instanceof

This function can be used to get the name of the constructor function that was used to create a struct. The struct itself should have been created using the new operator along with the constructor itself. You supply the variable with the struct reference to check and the function will return either a string with the constructor name or undefined.

TIP It's recommended to use is_instanceof to check the constructor of a struct, as it additionally allows you to check using parent constructors (i.e. constructors that the struct's constructor may have inherited from). is_instanceof also allows you to check using the constructor function reference directly instead of strings.

Usage Notes

• If you pass the function a struct literal (i.e.: a struct that was created without using a constructor function) then it will simply return the string "struct".
• If you pass the function the self keyword inside an object instance, it will return "instance".
• The returned constructor name will include additional text if the constructor function was not created in a script. If it was created inside an object, its name will include the object and the event where it was created. For example, a constructor called test_constructor created in the Create event of Object1 will be returned as "test_constructor_gml_Object_Object1_Create_0". To avoid this, create your constructors in a script.
• This function can also be used to check if a struct reference is a weak reference or not, in which case the function will return the string "weakref" instead of the name of the function that created the struct. For more information, see the function weak_ref_create().

Syntax:

instanceof(struct_id);

Returns:

String or undefined

Extended Example:

In this example we must first define the function that will be used as the constructor for our struct. The following function is defined in a script asset:

function init_struct(_a, _b, _c) constructor
{
    a = _a;
    b = _b;
    c = _c;
}

This function can then be used along with the new operator to create a struct and populate it with the variables set to the values of the arguments used in the function:

mystruct = new init_struct(10, 100, "Hello World");

We can then get the name of the constructor function that was used like this:

var _name = instanceof(mystruct);
if (is_string(_name))
{
    show_debug_message(_name);
}

This will print the string "init_struct" to the output log, which is the name of the constructor function as defined in its script.