Difference between revisions of "User talk:Kr/Parameterized Headers"

Revision as of 08:12, 30 March 2006

some thoughs about headers

HowTo Include C / C++ Headers

• A header provides the interface to (parts) of zero or multiple libraries.
• A header may includes other headers.
• A header may be parameterizeable (parameters may be mandantory): Parameterizeable Headers A header is parameterizeable, if it reacts on defines.
• A header inherits parameters from included headers.

Include headers in reverse order of Distance.

This ensures

• that the compiler produces an error in case the header is not complete,
• that successve (parameterizeable) headers are configured properly

Parameterize successive headers in the header and according to the headers code.

Examples

Matching header first

"mycode.hxx"

void testfun(void *);


"mycode.cxx"

// include matching header first
#include "mycode.hxx"

#include <anyotherheader.hxx>

Parameterize base header

"mycode.hxx"

#define PARAMETER_FOR_PARA_HEADER 27
#include <paraheader.hxx>

void testfun(void *)


"mycode.cxx"

#include <mycode.hxx>
// even if (in)directly including "paraheader.hxx" again, it is parameterized correctly (which would not be true, if including it first)
#include "paraheader.hxx"
</code>

Parameterizeable header

<paraheader.hxx>

#if PARAMETER_FOR_PARA_HEADER == 27
  void testfun(int para = "dies");
#else
  void testfun(int para = "dass");
#endif

Inherit Header Parameters

<mycode.hxx>

#include <paraheader.hxx>

 <mycode.cxx>
   #include <mycode.hxx>

   void aFun() {
   }