Re: [boost] [typeof] MSVC8 limits & preprocessing typeof/vector.hpp

From: Tobias Schwinger (tschwinger_at_[hidden])
Date: 2006-01-09 04:52:56

Arkadiy Vertleyb wrote:
> "Tobias Schwinger" <tschwinger_at_[hidden]> wrote
> 
> 
>>While having CVS access could be a good thing in general, it's probably
> 
> easier to
> 
>>use a ZIP, this time.
> 
> 
> For some reason it generates empty files...
> 
> What I did was to replace vector.hpp, copy preprocess.pl into
> libs/typeof/tools, and run the pipe version of your example.  It reported
> files being written, but all it wrote was copyright info...
>

Yeah it's all my fault, sorry. I just found out I messed up the preprocessing code 
by changing the name of a macro (but not everywhere).

vector.hpp (from line 24 on) should read:

     #if defined(BOOST_TYPEOF_PP_INCLUDE_EXTERNAL)

     #   undef BOOST_TYPEOF_PP_INCLUDE_EXTERNAL // <-- this line was bad
     #   undef BOOST_TYPEOF_VECTOR_HPP_INCLUDED

The ZIP has been updated with a corrected version too.

> My knowledge of perl is equal to zero :-(  

Then I should probably demystify that script for you:

The script beautifies and stores the code contained within. After preprocessing 
the perl interpreter sees something like that as the main program:

     $sewer = <<'some_crypic_end_marker'
     < code from external files we #include and which we don't wanna store
       stands here >
     some_cryptic_end_marker
     ; $sewer = '';

     &write_down("my_preprocessed_file.hpp",<<'some_crypric_end_marker'
     < the preprocessed code we want to keep >
     [...]
     some_cryptic_end_marker
     );

     &write_down("another_preprocessed_file.hpp",<<'some_crypric_end_marker'
     < more preprocessed code we want to keep >
     [...]
     some_cryptic_end_marker
     );

     [...]

Which discards an inline section, a.k.a. a here-document: a string literal 
spanning multiple lines (of C++ in this case).

And then invokes the subroutine 'write_down' with its first argument being the 
file name and the second argument being the content to store (another here-document).

The subroutine write_down runs a regex over the code (passed in via the second 
parameter) to remove all the stuff we don't want our preprocessed code to contain 
and stores it in a file with a license header.

That's all (the rest in there is just portable path twiddling and error handling)!

--
Tobias