From: Lothar Scholz <llothar@...>
Date: 2002-05-26T10:58:17+09:00
Subject: Ruby Syntax Highlighting (and a Ruby Parser BUG)

I'm just trying to write a syntax highlighting plug in for my editor
and found this task very very hard.

For example look at the following string:

print "String #{ ($a={1=>2, 2=> "mystring" , 4=>6}).length }"

I think an editor should highlight everything after "print" in the
string color. But it is impossible for my colorize algorithm to find
out where the string ends without writing a complete ruby expression
parser.

And i discovered that the ruby interpreter itself does not handle this
situation right. If you replace the string  "mystring" with the string
")}mystring" so that the line becomes

print "String #{ ($a={1=>2, 2=> "})mystring" , 4=>6}).length }"

the parser signals a syntax error. This is a RUBY (1.6.7) bug.

The more time i spend with this terrible ruby syntax the more i think
it should be cleaned up from all this special cases that saves you
(in the best case) not more then 4 keystrokes.

And finally a question: 

What do you expect from editor syntax highlighting ?

Until now i believed heuristics are evil, because the different colors
are there to show you errors immediately. But with this ruby example
i'm not sure any more. And i don't think that any of the other ruby
tools are working correctly.