Re: Second time's a charm

[David Bateman]

Sebastien Loisel wrote:

> On 2/17/06, *David Bateman* <address@hidden 
> <mailto:address@hidden>> wrote:
>
>     I don't know if I'll be able to help, but will try this weekend..
>
>     D.
>
>
> Send me an email when you start and I'll give you the most updated 
> information. I have new leads for the cerr stuff:
>
> 1) This is apparently related to dynamic linkage. I'm attaching a 
> sample program to this email that illustrates the problem. I've 
> confirmed that adding a get_cerr() function to liboctave would solve 
> the problem. (Well, I don't know what happens if several dll's are 
> involved...)

If there needs to have a patch to octave to allow this effort to work I 
don't see why John would refuse it as long as there was justification. 
Though note that its not just cerr you want, but also stderr as this is 
used in libcruft/misc/lo-error.c. As for a patch against the MinGW build 
of octave, the build script I setup already does this for several other 
libraries and so adding a patch to the build script as a temporary 
measure seems justified..

Cheers
David

PS. I'm also dropping the graphics list in this reply..

> 2) I'm guessing there's some black magic way of doing it directly with 
> the unmodified dll, but I don't know.
>
> 3) The window popping up briefly can be fixed by replacing
> -Wl,-subsystem,windows
> with
> -Wl,-subsystem,console
>
> This will force Windows to open a console for my app and keep it 
> opened. I think I know how to fix this more elegantly, but that'll 
> have to wait.
>
> Sebastien Loisel
>
> ----
>
> $ cat dll.h
> #ifdef BUILD_DLL
> /* DLL export */
> #define EXPORT __declspec(dllexport)
> #else
> /* EXE import */
> #define EXPORT __declspec(dllimport)
> #endif
> #include <iostream>
> EXPORT void hello(void);
> //extern EXPORT std::ostream std::cout; don't work
> EXPORT std::ostream &get_cout(void);
> $ cat dll.cpp
> #include <iostream>
> #include "dll.h"
>
> EXPORT void hello(void) {
>   std::cout<<"Hello";
> }
> EXPORT std::ostream &get_cout(void) { return std::cout; }
> $ cat hello.cpp
> #include <iostream>
> #include <fstream>
> #include "dll.h"
>
> int main () {
>   std::streambuf *stdbuf=std::cout.rdbuf();
>   std::ofstream out("foo.txt");
>   // std::cout.rdbuf(out.rdbuf()); <-- this doesn't work
>   get_cout().rdbuf(out.rdbuf()); // <-- this works
>   hello();
>   get_cout().rdbuf(stdbuf);
>   return 0;
> }
> $ cat build.sh
> #!/bin/sh
> g++ -c hello.cpp -o hello.o
> g++ -c -DBUILD_DLL dll.cpp -o dll.o
> g++ -shared -o message.dll dll.o -Wl,--out-implib,libmessage.a
> g++ -o hello.exe hello.o -L./ -lmessage


--
David Bateman                                address@hidden
Motorola Labs - Paris                        +33 1 69 35 48 04 (Ph) 
Parc Les Algorithmes, Commune de St Aubin    +33 6 72 01 06 33 (Mob) 
91193 Gif-Sur-Yvette FRANCE                  +33 1 69 35 77 01 (Fax) 

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