So I am parsing strings that represent python types and other custom objects. An example would be '<Vector (1.0 , 0.2 , 0.8) >' or '<Color (0.3 , 0.9 , 0.4 )>' etc But I dont want to use too many ifTrue , ifFalse and end up with a long method. So I was thinking creating a OrderedCollection that would be 2D , first dimension is the regex that fits the type the second is the pharo object that corresponds to this type . Then I will have a common method for each of those pharo object to deal with the parsing. But I was wondering how to use a class that I dont know its name until runtime. For example lets say i get a string aPythonString := '< Bone [ "side bone" , IK = True , ( 1.0 , 0.1 , 0.2) ]>' I would want in this case to send the message the EphBoneType parse : aPythonString. The problem is that I dont know the contents of the string until I receive it. So I want the name of the class to be composed according the string received . Is this possible ? Is this a smart way ? How would you do it ?