C# and VB Extensions to Support LINQ

C# and VB Extensions to Support LINQ

LINQ is responsible for most new language extensions in VS 2008. Here ’ s a list of the LINQ - related

extensions to C# 3.0 and VB 9.0 with brief descriptions of their purpose:

Implicitly typed local variables infer the type of local variables from the expressions used to

initialize them.

Object initializers simplify the construction and initialization of objects of arbitrary types.

Array initializers extend object initializers to elements of arrays of arbitrary types. VB 9.0

doesn ’ t support array initializers.

Collection initializers (also called implicitly typed array initializers) extend the array initializer

style to infer the element type of the collection from the initializer. VB 9.0 doesn ’ t support

collection initializers.

Anonymous types enable creating tuple types with object initializers whose CLR type is

inferred by the compiler. C# anonymous types are immutable, but some VB anonymous types

are mutable.

Extension methods enable extending existing and constructed types with new methods.

Lambda expressions enable C# 2.0 ’ s anonymous methods to deliver better type inference and

allow conversions to expression trees and delegate types. VB 9.0 supports Lambda expressions

but doesn ’ t expose anonymous methods to programmers.

Standard Query Operators (SQOs. Also called Standard Sequence Operators ) filter, transform,

join, group, and aggregate collections of CLR types.

Query expressions group SQOs into a high - level query language that is similar to SQL and

related to XQuery.

Expression trees permit lambda expressions to be represented as data (expression trees) instead

of as code (delegates).

IQueryable < T > and IOrderedQueryable < T > interfaces, in conjunction with expression trees,

facilitate third - party LINQ implementations for other data domains and enable the compiling

of queries for improved performance. IQueryable < T > and IOrderedQueryable < T > types

enable composable queries by passing them as the data source of one or more additional

LINQ queries.LINQ also relies on these language features of C# 2.0 and VB 8.0:

Generic types let you specify the precise data type that a method, class, structure, or interface

acts upon. The primary benefits of generics are type safety and increased code reusability.

Anonymous methods (also called anonymous delegates) let you define a nameless method

that ’ s called by a delegate and access variables that would normally be out of scope. VB doesn ’ t

support anonymous methods directly.

Iterators , specifically the generic, type - safe IEnumerable < T > interface, in the System

.Collections.Generic namespace, which supports iterating over a generic collection in a

foreach or For Each ... Next loop.

Programs that don ’ t execute LINQ queries can take advantage of most new VS 2008 features. LINQ will

introduce the more abstract functional constructs, such as lambda expressions and expression trees, to

most .NET developers.