Expression

An expression is a piece of source code that produces a value at runtime.

Related concepts:  EvaluationValue

Closest Wikipedia entry:  Expression (computer science) — In computer science, an expression is a syntactic entity in a programming language that may be evaluated to determine its value. It is a combination of one or more constants, variables, functions, and operators that the programming language interprets (according to its particular rules of precedence and of association) and computes to produce ("to return", in a stateful environment) another value. This process, for mathematical expressions, is called evaluation.

Misconceptions about Expression

51 documented Misconceptions

AssignCompares

= compares two values

CannotChainAttributeToObjectInstantiation

Method calls, and attribute accesses in general, cannot be chained to a constructor invocation.

ComparisonWithBoolLiteral

To test whether an expression is True or False, one must compare it to True or to False

MapToBooleanWithTernaryOperator

To map a boolean expression to a bool, a ternary conditional operator is necessary

NoAtomicExpression

Expressions must consist of more than one piece

NoShortCircuit

and/or always evaluate both operands

ObjectsMustBeNamed

A variable is needed to instantiate an object

OutsideInFunctionNesting

Nested function calls are invoked outside in

ParenthesesOnlyIfArgument

() are optional for function calls without arguments

PlusConcatenatesNumbers

The plus operator can concatenate strings and numbers

RightToLeftChaining

Chained accesses are invoked from right to left

SelfNoExpression

The name self is not an expression

VariablesHoldExpressions

= stores an expression: it stores a reference to the expression in a variable