CODEWITHSUNDEEP
ruby
yonso
yonso

Reputation: 275

Ruby raise method and implicit coercion

Consider the two following ways to raise an exception -

class ExampleError < StandardError; end

raise ExampleError.new

raise ExampleError

In the first way, an instance of ExampleError is given to the method raise. The raise method can accept an Exception parameter and everything is clear.

In the second way a Class instance is given to the method, yet this still works.

Due to the fact that raise can accept String, was there implicit conversion of the parameter from Class to String?

Thank you

Upvotes: 1

Views: 300

Answers (1)

Sergio Tulentsev
Sergio Tulentsev

Reputation: 230396

No, it does not get converted to String. In fact, your assumption was wrong. raise doesn't want an instance of some exception class. It would rather have the exception class itself. See documentation for Kernel#raise:

... With a single String argument, raises a RuntimeError with the string as a message. Otherwise, the first parameter should be the name of an Exception class (or an object that returns an Exception object when sent an exception message). ...

So, you can pass anything to raise, as long as it's a string or has exception method. Both your variants pass here:

class ExampleError < StandardError; end

ExampleError.exception # => #<ExampleError: ExampleError>
ExampleError.new.exception # => #<ExampleError: ExampleError>

Upvotes: 4

Related Questions