Filters out characters from input in LineEdit using a RegExp pattern of allowed characters

LineEdit.gd

extends LineEdit

var allowed_characters = "[A-Za-z]"

func _on_LineEdit_text_changed(new_text):
	var old_caret_position = self.caret_position

	var word = ''
	var regex = RegEx.new()
	regex.compile(allowed_characters)
	for valid_character in regex.search_all(new_text):
		word += valid_character.get_string()
	self.set_text(word)

	caret_position = old_caret_position

Source: https://www.reddit.com/r/godot/comments/gdck9a/how_to_control_lineedit_inputs/