RE: Templates

RE: Templates

[Ajay Bansal]

Still, if possible,

Can somebody post a working template example built with "--frepo
-fno-implicit-templates" 


-----Original Message-----
From: Matthias Oltmanns
[mailto:Mathias.Oltmanns.Oltmanns@sysde.eads.net] 
Sent: Thursday, March 27, 2003 2:13 PM
To: Matthieu Moy
Cc: gcc-help@gcc.gnu.org; eccf@super.unam.mx

Am Don, 2003-03-27 um 09.21 schrieb Matthieu Moy:
> Eduardo Cesar Cabrera Flores <eccf@super.unam.mx> writes:
> 
> > How to compile multiples files source code with templates classes 
> > and functions in a makefile?
> 
> When you  use templates,  gcc needs to  have all  the template-related

> code in the .h file.
> 

Thats right but it's not the point Eduardo talked about. As i
understand, he separates the template declaration from the definitions
by placing the definition in a .C file *AND* includes the .C file from
the .h file.
For me this way it works fine as long as i place the header and template
definitions files together in my include directories and do not mix them
with my regular source files.
Don't try to compile the template definition file. It should be enough
to just use them.

cu
Matthias

> --
> Matthieu
--
Matthias Oltmanns

Tel: 04421-1543-274
mail: Mathias.Oltmanns.Oltmanns@sysde.eads.net

RE: Templates

[Matthias Oltmanns]

Am Don, 2003-03-27 um 12.16 schrieb Ajay Bansal:
> Still, if possible,
> 
> Can somebody post a working template example built with "--frepo
> -fno-implicit-templates" 
> 

Ok, here is a short silly example:

all files in one directory:


Counter.h ---------------------------
#ifndef _Counter_h
#define _Counter_h

template <typename Number>
class Counter
{
 public:
  Counter();

  // increments and returns the counter
  Number get();

 private:
  Number m_counter;
};

#include "Counter.cc"

#endif

Counter.cc ---------------------------------
template<typename Number>
Counter<Number>::Counter() : m_counter(0)
{

}
template<typename Number>
Number Counter<Number>::get()
{
  return ++m_counter;
}

testCounter.cc ---------------------------------------------
#include <iostream>

#include "Counter.h"

int main(int, char**)
{
  Counter<double> d;
  Counter<long> l;

  std::cout << "d: " << d.get() << std::endl;
  std::cout << "d: " << d.get() << std::endl;
  std::cout << "d: " << d.get() << std::endl;

  std::cout << "l: " << l.get() << std::endl;
  std::cout << "l: " << l.get() << std::endl;
  std::cout << "l: " << l.get() << std::endl;

}


g++ -v
Reading specs from /usr/lib/gcc-lib/i386-redhat-linux/3.2/specs
Configured with: ../configure --prefix=/usr --mandir=/usr/share/man
--infodir=/usr/share/info --enable-shared --enable-threads=posix
--disable-checking --host=i386-redhat-linux --with-system-zlib
--enable-__cxa_atexit
Thread model: posix
gcc version 3.2 20020903 (Red Hat Linux 8.0 3.2-7)

g++ -o testCounter.o -c -frepo -fno-implicit-templates testCounter.cc

g++ -o testCounter testCounter.o
collect: recompiling testCounter.cc
collect: relinking

./testCounter
d: 1
d: 2
d: 3
l: 1
l: 2
l: 3

Did you really need the flag "-fno-implicit-templates" ? I've good
experiences without this flag.

cu
Matthias




> 
> -----Original Message-----
> From: Matthias Oltmanns
> [mailto:Mathias.Oltmanns.Oltmanns@sysde.eads.net] 
> Sent: Thursday, March 27, 2003 2:13 PM
> To: Matthieu Moy
> Cc: gcc-help@gcc.gnu.org; eccf@super.unam.mx
> 
> Am Don, 2003-03-27 um 09.21 schrieb Matthieu Moy:
> > Eduardo Cesar Cabrera Flores <eccf@super.unam.mx> writes:
> > 
> > > How to compile multiples files source code with templates classes 
> > > and functions in a makefile?
> > 
> > When you  use templates,  gcc needs to  have all  the template-related
> 
> > code in the .h file.
> > 
> 
> Thats right but it's not the point Eduardo talked about. As i
> understand, he separates the template declaration from the definitions
> by placing the definition in a .C file *AND* includes the .C file from
> the .h file.
> For me this way it works fine as long as i place the header and template
> definitions files together in my include directories and do not mix them
> with my regular source files.
> Don't try to compile the template definition file. It should be enough
> to just use them.
> 
> cu
> Matthias
> 
> > --
> > Matthieu
> --
> Matthias Oltmanns
> 
> Tel: 04421-1543-274
> mail: Mathias.Oltmanns.Oltmanns@sysde.eads.net
> 
-- 
Matthias Oltmanns

Tel: 04421-1543-274
mail: Mathias.Oltmanns.Oltmanns@sysde.eads.net

Re: Templates

[Matthias Oltmanns]

Am Don, 2003-03-27 um 09.21 schrieb Matthieu Moy:
> Eduardo Cesar Cabrera Flores <eccf@super.unam.mx> writes:
> 
> > How to compile multiples files source code with templates classes and
> > functions in a makefile?
> 
> When you  use templates,  gcc needs to  have all  the template-related
> code in the .h file. 
> 

Thats right but it's not the point Eduardo talked about. As i
understand, he separates the template declaration from the definitions
by placing the definition in a .C file *AND* includes the .C file from
the .h file.
For me this way it works fine as long as i place the header and template
definitions files together in my include directories and do not mix them
with my regular source files.
Don't try to compile the template definition file. It should be enough
to just use them.

cu
Matthias

> -- 
> Matthieu
-- 
Matthias Oltmanns

Tel: 04421-1543-274
mail: Mathias.Oltmanns.Oltmanns@sysde.eads.net

Re: Templates

[Matthieu Moy]

Eduardo Cesar Cabrera Flores <eccf@super.unam.mx> writes:

> How to compile multiples files source code with templates classes and
> functions in a makefile?

When you  use templates,  gcc needs to  have all  the template-related
code in the .h file. 

-- 
Matthieu

Templates

[Eduardo Cesar Cabrera Flores]

How to compile multiples files source code with templates classes and
functions in a makefile?

g++ -v
Reading specs from /local/gcc/lib/gcc-lib/i686-pc-linux-gnu/3.1/specs
Configured with: ./configure --prefix=/local/gcc
Thread model: single
gcc version 3.1


it works with g++ standalone  well, but when i try to complie with a
makefile or compile with options "-c" & "--frepo -fno-implicit-templates"
it fails!!!

in my ".h" file include my definitions of the funcion it means the ".C"
file

#include "my_definitions.C"


what is wrong?

Do u got some examples about compiling with a makefile with templates?

thanks in advance


cafe

Re: templates

[Nathan Sidwell]

Adrian Sandor wrote:
> let's say I have a simple template function:
> 
> template<class T>T sqr(T x){return x*x;}
> 
> then if I write "sqr(5)" then everything is ok
> but if I make some changes:
> 
> template<class T>struct dummy{typedef T type;};
> template<class T>T sqr(typename dummy<T>::type
> x){return x*x;}
> 
> then "sqr(5)" doesn't compile anymore; instead I have
> to write "sqr<int>(5)"
> what is the cause of this behaviour and how can I
> avoid it? (I need to use some type traits)
in handwaving terms, because template deduction doesn't recurse.
Consider if you had
	template<typename T> struct dummy{typedef T type;}
	template<> struct dummy<int> {typedef float type;}
that would be hard.
template <typename T> typename dummy<T>::type sqr (T);
would be deducible

please refer to a C++ news group/faq/list for further explanation

nathan

-- 
Nathan Sidwell    ::   http://www.codesourcery.com   ::     CodeSourcery LLC
          The voices in my head said this was stupid too
nathan@codesourcery.com : http://www.cs.bris.ac.uk/~nathan/ : nathan@acm.org

templates

[Adrian Sandor]

let's say I have a simple template function:

template<class T>T sqr(T x){return x*x;}

then if I write "sqr(5)" then everything is ok
but if I make some changes:

template<class T>struct dummy{typedef T type;};
template<class T>T sqr(typename dummy<T>::type
x){return x*x;}

then "sqr(5)" doesn't compile anymore; instead I have
to write "sqr<int>(5)"
what is the cause of this behaviour and how can I
avoid it? (I need to use some type traits)

thanks
Adrian

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