Getting 'message' from a custom exception class

Question

This question refers to an answer here. I need to access message of a custom exception. Is this possible?

I thought that directly calling message will suffice as in this example:

class MyCustomError < StandardError
  attr_reader :object

  def initialize(object)
    @object = object
    puts message
  end
end

but this is not what I expected it to be. It gave me some string like:

"MyModuleNameHere::MyCustomExceptionClassNameHere"

instead of:

"a message"

My intuition is leaning towards no, since the initialize constructor does not take the "a message" text.

What do you actually want to do with the message? You probably don't want to print it within `initialize`. — Stefan, May 24 '18 at 08:38

score 1 · Answer 1 · answered May 24 '18 at 08:09

1

You get the class name of the error as the default message because you have not set anything for message. Once you set something, you will get it.

answered May 24 '18 at 08:09

sawa

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score 1 · Answer 2 · answered May 24 '18 at 08:52

You can pass the message and call super which will normally take a message, e.g. StandardError.new("oh no").

class MyCustomError < StandardError

  def initialize(message, object)
    # ...
    super(message)
  end
end

MyCustomError.new("Oh no", thing).message # => "Oh no"

This ebook on Ruby exceptions is well worth it: http://exceptionalruby.com/

Getting 'message' from a custom exception class

2 Answers2

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