From: "nobu (Nobuyoshi Nakada)" <nobu@...>
Date: 2012-07-16T23:45:32+09:00
Subject: [ruby-core:46510] [ruby-trunk - Feature #6739][Feedback] One-line rescue statement should support specifying an exception class


Issue #6739 has been updated by nobu (Nobuyoshi Nakada).

Status changed from Open to Feedback

A rescue clause (non-modifier) can be followed by arbitrary expressions which would return a class or a module,
so the syntax in your proposal is unclear.

We had discussed about arguments to rescue-modifier when adding it, but no suitable syntax was found.
----------------------------------------
Feature #6739: One-line rescue statement should support specifying an exception class
https://bugs.ruby-lang.org/issues/6739#change-28149

Author: Quintus (Marvin G��lker)
Status: Feedback
Priority: Normal
Assignee: 
Category: core
Target version: 2.0.0


Hi there,

When wrapping up a single line inside a begin/rescue block I feel constantly annoyed that I have to create a whole lot of bloated code just to rescue from a specific exception. For example:

  begin
    File.read("myfile.txt")
  rescue Errno::ENOENT
    puts "No file there"
  end

Now it's possible to do this:

  File.read("myfile.txt") rescue puts "No file there"

But this forces me to rescue from StandardError which is not really what I want, because it swallows exceptions I'd rather have wanted to see, e.g. if I mistyped `File.read' as `File.raed' this would be swallowed as well. I know it is possible to compress the multiline statements above into a single line by using semicolons, but it's better to avoid them as they decrease readability.

So my suggestion is to add something like the following syntax to Ruby:

  File.read("myfile.txt") rescue Errno::ENOENT, puts "No file there"

This way it is more consise than having to write five lines (instead of just one) and still reads good (as opposed to the semicolon trick). Maybe the syntax isn't ideal as the comma operator is already used elsewhere, but the general idea should be clear though.

Valete,
Marvin


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