverse_iterator<_RanIt>
> &,const std::reverse_iterator<_RanIt2> &)' : could not deduce template
> argument for 'const std::reverse_iterator<_RanIt> &' from 'const element'
> c:\program files\microsoft visual studio 8\vc\include\xutility(1858)
> : see declaration of 'std::operator<='
> c:\program files\microsoft visual studio
> 8\vc\include\functional(164) : while compiling class template member
> function 'bool std::less_equal<_Ty>::operator ()(const _Ty&,const _Ty&)
> const'
> with
> [
> _Ty=element
> ]
>
>

From: Vladimir Grigoriev on 13 Jan 2010 08:41
Victor,
the sample code is the following

#include "stdafx.h"

#include <iostream>

#include <functional>

#include <algorithm>

#include <utility>

#define NAME_SIZE 10

struct element

{

int value;

char name[ NAME_SIZE ];

} first_init = { 1, "first" }, second_init = { 1, "second" };

bool operator <( const element &lhs, const element &rhs )

{

return ( lhs.value < rhs.value );

}

bool operator ==( const element &lhs, const element &rhs )

{

return ( ( lhs.value == rhs.value ) &&

( std::strcmp( lhs.name, rhs.name ) == 0 ) );

}

std::ostream & operator <<( std::ostream &os, const element &rhs )

{

os << '{' << rhs.value << ", " << rhs.name << '}';

return ( os );

}


int _tmain(int argc, _TCHAR* argv[])

{

using std::rel_ops::operator !=;

using std::rel_ops::operator >;

using std::rel_ops::operator <=;

using std::rel_ops::operator >=;

element el1 = first_init, el2 = second_init;

std::cout << "\nstd::min( " << el1 << ", " << el2

<< ", std::less_equal<element>() } = "

<< std::min( el1, el2, std::less_equal<element>() )

<< std::endl;

return 0;

}

Vladimir Grigoriev



"Victor Bazarov" <v.Abazarov(a)comAcast.net> wrote in message
news:hii95o$3f6$1(a)news.datemas.de...
> Vladimir Grigoriev wrote:
>> Another question.
>>
>> When I include std::rel_ops before the main() my code compiles.
>
> How do you "include" it? It's not like it's a header...
>
> > When I
>> include the operators inside the main the compiler issues errors. May I
>> use
>>
>> using std::rel_ops::operator !=;
>>
>> using std::rel_ops::operator >;
>>
>> using std::rel_ops::operator <=;
>>
>> using std::rel_ops::operator >=;
>>
>> statements inside a code block such a way that the compiler could deduce
>> template arguments?
>
> Are those by any chance templates?
>
>>
>>
>>
>> Vladimir Grigoriev
>>
>> c:\program files\microsoft visual studio 8\vc\include\functional(165) :
>> error C2784: 'bool std::operator <=(const std::reverse_iterator<_RanIt>
>> &,const std::reverse_iterator<_RanIt2> &)' : could not deduce template
>> argument for 'const std::reverse_iterator<_RanIt> &' from 'const element'
>> c:\program files\microsoft visual studio
>> 8\vc\include\xutility(1858) : see declaration of 'std::operator <='
>> c:\program files\microsoft visual studio
>> 8\vc\include\functional(164) : while compiling class template member
>> function 'bool std::less_equal<_Ty>::operator ()(const _Ty &,const _Ty &)
>> const'
>> with
>> [
>> _Ty=element
>> ]
>>
>
> And where is the code? Are we to divine it or read your mind (or, better
> yet, the mind of your computer)? Please post the code when asking a
> question about the code and the errors you get from compiling it.
>
> V
> --
> Please remove capital 'A's when replying by e-mail
> I do not respond to top-posted replies, please don't ask


From: Igor Tandetnik on 13 Jan 2010 09:03
Vladimir Grigoriev wrote:
> Victor,
> the sample code is the following
>
> #include "stdafx.h"
> #include <iostream>
> #include <functional>
> #include <algorithm>
> #include <utility>
> #define NAME_SIZE 10
>
> struct element
> {
> int value;
> char name[ NAME_SIZE ];
> } first_init = { 1, "first" }, second_init = { 1, "second" };
>
> bool operator <( const element &lhs, const element &rhs )
> {
> return ( lhs.value < rhs.value );
> }
>
> bool operator ==( const element &lhs, const element &rhs )
> {
> return ( ( lhs.value == rhs.value ) &&
> ( std::strcmp( lhs.name, rhs.name ) == 0 ) );
> }
>
> std::ostream & operator <<( std::ostream &os, const element &rhs )
> {
> os << '{' << rhs.value << ", " << rhs.name << '}';
> return ( os );
> }
>
> int _tmain(int argc, _TCHAR* argv[])
> {
> using std::rel_ops::operator !=;
> using std::rel_ops::operator >;
> using std::rel_ops::operator <=;
> using std::rel_ops::operator >=;

> element el1 = first_init, el2 = second_init;
> std::cout << "\nstd::min( " << el1 << ", " << el2
> << ", std::less_equal<element>() } = "
> << std::min( el1, el2, std::less_equal<element>() )
> << std::endl;
>
> return 0;
> }

For implicit instantiation of a template, the point of instantiation is right after the function where it is used. So, at the point where less_equal<element> is instantiated, those using declarations are not visible.
--
With best wishes,
Igor Tandetnik

With sufficient thrust, pigs fly just fine. However, this is not necessarily a good idea. It is hard to be sure where they are going to land, and it could be dangerous sitting under them as they fly overhead. -- RFC 1925
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