From: kackson@... (kackson)
Date: 2002-04-16T03:22:31+09:00
Subject: need help on using Ruby to replace some SED expressions

I tried sed. But it is getting really tough when I keep realizing I've
things to expand and expand and expand into a huge chunk of regular
expressions that now become completely unreadable and hard to
maintain.
So, as a beginner of Ruby, any advise on the question below is
apprecaited.

I need to:
1. read an input file
2. For everyline, if the FIRST word has a dot '.', replace it with $.
Note, the first word may/maynot have been indented.
3. For the rest of the line, replace all occurance of '@' with '^'.
4. If there is something like '(2 + 3)' somewhere along the line,
evaluate it and replace the entire expression i.e. (2 + 3) with the
result, i.e. 5. Note, the brackets are gone. And it could be +, *, -,
or divide. If it is even possible for mathmatical routines such as
log/sin, etc. That would be even better.

I'm running short of time to experiment all the powerful set of ruby
methods for now. I hope some ruby expert could help.

Thank you!!!