Generic Objects question

Monkey Forums/Monkey Programming/Generic Objects question

jondecker76

(Posted 2012) [#1]

I'm having some trouble grasping how to store generic objects. For example:

Class player
  Field x:float
  Field y:float
  Field data:Object
  '...etc
End Class
...
...
myPlayer:player = New player()
myPlayer:data="Test" 'Store a string object?
...
...
'Retreive the string object
Print myPlayer.data

I know its not a great example, but aren't strings Objects in Monkey? Is this the correct way to go about this?
I'm sure it has something to do with casting - can anyone point me in the right direction?

thanks!

slenkar

(Posted 2012) [#2]

you would have to create a string object class

class string_object
field str$
end class

to go into the data field

unless every player's data is going to be a string then just use string.

Also if every player's data is going to be a Bool,String,Int or Float you can convert them to strings to go into field data:String

muddy_shoes

(Posted 2012) [#3]

The monkey module has boxes.monkey, which contains classes for wrapping primitive types as objects.

AdamRedwoods

(Posted 2012) [#4]

The Object Class is not compatible with the String Class.

If you need generic data, you can use <T> type parameters or even use overloaded Getter/Setters.

Class Generic<T>
	Field data:T

	Method WhatType()
		If Int(data) =data
			Print "Int"
		Elseif Float(data) =data
			Print "Float"
		Elseif String(data) =data
			Print "String"
		Else
			Print "Unknown"
		Endif
	End
End


''use it like this

Local gs:Generic<String> = New Generic<String>
gs.data = "hello"
Local gf:Generic<Float> = New Generic<Float>
gf.data = 2.45
		
gs.WhatType() ''prints String
gf.WhatType() ''prints Float

hardcoal

(Posted 2012) [#5]

what is this signs means <X> in a class definition?

AdamRedwoods

(Posted 2012) [#6]

what is this signs means <X> in a class definition?

It is a TYPE PARAMETER, also used in C++ programming.

It means you can define a Class without a specific type, and in its place use "X". BUT-- when you use NEW you will need to define your type by using New Class<Int>. Or New Class<Float>. Or New Class<OtherClass>.

This is also how List<X> works.