Re: [boost] New dependency report

Andrey Semashev wrote:

On Thu, Jun 5, 2014 at 5:37 PM, Antony Polukhin wrote:

...

Would it be good to move a single header into the Boost.Core? This header depends only on Boost.Config. It adds dependency to a whole Boost.Functional library for the following libraries: array, container, filesystem, multiindex, thread, type_index, variant.

Hmm, although I can see benefits of it, I don't like tearing forward declarations from definitions.

I don't think it should go Core. On the other hand, the whole purpose of forward declarations is to let you not depend on the definition. This is still valuable when the _fwd header is in the same module, as it decreases the actual dependencies in terms of headers included, but this decrease doesn't show up in a module dependency report. Neither will it affect a module-based automatic downloader. Therefore, it might be worth thinking about a separate module that hosts just forward declarations. The danger of declarations and definitions going out of sync can be avoided by having tests (in the 'forward' module) that include both the declaration and the actual definition. Incidentally, 'functional/hash' has always bothered me. What was wrong with just 'hash'? Hierarchies do have its place but hash is hash, nothing particularly functional about it.