Expression.UnaryPlus Method (Expression, MethodInfo)
Creates a UnaryExpression that represents a unary plus operation.
Assembly: System.Core (in System.Core.dll)
- Type: System.Linq.Expressions.Expression
An Expression to set the Operand property equal to.
expression is null.
method is not null and the method it represents returns void, is not static (Shared in Visual Basic), or does not take exactly one argument.
method is null and the unary plus operator is not defined for expression.Type.
expression.Type (or its corresponding non-nullable type if it is a nullable value type) is not assignable to the argument type of the method represented by method.
The Method property of the resulting UnaryExpression is set to the implementing method. The Type property is set to the type of the node. If the node is lifted, the IsLifted and IsLiftedToNull properties are both true. Otherwise, they are false.
The following rules determine the implementing method for the operation:
If method is not null and it represents a non-void, static (Shared in Visual Basic) method that takes one argument, it is the implementing method for the node.
If expression.Type is a user-defined type that defines the unary plus operator, the MethodInfo that represents that operator is the implementing method.
Otherwise, if expression.Type is a numeric type, the implementing method is null.
Node Type and Lifted versus Non-Lifted
If the implementing method is not null:
If expression.Type is assignable to the argument type of the implementing method, the node is not lifted. The type of the node is the return type of the implementing method.
If the following two conditions are satisfied, the node is lifted and the type of the node is the nullable type that corresponds to the return type of the implementing method:
expression.Type is a nullable value type and the corresponding non-nullable value type is equal to the argument type of the implementing method.
The return type of the implementing method is a non-nullable value type.
If the implementing method is null, the type of the node is expression.Type. If expression.Type is non-nullable, the node is not lifted. Otherwise, the node is lifted.
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