Expression¶

class Expression

An Expression is a Lua scriptable control.

Hierarchy

class Expression < class ControlNode < class HostNode < class Node < class SelectableNode

Members

Plugs:

function	Code	R	The expression compiled code, dependent on Script
nil	Invalid	R	The message plug that dependends on all inputs, and on which all outputs depend
string	Script	RW	The expression Lua code

Methods:

ExpressionInput\|ExpressionOutput plug	add	( string name , types type , boolean isinput , ? value )	Add an input/output to the Expression
nil	setLua	( string script )	Set the expression Lua script

Inherited from class HostNode

Plugs:

types.string

HostPath

RW

The data archive to read HostPlugs value when baked

Methods:

nil	deleteinheritedattr	( string plugname )	Delete an inherited attribute plug from the node
nil	setinheritedattr	( string plugname , [bool\|nil] inherited , [ any value ] )	Set the inheritance status of the attribute
nil	overrideinheritedattr	( string plugname , any value )	Override the attribute

Inherited from class Node

Plugs:

string

Name

RW

The node name

Methods:

nil	onpathchanged	( )	Called by the framework when the name of this node or of one of its parent is modified
any value	eval	( Plug plug )	Called by the framework when plug (a node's plug) must be evaluated
boolean state	isselected	( )	Tell if the node is selected
Node parent	getparent	( )	Get the parent Node of this Node
boolean result	isparent	( Node child )	Tells if this node is parent of the potential child
Node parent	findparent	( string name )	Find the first parent Node of this Node of a specific class
string path	getpath	( )	Returns the node path as a string that can be reused with findchild
Node\|Plug child	findchild	( string path )	Find a child node or plug using a path
nil	move	( Node parent )	Move a node to a new parent
nil	delete	( )	Delete a node
nil	rename	( string name )	Rename a node
[string\|number] name	getname	( )	Get the Node name in its parent
Node result	getchild	( string name )	Get a child node by its name
boolean result	isreference	( )	Tells if a node comes from a reference project
Reference reference	getreference	( )	Returns the reference node it is connected to
Reference reference	gettopreference	( )	Returns the top reference node it is connected to
bool result	belongstoreference	( Reference ref )	Tells if the node belongs to the reference, or a sub reference
{Node} result	loadfile	( string filename )	load a file content in this node.
Node result	loadtemplate	( string template , string name )	load a template file
bool,string success,error	savefile	( string filename )	load a node to a file
string result	getstringcopy	( )	Return a copy of the node and its content as a string to be pasted
nil	setflags	( )	Set the node flags
bool result	ismoveable	( )	Tells if the node can be moved
{Node},string result,error	pastestringcopy	( string copy )	Paste a string copy into this node
of table	getreferences	( [ topref Reference ] )	Returns the references in the document sorted depth first.
boolean editable	iseditable	( )	Indicates if the node can be edited by the user in the UI
nil	seteditable	( boolean editable )	Change the editable state of the node

Inherited from class SelectableNode

Plugs:

boolean

Selected

R

True if the node is selected. Don't use this plug directly to select a node, use the Document's modifier select method.

Documentation

function Code R

The expression compiled code, dependent on Script

nil Invalid R

The message plug that dependends on all inputs, and on which all outputs depend

string Script RW

The expression Lua code

An Expression code is a Lua script that evaluates its output values using its input values. The Expression evaluation is dependent only on its inputs, meaning that if you use other values than declared inputs in your script, you might have invalidation problems.

Within the script context, inputs are accessible directly by their names, and output are also accessible by their names. For instance: Output = Input * 2 is a valid script, where Output and Input have been declared earlier (that is, added as ExpressionInput and ExpressionOutput to the Expression node).

On the other hand, Output = Document.Time:get ()*0.1 is a syntaxically correct script, though Guerilla won't recompute Output value when time changes. To do such a thing, you must first create an ExpressionInput (Time, for instance), and then Time will be available within the script.

ExpressionInput|ExpressionOutput plug add ( string name , types type , boolean isinput , ? value )

Add an input/output to the Expression

Creates an input/output to the Expression. This method fails if a plug of the same name already exists in the Expression.

Here an example of how to use Expression:

local mod = Document:modify ()

local expression = mod.createnode (Document, "Expression", "MyExpression")

local input = expression:add ("Value1", types.string, true, "")

local output = expression:add ("Output", types.string)

expression:setLua ("Output = 'Output value is : ' .. Value")

mod.finish ()

To remove an input or an output, simply use modifier.deleteplug function.

local mod = Document:modify ()

mod.deleteplug (expression.Value1)

mod.finish ()

Arguments:

name The input/output name
type the type of the input/output
isinput True to create an input
value The default value to assign to the input

Return:

plug

nil setLua ( string script )

Set the expression Lua script

Arguments:

script a Lua script