Re: [boost] boost.org Source-Code, Concepts & Idioms.

Subject: Re: [boost] boost.org Source-Code, Concepts & Idioms.
From: vicente.botet (vicente.botet_at_[hidden])
Date: 2008-10-14 18:49:36

----- Original Message ----- 
From: "Steven Watanabe" <watanabesj_at_[hidden]>
To: <boost_at_[hidden]>
Sent: Tuesday, October 14, 2008 9:12 PM
Subject: Re: [boost] boost.org Source-Code, Concepts & Idioms.

>
> AMDG
>
> Hartmut Kaiser wrote:
>>> Can this be made to format macro expansions nicely?
>>>
>>
>> What do you mean by that?
>>
>
> Since the point is to make the code more readable,
> if we do any macro expansion for instance:
>
> #define SOME_MACRO(...)   \
>  template<class T>       \
>  class C {               \
>    /*stuff*/             \
>  };
>
> SOME_MACRO(x, y, z)
>
> We don't want this all to end up on one line.
>
> In Christ,
> Steven Watanabe

Hi,

I'm not sure to understand what exactly you want, which are the two 
generated sources you are locking for.

Any way here they are my 2 cts.

If the problem is to have a single source able to generate the current 
files, and on the other hand a more readable pseudo C++, I think that we 
need a different preprocesor.

I've made something like that some years ago (lost now)

The preprocessor
* allow to define one line macros
@@define SOME_MACRO(...) XXXX

* allow to define multi line macros preserving white spaces and line breaks

@@define_begin SOME_MACRO(...)
  template<class T>
  class C {
    /*stuff*/
 };
@@define_end

* allow conditional preprocesing
@@if
@@else
@@endif

* file inclusion
@@include "file"

The preprocessing was done using some sed/awk and the CPP preprocessor, on 
three phases.
1st.  Prepare the input to the CPP
     .  Replace all the CPP preprocessing  # directives by $$
     .  Add a end of line pattern $$
     .  Replace n white spaces by  " $$n$$ "
     .  Add the \ at the end of the multi line macros and remove the 
@@define_end
     .  Replace the new preprocesing directives @@ by  #
     .  Replace C comments /* */ by  $$* *$$
     .  Replace C++ comments // by  $$$$
2nd. apply the CPP preprocessor
3rd. restore the initial CPP directives
     .  Replace all the CPP preprocessing  $$ directives by #
     .  Replace the pattern $$ by a end of line
     .  Replace the pattern " $$n$$ " by n white spaces
     .  Replace the patterns by  $$* *$$ by /* */
     .  Replace the pattern $$$$ by //

The problem is if library authors will use this preprocessing to get the two 
required outputs.

I don't know if this can help.

Vicente