Getting the last member of a group

[Barade]

Hello,
for my creep respawn system I would like to get the last unit of a group. However, there seems to be an issue when getting the last member.
This is my JASS code:

function GetLastMemberOfGroup takes group whichGroup returns unit
    local group tmpGroup = CreateGroup()
    local unit tmpLast = null
    local unit last = null
    call GroupAddGroup(whichGroup, tmpGroup)
    loop
        set tmpLast = FirstOfGroup(tmpGroup)
        exitwhen (tmpLast == null)
        set last = tmpLast
        call GroupRemoveUnit(tmpGroup, last)
    endloop
    call DestroyGroup(tmpGroup)
    set tmpGroup = null
    set tmpLast = null
    return last
endfunction

function GetLastIndexOfGroup takes group whichGroup returns integer
    local group tmpGroup = CreateGroup()
    local unit tmpLast = null
    local integer last = -1
    call GroupAddGroup(whichGroup, tmpGroup)
    loop
        set tmpLast = FirstOfGroup(tmpGroup)
        exitwhen (tmpLast == null)
        call GroupRemoveUnit(tmpGroup, tmpLast)
        set last = last + 1
    endloop
    call DestroyGroup(tmpGroup)
    set tmpGroup = null
    set tmpLast = null
    return last
endfunction

function AssignUnitToCurrentGroup takes nothing returns nothing
    local integer lastIndex = GetLastIndexOfGroup(udg_RespawnGroup[udg_TmpGroupIndex])
    local integer memberIndex = Index2D(udg_TmpGroupIndex, lastIndex, udg_RespawnGroupMaxMembers)
    local unit lastMember = GetLastMemberOfGroup(udg_RespawnGroup[udg_TmpGroupIndex])
    call BJDebugMsg("Assign to unit " + GetUnitName(lastMember) + " with handle ID " + I2S(GetHandleId(lastMember)) + " with index " + I2S(lastIndex) + " the current group " + I2S(udg_TmpGroupIndex) + " the unit group has a size of " + I2S(CountUnitsInGroup(udg_RespawnGroup[udg_TmpGroupIndex])))
    set udg_RespawnUnitType[memberIndex] = GetUnitTypeId(lastMember)
    set udg_RespawnLocationPerUnit[memberIndex] = GetUnitLoc(lastMember)
    call AssignUnitToGroup(lastMember, udg_TmpGroupIndex)
    set lastMember = null
endfunction

function InitCurrentGroup takes nothing returns nothing
    set udg_TmpGroupIndex = udg_TmpGroupIndex + 1
    set udg_RespawnGroup[udg_TmpGroupIndex] = CreateGroup()
endfunction

And this is my trigger to create a respawn group:

• Actions
  • Set VariableSet TmpGroupIndex = -1
  • -------- KALIMDOR --------
  • -------- Trolle 1 --------
  • Custom script: call InitCurrentGroup()
  • Unit Group - Add Dunkeltrollfallensteller 0348 <gen> to RespawnGroup[TmpGroupIndex]
  • Custom script: call AssignUnitToCurrentGroup()
  • Unit Group - Add Dunkeltrollhohepriester 0350 <gen> to RespawnGroup[TmpGroupIndex]
  • Custom script: call AssignUnitToCurrentGroup()
  • Unit Group - Add Dunkeltrollberserker 0353 <gen> to RespawnGroup[TmpGroupIndex]
  • Custom script: call AssignUnitToCurrentGroup()
  • Unit Group - Add Dunkeltrollberserker 0351 <gen> to RespawnGroup[TmpGroupIndex]
  • Custom script: call AssignUnitToCurrentGroup()
  • Set VariableSet RespawnItemType[TmpGroupIndex] = Heilsalbe

GetLastMemberOfGroup returns twice the exact same unit (same handle ID) although the group is growing and I add two different units of the same type.
It behaves like I would have added the same unit twice to the group.
When I switch the two lines of "Dunkeltrollberserker":

• Unit Group - Add Dunkeltrollberserker 0351 <gen> to RespawnGroup[TmpGroupIndex]
• Custom script: call AssignUnitToCurrentGroup()
• Unit Group - Add Dunkeltrollberserker 0353 <gen> to RespawnGroup[TmpGroupIndex]
• Custom script: call AssignUnitToCurrentGroup()

It suddenly works and I have two different units in the group.
I am confused.
I have attached the corresponding map. The trigger is called "Kalimdor Creep Groups". You should see the debug output in the beginning of the game.

 

[IcemanBo]

A custom group/list implementation should probably be used if the order of stored units in a gorup matters.
@DracoL1ch made an interesting thread where he shares some insights of how a group might be built up, which is not simply the order in which the units are added. Group unit's ordering

 

[DracoL1ch]

it's not "might" tho

 

[Barade]

Hmm, maybe it is easier to create a hook using vJass for the function:

function GroupAddUnitSimple takes unit whichUnit, group whichGroup returns nothing
    call GroupAddUnit(whichGroup, whichUnit)
endfunction

and store the last added unit somewhere?

 

[IcemanBo]

If only last unit is needed, one might also just do something like:

hashtable hash = InitHashtable()
constant integer PARENT_KEY_LAST_UNIT = 0

function GroupAddUnitTracked takes unit u, group g, returns nothing
    local integer childKey = GetHandleId(g)
    call SaveUnitHandle(hash, PARENT_KEY_LAST_UNIT, childkey, u)
endfunction

function GroupGetLastAddedUnit takes group g returns unit
    local integer childKey = GetHandleId(g)
    return LoadUnitHandle(hash, PARENT_KEY_LAST_UNIT, childkey)
endfunction

Edit:

Well, it might be needed actually to track also removed units from group etc, like in example the last unit gets removed from group, then an other unit would get last. So maybe just custom list would be good.. ;D

 

[Barade]

But I want to use the GUI trigger actions, so I can select units on the map via the trigger editor.

 

[IcemanBo]

But you can select the unit via GUI, fill a unit variable with it, and then run a custom script or other trigger as next action.

Just a random other idea instead of implementing a doubly linked list:

You could try a pseudo time-stamp attempt in form of a variable tracking a unit's entry number for the group. Each group has its own counter (hashtable), and when ever a unit joins, the counter gets increased, and the number gets attached to the unit.

For example "integer array GroupEntryNumber[]" would track all units' last entry number when joining a group, using a unit's index as key.

function AddUnit takes unit u , group greturns nothing
    local integer groupCounter = LoadInteger(hash, GetHandleId(g), 0)
    local integer groupEntryNumber = groupCounter + 1
    local integer unitIndex = GetUnitIndex(u)
    set GroupEntryNumber[unitIndex] = groupEntryNumber

And when searching for the last unit that was added there can be a loop through all units inside the group, and the unit with the highest GroupEntryNumber would win. It's not perfect, but the max integer value ( 2147483647 ) could be enough, even the counter would never reset.

 

[Barade]

True, didn't think about the variant setting it into a global variable. I might do that. I don't even need a custom group implementation that way since I have to add it after getting it.

 

[Macadamia]

Hello there.

Why didn't you simply use :

function GetLastMemberOfGroup takes group whichGroup returns unit
    return BlzGroupUnitAt(whichGroup, BlzGroupGetSize(whichGroup))
endfunction

?

 

[Barade]

Because I don't know the new functions. Thx.

edit:
But if the ordering is not strict, it won't work anyway.

 

[Macadamia]

Because I don't know the new functions. Thx.

edit:
But if the ordering is not strict, it won't work anyway.

I know the feeling, I keep discovering these when I spend time reading the new common.j file !

I am sure this will make things much easier for you, as it did for myself !

Take care !