[Boost-users] Header file granularity policy?

From: Scott Meyers (usenet_at_[hidden])
Date: 2006-08-19 01:49:38

Some Boost libraries, such as SmartPtr and Variant, offer a single header with 
declarations for all library functionality as well as a set of headers for 
subsets of functionality.  For example, smart_ptr.hpp declares all of 
shared_ptr, shared_array, weak_ptr, scoped_ptr, scoped_array, and intrusive_ptr. 
  If I don't want all these declarations, I can use more specific headers, e.g., 
shared_ptr.hpp or scoped_array.hpp.  Such libraries allow me to choose between 
the convenience of a single comprehensive header or the precision of multiple 
targeted headers.

Other libraries seem to offer only the collection of targeted headers.  For 
example, FileSystem offers five headers, but there doesn't seem to be a 
comprehensive filesystem.hpp.  Similarly, Lambda seems to offer only targeted 
headers;  there doesn't seem to be a single "declare everything in Lambda" 
header.  (There is a lambda.hpp, but it's not comprehensive, e.g., it doesn't 
declare Lambda's bind.)

I find that this kind of inconsistency among libraries degrades my experience as 
a Boost user, especially when I'm first learning to use a library.  More than 
once I've spent time puzzling over a compilation error, only to discover that my 
mistake was not including a needed header.  (I seem to make this error most 
commonly when using Lambda.)  Is there some kind of Boost convention or policy 
on whether a library should offer a comprehensive "declare everything in the 
library" header in addition to more targeted headers?

Thanks,

Scott