User talk:Kr/Parameterized Headers

Some thoughts about C/C++ headers.

Kinds of C/C++ Headers

• A header provides the interface to (parts) of zero or multiple libraries.
• A header may include other headers.
• A header may be parametrizable (parameters may be mandatory), a header is parametrizable, if it reacts on defines.
• A header inherits parameters from included headers.
• A header may be comprehensive.

Tips

Include headers in reverse order of Distance.

This ensures

• that the compiler produces an error in case the header is not complete, and
• that successive (parametrizable) headers are configured properly.

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

Examples

Matching header first

"mycode.hxx" [cpp]

void testfun(void *); "mycode.cxx"[cpp] // include matching header first

1. include "mycode.hxx"
   
2. include <anyotherheader.hxx>

Parameterize base header

"mycode.hxx"[cpp]

1. define PARAMETER_FOR_PARA_HEADER 27
2. include <paraheader.hxx>

void testfun(void *) "mycode.cxx"[cpp]

1. include <mycode.hxx>

/* Even if (in)directly including "paraheader.hxx" again,

  it is parametrized correctly (which would not be true, if including it first). */

1. include "paraheader.hxx"

Parameterizeable header

"paraheader.hxx"[cpp]

1. if PARAMETER_FOR_PARA_HEADER == 27

 void testfun(int para = "dies");

1. else

 void testfun(int para = "dass");

1. endif

Inherit Header Parameters

"mycode.hxx"[cpp]

1. include <paraheader.hxx>

"mycode.cxx"[cpp]

1. include <mycode.hxx>

void aFun() { }