module DissociatedIntrospection
Constants
- Block
- LISTEN_TO_CLASS_METHODS
- VERSION
Public Class Methods
# File lib/dissociated_introspection.rb, line 34 def listen_to_defined_class_methods @listen_to_defined_class_methods ||= LISTEN_TO_CLASS_METHODS end
# File lib/dissociated_introspection.rb, line 30 def listen_to_defined_class_methods=(*methods) listen_to_defined_class_methods.concat(methods) end
Public Instance Methods
class Object
Invokes the public method whose name goes as first argument just like public_send
does, except that if the receiver does not respond to it the call returns nil
rather than raising an exception.
This method is defined to be able to write
@person.try(:name)
instead of
@person.name if @person
try
calls can be chained:
@person.try(:spouse).try(:name)
instead of
@person.spouse.name if @person && @person.spouse
try
will also return nil
if the receiver does not respond to the method:
@person.try(:non_existing_method) # => nil
instead of
@person.non_existing_method if @person.respond_to?(:non_existing_method) # => nil
try
returns nil
when called on nil
regardless of whether it responds to the method:
nil.try(:to_i) # => nil, rather than 0
Arguments and blocks are forwarded to the method if invoked:
@posts.try(:each_slice, 2) do |a, b| ... end
The number of arguments in the signature must match. If the object responds to the method the call is attempted and ArgumentError
is still raised in case of argument mismatch.
If try
is called without arguments it yields the receiver to a given block unless it is nil
:
@person.try do |p| ... end
You can also call try with a block without accepting an argument, and the block will be instance_eval'ed instead:
@person.try { upcase.truncate(50) }
Please also note that try
is defined on Object
. Therefore, it won't work with instances of classes that do not have Object
among their ancestors, like direct subclasses of BasicObject
.
# File lib/dissociated_introspection/try.rb, line 38
Same as try
, but raises a NoMethodError exception if the receiver is not nil
and does not implement the tried method.
"a".try!(:upcase) # => "A" nil.try!(:upcase) # => nil 123.try!(:upcase) # => NoMethodError: undefined method `upcase' for 123:Fixnum
end
# File lib/dissociated_introspection/try.rb, line 103