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In computer programming, initialization or initialisation is the assignment of an initial value for a data object or variable. The manner in which initialization is performed depends on the programming language , as well as the type, storage class, etc., of an object to be initialized.
In Objective-C, the constructor method is split across two methods, "alloc" and "init" with the alloc method setting aside (allocating) memory for an instance of the class, and the init method handling the bulk of initializing the instance. A call to the method "new" invokes both the alloc and the init methods, for the class instance.
do end: f do ensure tag: expression end: f do check tag: expression end end: class X invariant tag: expression end: from instructions invariant tag: expression until expr loop instructions variant tag: expression end: Python — PHP Perl Raku PRE {condition } POST {condition } Ruby — Windows PowerShell OCaml F# COBOL
In Python, everything is an object, even classes. Classes, as objects, have a class, which is known as their metaclass. Python also supports multiple inheritance and mixins. The language supports extensive introspection of types and classes. Types can be read and compared—types are instances of type. The attributes of an object can be ...
Python is known as a glue language, [75] able to work very well with many other languages with ease of access. Python uses dynamic typing and a combination of reference counting and a cycle-detecting garbage collector for memory management. [76] It uses dynamic name resolution (late binding), which binds method and variable names during program ...
In Ruby, all classes are open. In Python, classes can be created at runtime, and all can be modified afterward. [43] Objective-C categories permit the programmer to add methods to an existing class without the need to recompile that class or even have access to its source code.
Additionally, they permit lazy allocation and initialization, whereas global variables in many languages will always consume resources. [ 1 ] [ 3 ] The singleton pattern can also be used as a basis for other design patterns, such as the abstract factory , factory method , builder and prototype patterns.
Resource acquisition is initialization (RAII) [1] is a programming idiom [2] used in several object-oriented, statically typed programming languages to describe a particular language behavior. In RAII, holding a resource is a class invariant , and is tied to object lifetime .