Help with List field in a type
BlitzMax Forums/BlitzMax Beginners Area/Help with List field in a type
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| I'm trying to find examples of adding Types to a list field in another type but just not having any luck at the moment The code is listed below, just as an example to refer to. Basically I just want to add say 2 weapons to first ship , 3 weapons to the next etc Also how do you reference the fields of a type that are in a list when you use the List.First() method Thanks a lot
Strict
Graphics 1024,768
Global ShipList:TList = CreateList()
' ship type
Type TShip
Field Name:String
Field Fuel:Int
Field Weapons:TList = CreateList() ' list of weapons each ship can have
'create a ship
Function Build(ShipName:String, ShipFuel:Int)
Local NewShip:TShip
NewShip = New TShip
NewShip.Name = ShipName
NewShip.Fuel = ShipFuel
ShipList.AddLast(NewShip)
End Function
' add a weapon , not sure if this works
Method AddWeapon(WeaponName:String, WeaponPower:Int)
Local NewWeapon:TWeapon
NewWeapon = New TWeapon
NewWeapon.Name = WeaponName
NewWeapon.Power = WeaponPower
Weapons.Addlast(NewWeapon)
End Method
End Type
' weapons type
Type TWeapon
Field Name:String
Field Power:Int
End Type
' create the ships
CreateShips()
' main loop
While Not KeyHit(KEY_ESCAPE)
Cls
Local y:Int = 12
Local s:TShip
' print a list of the ships
For s = EachIn ShipList
DrawText ("Ship name: " + s.Name + " - " + "Ship Fuel: " + s.Fuel,20,y)
y = y + 12
Next
Flip
Wend
' create new ships
Function CreateShips()
Local s:TShip
'Local w:TWeapon
'Think you have to use the TShip name otherwise gives an error
TShip.Build("Fighter",80)
TShip.Build("Cruiser",34)
TShip.Build("Transporter",64)
TShip.Build("Scout",74)
' I want to add 2 weapons to the first ship, 3 to the second and 1 to the 3rd ship
' add weapons to the first ship
'If ShipList.First() <> Null
' DrawText (ShipList.First().s.Name,10,200)
'EndIf
End Function
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| Why not have TShip.Build() return an instance of the ship you just made. Then you can call newship.AddWeapon()... eg
Function Build:TShip(ShipName:String, ShipFuel:Int)
...
Return NewShip
End Function
Function CreateShips()
...
Local s:TShip = TShip.Build("Fighter",80)
s.AddWeapon(...)
...
End Function
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| okee: Also how do you reference the fields of a type that are in a list when you use the List.First() method Use:
'general: TMyType( list.First() ).fieldName
TShip(shipList).AddWeapon("Chicken Thrower", 1)
This is needed as "first()" returns an "Object". Objects do not know about a TShips functions or variables. By casting it to the type "TShip" you tell the compiler that you know that this First()-object is of type "TShip". If this is _not_ the case, your app will crash on that line (because it accesses something which does not exist). Instead of "First()" you also could use "TShip(shipListValueAtIndex(0))". Another hint: if you do not add weapons that often, you might use less memory with arrays (TWeapon[]). Of course removing a weapon then benefits from a rebuilding of that array (loop over existing ones, add them to a new array - and at the end, assign this new array to the variable holding the old one) one possible approach: Weapons[i] = null 'remove weapon at desired index local newWeapons:TWeapons[] For local w:TWeapon = eachIn Weapons if Weapons[i] then newWeapons :+ [w] Next Weapons = newWeapons Of course it is also possible to use "array slices" (array = array[start ...entry] + array[entry+1 .. end]). bye Ron |
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This is another way to find and manipulate ships after they are already created. The function searches for a ship's name and return the ship as an object:Type TShip Field Name:String Field Fuel:Int Field Weapons:TList = CreateList() ' list of weapons each ship can have Function Build(ShipName:String, ShipFuel:Int) Local NewShip:TShip= New TShip NewShip.Name = ShipName NewShip.Fuel = ShipFuel ShipList.AddLast(NewShip) End Function Method AddWeapon(WeaponName:String, WeaponPower:Int) Local NewWeapon:TWeapon = New TWeapon NewWeapon.Name = WeaponName NewWeapon.Power = WeaponPower Weapons.Addlast(NewWeapon) End Method Function Find:TShip(ShipName:String) For Local Ship:TShip = EachIn ShipList If Ship.Name = ShipName Return Ship Endif Next Return NULL End Function End Type With this you can do things like this: TShip.Find("Fighter").AddWeapon("gun",100)
....
TShip.Find("Fighter").Fuel=0
....
ShipList.Remove TShip.Find("Fighter")
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| If a shipname is really unique, you would better have a TMap instead of a TList, as you then just do 'map.ValueForKey("Fighter")'. If shipname is not unique, you end up iterating through all ships and returning the first hit ship. bye Ron |
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| Thanks guys, those tips helped a lot |
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