Structs

Structs

Structs were one feature that I really wanted to improve. They work pretty similar as they do in vJASS, but do keep in mind that they use Hashtable instead of arrays (you can avoid this by using static).

How to allocate/create an instance?

You only have to generate an unique integer id (you can use GetHandleId if you want):

globals
    integer instances = 0
end

function allocate returns integer
    set instances += 1
    return instances
end

struct foo
    public static method allocate returns foo
        return cast allocate() to foo
    end
end

Do keep in mind that an instance equal to cero means null (not allocated).

How to deallocate/destroy an instance?

struct foo
    method deallocate
        call FlushChildHashtable(vrjass_structs, cast this to integer)
    end
end

vrjass_structs is a global hashtable created by the compiler where all the data of the structs is stored.

Abstract

abstract struct foo
    public method bar takes integer i returns nothing

    public method someFeature takes nothing returns nothing
        call this.bar()
    endmethod
endstruct

struct baz extends foo
    public method bar takes integer i returns nothing
    endmethod
endstruct

In this example, the abstract foo struct enforces child structs to implement a public method called bar. We can also create methods that child structs are going to inherit (in this example, someFeature).

Modules were not implemented in vrJASS since abstract structs can accomplish the same.

Override / stubs

In vJASS, to override a method it must be declared as stub. This is not the case in vrJASS

struct foo
    public method baz takes nothing returns nothing
        call BJDebugMsg("foo")
    endmethod
endstruct

struct bar extends foo
    public method baz takes nothing returns nothing
        call BJDebugMsg("bar")
    endmethod
endstruct

...

local foo instance = foo.create()
call instance.baz() // prints "foo"

set instance = bar.create()
call instance.baz() // prints "bar"

Typecheck / cast

struct foo ...
struct bar ...

local foo f = foo.create()
set f = bar.create() // ERROR f must have a foo value

You can however use cast if needed

set f = cast bar.create() to foo

Null

null can be used in place of an instance so for example

function foo takes someStruct instance
endfunction

call foo(null)

Is valid.

Initializer

If there is an onInit static method vrJASS will call it automatically at map initialization.

Array members

Structs can contain arrays. Do keep in mind that they use Hashtable (they're not real arrays) but have the same length limit (8191)

struct foo
    integer array bar

    method someMethod
        set this.bar[1] = 42
    endmethod
endstruct

Visibility

Struct members can be public, protected and private. By default, if no visibility is specified, the member will be private.

public: Can be used from anywhere.

protected: Can be used from child structs (inheritance).

private: Can only be used where it is declared.