Getting a specific instance of a struct

[GIMLI_2]

Hi there,

i have a function

function AddTile takes integer x, integer y, Tile whichtile returns nothing

now, i want to be able to simply put a created tile (an instance of Tile) into the function like this:

local Tile forest = Tile.create("Forest")
local Tile mountain = Tile.create("Mountain")
local Tile castle = Tile.create("Castle")
// ---------------------
set forest.evasion = 20
set forest.defense = 1
// ---------------------
set mountain.evasion = 30
set mountain.defense = 1
// ---------------------
set castle.evasion = 20
set castle.defense = 2
set castle.healing = 20

call ch1.AddTile(0, 0, Tile["Forest"])

for now, i came up with this solution, looping through every instance and searching for the same name:

library TileLib
   
    struct Tile
       
        static integer index = 0
        static integer array tileid
        static string array tilename
       
        integer evasion
        integer defense
        integer healing
        string name
       
        static method operator [] takes string s returns thistype
            local integer i = 0
            loop
                if tilename[i] == s then
                    return tileid[i]
                endif
                set i = i + 1
                exitwhen i == index
            endloop
            return 0
        endmethod
   
        static method create takes string s returns thistype
            local thistype this = thistype.allocate()
            set tileid[index] = this
            set tilename[index] = s
            set index = index + 1
            return this
        endmethod
       
        method destroy takes nothing returns nothing
            call this.deallocate()
        endmethod
   
    endstruct

endlibrary

is there a better solution for this? it doenst have to be a string, i can be something similar that makes it as readable.

 

[Wareditor]

Your solution is fine and shouldn't cause any issue.
Alternatively you could store the struct instance into an hashtable. Try using the Table library.
However, I couldn't say which is better because it depends on the actual usage and what are you looking for.

 

[MyPad]

I'm not sure if this still works, but are you going to try StringHash as a possible way of getting an index from a string sequence? This would require Table, of course.

 

[Anitarf]

StringHash + hashtable is the solution (assuming recent patches ahven't broken anything).

Use StringHash as a hashtable key and store the instance (cast to integer) into the hashtable using that key when you create the instance.

Then, retrieve the instance from the hashtable in your [] operator.

 

[GIMLI_2]

thanks for the replies.
what does StringHash do? convert a string into an integer?

 

[IcemanBo]

Yes it does return a unique integer for strings. So StringHash("GIM") value differs from StringHash("Li"). You might bind data like this to strings via hashtable.
Though, it's not case sensitive (at least it was I think), so StringHash("HELLO") would equal StringHash("hello"), etc.

 

[~El]

Yes it does return a unique integer for strings. So StringHash("GIM") value differs from StringHash("Li"). You might bind data like this to strings via hashtable.
Though, it's not case sensitive (at least it was I think), so StringHash("HELLO") would equal StringHash("hello"), etc.

It is, indeed, non-case sensitive. There are also some other caveats - for example, the algorithm used doesn't distinguish between forward and backward slashes - / and \ are the same to it.

It may also produce collisions in other cases - though uncommon, it can still happen, meaning that 2 different strings may produce the same hash.

 

[GIMLI_2]

alright, thanks alot!
soo.. i dont actually need a hashtable, right?

static integer array structinstances
set structinstances[StringHash("text")] = this

meaning that 2 different strings may produce the same hash.

that is unfortunate :/

 

[IcemanBo]

ArrayIndex is limited to maximum array size - 1, but StringHash is maximum integer size, so hashatable would be useful.

 

[GIMLI_2]

ArrayIndex is limited to maximum array size - 1, but StringHash is maximum integer size, so hashatable would be useful.

ah ok. thank you