From: Kirk Haines <wyhaines@...>
Date: 2010-11-10T06:03:58+09:00
Subject: Re: Analyzer for errors in code ?

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On Nov 9, 2010 11:56 AM, "David Unric" <dunric29a@gmail.com> wrote:

Robert Klemme wrote in post #960353:

> On Tue, Nov 9, 2010 at 5:00 PM, David Unric <dunric29a@gmail.com> wrote:
>> I would like to check ...
I understand it is difficult because the dynamic nature of Ruby, but
Python is in the same league and PyLint tool does "wonders" at detecting
possible errors without code execution
(http://www.logilab.org/card/pylintfeatures). It uses Abstract Syntax
Tree parser and Ruby also has its own AST so it would be possible.

But I asked for something more simplistic, like revealing trivial errors
like mentioned variable name typo.

See the following example:

Running with 'ruby -c' returns 'Syntax OK'.
Running with 'ruby -w' also doesn't warn about undefined 'mymsg'
variable.

Only when the condition becomes true, execution aborts with `<main>':
undefined local variable or method `mymsg' for main:Object (NameError)

if __FILE__ == $0
   my_msg = 'Hello'
   if ARGV[0] == 'doit'
       puts mymsg
   else
       puts 'Nope'
   end
end


How to avoid such pitfalls with writing more complex ruby code ? I can't
believe there is no other way how to verify the code without 'waiting
for exception at proper conditions' and then solve the bug.


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