bearophile wrote: > Andrei: > >> FWIW I just posted a response to a question asking for a comparison >> between Clay and D2. >> >> http://www.reddit.com/r/programming/comments/es2jx/clay_programming_language_wiki/ > > Just few comments: > >> The docs offer very little on Clay's module system (which is rock solid >> in D2). > > D2 module system may be fixed, but currently it's not even bread-solid. > > The Clay syntax for imports is more similar to what I have desired for D > (but that () syntax is not so good): > > import foo.bar; // Imports module foo.bar as a qualified path > // use "foo.bar.bas" to access foo.bar member bas > import foo.bar as bar; // Imports module foo.bar with alias bar > // use "bar.bas" to access foo.bar member bas > import foo.bar.(bas); // Imports member bas from module foo.bar > // use "bas" to access foo.bar member bas > import foo.bar.(bas as fooBarBas) // Imports member bas with alias > fooBarBas import foo.bar.*; // Imports all members from module foo.bar
This looks like a subset of the D module system. The only difference is 'static' import by default and the .* feature which has to be implemented by the library author in D. Are those the things you find missing in D? > I don't know about Modula3 module system, I will search info about it. > > >>Clay mentions multiple dispatch as a major feature. Based on extensive >>experience in the topic I believe that that's a waste of time. Modern C++ >>Design has an extensive chapter on multiple dispatch, and I can vouch next >>to nobody uses it in the real world. Sure, it's nice to have, but its >>actual applicability is limited to shape collision testing and a few toy >>examples.< > > I think double dispatch is enough, it cover most cases and keeps both > compiler complexity low enough. If you put double dispatch with a nice > syntax in D then maybe people will use it. There are many things that > people in other languages use that C++ programmers don't use because using > it in C++ is ugly, a pain, unsafe, etc. The visitor pattern is used enough > in Java (Scala too was designed to solve this problem). > > Bye, > bearophile I think I agree here. I have never programmed much in a language with multiple dispatch, but everytime I see dynamic casting or the visitor pattern in an OOP program I think about how that would be so much better. Honestly its just speculation, but I guess that the lack of interest is because it is not a widely known and available solution. Library implementations have issues, both usability and performance wise.
