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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 object member access, array index, or lambda invocation). It is used to avoid sequential explicit null checks and assignments and replace them with method/property chaining. In programming languages where the navigation operator (e.g. ".") leads to an error if applied to a null object, the safe navigation operator stops the evaluation of a method/field chain and returns null as the value of the chain expression. It was first used by Groovy 1.0 in 2007 and is currently supported in languages such as C#, Swift, TypeScript, Ruby, Kotlin, Rust and others. There is currently no common naming convention for this operator, but safe navigation o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Object-oriented Programming
Object-oriented programming (OOP) is a programming paradigm based on the concept of "objects", which can contain data and code. The data is in the form of fields (often known as attributes or ''properties''), and the code is in the form of procedures (often known as ''methods''). A common feature of objects is that procedures (or methods) are attached to them and can access and modify the object's data fields. In this brand of OOP, there is usually a special name such as or used to refer to the current object. In OOP, computer programs are designed by making them out of objects that interact with one another. OOP languages are diverse, but the most popular ones are class-based, meaning that objects are instances of classes, which also determine their types. Many of the most widely used programming languages (such as C++, Java, Python, etc.) are multi-paradigm and they support object-oriented programming to a greater or lesser degree, typically in combination with imper ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Null Coalescing Operator
The null coalescing operator (called the Logical Defined-Or operator in Perl) is a binary operator that is part of the syntax for a basic conditional expression in several programming languages, including C#, PowerShell as of version 7.0.0, Perl as of version 5.10, Swift, and PHP 7.0.0. While its behavior differs between implementations, the null coalescing operator generally returns the result of its left-most operand if it exists and is not null, and otherwise returns the right-most operand. This behavior allows a default value to be defined for cases where a more specific value is not available. In contrast to the ternary conditional if operator used as x ? x : y, but like the binary Elvis operator used as x ?: y, the null coalescing operator is a binary operator and thus evaluates its operands at most once, which is significant if the evaluation of x has side-effects. Examples by languages Bourne-like Shells In Bourne shell (and derivatives), "If ''parameter'' is uns ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Conditional Constructs
Conditional (if then) may refer to: *Causal conditional, if X then Y, where X is a cause of Y *Conditional probability, the probability of an event A given that another event B has occurred *Conditional proof, in logic: a proof that asserts a conditional, and proves that the antecedent leads to the consequent *Strict conditional, in philosophy, logic, and mathematics *Material conditional, in propositional calculus, or logical calculus in mathematics * Relevance conditional, in relevance logic *Conditional (computer programming), a statement or expression in computer programming languages *A conditional expression in computer programming languages such as ?: *Conditions in a contract Grammar and linguistics *Conditional mood (or conditional tense), a verb form in many languages *Conditional sentence, a sentence type used to refer to hypothetical situations and their consequences **Indicative conditional, a conditional sentence expressing "if A then B" in a natural language **Cou ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Operators (programming)
Operator may refer to: Mathematics * A symbol indicating a mathematical operation * Logical operator or logical connective in mathematical logic * Operator (mathematics), mapping that acts on elements of a space to produce elements of another space, e.g.: ** Linear operator ** Differential operator ** Integral operator (other) Computers * Computer operator, an occupation * Operator (computer programming), a type of computer program function * Operator (extension), an extension for the Firefox web browser, for reading microformats * Ableton Operator, a software synthesizer developed by Ableton Science * Operator (biology), a segment of DNA regulating the activity of genes * Operator (linguistics), a special category including wh- interrogatives * Operator (physics), mathematical operators in quantum physics Music * Operator (band), an American hard rock band * Operators, a synth pop band led by Dan Boeckner * ''Operator'' (album), a 2016 album by Mstrkrft * "Operator ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Null Coalescing Operator
The null coalescing operator (called the Logical Defined-Or operator in Perl) is a binary operator that is part of the syntax for a basic conditional expression in several programming languages, including C#, PowerShell as of version 7.0.0, Perl as of version 5.10, Swift, and PHP 7.0.0. While its behavior differs between implementations, the null coalescing operator generally returns the result of its left-most operand if it exists and is not null, and otherwise returns the right-most operand. This behavior allows a default value to be defined for cases where a more specific value is not available. In contrast to the ternary conditional if operator used as x ? x : y, but like the binary Elvis operator used as x ?: y, the null coalescing operator is a binary operator and thus evaluates its operands at most once, which is significant if the evaluation of x has side-effects. Examples by languages Bourne-like Shells In Bourne shell (and derivatives), "If ''parameter'' is uns ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nullable Type
Nullable types are a feature of some programming languages which allow a value to be set to the special value NULL instead of the usual possible values of the data type. In statically typed languages, a nullable type is an option type, while in dynamically typed languages (where values have types, but variables do not), equivalent behavior is provided by having a single null value. NULL is frequently used to represent a missing value or invalid value, such as from a function that failed to return or a missing field in a database, as in NULL in SQL. In other words NULL is undefined. Primitive types such as integers and Booleans cannot generally be null, but the corresponding nullable types (nullable integer and nullable Boolean, respectively) can also assume the NULL value. This can be represented in ternary logic as FALSE,NULL,TRUE as in three-valued logic. Example An integer variable may represent integers, but 0 (zero) is a special case because 0 in many programming language ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Value Type
In computer programming, data types can be divided into two categories: value types (or by-value types) and reference types (or by-reference types). Value types are completely represented by their meaning, while reference types are references to another value. Value types A value is a fully self-describing piece of data. Equal values are indistinguishable at during program runtime. That is, they lack identity. For example, in the C++ and Java programming languages, the integer literal is a value. It is indistinguishable from any other at runtime, and there is no way to mutate the literal to be a different value such as . In many programming languages, value types are often represented and stored in an efficient manner. For example, booleans, fixed-size integers, and fixed-size floating-point types may be compactly stored and passed in the registers of the CPU. Reference types Reference types are represented as a reference to another value, which may itself be either a va ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Elvis Operator
In certain computer programming languages, the Elvis operator, often written ?:, is a binary operator that returns its first operand if that operand evaluates to a true value, and otherwise evaluates and returns its second operand. This is identical to a short-circuit ''or'' with "last value" semantics. The notation of the Elvis operator was inspired by the ternary conditional operator, ? : since the Elvis operator expression A ?: B is approximately equivalent to the ternary conditional A ? A : B. The name "Elvis operator" refers to the fact that when its common notation, ?:, is viewed sideways, it resembles an emoticon of Elvis Presley with his signature hairstyle. A similar operator is the null coalescing operator, where the boolean truth check is replaced with a check for non-null instead. This is usually written ??, and can be seen in languages like C#. Alternative syntaxes In several languages, such as Common Lisp, Clojure, Lua, Object Pascal, Perl, Python, Ruby, and J ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Salesforce
Salesforce, Inc. is an American cloud-based software company headquartered in San Francisco, California. It provides customer relationship management (CRM) software and applications focused on sales, customer service, marketing automation, analytics, and application development. Founded by former Oracle executive Marc Benioff, Salesforce quickly grew into one of the largest companies in the world, making its IPO in 2004. Salesforce's continued growth makes it into the first cloud computing company to reach US$1billion in annual revenue by fiscal year 2009, and the world's largest enterprise software firm by 2022. Today, Salesforce is one of the largest technology companies in the world, and as of September 19, 2022, is the 61st largest company in the world by market cap with a value of nearly US$153 billion. Salesforce ranked 136th on the most recent edition of the ''Fortune'' 500, making US$26.5billion in 2022. Since 2020, Salesforce has also been a component of the Dow ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pyramid Of Doom (programming)
In computer programming, the pyramid of doom is a common problem that arises when a program uses many levels of nested indentation to control access to a function. It is commonly seen when checking for null pointers or handling callbacks. Two examples of the term are related to a particular programming style in JavaScript, and the nesting of if statements that occurs in object-oriented programming languages when one of the objects may be a null pointer. Examples Most modern object-oriented programming languages use a coding style known as dot notation that allows multiple method calls to be written in a single line of code, each call separated by a period. For instance: theWidth = windows("Main").views(5).size().width(); This code contains four different instructions; it first looks in the collection of windows for a window with the name "Main", then looks in that window's views collection for the 5th subview within it, then calls the size method to return a structure with ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Null Pointer
In computing, a null pointer or null reference is a value saved for indicating that the pointer or reference does not refer to a valid object. Programs routinely use null pointers to represent conditions such as the end of a list of unknown length or the failure to perform some action; this use of null pointers can be compared to nullable types and to the ''Nothing'' value in an option type. A null pointer should not be confused with an uninitialized pointer: a null pointer is guaranteed to compare unequal to any pointer that points to a valid object. However, depending on the language and implementation, an uninitialized pointer may not have any such guarantee. It might compare equal to other, valid pointers; or it might compare equal to null pointers. It might do both at different times; or the comparison might be undefined behaviour. C In C, two null pointers of any type are guaranteed to compare equal. The preprocessor macro NULL is defined as an implementation-defined n ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
