From: Jamis Buck <jgb3@...>
Date: 2004-01-06T09:43:03+09:00
Subject: Re: proc question and instance_methods

GGarramuno wrote:

>Continuing with the sets of newbie questions...
>
>Some doubts about proc:
>
>1) I assume the question will be no, but is it possible to evaluate a
>piece of proc code for syntax errors?  That is, I have a construct of
>the form:
>
>       text = "some text coming from somewhere"
>       code = proc { text }
>
>I'd like to know whether text is valid ruby code (syntactically),
>without having to run the proc.  In perl, this would be done by
>running eval on the code, as perl compiles to bytecode the proc even
>if not running it.
>But in ruby, it seems the proc is not "compiled" until run.  Is there
>any work-around for this?
>  
>

If you pass the code to eval, you can then test for a SyntaxError 
exception, like so:

  text = "some text coming from somewhere"
  begin
     eval "text"
  rescue SyntaxError => e
     # do something when it has a syntax error
  end

>
>2) I am currently using DelimScanner, a module written by Michael
>Granger.
>   Under 1.8, I get the message:
>
>../DelimScanner.rb:143: warning: instance_methods: parameter will
>default to 'true' as of 1.8.1
>
>for the following line in the code:
>
>    def_delegators :@scanner,
>        *( StringScanner.instance_methods -
>NeedCastingDelegators.collect {|sym| sym.id2name} )
>
>Now, if instance_methods is to be obsolete, what should be the proper
>replacement?  Both methods() and public_methods() seem to return a
>different (ie. more) set of functions than instance_methods().
>  
>

I don't think it's saying that instance_methods will be obsolete, I 
think it's just saying the (optional) boolean parameter it expects will 
default to true in 1.8.1.  I can only assume it defaulted to false before.

- Jamis

-- 
Jamis Buck
jgb3@email.byu.edu

ruby -h | ruby -e 'a=[];readlines.join.scan(/-(.)\[e|Kk(\S*)|le.l(..)e|#!(\S*)/) {|r| a << r.compact.first };puts "\n>#{a.join(%q/ /)}<\n\n"'