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/Godot 3.1

Expression

Inherits: Reference < Object

Category: Core

Brief Description

A class that stores an expression you can execute.

Methods

Variant execute ( Array inputs=[ ], Object base_instance=null, bool show_error=true )
String get_error_text ( ) const
bool has_execute_failed ( ) const
Error parse ( String expression, PoolStringArray input_names=PoolStringArray( ) )

Description

An expression can be made of any arithmetic operation, built-in math function call, method call of a passed instance, or built-in type construction call.

An example expression text using the built-in math functions could be sqrt(pow(3,2) + pow(4,2)).

In the following example we use a LineEdit node to write our expression and show the result.

onready var expression = Expression.new()

func _ready():
    $LineEdit.connect("text_entered", self, "_on_text_entered")

func _on_text_entered(command):
    var error = expression.parse(command, [])
    if error != OK:
        print(expression.get_error_text())
        return
    var result = expression.execute([], null, true)
    if not expression.has_execute_failed():
        $LineEdit.text = str(result)

Method Descriptions

Variant execute ( Array inputs=[ ], Object base_instance=null, bool show_error=true )

Executes the expression that was previously parsed by parse and returns the result. Before you use the returned object, you should check if the method failed by calling has_execute_failed.

If you defined input variables in parse, you can specify their values in the inputs array, in the same order.

String get_error_text ( ) const

Returns the error text if parse has failed.

bool has_execute_failed ( ) const

Returns true if execute has failed.

Error parse ( String expression, PoolStringArray input_names=PoolStringArray( ) )

Parses the expression and returns a Error.

You can optionally specify names of variables that may appear in the expression with input_names, so that you can bind them when it gets executed.

© 2014–2019 Juan Linietsky, Ariel Manzur, Godot Engine contributors
Licensed under the MIT License.
http://docs.godotengine.org/en/3.1/classes/class_expression.html