Lecture thumbnail 0:18 / 1:27 So one of the things that’s worth mentioning since a proxy looks a lot like a decorator is what exactly
is the difference between the two?
So the differences are as follows.
First of all, typically proxy provides an identical interface to the object that it’s proxying things
to, whereas the decorator provides an enhanced interface.
So the decorator, it decorates an object.
It may replicate some of its APIs or indeed all of its APIs, especially if you’re using Resharper,
you’re going to get that delegating members generated for free basically.
So why not have the entire interface?
But in addition, the decorator is designed specifically so that it adds additional functionality so
that it adds additional operations, additional traits and so on and so forth.
Now, the decorator typically aggregates or has a reference to what it is decorating, so typically
takes the decorated object as a constructor argument that suddenly the implementation, if you have
a dynamic decorator now the proxy doesn’t have to do this and in actual fact, the proxy doesn’t even
have to work with a materialized object, an object that exists.
So, for example, you could have a proxy providing an interface over an object that hasn’t been constructed
and that is being defined as a purely a lazy object which will only be made whenever there is a first
call to that particular object.
So you can think of a proxy in this way as a kind of implementation of lazy over the whole type, for
example.
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