how can i store and reuse pieces of my lambda expressions

Question

I have a block of code where a piece of the lambda expression is used again and again. How can store this logic so that i can reuse this expression piece?

Eg: lets take

Answer 1

You haven't told us if the lambda expressions are being converted to expression-trees or to delegates, but assuming the former, I recommend using PredicateBuilder.

Expression predicate = map =>  map.User.Key == _users.PublicUser.Key 
                                       || map.User.Key == _users.CurrentUser.Key;

Then your first query becomes:

var pred1 = predicate.And
            (map => map.AccessLevel.ToAccessLevel() == AccessLevel.Write);

var query1 = Session.Query
    (dimgroup => dimgroup.Users.Where(pred1).Count() > 0);

And your second:

var pred2 = predicate.And
            (map => map.AccessLevel.ToAccessLevel() == AccessLevel.Read);

var query2 = Session.Query
    (dimgroup => dimgroup.Users.Where(pred2).Count() > 0);

As you can see, there is scope for factoring out even more commonalities; since the queries appear to only differ by different AccessLevels.