Function object
In Ruby, several objects can be considered function objects, in particular Method and Proc objects. Ruby also has two kinds of objects that can be thought of as semi-function objects: UnboundMethod and block. UnboundMethods must first be bound to an object (thus becoming a Method) before they can be used as a function object. Blocks can be called like function objects, but to be used in any other capacity as an object (e.g. passed as an argument) they must first be converted to a Proc. More recently, symbols (accessed via the literal unary indicator codice_35) can also be converted to codice_36s. Using Ruby's unary codice_37 operator—equivalent to calling codice_38 on an object, and assuming that method exists—the Ruby Extensions Project created a simple hack.
Uniform access principle
Strictly speaking, Ruby does not follow Meyer's original UAP in that the syntax for accessing an attribute is different from the syntax for invoking a method. But here, the access for an attribute will always actually be through a function which is often automatically generated. So in essence, either type of access invokes a function and the language does follow Meyer's revised Uniform Access Principle.