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In object-oriented programming, the iterator pattern is a design pattern in which an iterator is used to traverse a container and access the container's elements. The iterator pattern decouples algorithms from containers; in some cases, algorithms are necessarily container-specific and thus cannot be decoupled.
A resurrected object may be treated the same as other objects, or may be treated specially. In many languages, notably C#, Java, and Python (from Python 3.4), objects are only finalized once, to avoid the possibility of an object being repeatedly resurrected or even being indestructible; in C# objects with finalizers by default are only finalized once, but can be re-registered for finalization.
The iterator object can then be iterated with the next() function, which uses the __next__() method internally, which returns the next element in the container. (The previous statement applies to Python 3.x. In Python 2.x, the next() method is equivalent.) A StopIteration exception will be raised when no more elements are left. The following ...
In object-oriented languages, an iterator, even if implicit, is often used as the means of traversal. The foreach statement in some languages has some defined order, processing each item in the collection from the first to the last. The foreach statement in many other languages, especially array programming languages, does not have any ...
Folds can be regarded as consistently replacing the structural components of a data structure with functions and values. Lists, for example, are built up in many functional languages from two primitives: any list is either an empty list, commonly called nil ([]), or is constructed by prefixing an element in front of another list, creating what is called a cons node ( Cons(X1,Cons(X2,Cons ...
In some programming languages, an assignment statement returns a value, while in others it does not. In most expression-oriented programming languages (for example, C), the assignment statement returns the assigned value, allowing such idioms as x = y = a, in which the assignment statement y = a returns the value of a, which is then assigned to x.
Python. The use of the triple-quotes to comment-out lines of source, does not actually form a comment. [19] The enclosed text becomes a string literal, which Python usually ignores (except when it is the first statement in the body of a module, class or function; see docstring). Elixir
Python supports most object oriented programming (OOP) techniques. It allows polymorphism, not only within a class hierarchy but also by duck typing. Any object can be used for any type, and it will work so long as it has the proper methods and attributes. And everything in Python is an object, including classes, functions, numbers and modules.