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  2. Null coalescing operator - Wikipedia

    en.wikipedia.org/wiki/Null_coalescing_operator

    The null coalescing operator is a binary operator that is part of the syntax for a basic conditional expression in several programming languages, such as (in alphabetical order): C# [1] since version 2.0, [2] Dart [3] since version 1.12.0, [4] PHP since version 7.0.0, [5] Perl since version 5.10 as logical defined-or, [6] PowerShell since 7.0.0, [7] and Swift [8] as nil-coalescing operator.

  3. Null object pattern - Wikipedia

    en.wikipedia.org/wiki/Null_object_pattern

    In object-oriented computer programming, a null object is an object with no referenced value or with defined neutral (null) behavior.The null object design pattern, which describes the uses of such objects and their behavior (or lack thereof), was first published as "Void Value" [1] and later in the Pattern Languages of Program Design book series as "Null Object".

  4. Safe navigation operator - Wikipedia

    en.wikipedia.org/wiki/Safe_navigation_operator

    In object-oriented programming, the safe navigation operator (also known as optional chaining operator, safe call operator, null-conditional operator, null-propagation operator) is a binary operator that returns null if its first argument is null; otherwise it performs a dereferencing operation as specified by the second argument (typically an ...

  5. Associative array - Wikipedia

    en.wikipedia.org/wiki/Associative_array

    In computer science, an associative array, map, symbol table, or dictionary is an abstract data type that stores a collection of (key, value) pairs, such that each possible key appears at most once in the collection. In mathematical terms, an associative array is a function with finite domain. [1] It supports 'lookup', 'remove', and 'insert ...

  6. Ternary conditional operator - Wikipedia

    en.wikipedia.org/wiki/Ternary_conditional_operator

    In the above example, IIf is a ternary function, but not a ternary operator. As a function, the values of all three portions are evaluated before the function call occurs. This imposed limitations, and in Visual Basic .Net 9.0, released with Visual Studio 2008, an actual conditional operator was introduced, using the If keyword instead of IIf ...

  7. Lazy evaluation - Wikipedia

    en.wikipedia.org/wiki/Lazy_evaluation

    After a function's value is computed for that parameter or set of parameters, the result is stored in a lookup table that is indexed by the values of those parameters; the next time the function is called, the table is consulted to determine whether the result for that combination of parameter values is already available. If so, the stored ...

  8. Fold (higher-order function) - Wikipedia

    en.wikipedia.org/wiki/Fold_(higher-order_function)

    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 ...

  9. eval - Wikipedia

    en.wikipedia.org/wiki/Eval

    In PowerShell, the Invoke-Expression Cmdlet serves the same purpose as the eval function in programming languages like JavaScript, PHP and Python. The Cmdlet runs any PowerShell expression that is provided as a command parameter in the form of a string and outputs the result of the specified expression.