Represents a strongly typed lambda expression as a data structure in the form of an expression tree. This class cannot be inherited.
See Also: Expression<TDelegate> Members
Syntax
Type Parameters
- TDelegate
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Remarks
When a lambda expression is assigned to a variable, field, or parameter whose type is System.Linq.Expressions.Expression`1, the compiler emits instructions to build an expression tree.
A conversion from a lambda expression to type Expression<D> (Expression(Of D) in Visual Basic) exists if a conversion from the lambda expression to a delegate of type D exists. However, the conversion may fail, for example, if the body of the lambda expression is a block. This means that delegates and expression trees behave similarly with regard to overload resolution.
The expression tree is an in-memory data representation of the lambda expression. The expression tree makes the structure of the lambda expression transparent and explicit. You can interact with the data in the expression tree just as you can with any other data structure.
The ability to treat expressions as data structures enables APIs to receive user code in a format that can be inspected, transformed, and processed in a custom manner. For example, the vbtecdlinq data access implementation uses this facility to translate expression trees to Transact-SQL statements that can be evaluated by the database.
Many standard query operators defined in the System.Linq.Queryable class have one or more parameters of type System.Linq.Expressions.Expression`1.
The Expression.NodeType of an System.Linq.Expressions.Expression`1 is ExpressionType.Lambda.
Use the Expression.Lambda``1(Expression, IEnumerable<ParameterExpression>) or Expression.Lambda``1(Expression, ParameterExpression[]) method to create an System.Linq.Expressions.Expression`1 object.
Requirements
Assembly: System.Core (in System.Core.dll)
Assembly Versions: 3.5.0.0, 4.0.0.0