Interface getType() issue in .create method

05-09-2014, 09:31 PM

Hey~ I'm trying to use interfaces and ran into a strange problem

JASS:

library a initializer init

    interface eventHandler
    endinterface
    struct Buff extends eventHandler
        static method create takes nothing returns thistype
            local eventHandler this = thistype.allocate() // if use thistype then this.getType() is compiled to the typeid of Buff
            
            // how to get correct typeid in this func ?
            call BJDebugMsg("Buff: " + I2S(this.getType())) // displays 2 (should be 3)
            return this 
        endmethod
    endstruct
    struct BuffTypeA extends Buff
    endstruct
    private function init takes nothing returns nothing
        local Buff this = BuffTypeA.create()
        call BJDebugMsg("BuffTypeA: " + I2S(this.getType())) // displays 3
    endfunction
endlibrary

If you look at the jass generated from jasshelper:

JASS:

//Generated allocator of BuffTypeA
function s__BuffTypeA__allocate takes nothing returns integer
 local integer this=sc__Buff_create()
 local integer kthis
    if(this==0) then
        return 0
    endif
    set si__eventHandler_type[this]=3
    set kthis=this

 return this
endfunction

The typeid of the interface is stored after the parent struct's create function is called, making it impossible to access in the parent's create function

Does anyone know of a way around this without having to call a second function or using a 0 second timer in the create function ? Both have their own issues for the API

~~

I'm also having a similar issue with interface variables as well. Not being able to access them in the create method of parent structs (as the create method is always called for parent struct before variables of child struct are initialized)

JASS:

    private interface eventHandler
        integer abiliconrawcode=0
    endinterface
    
    struct Buff extends eventHandler
        static method create takes unit whichUnit returns thistype
            local thistype this = thistype.allocate()
            
                                         //abiliconrawcode is always 0 here
                                         // as it is not setup if called by
                                         // child struct until after create
                                         // method is finished
            call UnitAddAbility(whichUnit, abiliconrawcode)
            
            return this
        endmethod
    endstruct
    
    struct BuffTypeA extends Buff
        integer abiliconrawcode='A000'
    endstruct

After Compiling:

//Generated allocator of BuffTypeA
function s__BuffTypeA__allocate takes unit whichUnit returns integer
 local integer this=sc__Buff_create(whichUnit) // parent create called
 local integer kthis
    if(this==0) then
        return 0
    endif
    set si__b___eventHandler_type[this]=3
    set kthis=this

   set s__b___eventHandler_abiliconrawcode[this]='A000' // variable set
 return this
endfunction

I know it's possible to workaround by making a module require to be implemented to each child struct; but I'd rather find a way to do it without any changes to API

05-10-2014, 12:02 PM

Anitarf

I'm not sure why it is even important for the parent struct to know these things. You could pass the type id to the parent struct allocator as a parameter but that kind of defeats the purpose of using inheritance. That is my recommendation, though, don't use inheritance, it might seem like the logical thing to use but it's not really and existing buff systems don't use it. In fact, my recommendation would be to save yourself the trouble and use an existing buff system.