CLOS Eiffel and Sather: A Comparison

data types, inheritance, dynamic binding and garbage collection. bstract data types provide encapsulation and inheritance eases reuse. Both promote extensibility and modi ability. These two requirements seem widely accepted and we will not address them further. ynamic binding of functions to function names is one key to the exibility and extensibility of object-oriented languages. It allows new code to be called from unaltered old code by passing data of new types to old operations or assigning them to old variables. It is implemented by dynamic dispatch in which run-time type information is used to lookup, or bind to, the proper function. Lisp-machine operating systems typically have over 2000 classes and Smalltalk systems have about 1000. These systems have evolved over fteen years and rely on incremental compilation and dynamic dispatch to allow extensions and reuse of the existing class hierarchies while the system is running. Dynamic dispatch makes