What does "Property where class => someFunction" mean in C #

Question

I look through the EF7 code on Github and find a line that looks like this:

public virtual DbSet<TEntity> Set<TEntity>() where TEntity : class => _setInitializer.Value.CreateSet<TEntity>(this); 

I saw this syntax before at the class level, for example:

 public class SomeClass<T> where T : class 

Which says that T must be a class type. But the line from the source EF7 confuses me. I'm not sure what he is doing.

Answer 1

This is a physique expression , new syntax in C # 6.

This is a method, not a property. C # does not allow you to create common properties.

This is the same as

 public virtual DbSet<TEntity> Set<TEntity>() where TEntity : class { return _setInitializer.Value.CreateSet<TEntity>(this); } 

Answer 2

This syntax is really a bit confusing, but actually the lambda construct here has nothing to do with the general limitations. This is just the Expression-Bodied Method , which had a common limitation.

You can think of it as:

 public virtual DbSet<TEntity> Set<TEntity>() where TEntity : class { return _setInitializer.Value.CreateSet<TEntity>(this); } 

See Roslyn Wiki

Answer 3

This is a C # 6.0 feature called the Expression Bodied Method.

Read about it here .

The code is equivalent to:

 public virtual DbSet<TEntity> Set<TEntity>() where TEntity : class { return _setInitializer.Value.CreateSet<TEntity>(this); }