[ruby-core:44727] [ruby-trunk - Feature #6372][Assigned] More specific error for uncaught throw

Issue #6372 has been updated by mame (Yusuke Endoh).

Status changed from Feedback to Assigned
Target version changed from 1.9.3 to 2.0.0

Because you didn't explain use case at all, I didn't understand the spec of your code nor what you really want.  You are talking about tests, right?

Yes, the current design of exception class hierarchy is too coarse for tests.  The fact does not applies only to throw.  The following examples do all raise an ArgumentError, but their meanings vary very much.

  def foo(x); end; foo(1, 2)  #=> wrong number of arguments (2 for 1) (ArgumentError)

  1.step(10, 0) { }  #=> step can't be 0 (ArgumentError)

  a = []; a << a; a.flatten  #=> tried to flatten recursive array (ArgumentError)

A general policy for exception class design is required, I think.

Indeed we can define a specific sub exception class for each, but the task may be expensive.
And, it may make new feature proposal slightly difficult: "the feature is good, the method name is also good, but the name of exception class for its corner case is not good, so we need more discussion..."

-- 
Yusuke Endoh <[e-mail]>
----------------------------------------
Feature #6372: More specific error for uncaught throw
https://bugs.ruby-lang.org/issues/6372#change-26288

Author: trans (Thomas Sawyer)
Status: Assigned
Priority: Normal
Assignee: matz (Yukihiro Matsumoto)
Category: core
Target version: 2.0.0


I have this method:

=begin
  class Symbol
    # Does the block throw the symbol?
    # 
    def thrown?
      catch(self) do
        begin
          yield
          true
        rescue ArgumentError => err     # 1.9 exception
          false
        rescue NameError => err         # 1.8 exception
          false
        end
      end
    end
  end
=end

But it was recently pointed out to me that the rescue of ArgumentError and NameError is not good enough b/c they might rescue an unrelated error of the same type. So to make this right there needs to be a more specific error. Perhaps `class ThrowError < ArgumentError`.



-- 
http://bugs.ruby-lang.org/