Implementing Linq IENumerable<T> without new() constraint

  • Thread starter Thread starter Andrus
  • Start date Start date
A

Andrus

I noticed that Linq-SQL DataContext ExecuteQuery method does not have new()
constraint:

IEnumerable<TResult> ExecuteQuery( command, ... )

IEnumerable must return object so it must create this object in some way.

Any idea why and how ExecuteQuery<T> can be implemented witout new()
constraint ?

Andrus.
 
Andrus said:
I noticed that Linq-SQL DataContext ExecuteQuery method does not have new()
constraint:

IEnumerable<TResult> ExecuteQuery( command, ... )

IEnumerable must return object so it must create this object in some way.

Any idea why and how ExecuteQuery<T> can be implemented witout new()
constraint ?
Click to expand...

Given that there's quite a bit of reflection involved (well, at least
initially - it's all compiled into lightweight functions, I believe)
one more bit to create instances isn't that much of a worry.

The new() constraint just lets the compiler use
Activator.CreateInstance, knowing that there'll be a parameterless
constructor avaialable (for classes - it uses initobj for value types).
 

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