Wed, 29 Jul 2009 00:42:31 +0100, Stewart Gordon wrote: > Sergey Gromov wrote: >> Mon, 27 Jul 2009 07:59:40 -0500, Andrei Alexandrescu wrote: >> >>>> Is it appropriate to define multiple classes, structs, templates, etc >>>> within a single module? What considerations should inform the decision >>>> regarding the placement of module boundaries? >>> I think it's appropriate because many pieces of functionality come as a >>> bundle. The rule of thumb is, module provides the functionality, and >>> it's up to the designer to decide what that entails. >> >> That's the problem. On one hand, it's desirable to see a module as a >> functionality bundle. On the other hand, module is the smallest >> available unit of encapsulation. That is, if you have a class and >> change its private implementation, this may affect *anything* in the >> same module. Hence Tango's hundreds of modules in dozens of packages, I >> think. > > I guess that's meant to encourage you to keep your modules small enough > that you know what you're doing.
Yes you can do a finer-grained encapsulation, but then you end up without "functionality bundle." And even if you create a collective import module I think there is no way to make it stand out as such. Though this is no different from C. > At the smallest level, it would be a matter of: If in C++ you would > declare Qwert to be a friend of Yuiop, then in D you put Qwert and Yuiop > in the same module. You could implement the converse as well, but for a > bunch of small classes it usually isn't worth it. This is understandable. >> It also adds to the problem that most people familiar with OO paradigm >> consider classes to be such encapsulation units. Surprizes are >> inevitable. > > I once came up with the idea a 'veryprivate' protection attribute that > would do this, but I can't seem to find the post now. I wonder how much code will break if "private" keyword becomes really private. You can always implement tight coupling with package visibility which C++ lacks.