Expression.Block Method

Definition

Namespace:

System.Linq.Expressions

Assembly:

System.Linq.Expressions.dll

Creates a BlockExpression.

Overloads

Block(Type, IEnumerable<ParameterExpression>, IEnumerable<Expression>)	Creates a BlockExpression that contains the given variables and expressions.
Block(Expression, Expression, Expression)	Creates a BlockExpression that contains three expressions and has no variables.
Block(Expression, Expression, Expression, Expression, Expression)	Creates a BlockExpression that contains five expressions and has no variables.
Block(Type, IEnumerable<ParameterExpression>, Expression[])	Creates a BlockExpression that contains the given variables and expressions.
Block(Type, Expression[])	Creates a BlockExpression that contains the given expressions, has no variables and has specific result type.
Block(Expression, Expression, Expression, Expression)	Creates a BlockExpression that contains four expressions and has no variables.
Block(Expression, Expression)	Creates a BlockExpression that contains two expressions and has no variables.
Block(IEnumerable<ParameterExpression>, Expression[])	Creates a BlockExpression that contains the given variables and expressions.
Block(IEnumerable<ParameterExpression>, IEnumerable<Expression>)	Creates a BlockExpression that contains the given variables and expressions.
Block(Expression[])	Creates a BlockExpression that contains the given expressions and has no variables.
Block(IEnumerable<Expression>)	Creates a BlockExpression that contains the given expressions and has no variables.
Block(Type, IEnumerable<Expression>)	Creates a BlockExpression that contains the given expressions, has no variables and has specific result type.

Block(Type, IEnumerable<ParameterExpression>, IEnumerable<Expression>)

Source:

BlockExpression.cs

Creates a BlockExpression that contains the given variables and expressions.

public:
 static System::Linq::Expressions::BlockExpression ^ Block(Type ^ type, System::Collections::Generic::IEnumerable<System::Linq::Expressions::ParameterExpression ^> ^ variables, System::Collections::Generic::IEnumerable<System::Linq::Expressions::Expression ^> ^ expressions);

public static System.Linq.Expressions.BlockExpression Block (Type type, System.Collections.Generic.IEnumerable<System.Linq.Expressions.ParameterExpression>? variables, System.Collections.Generic.IEnumerable<System.Linq.Expressions.Expression> expressions);

static member Block : Type * seq<System.Linq.Expressions.ParameterExpression> * seq<System.Linq.Expressions.Expression> -> System.Linq.Expressions.BlockExpression

Public Shared Function Block (type As Type, variables As IEnumerable(Of ParameterExpression), expressions As IEnumerable(Of Expression)) As BlockExpression

Parameters

type

Type

The result type of the block.

variables

IEnumerable<ParameterExpression>

The variables in the block.

expressions

IEnumerable<Expression>

The expressions in the block.

Returns

BlockExpression

The created BlockExpression.

Block(Expression, Expression, Expression)

Source:

BlockExpression.cs

Creates a BlockExpression that contains three expressions and has no variables.

public:
 static System::Linq::Expressions::BlockExpression ^ Block(System::Linq::Expressions::Expression ^ arg0, System::Linq::Expressions::Expression ^ arg1, System::Linq::Expressions::Expression ^ arg2);

public static System.Linq.Expressions.BlockExpression Block (System.Linq.Expressions.Expression arg0, System.Linq.Expressions.Expression arg1, System.Linq.Expressions.Expression arg2);

static member Block : System.Linq.Expressions.Expression * System.Linq.Expressions.Expression * System.Linq.Expressions.Expression -> System.Linq.Expressions.BlockExpression

Public Shared Function Block (arg0 As Expression, arg1 As Expression, arg2 As Expression) As BlockExpression

Parameters

arg0

Expression

The first expression in the block.

arg1

Expression

The second expression in the block.

arg2

Expression

The third expression in the block.

Returns

BlockExpression

The created BlockExpression.

Remarks

When the block expression is executed, it returns the value of the last expression in the block.

Block(Expression, Expression, Expression, Expression, Expression)

Source:

BlockExpression.cs

Creates a BlockExpression that contains five expressions and has no variables.

public:
 static System::Linq::Expressions::BlockExpression ^ Block(System::Linq::Expressions::Expression ^ arg0, System::Linq::Expressions::Expression ^ arg1, System::Linq::Expressions::Expression ^ arg2, System::Linq::Expressions::Expression ^ arg3, System::Linq::Expressions::Expression ^ arg4);

public static System.Linq.Expressions.BlockExpression Block (System.Linq.Expressions.Expression arg0, System.Linq.Expressions.Expression arg1, System.Linq.Expressions.Expression arg2, System.Linq.Expressions.Expression arg3, System.Linq.Expressions.Expression arg4);

static member Block : System.Linq.Expressions.Expression * System.Linq.Expressions.Expression * System.Linq.Expressions.Expression * System.Linq.Expressions.Expression * System.Linq.Expressions.Expression -> System.Linq.Expressions.BlockExpression

Public Shared Function Block (arg0 As Expression, arg1 As Expression, arg2 As Expression, arg3 As Expression, arg4 As Expression) As BlockExpression

Parameters

arg0

Expression

The first expression in the block.

arg1

Expression

The second expression in the block.

arg2

Expression

The third expression in the block.

arg3

Expression

The fourth expression in the block.

arg4

Expression

The fifth expression in the block.

Returns

BlockExpression

The created BlockExpression.

Remarks

When the block expression is executed, it returns the value of the last expression in the block.

Block(Type, IEnumerable<ParameterExpression>, Expression[])

Source:

BlockExpression.cs

Creates a BlockExpression that contains the given variables and expressions.

public:
 static System::Linq::Expressions::BlockExpression ^ Block(Type ^ type, System::Collections::Generic::IEnumerable<System::Linq::Expressions::ParameterExpression ^> ^ variables, ... cli::array <System::Linq::Expressions::Expression ^> ^ expressions);

public static System.Linq.Expressions.BlockExpression Block (Type type, System.Collections.Generic.IEnumerable<System.Linq.Expressions.ParameterExpression>? variables, params System.Linq.Expressions.Expression[] expressions);

static member Block : Type * seq<System.Linq.Expressions.ParameterExpression> * System.Linq.Expressions.Expression[] -> System.Linq.Expressions.BlockExpression

Public Shared Function Block (type As Type, variables As IEnumerable(Of ParameterExpression), ParamArray expressions As Expression()) As BlockExpression

Parameters

type

Type

The result type of the block.

variables

IEnumerable<ParameterExpression>

The variables in the block.

expressions

Expression[]

The expressions in the block.

Returns

BlockExpression

The created BlockExpression.

Block(Type, Expression[])

Source:

BlockExpression.cs

Creates a BlockExpression that contains the given expressions, has no variables and has specific result type.

public:
 static System::Linq::Expressions::BlockExpression ^ Block(Type ^ type, ... cli::array <System::Linq::Expressions::Expression ^> ^ expressions);

public static System.Linq.Expressions.BlockExpression Block (Type type, params System.Linq.Expressions.Expression[] expressions);

static member Block : Type * System.Linq.Expressions.Expression[] -> System.Linq.Expressions.BlockExpression

Public Shared Function Block (type As Type, ParamArray expressions As Expression()) As BlockExpression

Parameters

type

Type

The result type of the block.

expressions

Expression[]

The expressions in the block.

Returns

BlockExpression

The created BlockExpression.

Block(Expression, Expression, Expression, Expression)

Source:

BlockExpression.cs

Creates a BlockExpression that contains four expressions and has no variables.

public:
 static System::Linq::Expressions::BlockExpression ^ Block(System::Linq::Expressions::Expression ^ arg0, System::Linq::Expressions::Expression ^ arg1, System::Linq::Expressions::Expression ^ arg2, System::Linq::Expressions::Expression ^ arg3);

public static System.Linq.Expressions.BlockExpression Block (System.Linq.Expressions.Expression arg0, System.Linq.Expressions.Expression arg1, System.Linq.Expressions.Expression arg2, System.Linq.Expressions.Expression arg3);

static member Block : System.Linq.Expressions.Expression * System.Linq.Expressions.Expression * System.Linq.Expressions.Expression * System.Linq.Expressions.Expression -> System.Linq.Expressions.BlockExpression

Public Shared Function Block (arg0 As Expression, arg1 As Expression, arg2 As Expression, arg3 As Expression) As BlockExpression

Parameters

arg0

Expression

The first expression in the block.

arg1

Expression

The second expression in the block.

arg2

Expression

The third expression in the block.

arg3

Expression

The fourth expression in the block.

Returns

BlockExpression

The created BlockExpression.

Remarks

When the block expression is executed, it returns the value of the last expression in the block.

Block(Expression, Expression)

Source:

BlockExpression.cs

Creates a BlockExpression that contains two expressions and has no variables.

public:
 static System::Linq::Expressions::BlockExpression ^ Block(System::Linq::Expressions::Expression ^ arg0, System::Linq::Expressions::Expression ^ arg1);

public static System.Linq.Expressions.BlockExpression Block (System.Linq.Expressions.Expression arg0, System.Linq.Expressions.Expression arg1);

static member Block : System.Linq.Expressions.Expression * System.Linq.Expressions.Expression -> System.Linq.Expressions.BlockExpression

Public Shared Function Block (arg0 As Expression, arg1 As Expression) As BlockExpression

Parameters

arg0

Expression

The first expression in the block.

arg1

Expression

The second expression in the block.

Returns

BlockExpression

The created BlockExpression.

Remarks

When the block expression is executed, it returns the value of the last expression in the block.

Block(IEnumerable<ParameterExpression>, Expression[])

Source:

BlockExpression.cs

Creates a BlockExpression that contains the given variables and expressions.

public:
 static System::Linq::Expressions::BlockExpression ^ Block(System::Collections::Generic::IEnumerable<System::Linq::Expressions::ParameterExpression ^> ^ variables, ... cli::array <System::Linq::Expressions::Expression ^> ^ expressions);

public static System.Linq.Expressions.BlockExpression Block (System.Collections.Generic.IEnumerable<System.Linq.Expressions.ParameterExpression>? variables, params System.Linq.Expressions.Expression[] expressions);

static member Block : seq<System.Linq.Expressions.ParameterExpression> * System.Linq.Expressions.Expression[] -> System.Linq.Expressions.BlockExpression

Public Shared Function Block (variables As IEnumerable(Of ParameterExpression), ParamArray expressions As Expression()) As BlockExpression

Parameters

variables

IEnumerable<ParameterExpression>

The variables in the block.

expressions

Expression[]

The expressions in the block.

Returns

BlockExpression

The created BlockExpression.

Remarks

When the block expression is executed, it returns the value of the last expression in the block.

Block(IEnumerable<ParameterExpression>, IEnumerable<Expression>)

Source:

BlockExpression.cs

Creates a BlockExpression that contains the given variables and expressions.

public:
 static System::Linq::Expressions::BlockExpression ^ Block(System::Collections::Generic::IEnumerable<System::Linq::Expressions::ParameterExpression ^> ^ variables, System::Collections::Generic::IEnumerable<System::Linq::Expressions::Expression ^> ^ expressions);

public static System.Linq.Expressions.BlockExpression Block (System.Collections.Generic.IEnumerable<System.Linq.Expressions.ParameterExpression>? variables, System.Collections.Generic.IEnumerable<System.Linq.Expressions.Expression> expressions);

static member Block : seq<System.Linq.Expressions.ParameterExpression> * seq<System.Linq.Expressions.Expression> -> System.Linq.Expressions.BlockExpression

Public Shared Function Block (variables As IEnumerable(Of ParameterExpression), expressions As IEnumerable(Of Expression)) As BlockExpression

Parameters

variables

IEnumerable<ParameterExpression>

The variables in the block.

expressions

IEnumerable<Expression>

The expressions in the block.

Returns

BlockExpression

The created BlockExpression.

Examples

The following code example shows how to pass a parameter to a block expression and process this parameter within a block.

// Add the following directive to your file:
// using System.Linq.Expressions;

// This block has a parameter expression
// that represents a variable within the block scope.
// It assigns a value to the variable,
// and then adds a constant to the assigned value.

ParameterExpression varExpr = Expression.Variable(typeof(int), "sampleVar");
BlockExpression blockExpr = Expression.Block(
    new ParameterExpression[] { varExpr },
    Expression.Assign(varExpr, Expression.Constant(1)),
    Expression.Add(varExpr, Expression.Constant(5))
);

// Print out the expressions from the block expression.
Console.WriteLine("The expressions from the block expression:");
foreach (var expr in blockExpr.Expressions)
    Console.WriteLine(expr.ToString());

Console.WriteLine("The result of executing the expression tree:");
// The following statement first creates an expression tree,
// then compiles it, and then executes it.
Console.WriteLine(
    Expression.Lambda<Func<int>>(blockExpr).Compile()());

// This code example produces the following output:
// The expressions from the block expression:
// (sampleVar = 1)
// (sampleVar + 5)
// The result of executing the expression tree:
// 6

' Add the following directive to your file:
' Imports System.Linq.Expressions  


' This block has a parameter expression
' that represents a variable within the block scope.
' It assigns a value to the variable,
' and then adds a constant to the assigned value. 

Dim varExpr As ParameterExpression = Expression.Variable(GetType(Integer), "sampleVar")
Dim blockExpr As BlockExpression = Expression.Block(
    New ParameterExpression() {varExpr},
    Expression.Assign(varExpr, Expression.Constant(1)),
    Expression.Add(varExpr, Expression.Constant(5))
)

' Print the expressions from the block expression.

Console.WriteLine("The expressions from the block expression:")
For Each expr In blockExpr.Expressions
    Console.WriteLine(expr.ToString())
Next

Console.WriteLine("The result of executing the expression tree:")

' The following statement first creates an expression tree,
' then compiles it, and then executes it.
Console.WriteLine(
    Expression.Lambda(Of Func(Of Integer))(blockExpr).Compile()())

' This code example produces the following output:
'
' The expressions from the block expression:
' (sampleVar = 1)
' (sampleVar + 5)
' The result of executing the expression tree:
' 6

Remarks

When the block expression is executed, it returns the value of the last expression in the block.

Block(Expression[])

Source:

BlockExpression.cs

Creates a BlockExpression that contains the given expressions and has no variables.

public:
 static System::Linq::Expressions::BlockExpression ^ Block(... cli::array <System::Linq::Expressions::Expression ^> ^ expressions);

public static System.Linq.Expressions.BlockExpression Block (params System.Linq.Expressions.Expression[] expressions);

static member Block : System.Linq.Expressions.Expression[] -> System.Linq.Expressions.BlockExpression

Public Shared Function Block (ParamArray expressions As Expression()) As BlockExpression

Parameters

expressions

Expression[]

The expressions in the block.

Returns

BlockExpression

The created BlockExpression.

Examples

The following code example shows how to create a block expression. The block expression consists of two MethodCallExpression objects and one ConstantExpression object.

// Add the following directive to your file:
// using System.Linq.Expressions;

// The block expression allows for executing several expressions sequentually.
// When the block expression is executed,
// it returns the value of the last expression in the sequence.
BlockExpression blockExpr = Expression.Block(
    Expression.Call(
        null,
        typeof(Console).GetMethod("Write", new Type[] { typeof(String) }),
        Expression.Constant("Hello ")
       ),
    Expression.Call(
        null,
        typeof(Console).GetMethod("WriteLine", new Type[] { typeof(String) }),
        Expression.Constant("World!")
        ),
    Expression.Constant(42)
);

Console.WriteLine("The result of executing the expression tree:");
// The following statement first creates an expression tree,
// then compiles it, and then executes it.
var result = Expression.Lambda<Func<int>>(blockExpr).Compile()();

// Print out the expressions from the block expression.
Console.WriteLine("The expressions from the block expression:");
foreach (var expr in blockExpr.Expressions)
    Console.WriteLine(expr.ToString());

// Print out the result of the tree execution.
Console.WriteLine("The return value of the block expression:");
Console.WriteLine(result);

// This code example produces the following output:
//
// The result of executing the expression tree:
// Hello World!

// The expressions from the block expression:
// Write("Hello ")
// WriteLine("World!")
// 42

// The return value of the block expression:
// 42

' Add the following directive to your file:
' Imports System.Linq.Expressions

' The block expression enables you to execute several expressions sequentually.
' When the block expression is executed,
' it returns the value of the last expression in the sequence.
Dim blockExpr As BlockExpression = Expression.Block(
    Expression.Call(
        Nothing,
        GetType(Console).GetMethod("Write", New Type() {GetType(String)}),
        Expression.Constant("Hello ")
       ),
    Expression.Call(
        Nothing,
        GetType(Console).GetMethod("WriteLine", New Type() {GetType(String)}),
        Expression.Constant("World!")
        ),
    Expression.Constant(42)
)

Console.WriteLine("The result of executing the expression tree:")
' The following statement first creates an expression tree,
' then compiles it, and then executes it.           
Dim result = Expression.Lambda(Of Func(Of Integer))(blockExpr).Compile()()

' Print the expressions from the block expression.
Console.WriteLine("The expressions from the block expression:")
For Each expr In blockExpr.Expressions
    Console.WriteLine(expr.ToString())
Next

' Print the result of the tree execution.
Console.WriteLine("The return value of the block expression:")
Console.WriteLine(result)

' This code example produces the following output:
'
' The result of executing the expression tree:
' Hello World!

' The expressions from the block expression:
' Write("Hello ")
' WriteLine("World!")
' 42

' The return value of the block expression:
' 42

Remarks

When the block expression is executed, it returns the value of the last expression in the block.

Block(IEnumerable<Expression>)

Source:

BlockExpression.cs

Creates a BlockExpression that contains the given expressions and has no variables.

public:
 static System::Linq::Expressions::BlockExpression ^ Block(System::Collections::Generic::IEnumerable<System::Linq::Expressions::Expression ^> ^ expressions);

public static System.Linq.Expressions.BlockExpression Block (System.Collections.Generic.IEnumerable<System.Linq.Expressions.Expression> expressions);

static member Block : seq<System.Linq.Expressions.Expression> -> System.Linq.Expressions.BlockExpression

Public Shared Function Block (expressions As IEnumerable(Of Expression)) As BlockExpression

Parameters

expressions

IEnumerable<Expression>

The expressions in the block.

Returns

BlockExpression

The created BlockExpression.

Remarks

When the block expression is executed, it returns the value of the last expression in the block.

Block(Type, IEnumerable<Expression>)

Source:

BlockExpression.cs

Creates a BlockExpression that contains the given expressions, has no variables and has specific result type.

public:
 static System::Linq::Expressions::BlockExpression ^ Block(Type ^ type, System::Collections::Generic::IEnumerable<System::Linq::Expressions::Expression ^> ^ expressions);

public static System.Linq.Expressions.BlockExpression Block (Type type, System.Collections.Generic.IEnumerable<System.Linq.Expressions.Expression> expressions);

static member Block : Type * seq<System.Linq.Expressions.Expression> -> System.Linq.Expressions.BlockExpression

Public Shared Function Block (type As Type, expressions As IEnumerable(Of Expression)) As BlockExpression

Parameters

type

Type

The result type of the block.

expressions

IEnumerable<Expression>

The expressions in the block.

Returns

BlockExpression

The created BlockExpression.