Why would you use Expression> rather than Func?

Question

I understand lambdas and the Func and Action delegates. But expressions stump me.

In what circumstances would you use an Expression

Answer 1

The primary reason is when you don't want to run the code directly, but rather, want to inspect it. This can be for any number of reasons:

• Mapping the code to a different environment (ie. C# code to SQL in Entity Framework)
• Replacing parts of the code in runtime (dynamic programming or even plain DRY techniques)
• Code validation (very useful when emulating scripting or when doing analysis)
• Serialization - expressions can be serialized rather easily and safely, delegates can't
• Strongly-typed safety on things that aren't inherently strongly-typed, and exploiting compiler checks even though you're doing dynamic calls in runtime (ASP.NET MVC 5 with Razor is a nice example)