Class reference
Expression
Inherits RefCounted
A class that stores an expression you can execute.
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.
var expression = Expression.new()
func _ready():
$LineEdit.text_submitted.connect(self._on_text_submitted)
func _on_text_submitted(command):
var error = expression.parse(command)
if error != OK:
print(expression.get_error_text())
return
var result = expression.execute()
if not expression.has_execute_failed():
$LineEdit.text = str(result)
private Expression _expression = new Expression();
public override void _Ready()
{
GetNode<LineEdit>("LineEdit").TextSubmitted += OnTextEntered;
}
private void OnTextEntered(string command)
{
Error error = _expression.Parse(command);
if (error != Error.Ok)
{
GD.Print(_expression.GetErrorText());
return;
}
Variant result = _expression.Execute();
if (!_expression.HasExecuteFailed())
{
GetNode<LineEdit>("LineEdit").Text = result.ToString();
}
}
Methods
Variant execute(Array inputs = [], Object base_instance = null, bool show_error = true, bool const_calls_only = false)
Variant execute(Array inputs = [], Object base_instance = null, bool show_error = true, bool const_calls_only = false)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
String get_error_text() constbool has_execute_failed() const
bool has_execute_failed() constReturns true if execute() has failed.
int parse(String expression, PackedStringArray input_names = PackedStringArray())
int parse(String expression, PackedStringArray input_names = PackedStringArray())Parses the expression and returns an Error code. 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.