Hello,

Here's a short program which creates a type for points and overloads '+' to do element wise addition as well as addition to floats, however it produces an error:

----------------------------------------------------------------------
import std.stdio ;

struct Pt
{
  float x , y ;

  Pt opBinary ( string op ) ( Pt a ) if ( op == "+" )
    { return Pt ( x + a.x , y + a.y ) ; }

  Pt opBinary ( string op ) ( float a ) if ( op == "+" )
    { return Pt ( x + a , y + a ) ; }
}

void main () { Pt ( 1.0 , 2.0 ) + Pt ( 3.0 , 4.0 ) ; }
----------------------------------------------------------------------

The error:

pt_overload_test_a.d(15): Error: template instance opBinary!("+") matches more than one template declaration, pt_overload_test_a.d(8):opBinary(string op) if (op == "+") and pt_overload_test_a.d(11):opBinary(string op) if (op == "+")

So, how should I go about this? :-)

Ed

Eduardo Cavazos <wayo.cavazos@gmail.com> wrote:

> Hello,
>
> Here's a short program which creates a type for points and overloads '+' to do element wise addition as well as addition to floats, however it produces an error:
>
> ----------------------------------------------------------------------
> import std.stdio ;
>
> struct Pt
> {
>    float x , y ;
>
>    Pt opBinary ( string op ) ( Pt a ) if ( op == "+" )
>      { return Pt ( x + a.x , y + a.y ) ; }
>
>    Pt opBinary ( string op ) ( float a ) if ( op == "+" )
>      { return Pt ( x + a , y + a ) ; }
> }
>
> void main () { Pt ( 1.0 , 2.0 ) + Pt ( 3.0 , 4.0 ) ; }
> ----------------------------------------------------------------------
>
> The error:
>
> pt_overload_test_a.d(15): Error: template instance opBinary!("+") matches more than one template declaration, pt_overload_test_a.d(8):opBinary(string op) if (op == "+") and pt_overload_test_a.d(11):opBinary(string op) if (op == "+")
>
> So, how should I go about this? :-)

That is indeed a perplexing error. It is caused by dmd not knowing
how to overload template functions based on both normal and template
parameters.

As for the solution:

Pt opBinary( string op : "+", T : Pt )( T a ) {...}
Pt opBinary( string op : "+", T : float )( T a ) {...}

should work. More explicitly:

Pt opBinary( string op, T )( T a ) if ( ( op == "+" ) && is( T == Pt ) ) {...}
Pt opBinary( string op, T )( T a ) if ( ( op == "+" ) && is( T == float ) ) {...}

-- 
Simen

>>
Stanislav Blinov <blinov loniir.ru> writes:
Content-Type: text/plain; charset=UTF-8; format=flowed
Content-Transfer-Encoding: 7bit

  Hello,

I'm receiving strange results with reading stdin on Windows 7. Consider
this code:

module test;

import std.stdio;

void main(string[] args)
{
         foreach (int i, string line; lines(stdin))
         {
                 write(line);
         }
}

On Linux, if I do 'cat test.d | ./test' I get test.d contents on stdout.
But on Windows 7, ('type test.d | ./test.exe') the output is this:

std.stdio.StdioException: Bad file descriptor
module test;

import std.stdio;

void main(string[] args)
{
         foreach (int i, string line; lines(stdin))
         {
                 writef(line);
         }
}

So I too get type.d contents on stdout, but preceeded by StdioException
string. This happens with dmd 2.047 and 2.048.

Is this my error, dmd's, or Windows's piping?
-- 
Aug 17

<<

>Jesse Phillips <jessekphillips+D gmail.com>
>In my experience Windows hasn't gotten piping right. And it has been >known to
>have bugs, this might be related:
>http://stackoverflow.com/questions/466801/python-piping-on-windows-why-does-this-not-work
> Aug 18

Joel Christensen <joelcnz gmail.com>:
Just dug up this problem. I have trouble with Thunderbird and so couldn't put reply.

I've tried that solution on my Windows 7, but got no effect at all.
Sept 1

I get the same thing on XP.

If you swap the two like so:
type.exe | type.d

Then it works but it will wait on exit.

This works nicely:

type.exe < type.d

Joel Christensen Wrote:

>  >>
> Stanislav Blinov <blinov loniir.ru> writes:
> Content-Type: text/plain; charset=UTF-8; format=flowed
> Content-Transfer-Encoding: 7bit
> 
>    Hello,
> 
> I'm receiving strange results with reading stdin on Windows 7. Consider this code:
> 
> module test;
> 
> import std.stdio;
> 
> void main(string[] args)
> {
>           foreach (int i, string line; lines(stdin))
>           {
>                   write(line);
>           }
> }
> 
> On Linux, if I do 'cat test.d | ./test' I get test.d contents on stdout. But on Windows 7, ('type test.d | ./test.exe') the output is this:
> 
> std.stdio.StdioException: Bad file descriptor
> module test;
> 
> import std.stdio;
> 
> void main(string[] args)
> {
>           foreach (int i, string line; lines(stdin))
>           {
>                   writef(line);
>           }
> }
> 
> So I too get type.d contents on stdout, but preceeded by StdioException string. This happens with dmd 2.047 and 2.048.
> 
> Is this my error, dmd's, or Windows's piping?
> -- 
> Aug 17
> 
> <<
> 
>  >Jesse Phillips <jessekphillips+D gmail.com>
>  >In my experience Windows hasn't gotten piping right. And it has been
>  >known to
>  >have bugs, this might be related:
>  >http://stackoverflow.com/questions/466801/python-piping-on-windows-why-does-this-not-work
>  > Aug 18
> 
> Joel Christensen <joelcnz gmail.com>:
> Just dug up this problem. I have trouble with Thunderbird and so
> couldn't put reply.
> 
> I've tried that solution on my Windows 7, but got no effect at all. Sept 1

Oooops, I meant:

std.stdio.StdioException: Bad file descriptor
type test.d | test.exe

works, but waits on exit:
test.exe | type test.d

works fine:
test.exe < test.d

Andrej Mitrovic Wrote:

> I get the same thing on XP.
> 
> If you swap the two like so:
> type.exe | type.d
> 
> Then it works but it will wait on exit.
> 
> This works nicely:
> 
> type.exe < type.d
> 
> Joel Christensen Wrote:
> 
> >  >>
> > Stanislav Blinov <blinov loniir.ru> writes:
> > Content-Type: text/plain; charset=UTF-8; format=flowed
> > Content-Transfer-Encoding: 7bit
> > 
> >    Hello,
> > 
> > I'm receiving strange results with reading stdin on Windows 7. Consider this code:
> > 
> > module test;
> > 
> > import std.stdio;
> > 
> > void main(string[] args)
> > {
> >           foreach (int i, string line; lines(stdin))
> >           {
> >                   write(line);
> >           }
> > }
> > 
> > On Linux, if I do 'cat test.d | ./test' I get test.d contents on stdout. But on Windows 7, ('type test.d | ./test.exe') the output is this:
> > 
> > std.stdio.StdioException: Bad file descriptor
> > module test;
> > 
> > import std.stdio;
> > 
> > void main(string[] args)
> > {
> >           foreach (int i, string line; lines(stdin))
> >           {
> >                   writef(line);
> >           }
> > }
> > 
> > So I too get type.d contents on stdout, but preceeded by StdioException string. This happens with dmd 2.047 and 2.048.
> > 
> > Is this my error, dmd's, or Windows's piping?
> > -- 
> > Aug 17
> > 
> > <<
> > 
> >  >Jesse Phillips <jessekphillips+D gmail.com>
> >  >In my experience Windows hasn't gotten piping right. And it has been
> >  >known to
> >  >have bugs, this might be related:
> >  >http://stackoverflow.com/questions/466801/python-piping-on-windows-why-does-this-not-work
> >  > Aug 18
> > 
> > Joel Christensen <joelcnz gmail.com>:
> > Just dug up this problem. I have trouble with Thunderbird and so
> > couldn't put reply.
> > 
> > I've tried that solution on my Windows 7, but got no effect at all. Sept 1
> 

On 01-Sep-10 12:54 PM, Andrej Mitrovic wrote:
> Oooops, I meant:
>
> std.stdio.StdioException: Bad file descriptor
> type test.d | test.exe
>
> works, but waits on exit:
> test.exe | type test.d
>
> works fine:
> test.exe<  test.d
>
I think I get the same as you. Have to put Ctrl+C (or some thing) to get out, for 'test.exe | type test.d'

I recon I can use 'test.exe < test.d' sort of thing, any how. It'd complement 'test.exe > test.txt' (which I have knowen and do use some times).