Ruby – Display error mode

module MyLib
 VERSION = "0.1 .1"
 ERROR = [
 "You can either give one arg and a block or two args, not both.",
 "Yadda yadda..."
 ]< br />end

def my_method(*args, &blk)
 raise( ArgumentError, MyLib::ERROR[0]) if (...condition snipped...)
end

module MyLib
 class FooError  def to_s
 "You can either give one arg and a block or two args, not both.",
 end< br /> end
end

raise MyLib::FooError
MyLib:: FooError: You can either give one arg and a block or two args, not both.
 from (irb):46

rescue MyLib::FooError

In my code, I usually use the following settings:

module MyLib
 VERSION = "0.1.1"
 ERROR = [
 "You can either give one arg and a block or two args, not both.",
 "Yadda yadda..."
 ]
end

and then somewhere in my code:

 def my_method(*args, &blk)
 raise(ArgumentError, MyLib::ERROR[0]) if (...condition snipped...)
end

A good way to define the error message?

You can define your own exception class:

module MyLib
 class FooError  def to_s
 "You can either give one arg and a block or two args, not both.",
 end
 end
end

Now, if you raise it:

raise MyLib::FooError
MyLib::FooError: You can either give one arg and a block or two args, not both.
 from (irb):46

If you want to deal with it:

rescue MyLib::FooError