As the title says, if var a="print (1)", how can I make this a code run
var a="print (1)",
You could try the Expression class, but it only supports some expressions. https://docs.godotengine.org/en/stable/classes/class_expression.html
Or maybe the Script class. https://docs.godotengine.org/en/stable/classes/class_script.html
Godot 4 has lambda functions, which are somewhat similar to what you want. https://docs.godotengine.org/en/latest/tutorials/scripting/gdscript/gdscript_basics.html#lambda-functions
DaveTheCoder Thank you very much. It's very helpful to me
