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

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(Parameterized Headers)
 
m (Some fixes.)
 
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some thoughs about headers
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Some thoughts about C/C++ headers.
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HowTo
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Include C / C++ Headers
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==Kinds of C/C++ Headers==
 
* A header provides the interface to (parts) of zero or multiple libraries.
 
* A header provides the interface to (parts) of zero or multiple libraries.
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* A header may includes other headers.
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* A header may include other headers.
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* A header may be parameterizeable (parameters may be mandantory): Parameterizeable Headers A header is parameterizeable, if it reacts on defines.
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* 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 inherits parameters from included headers.
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* A header may be comprehensive.
  
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Include headers in reverse order of Distance.
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==Tips==
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Include headers in reverse order of Distance.
  
 
This ensures
 
This ensures
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* that the compiler produces an error in case the header is not complete,
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* that the compiler produces an error in case the header is not complete, and
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* that successve (parameterizeable) headers are configured properly
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* that successive (parametrizable) headers are configured properly.
  
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Parameterize successive headers in the header and according to the headers code.
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Parametrize successive headers in the header and according to the headers code.
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Examples
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==Examples==
 
;Matching header first:
 
;Matching header first:
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  "mycode.hxx"
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  "mycode.hxx" <code>[cpp]
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<code>
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void testfun(void *);
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void testfun(void *);
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</code>"mycode.cxx"<code>[cpp]
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</code><br>
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// include matching header first
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"mycode.cxx"
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#include "mycode.hxx"<br>
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<code>
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#include <anyotherheader.hxx>
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// include matching header first
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</code>
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#include "mycode.hxx"<br>
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#include <anyotherheader.hxx>
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</code>
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;Parameterize base header:
 
;Parameterize base header:
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  "mycode.hxx"
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  "mycode.hxx"<code>[cpp]
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<code>
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#define PARAMETER_FOR_PARA_HEADER 27
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#define PARAMETER_FOR_PARA_HEADER 27
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#include <paraheader.hxx>
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#include <paraheader.hxx><br>
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void testfun(void *)
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void testfun(void *)
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</code><br>
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</code>"mycode.cxx"<code>[cpp]
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"mycode.cxx"<br>
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#include <mycode.hxx>
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#include <mycode.hxx>
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/* Even if (in)directly including "paraheader.hxx" again,  
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// even if (in)directly including "paraheader.hxx" again, it is parameterized correctly (which would not be true, if including it first)
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  it is parametrized correctly (which would not be true, if including it first). */
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#include "paraheader.hxx"
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#include "paraheader.hxx"
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</code>
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</code>
  
 
;Parameterizeable header:
 
;Parameterizeable header:
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  <paraheader.hxx>
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  "paraheader.hxx"<code>[cpp]
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<code>
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#if PARAMETER_FOR_PARA_HEADER == 27
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#if PARAMETER_FOR_PARA_HEADER == 27
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  void testfun(int para = "dies");
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  void testfun(int para = "dies");
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#else
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#else
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  void testfun(int para = "dass");
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  void testfun(int para = "dass");
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#endif
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#endif
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</code>
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</code>
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;Inherit Header Parameters:
 
;Inherit Header Parameters:
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  <mycode.hxx>
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  "mycode.hxx"<code>[cpp]
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<code>
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#include <paraheader.hxx>
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#include <paraheader.hxx>
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</code>"mycode.cxx"<code>[cpp]
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#include <mycode.hxx>
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  <mycode.cxx>
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    #include <mycode.hxx>
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    void aFun() {
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void aFun() {
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    }</code>
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}
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</code>

Latest revision as of 09:00, 10 September 2007

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() { }

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