Re: SV: [boost] #ifndef paradigm

From: Greg Colvin (Gregory.Colvin_at_[hidden])
Date: 2002-08-27 17:44:33

At 04:23 PM 8/27/2002, Henrik Ravn wrote:
>> Often, when one wants to make sure a header is included only 
>> once, s/he uses
>> the paradigm:
>> 
>> #ifndef HEADER_NAME_H__
>> #define HEADER_NAME_H__
>> 
>> // code here...
>> 
>> #endif // HEADER_NAME_H__ -- this comment is to make it clear 
>> what the endif
>> is for
>> 
>> 
>> It is better to remove the duality of the comment at the end, 
>> by switching
>> to this paradigm:
>> 
>> 
>> #ifndef HEADER_NAME_H__
>> 
>> // code here...
>> 
>> #define HEADER_NAME_H__
>> #endif
>
>I would argue that the easiest idiom to use is this:
>
>#ifndef HEADER_NAME
>#define HEADER_NAME
>
>// code here ...
>
>#endif // include guard 
>
>in this way you don't have to update the header file both at the top and
>the bottom in the infrequent event of a rename.

And of course an even easier idiom is:

   #ifndef HEADER_NAME
   #define HEADER_NAME
   ...
   #endif