Match Guards

A guard adds a condition to a pattern. Write when and a condition after the pattern: the pattern matches only if the value fits the pattern and the condition is true. Guards exist since Godot 4.4.

var hp := 15
match hp:
	0:
		print("Defeated")
	var h when h < 20:
		print("Low health: ", h)
	_:
		print("Healthy")

Low health: 15

GDScript has no range patterns such as 1..10. A binding pattern with a guard does that job: var h when h < 20: matches every value below 20 and names it h.

When a guard is false, match goes on to the next pattern. The patterns are tried from top to bottom, so the order decides which block runs:

var temp := 32
match temp:
	var t when t <= 0:
		print("Freezing")
	var t when t < 15:
		print("Cold")
	var t when t < 30:
		print("Warm")
	_:
		print("Hot")

Hot

The second pattern does not need t > 0: a temperature of 0 or below already matched the first one. A guard can use any condition, with other variables and and or or, and it fits any pattern: 5 when hard_mode: matches 5 only while hard_mode is true.