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Contract.Requires Method (Boolean, String)

Specifies a precondition contract for the enclosing method or property, and displays a message if the condition for the contract fails.

Namespace:  System.Diagnostics.Contracts
Assemblies:   mscorlib (in mscorlib.dll)
  System.Diagnostics.Contracts (in System.Diagnostics.Contracts.dll)

'Declaration
<ConditionalAttribute("CONTRACTS_FULL")> _
Public Shared Sub Requires ( _
	condition As Boolean, _
	userMessage As String _
)

Parameters

condition
Type: System.Boolean

The conditional expression to test.

userMessage
Type: System.String

The message to display if the condition is false.

  • This method call must be at the beginning of a method or property, before any other code.

  • This contract is exposed to clients; therefore, it must only reference members that are at least as visible as the enclosing method.

  • Use this method instead of the Contract.Requires(Of TException)(Boolean, String) method when backward compatibility does not force you to throw a particular exception.

.NET Framework

Supported in: 4.6, 4.5, 4

.NET Framework Client Profile

Supported in: 4

.NET for Windows Phone apps

Supported in: Windows Phone 8.1, Windows Phone Silverlight 8.1, Windows Phone Silverlight 8

Portable Class Library

Supported in: Portable Class Library
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