Language overview

The online documentation for Lua can be found here: http://www.lua.org/manual/5.1/

Lua is a dynamically typed language. No type definitions are needed for variables in the language; each value carries its own type. Eight default types are used in Lua: nil, Boolean, number, string, userdata, function, thread, and table

Global context and objects:

In Lua, all variables are global variables by default. To create local variables, define the variable with the local statement:

i = 10 <-- global variable

local i = 1 <-- local variable

Lua Examples

Todo here

client.alert(type(a)) -> nil # as ‘a’ has not been initialized.

a = 1

client.alert(type(a)) -> number

client.alert(type(a)) -> Boolean

Pease note: In DragonRAD application, if variable's value is getting from a Boolean Column, it's value might be displayed as "true" or "false" but it's type is actually a string type.

For Example:

a = aRow.getColumnValue("aTable.BooleanColumn") <-- here the BooleanColumn value is true

client.alert(a) -> Display as "true"

client.alert(type(a)) -> string

a= “a string”

client.alert(type(a)) -> string

a = type <- this is assigning a function to a variable.

client.alert(type(a)) -> function

a = {}

client.alert(type(a)) -> table or array

k = “x”

a[k] = 10 or a[“x”] = 10

client.alert(a[“x”)]) -> 10

a[“x”] == a.x

client.alert(a.x) -> 10

#a means the item for array a{}

Basic Lua Expressions

Arithmetic Operators:

+, -, *, /, ^, %, - (negation)

Relational Operators:

<, >, <=, >=, =, ~

Logical Operators:

and, or, not

Example 1) when flag is not set, set flag to Aflag value; otherwise, set flag to itself.

Example 2) select the maximum number from a and b

String Concatenation Operator:

Example:

See the string library for additional string functions.

Escape Operator: “\”

Statements:

If Statements:

For Statements:

Function Example: (Note: the function has to be defined before it can be used)

Comments:

Note, please check the forum if you have questions or email support@dragonrad.com