This is a pretty vague topic, but here are a few things to consider -
Delegates are basically a cleaner, easier function pointer. Any place where function pointers were used in C++, you can think delegate.
Advantages to using them in design:
- Can lead to easy reuse of code
- Can provide a great amount of flexibility in your designs
- Allow you to develop libraries and classes that are easily extensible, since it provides an easy way to hook in other functionality (for example, a where clause in LINQ can use a delegate
[Func] to filter on, without having to write new code in the Where method
Potential disadvantages:
- They
~can~, particularly if used naively, lead to code that is more difficult to read
- They can introduce behavior into your component that is unexpected, since 3rd party code out of your control will get called (For example, if somebody attaches a delegate to one of your events that causes an infinite loop, it can make your class look bad, even though it has nothing to do with you)
