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For example, Lua provides tables. Although Lua stores lists that have numerical indices as arrays internally, they still appear as dictionaries. [4] In Lisp, lists are the fundamental data type and can represent both program code and data. In most dialects, the list of the first three prime numbers could be written as (list 2 3 5).
Templates are a feature of the C++ programming language that allows functions and classes to operate with generic types.This allows a function or class declaration to reference via a generic variable another different class (built-in or newly declared data type) without creating full declaration for each of these different classes.
In other words, C++ does not have "submodules", meaning the . symbol which may be included in a module name bears no syntactic meaning and is used only to suggest the association of a module. As an example, std.compat is not a submodule of std , but is named so to indicate the association the module bears to the std module (as a "compatibility ...
Nonetheless, the principle is useful in reasoning about the design of class hierarchies. Liskov substitution principle imposes some standard requirements on signatures that have been adopted in newer object-oriented programming languages (usually at the level of classes rather than types; see nominal vs. structural subtyping for the distinction):
The "generic programming" paradigm is an approach to software decomposition whereby fundamental requirements on types are abstracted from across concrete examples of algorithms and data structures and formalized as concepts, analogously to the abstraction of algebraic theories in abstract algebra. [6]
In Java, is-a relation between the type parameters of one class or interface and the type parameters of another are determined by the extends and implements clauses. Using the Collections classes, ArrayList<E> implements List<E>, and List<E> extends Collection<E>. So ArrayList<String> is a subtype of List<String>, which is a subtype of ...
There was a proposal to add concepts as an explicit language feature in C++11, though it was rejected as "not ready". C++20 eventually accepted the refined design of concept. Concepts are an example of structural typing. As generics in Java and C# have some similarities to C++'s templates, the role of concepts there is played by interfaces ...
Presented below is a simple (contrived) example of a C++ hello world program, where the text to be printed and the method of printing it are decomposed using policies.In this example, HelloWorld is a host class where it takes two policies, one for specifying how a message should be shown and the other for the actual message being printed.