[macstl-dev] template with C linkage

[Glen Low]

On 05/02/2005, at 11:27 AM, David Chilton wrote:

> Glen,
>
> I successfully built and executed the benchmark target in the macstl 
> xcode project, and it looks great.  Now I'm trying to test 
> incorporating macstl into the code for my honors thesis, which relies 
> heavily on valarray's read from FITS files, but I can't seem to get 
> gcc to build it.  I continually get "template with C linkage" errors.  
> The same code compiles fine using the standard library valarray.  
> below is an example:
>
> #include <macstl/valarray.h>
> using stdext::valarray;
>
> class TestClass
> {
>         public:
>                 static size_t testStatic;
>                 TestClass(size_t n):index(n) {}
>                 TestClass():index(0){}
>                 size_t getindex() { return index;}
>                 valarray<size_t> testFunc(valarray<TestClass>& input){
>                         valarray<size_t> d(input.size());
>                         for(size_t i =0; i<input.size();i++)
>                                 d[i]=input[i];
>                         return d;
>                 }
>         private:
>                 size_t index;
> }
> size_t TestClass testStatic = size_t(0);
>
> compile with: gcc -c -o test.o test.cpp
>
> and tons of errors are given
>
> Any suggestions would be appreciated.
>

Thanks for evaluating macstl and joining the list, hope you find both 
activities useful!

The program above has a few syntax errors, allow me to correct:

#include <macstl/valarray.h>
using stdext::valarray;

class TestClass
{
         public:
                 static size_t testStatic;
                 TestClass(size_t n):index(n) {}
                 TestClass():index(0){}
                 size_t getindex() { return index;}
                 valarray<size_t> testFunc(valarray<TestClass>& input){
                         valarray<size_t> d(input.size());
                         for(size_t i =0; i<input.size();i++)
                                 d[i]=input[i].getindex();	// no 
conversion to size_t, I assume you left out getindex
                         return d;
                 }
         private:
                 size_t index;
};
size_t TestClass::testStatic = size_t(0);	// needs the ::

On the macstl side there's one minor bug, valarray_vec.h:38 should read

#include <macstl/vec.h>

And the above, if put into main.cpp, should compile cleanly on Apple 
gcc 3.3.

I'm not sure where the "template with C linkage" errors are coming 
from, perhaps you are compiling a .c file instead of a .cpp file? Or 
can you submit an example of the error?

Note that valarray <size_t> is unlikely to be optimized, because size_t 
is usually a typedef for long, and only ints are Altivec optimized. On 
32-bit gcc, long is 32 bits which is equivalent to an int, but on 
64-bit gcc, long is 64 bits which is no longer the size of an int, so I 
didn't want to trigger the issue in macstl. (I may do some template 
metaprogramming to get 32-bit longs optimized and skip 64-bit longs, 
we'll see.)

Cheers, Glen Low


---
pixelglow software | simply brilliant stuff
www.pixelglow.com