From: Run Paint Run Run <redmine@...>
Date: 2009-06-13T02:51:55+09:00
Subject: [ruby-core:23827] [Bug #1618] Kernel.catch without Arguments

Bug #1618: Kernel.catch without Arguments
http://redmine.ruby-lang.org/issues/show/1618

Author: Run Paint Run Run
Status: Open, Priority: Normal
ruby -v: ruby 1.9.2dev (2009-06-01 trunk 23614) [i686-linux]

In 1.9 Kernel.catch can be called with neither a symbol nor object to catch, e.g.:

    catch { }

In 1.8 this usage raised an ArgumentError.

The test/ruby/test_system.rb file from the Ruby repository contains:

    def valid_syntax?(code, fname)
      code.force_encoding("ascii-8bit")
      code = code.sub(/\A(?:\s*\#.*$)*(\n)?/n) {
        "#$&#{"\n" if $1 && !$2}BEGIN{throw tag, :ok}\n"
      }
      catch {|tag| eval(code, binding, fname, 0)}
    end

With the help of #rubyspec, I've reduced this down to:

    catch {|wtf| throw wtf}

This passes an instance of Object into the block.

So, assuming that this must be a feature, could the documentation be updated with an explanation, and suggestions proffered as to the purpose of this invocation?


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