How to manually create exception with message and backtrace

Question

How can I create an exception with backtrace?

I know we could do something like this to achieve this:

begin
  raise StandardError, "message"
rescue StandardError => exception
  exception.backtrace
end

Or

exception = StandardError.new("message")
exception.set_backtrace(caller)

But I am looking for something like this:

exception = StandardError.new("message", backtrace: caller)

Is there a way that I can initialize an exception with customized message and backtrace?

Answer 1

You can't initialize an exception with a backtrace, but you can assign one right after initialization.

exception = StandardError.new("message")
exception.set_backtrace(caller)

Answer 2

Wrap in an functional class by yourself:

class ErrorCreator
  def self.new(error, message = nil, backtrace: caller)
    exception = error.new(message)
    exception.set_backtrace(backtrace)
    exception
  end
end

Use:

ErrorCreator.new(StandardError, "failed")
ErrorCreator.new(StandardError, "failed", backtrace: caller)

I created a gem for anyone to use: https://github.com/JuanitoFatas/active_error.

Answer 3

You can create your own exceptions like this :

Create a file in app > exceptions > name_exception.rb

name_exception.rb

class NameException < StandardError
  def initialize(message, backtrace)
    super
    backtrace
  end
end

Then in your file

raise NameException.new(message, backtrace)

You can adapt it to your needs but the pattern is here.