Dynamic Typing without duck typing?

I'm used to dynamic typing meaning checking for type info of object/non o开发者_如何学编程bject oriented structure at runtime and throwing some sort of type error, ie if it quacks like a duck its a duck. Is there a different type of dynamic typing (please go into details).

Yes, absolutely. Duck-typing is an idiom which says that the type of a value at this moment in time is based on the fields and methods that it has right now. Dynamic typing just says that types are associated with run-time values, not with static variables and parameters. There is a difference between the two, and you can use the latter without the former.

For example, if you programmed in PHP and limited yourself to the basic types without using OO, then you would be using dynamic typing without using duck-typing.

No, dynamic typing is when values have type but variables do not, so most type checking is done at runtime. So, basically, if the value walks or quacks like a duck, it's a duck, else an error is thrown. Duck typing really just describes a feature of dynamic typing that ensures it will be typesafe (i.e. a method will only run if variable foo'has the right attribute or can execute that method).