Lua Programming/variable

A variable is a symbolic name associated with a value. A variable acts as a container and the value it contains may be changed from within a running program, enabling data manipulation to take place from within the program.

Variables are dynamically typed.

In lua variables are dynamically typed, so no explicit typecasting is necessary.

Variables do not need predefinition prior to use

In lua, there is no need to declare or initialize variables before they are used. By default, variables are initialized to the value of nil.

Variable names

As in most programming languages, the name of a variable must be a sequence of letters, digits, or underscore symbols, and may not begin with a digit. The Lua interpreter is lettercase sensitive so variables with uppercase and lowercase names are distinct and separate from each other. It is not permissible to use keywords as variable names.

Variables do not need a sigil

Variables in lua are referenced by name only and are dynamically typed, so a sigil is not required when a variable is referenced.

Variables are global by default

In lua, variables are global by default, unless they are declared as local via a qualifier.

Variable names inside string constants are not expanded in Lua

The lua interpreter does not expand variables inside string constants. This means that "hello username" is always interpreted as constant string, even if username is a the name of a variable. Instead of using interpolation, new strings are constructed from string constants and variables, using concatenation operators.

Local variables have lexical scope

In lua, local variables have lexical scope and are visible to functions defined inside the variable scope.

Global variables are stored in environment tables

In lua, global variables are stored as fields in environment tables.