Contextualizing keywords

[Robert Fraser]

Hi, hope you're all enjoying the properties debate.

I've been seeing the "too many keywords" argument a lot lately, and I 
think it's definitely a valid argument. "shared" and "body" in 
particular are rather annoying keywords since I frequently use them in 
code. And if users are deciding not to use D because of the number of 
keywords, that's even worse.

The idea of "kewyord" as a parser construct is antiquated thinking. Look 
at C#: "get", "set", "value", "event", "var", etc. are only keywords in 
a particular context. C++/CLI takes it a step further (from 
http://blogs.msdn.com/hsutter/archive/2003/11/23/53519.aspx ). There are 
three new reserved words ("gcnew", "generic", "nullptr") and a few 
multi-word keywords ("for each", "enum/interface/ref/value 
class/struct") as well as some contextual keywords that can only appear 
in certain positions.

In D, without a significant change to the lexer/parser, any keywords 
that cannot appear in the same place as an identifier could be made 
legal identifiers easily. Off the top of my head, "in", "out", "body", 
"module", "unittest", "import", "throw" and probably a few others could 
be freed up.

With some parser lookahead, you could add modifiers and storage classes 
to the list and probably dozens of others. If braces were required in 
try/catch statements, "try", "catch", and "finally" could be added.

Further, this might be pretty easy to implement (i.e. Walter, if you're 
interested, I'm willing to make a patch). It's all backwards-compatible 
and would even work in D1.

Thoughts?