lists in types

Hey all
is it poss to have a List as a field in a type? the list would be of another type e.g:

type units
field uType:string
end type

type player
field unit:tList = CreateList()
end type
u:units = new units
u.uType = "hello"
p:player = new player
listaddlast p.unit, u

would work ok. but if i try to go thru the objects with:

For a = EachIn p.units
Print p.units.uType
Next

would give me an error 'foreach index variable must be an object'
but i thought it was :)

cheers

First of all, it's p.unit, not p.units as you coded in your For statement. The variable defined in type player is unit:TList not units:TList. Second of all, since p.unit is a list it returns objects, not integers. So your For statement is wrong because variable a is automatically an integer. You want to say a:units since that is the type that is being returned from the TList p.unit. And then in your loop, you say Print String(a.uType). It would be:

Type units 
 Field uType:String 
EndType 

Type player 
 Field unit:TList = CreateList() 
End Type 

u:units = New units 
u.uType = "hello" 

p:player = New player 
ListAddLast p.unit, u 

For a:units = EachIn p.unit
 Print String(a.utype)
Next

lol, excuse the typo's it was getting late (i notice when ppl make alot of typo's they generally blame time)

but i'll give that a blast, the code i have in my .bmx file is free of typo's (i didnt copy and paste the code)

thx Rich05

that works great thanks. Only other question is once i've called the listaddlast can i then reuse u?

i.e
u.uType = "Hello"
lisaddlast p.units, u
u.uType = "goodbye"
lisaddlast p.units, u

at the moment i end up with 2 goodbyes if i do this??

or does u have to remain unique for the life of the linked list?

You can reuse "u", but not in the way you did it here.

What you did here:
"u" points to an object of type "units".
You set the field "uType" by doing: u.uType = "Hello"
Then you add the pointer u to the list, so that a new pointer is added to the list, which points to the same object each time.
Then you change the uType field in the object u and add that one to the list too (but it's the same object).
Using this code:

Type units 
 Field uType:String 
EndType 

Type player 
 Field unit:TList = CreateList() 
End Type 

p:player = New player 
u:units = New units 

u.uType = "hello" 
ListAddLast p.unit, u 

u.uType = "Hello"
ListAddLast p.unit, u
u.uType = "goodbye"
ListAddLast p.unit, u

For a:units = EachIn p.unit
 Print String(a.utype)
Next

This generates only 1 object, while the list has 3 pointers to it.
This code prints "Goodbye" 3 times, as there's only 1 object created and you change the field uType a couple of times.

If you want to reuse "u" and add 3 objects to the list, each one with it's own setting for the uType field, you can use this code:

Type units 
 Field uType:String 
EndType 

Type player 
 Field unit:TList = CreateList() 
End Type 

p:player = New player 
u:units = New units 

u.uType = "hello" 
ListAddLast p.unit, u 

u:units = New units ' Create a new object and put it's pointer inside "u"
u.uType = "Hello"
ListAddLast p.unit, u

u:units = New units ' Create a new object and put it's pointer inside "u"
u.uType = "goodbye"
ListAddLast p.unit, u

For a:units = EachIn p.unit
 Print String(a.utype)
Next

This code creates 3 objects that are added to the list.
Each time the "u" variable holds the pointer to the just created object.
So in fact, each time you're calling "u:units = new units",
you're overwriting the pointer to the previous object with the pointer to the new object (the previous object isn't lost, because it exists inside the list).

ure a diamond, thx