Evaluate(T) Method (ConditionValidator(T), Expression(Func(T, Boolean)), String)

CuttingEdge.Conditions

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Checks whether the specified expression evaluates true on the given value. An exception is thrown otherwise.

Namespace:  CuttingEdge.Conditions
Assembly:  CuttingEdge.Conditions (in CuttingEdge.Conditions.dll)

Syntax

Visual Basic (Declaration)
Public Shared Function Evaluate(Of T) ( _
	validator As ConditionValidator(Of T), _
	expression As Expression(Of Func(Of T, Boolean)), _
	conditionDescription As String _
) As ConditionValidator(Of T)
C#
public static ConditionValidator<T> Evaluate<T>(
	ConditionValidator<T> validator,
	Expression<Func<T, bool>> expression,
	string conditionDescription
)
Visual C++
public:
generic<typename T>
static ConditionValidator<T>^ Evaluate(
	ConditionValidator<T>^ validator, 
	Expression<Func<T, bool>^>^ expression, 
	String^ conditionDescription
)
JavaScript
JavaScript does not support generic types or methods.

Parameters

validator
Type: CuttingEdge.Conditions..::.ConditionValidator<(Of <(T>)>)
The ConditionValidator<(Of <(T>)>) that holds the value that has to be checked.
expression
Type: System.Linq.Expressions..::.Expression<(Of <(Func<(Of <(T, Boolean>)>)>)>)
The Expression<(Of <(TDelegate>)>) that will be compiled to an Func<(Of <(T, TResult>)>) and executed. When the expression is a null reference (Nothing in VB) it is considered to evaluate false.
conditionDescription
Type: System..::.String
Describes the condition that should hold. i.e.: 'value should be valid'. When the description contains a {0} marker, that marker will be replaced with the actual name of the parameter. The description will be used in the message of the thrown exception.

Type Parameters

T
The type of the Value of the specified validator.

Return Value

The specified validator instance.

Remarks

This method will display a string representation of the specified expression. Although it can therefore give a lot of useful information in the exception message, it the expression has to be compiled on each call. Try using the other Evaluate<(Of <(T>)>)(ConditionValidator<(Of <(T>)>), Boolean) overload in performance sensitive parts of your program.

Exceptions

ExceptionCondition
System..::.ArgumentExceptionThrown when the expression evaluated false or is a null reference, while the specified validator is created using the Requires extension method.
System..::.ArgumentNullExceptionThrown when the expression evaluated false or is a null reference and the Value of the specified validator is a null reference, while the specified validator is created using the Requires extension method.
System.ComponentModel..::.InvalidEnumArgumentExceptionThrown when the expression evaluated false or is a null reference and the Value of the specified validator is an Enum type, while the specified validator is created using the Requires extension method.
CuttingEdge.Conditions..::.PostconditionExceptionThrown when the expression evaluated false or is a null reference, while the specified validator is created using the Ensures extension method.

See Also

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