Re: [v2] header file conversion

From: Alexey Syomichev (asyomichev_at_[hidden])
Date: 2004-12-25 11:52:35

David Abrahams wrote:
> Alexey Syomichev wrote:
>>I need to preprocess some header files with a perl script. Say, I have 
>>"a.cpp" that includes "a.hpp", which needs to be created first from 
>>"a.h". I need to 1) run the perl script taking a.h and creating a.hpp 
>>and then to 2) compile a.cpp as part of the library. Also I need to keep 
>>track of the dependency between a.h and a.cpp.
> 
> Meaning that you might later hand-edit a.h?

Well, yes. In case ".h" changes, ".hpp" must be re-generated, ".cpp" 
recompiled and library relinked.

>>It looks like I canot register a new generator, because the suffix ".h" 
>>is already assigned to a type "H". 
> 
> How does that prevent you from registering a new generator?

You are right, it does not. Following the extender manual, I was trying 
to register my own type for the sufix ".h" before I register the 
generator, which is wrong.
Now I have a ".h -> .hpp" generator. How do i invoke it? If I simply 
list ".h" file in "sources", nothing is happening.
Additional generator, creating empty .cpp from .hpp, seems to do the 
trick and the .h -> .hpp generator gets invoked. When I re-run the 
build, updates happen only if I touch the .h or clean the intermediates. 
Cool!
Two little problems: there are extra .cpp and .o files involved, which 
is just not elegant, and the dummy .cpp can clash with an existing .cpp, 
which is a more serious limitation. Is there a better way?

One more question: during generator registration, how do I reference 
rules/actions from the local Jamfile? I created a small module 
"preprocess" and referenced an action as "preprocess.convert", which 
works. Then I tried placing the contents of "preprocess.jam" in the 
Jamfile itself and changing the reference to plain "convert", but it 
fails to look up an action by the unqualified name. Is there some magic 
qualifier for local rules/actions?

Thanks,
-Alexey