From: James Edward Gray II <james@...>
Date: 2007-06-28T05:48:39+09:00
Subject: Re: Regexp rescue method

On Jun 27, 2007, at 3:05 PM, Tim Hunter wrote:

> th8254 wrote:
>> How would I write a rescue method to recover from a failed regexp
>> parsing?
>>
>> -Thanks
>>
>>
> I don't think that raises an error. You'd have to check for a nil  
> result instead.

I took the question to mean, how would I recover from a malformed  
Regexp error like:

 >> re = /[/
SyntaxError: compile error
(irb):1: invalid regular expression; '[' can't be the last character  
ie. can't start range at the end of pattern: /[/
         from (irb):1

I don't know of a way to recover from that specific example either,  
which is why I didn't jump to answer:

 >> begin
?>   re = /[/
 >> rescue SyntaxError
 >>   puts "Your Regexp is malformed."
 >> end
SyntaxError: compile error
(irb):3: invalid regular expression; '[' can't be the last character  
ie. can't start range at the end of pattern: /[/
         from (irb):6

But, if you change the way the expression is built, it does seem to  
become a recoverable error:

 >> begin
?>   re = Regexp.new("[")
 >> rescue RegexpError
 >>   puts "Your Regexp is malformed."
 >> end
Your Regexp is malformed.
=> nil

James Edward Gray II