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In computer programming, lazy initialization is the tactic of delaying the creation of an object, the calculation of a value, or some other expensive process until the first time it is needed.
Implementations of the singleton pattern ensure that only one instance of the singleton class ever exists and typically provide global access to that instance. Typically, this is accomplished by: Declaring all constructors of the class to be private, which prevents it from being instantiated by other objects
The user can search for elements in an associative array, and delete elements from the array. The following shows how multi-dimensional associative arrays can be simulated in standard AWK using concatenation and the built-in string-separator variable SUBSEP:
Virtual method tables also only work if dispatching is constrained to a known set of methods, so they can be placed in a simple array built at compile time, in contrast to duck typing languages (such as Smalltalk, Python or JavaScript).
[1] [2] An instance variable has similarities with a class variable, [3] but is non-static. An instance variable is a variable which is declared in a class but outside of constructors, methods, or blocks. Instance variables are created when an object is instantiated, and are accessible to all the constructors, methods, or blocks in the class.
This is most commonly implemented in the underlying object model, like .Net or Cocoa, which includes standard functions that convert the internal data into text. The program can create a complete text representation of any group of objects by calling these methods, which are almost always already implemented in the base associative array class ...
Arrays and structs can be viewed as predefined generic types. Every usage of an array or struct type instantiates a new concrete type, or reuses a previous instantiated type. Array element types and struct element types are parameterized types, which are used to instantiate the corresponding generic type.
A class variable is not an instance variable. It is a special type of class attribute (or class property, field, or data member). The same dichotomy between instance and class members applies to methods ("member functions") as well; a class may have both instance methods and class methods.