Linked List Remove problem

I am having some problems removing objects from the linked lists, and after a number of attempts I am going to get your help on this.

Global zObjectList:TList = CreateList()
Type zObject
	Field x
	Field y

	Method New()
		zObjectList.AddLast(Self)
	End Method

	Function create:zObject( x, y )
		Local obj:zObject = New zObject
		obj.x = x
		obj.y = y
		Return obj
	End Function

End Type

z1:zObject = zObject.create( 10, 10 )
z2:zObject = zObject.create( 20, 20 )
z3:zObject = zObject.create( 30, 30 )
z4:zObject = zObject.create( 40, 40 )
z5:zObject = zObject.create( 50, 50 )

Print z1.x + ","+z1.y
Print z2.x + ","+z2.y
Print z3.x + ","+z3.y
Print z4.x + ","+z4.y
Print z5.x + ","+z5.y

WaitKey

In the above code, how would you remove, lets say, object z3 ?

Also, should I be creating the objects differently?

zObjectList.Remove(z3)
z3=Null
FlushMem

Not quite sure if that will work, but give it a shot.

I generally create the list within the Create function, but first check if the list already exists...

If zObjectList=Null Then zObjectList=CreateList()

I've not seen your way of doing the creation before, but it looks neat and I can't think why it wouldn't work a treat.

Global zObjectList:TList = CreateList()
Type zObject
	Field x
	Field y

	Method New()
		zObjectList.AddLast(Self)
	End Method

	Method remove()
		ListRemove(zObjectList,Self)
		FlushMem
	
	End Method

	Function create:zObject( x, y )
		Local obj:zObject = New zObject
		obj.x = x
		obj.y = y
		Return obj
	End Function

End Type

z1:zObject = zObject.create( 10, 10 )
z2:zObject = zObject.create( 20, 20 )
z3:zObject = zObject.create( 30, 30 )
z4:zObject = zObject.create( 40, 40 )
z5:zObject = zObject.create( 50, 50 )

z4.remove
Print "Here are the Zobjects referenced outside of ny list"
Print z1.x + ","+z1.y
Print z2.x + ","+z2.y
Print z3.x + ","+z3.y
Print z4.x + ","+z4.y
Print z5.x + ","+z5.y

Print "here are the items in the zObjectList"
For n:zObject = EachIn zObjectList

	Print n.x +","+ n.y

Next

z4 = Null
FlushMem

Print z1.x + ","+z1.y
Print z2.x + ","+z2.y
Print z3.x + ","+z3.y
Print z4.x + ","+z4.y
Print z5.x + ","+z5.y


WaitKey

Does this help any... may be way off for what you are looking for

Global zObjectList:TList = CreateList()
Type zObject
	Field Name:String
	Field x
	Field y

	Method New()
		zObjectList.AddLast(Self)
	End Method

	Method remove()
		ListRemove(zObjectList,Self)
		FlushMem
	
	End Method

	Function create:zObject(Name:String, x, y )
		Local obj:zObject = New zObject
		obj.name = name
		obj.x = x
		obj.y = y
		Return obj
	End Function
	
	Function zdelete:zObject(Name:String)
		For n:zObject = EachIn zObjectList
			If n.name = Name
				zObjectList.Remove(n)
				'Return True
			EndIf
			
		Next

		
	End Function


End Type

zObject.create( "Z1", 10, 10 )
zObject.create( "Z2", 20, 20 )
zObject.create( "Z3", 30, 30 )
zObject.create( "Z4", 40, 40 )
zObject.create( "Z5", 50, 50 )

Print "here are the items in the zObjectList"
For n:zObject = EachIn zObjectList

	Print n.name +":"+n.x +","+ n.y

Next

zObject.zDelete("Z4")
For n:zObject = EachIn zObjectList

	Print n.name +":"+n.x +","+ n.y

Next

I see always

varxyz=Null

but are some other people here, they see, that here is a problem with this????

Sample:

1) i create window-object (window:Twindow)
and i add this objekt to window list

2) i create button-object (button:Twindow)
and i add this object to button-list

3) i click to close - and now i call window.close()-function
how can my program delete all objects in this window without mem-leaks??? I don't see it. If i remove this objects from lists - how can my programm set all variables to null????????

and if i have 100 gadgets in my window should i do this:

window.close() 'delete win+gadgets from lists - no problem
and than:

button1=null
button2=null
button3=null
button4=null
button5=null
button6=null
button7=null
button8=null
button9=null
...
button999=null

yes - i could create a array for this - but this is bad, if i have other variable names:
button_ok
button_cancel
button_back
button_stop
checkbox_blub
tabber_main
...

or should i use a array with constants:

gadget[button_ok]
gadget[button_stop]
...

but oh my god, i have so large names!

i think BBmax-types are bad - BB2D/2D/Plus-Types was fantastic!!!

"i think BBmax-types are bad - BB2D/2D/Plus-Types was fantastic!!!"

i thought that at first as well, but as soon as you get to grips with them you realise how powerful they are

powerful yes - but very hard to delete

@ Bill, I got it working by using your example. The reason it didn't really work on the main code I was working with, is that the type had fields that were references to other type lists, and the garbage collector doesn't remove the type then, so I had to null out those fields and then it works. Thanks for helping out.

ummm... are they?

Strict

Type TTile
	Field X:Int
	Field Y:Int
End Type

Type TMapLayer
	Field tiles:TTile [][]
	Field ID:Int
	
	Function Free(Layer:TMapLayer)
		For Local x:TTile[] = EachIn Layer.Tiles
			For Local Y:TTile = EachIn x
				y = Null
			Next
		Next
		Layer = Null
		FlushMem
	End Function
	
	Function Create:TMapLayer(Width:Int, Height:Int, ID:Int)
		Local tempLayer:TMapLayer = New TMapLayer
			tempLayer.Tiles = tempLayer.Tiles[..Width]
			For Local h:TTile[] = EachIn tempLayer.Tiles
				h = h[..Height]
			Next
			
			For Local x:Int = 0 To width -1
				For Local Y:Int = 0 To Height - 1
					tempLayer.tiles[x][y] = New TTile
				Next
			Next
			
		Return tempLayer
	End Function
	
End Type

Type TMap
	Field Name:String
	Field Tileset:TImage
	Field Layers:TMapLayer[]
	Field Width:Int
	Field Height:Int
	
	Method AddLayer(ID:Int)
		Layers = Layers[..Len(Layers)+1]
		Layers[Len(Layers)] = TMapLayer.Create(Width, Height, ID)
	End Method
	
	Function Free(Map:TMap)
		For Local tempLayer:TMapLayer = EachIn Map.Layers
			tempLayer.Free(tempLayer)
		Next
		Map = Null
		FlushMem
	End Function
	
	Function Create:TMap(Name:String, TilesetFile:String, Width:Int, Height:Int)
		Local tempMap : TMap = New TMap
			tempMap.Name = Name
			tempMap.TileSet = LoadImage(TilesetFile)
			tempMap.Width = Width
			tempMap.Height = Height
			tempMap.AddLayer(0)
		Return tempMap
	End Function
End Type

Use a Composite Pattern. That's the main problem it attacks. When you need to treat a collection of objects as a single object, use the Composite Pattern.

@Perturbatio: you do not understand. BBmax newer delete somethink, if you set a reference to a type-object in other variables

Local test1:Tmytype=New Tmytype
Local test2:Tmytype=test1
test1=NULL
FlushMem

and if you forgot test2 - you do not delete this object...

ok - but what, if you create somewhere lists and you forget this list

The problem is other:

In classic BB:
DELETE - if you call it - you delete your object in this time (ok memory was not reallocated, but its ok - you have no access to this, and new object take the memory from deleted object - and all other variables that linked to this type have value NULL - nice!!!!!!!!)

In BBmax:
var=NULL - you don't know. do you remove it or not. you have only a chance with user definded delete-functions, that remove objects from lists. after you call FlushMem you don't know what obj. was deleted or not-you have no guarantie for this. Other variables can link to a object (<>NULL) and bbmax don't kill this objects... this is abit harder to write applications. if you create list and newer reference obj. in other variables - you have good clean programs (partikel effects). if you create gui - where you use returned object - you have unclean sources (postet on top)... you have only a chance using ID-number or something...