Exception: NameError

Inherits:
Exception show all
Defined in:
activesupport/lib/active_support/core_ext/name_error.rb

Direct Known Subclasses

ActionDispatch::MissingController

Instance Method Summary collapse

Methods inherited from Exception

#as_json

Instance Method Details

#missing_nameObject

Extract the name of the missing constant from the exception message.

begin
  HelloWorld
rescue NameError => e
  e.missing_name
end
# => "HelloWorld"

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# File 'activesupport/lib/active_support/core_ext/name_error.rb', line 12

def missing_name
  # Since ruby v2.3.0 `did_you_mean` gem is loaded by default.
  # It extends NameError#message with spell corrections which are SLOW.
  # We should use original_message message instead.
  message = respond_to?(:original_message) ? original_message : self.message
  return unless message.start_with?("uninitialized constant ")

  receiver = begin
    self.receiver
  rescue ArgumentError
    nil
  end

  if receiver == Object
    name.to_s
  elsif receiver
    "#{real_mod_name(receiver)}::#{self.name}"
  else
    if match = message.match(/((::)?([A-Z]\w*)(::[A-Z]\w*)*)$/)
      match[1]
    end
  end
end

#missing_name?(name) ⇒ Boolean

Was this exception raised because the given name was missing?

begin
  HelloWorld
rescue NameError => e
  e.missing_name?("HelloWorld")
end
# => true

Returns:

  • (Boolean)

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# File 'activesupport/lib/active_support/core_ext/name_error.rb', line 44

def missing_name?(name)
  if name.is_a? Symbol
    self.name == name
  else
    missing_name == name.to_s
  end
end