Monday, September 21, 2015

Digest for comp.lang.c++@googlegroups.com - 20 updates in 5 topics

Rosario19 <Ros@invalid.invalid>: Sep 21 11:43AM +0200

On Sun, 20 Sep 2015 02:43:15 -0500, Paavo Helde wrote:
 
 
>See also https://isocpp.org/wiki/faq/templates#templates-defn-vs-decl
 
>hth
>Paavo
 
thank you
 
but it is possible put only dichiarations [member, functions,
operators etc] of the template class in the header file, and put all
the code of that member functions, operators etc of the template class
in the .dll file [in a way it is possible use that template class from
some other .cpp file]?
Rosario19 <Ros@invalid.invalid>: Sep 21 12:11PM +0200

On Mon, 21 Sep 2015 11:43:18 +0200, Rosario19 wrote:
 
>the code of that member functions, operators etc of the template class
>in the .dll file [in a way it is possible use that template class from
>some other .cpp file]?
 
it seems to me
that this compile for the creation of the .dll
 
but when i want to use the compiler on other .cpp file that call one
instance of that template class...
the compiler says "unrisolved external" even if i put __extern in the
code of that template in the .dll
 
so i would use only the .h file for template....
 
but doing so there could be problem in call functions expecially
input/ output
where their definitions, in the few i understand, are in one other
file header afther, in include, the header where there is the template
class
Louis Krupp <lkrupp@nospam.pssw.com.invalid>: Sep 21 05:01AM -0600

On Mon, 21 Sep 2015 12:11:04 +0200, Rosario19 <Ros@invalid.invalid>
wrote:
 
>where their definitions, in the few i understand, are in one other
>file header afther, in include, the header where there is the template
>class
 
If you could post two or three small files you're trying to compile
(and possibly link) along with the errors you're getting, I think it
would be helpful.
 
Louis
Paavo Helde <myfirstname@osa.pri.ee>: Sep 21 10:10AM -0500

Rosario19 <Ros@invalid.invalid> wrote in
>>the code of that member functions, operators etc of the template class
>>in the .dll file [in a way it is possible use that template class from
>>some other .cpp file]?
 
Yes, to some extent, via explicit instantiations.
 
> the compiler says "unrisolved external" even if i put __extern in the
> code of that template in the .dll
 
> so i would use only the .h file for template....
 
Ok, fine.
 
> where their definitions, in the few i understand, are in one other
> file header afther, in include, the header where there is the template
> class
 
Template classes should be included first. Template definitions can
access types and functions which are not yet declared, assuming that
these types and functions depend on the template parameters. Such names
are resolved in a later compilation stage, so there should be no problem.
Example:
 
template<class T>
class Foo: public T{
public:
int f() {
return T::bar; // bar not yet declared, OK (as it depends on T)
}
};
 
class A {
protected:
const static int bar = 42;
};
 
int main() {
Foo<A> a;
return a.f(); // ok
}
 
Note that leaving out T:: in f() would make the code invalid.
 
hth
Paavo
Rosario19 <Ros@invalid.invalid>: Sep 21 07:18PM +0200

On Mon, 21 Sep 2015 05:01:13 -0600, Louis Krupp wrote:
>(and possibly link) along with the errors you're getting, I think it
>would be helpful.
 
>Louis
 
i think is not possible put code of the class template in the ndll.cpp
file right?
[pheraps only the code of the template not use type <T>]
-----------------------
/*
FILE ndll.cpp
build the .dll and .lib
usare:
>bcc32 -v -WD ndll.cpp
>implib ndll.lib ndll.dll
*/
 
 
#include "fileI.h"
#include <stdio.h>
#include <stdarg.h>
 
int WINAPI
DllEntryPoint(HINSTANCE hinst, unsigned long reason, void* lpReserved)
{(void) hinst; (void) lpReserved;
if(reason == DLL_PROCESS_ATTACH){}
else if(reason == DLL_PROCESS_DETACH){}
R 1;
}
 
int __export P(char* fmt, ... )
{va_list args;
int r;
va_start(args, fmt);
r=vfprintf(stderr, fmt, args);
va_end(args);
R r;
}
 
template<class T> __export permutazioni<T>::permutazioni(u32 a)
{u32 i;
n=0; arr=0; c=0; cnt=0; ji=0;
if(a==0||a>0xFF) {PBadAlloc=1; R;}
arr=(T*)MM( a*S(T) );
if(arr==0){PBadAlloc=1; R;}
c=(u32*)MM( a*S(u32) );
if(c==0){FF(arr); PBadAlloc=1; arr=0; R;}
n=a;
F(i=0; i<n; ++i){c[i]=0; arr[i]=i;}
}
 
template<class T> __export permutazioni<T>::~permutazioni(){FF(c);
FF(arr);}
 
template<class T> u32 __export permutazioni<T>::swp(T* a, u32 i, u32
j)
{T x;
if(i>=n||j>=n) R -1;
if(i==j) R 0;
x=a[i]; a[i]=a[j]; a[j]=x; ++cnt;
R 0;
}
 
template<class T> u32 __export permutazioni<T>::index(T* a)
{u32 r;
if(arr==0||a==0) R -1;
if( !(arr<=a&&a<arr+n) ) R -1;
r=a-arr;
if(r>0xFFFFFF) R -1;
r=r/S(T);
R r;
}
 
// b=a^-1 b[a]=I=1,2,3,4,5...n
// a= 1 3 2 (1->1, 2->3 3->2) b= 1 3 2
// i->j j->i
template<class T> i32 __export
permutazioni<T>::inverse(permutazioni<T>& a)
{u32 i;
T t;
 
if(arr==0||n!=a.n) R -1; // devono avere lo stesso n
F(i=0; i<n; ++i)
{t=a.arr[i];
if(!(0<=t&&t<n)) R -1;
arr[t]= i ; // deve essere arr[a.arr[i]]=i;
}
nextP(0); // azzera next permutation
}
 
/* from Sedgewick, result in arr [3!=6] */
template<class T> u32 __export permutazioni<T>::nextP(u32 a)
{u32 k;
 
if(a==0)
{F(k=0; k<n; ++k) c[k]=0;
ji=0; cnt=0;
R 1;
}
F( ; ji<n; )
{if(c[ji]<ji)
{swp(arr, ((ji+1)%2? 0: c[ji]) , ji);
++c[ji]; ji=1; // can be ok ji=0; too
R 1; // ok
}
else c[ji++]=0;
}
R 0; // for end
}
 
 
template<class T> i32 __export permutazioni<T>::e(void){R
PBadAlloc;}
 
template<class T> T& __export permutazioni<T>::operator[](i32 i){R
arr[i];}
 
template<class T> void __export permutazioni<T>::print(void)
{u32 i;
F(i=0; i<n; ++i)
if(i==0 ) cout<<"[ "<< arr[i]<<" ";
else if(i==n-1) cout<<arr[i]<<" ] ";
else cout<<arr[i]<<" ";
}
 
------------------------
/*FILE fileI.h */
#ifndef fileI
#define fileI
 
#ifndef fileII
#include "fileII.h"
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