attr_reader :attr1, :attr2, and when reading other people's code you can be sure that there isn't a typo that let
Just as I was embracing the idea that macros are absolutely necessary for much stuff,
ruby came along and brought block arguments. And tada, you can do map and everything without macros just as regular function. Some guys even ported the idea to java. So I became unsure whether macros are really necessary. Ok, basically I still believe that because (programmatic) macros can do anything; I think they are the best way to integrate custom code generators.
And then came along Raganwald and wanted something like
ph = find_whatever()&&.author&&.phone: Call
find_whatever, and if it returns something, get the author, and if there is one, get his phone number. Otherwise the whole expression is
Now it is amazing that you can get ruby to do something like that at all, even though it cheats on two points: It does not use the intended syntax (
obj.andand.name(note the conspicious second dot), and it does not actually take the shortcut but instead goes through the rest with a dummy object.
But he does not just to avoid the helper variables, but also to get a left-to-right reading. You just can't do that in lisp, for instance. (Ok, it's going to be the inverse.)
But why this hit me: While I have somes idea how I would bring macros into language with syntax, I have no idea yet how I would make
&&.definable. The problems here:
- When you get to the
&&.you are already in the middle of the expression the macro would need to replace, so there would be a need to allow operators be a kind of macro
- Member selection is not a binary, but a postfix operator! While it looks like one, the right hand side is not an expression, but a compile-time constant. (In a sense there are many different operators, one for each possible member name.)
I guess I need to think about that some more...how to enable user-defined operators not only as functions, but also as macros.