Re: [boost] [forward_declare] Interest Inquiry toward Faster Compile Times

Subject: Re: [boost] [forward_declare] Interest Inquiry toward Faster Compile Times
From: Daniel Larimer (dlarimer_at_[hidden])
Date: 2012-08-02 08:12:00

>> 
> 
> Hi,
> 
> I believe the general idea has been around for years [1]. I wonder if a
> utility like this gets accepted to Boost. You have my interest.
> 
> I think you can save a few more lines of code in the headers by separating
> some of the member functions of fwd (like the constructors and the
> destructor)  into another header file, that will only get included in .cpp
> files.
> 
There is a trade off between lines of code an 'number of files loaded'.  But I think you are right it could be split out.

As I think of more features to add to fwd this becomes important.  In my latest test I show how operators can be transparently supported.

fwd only solves the problem for some classes.   Classes like std::string pose a bigger challenge because they cannot be forward declared even if all you want to use is a std::string* because it is really a template / typedef.  My partial solution was to attempt a class that was 'reinterpret_castable' to std string.  

Simply including <string> adds 4000+ lines of code to the build.   Including my string.hpp adds 61 lines and is sufficient for 95% of the usage of std::string (I would finish out the interface to mirror most of std::string) leaving only a few edge cases. where std::string would be required.  In the .cpp it would use the real string to implement everything.

> Cheers,
> Kris
> 
> [1] http://www.gotw.ca/gotw/028.htm
> 
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