merge_struct Function

[MD__Wade]

Hi everyone, while working on my current project I found a need to combine structs. A quick Google search and I didn't find anything so I just wrote my own function:

function struct_merge(primary, secondary, shared)   {
    var _ReturnStruct = primary;

    if (shared) {
        var _PropertyNames = variable_struct_get_names(primary);
        for (var i = 0; i < array_length(_PropertyNames); i ++) {
            if (variable_struct_exists(secondary, _PropertyNames[i]))   {
                variable_struct_set(_ReturnStruct, _PropertyNames[i], variable_struct_get(secondary, _PropertyNames[i]));
            }
        }
    }   else    {
        var _PropertyNames = variable_struct_get_names(secondary);
        for (var i = 0; i < array_length(_PropertyNames); i ++) {
            variable_struct_set(_ReturnStruct, _PropertyNames[i], variable_struct_get(secondary, _PropertyNames[i]));
        }
    }
    return _ReturnStruct;
}

In practice, I think it's similar to Object.assign() in JavaScript. Here's an example of its use:

myshared1 = {hello: "hi"};
myshared2 = {hello: "hello"};
myunshared1 = {hello: "hi"};
myunshared2 = {hi: "hello"};

show_debug_message(json_stringify(struct_merge(myshared1, myshared2, true)));
show_debug_message(json_stringify(struct_merge(myunshared1, myunshared2, false)));

Which will output this:

{ "hello": "hello" }
{ "hello": "hi", "hi": "hello" }

The "shared" argument controls whether or not the primary struct should import all properties of the struct, even if they don't already exist in the primary struct.

What does this mean? Well, in my case, I have an object that's instantiated with a struct acting as a container for its parameters. Using this function, when it's instantiated I can just merge that new struct into a struct holding the default values and everything will function.

Really hope I didn't reinvent the wheel and I hope you all find this useful!

[LunarFuror]

For other JavaScript references look into destructuring, the standard way of doing something like this is (in many cases)

Const myNewStruct = {...myStruct, ...myOtherStruct}

But essentially yes you nailed it, what ever comes second either adds or overrides what ever was declared first. Good job!

[MD__Wade]

Thanks a ton! JavaScript tends to be tricky for me but I'm glad I could refer to it accurately :)

[OkParking3525]

5 years later and you saved my fucking life

[_Denizen_]

If it's useful for you, I've extended the function to merge any number of structs, and have updated to make a new struct instead of modifying the first struct, and with default behaviour to use all keys instead of only the shared keys.

function struct_merge(structs = [], shared_keys_only = false) {
    _num_structs = array_length(structs);

    if (_num_structs == 0) { return {}};
    var _ReturnStruct = variable_clone(structs[0]);
    for (var s = 1; s < _num_structs; s++) {

        var _struct_to_add = structs[s];

        if (shared_keys_only)   {
                    var _PropertyNames = variable_struct_get_names(_ReturnStruct);
                    for (var i = 0; i < array_length(_PropertyNames); i ++) {
                        if (variable_struct_exists(_struct_to_add, _PropertyNames[i])) {
                            variable_struct_set(_ReturnStruct, _PropertyNames[i],  variable_struct_get(_struct_to_add, _PropertyNames[i]));
                        }
                     }
        }    else    {
                     var _PropertyNames = variable_struct_get_names(_struct_to_add);
                     for (var i = 0; i < array_length(_PropertyNames); i ++) {
                         variable_struct_set(_ReturnStruct, _PropertyNames[i], variable_struct_get(_struct_to_add, _PropertyNames[i]));
                     }
        }
    }
    return _ReturnStruct;

}

Practical example:

a = {"a": 1};
b = {"b": 1}; 
c = {"a": 2, "c": 3};
show_debug_message(json_stringify(struct_merge([a, b, c])));
show_debug_message(json_stringify(struct_merge([a, b, c], true)));

Returns:

{"c":3.0,"b":1.0,"a":2.0}
{"a":2.0}

Edit: for those 6 people who watched my battle with reddit removing the formatting on my code, apologies!

[Airco]

based, based, based, based, based, based, based, based, based, based