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Switch<T> Class

Selects one choice from a number of activities to execute, based on the value of a given expression of the type specified in this object’s type specifier.

System.Object
  System.Activities.Activity
    System.Activities.NativeActivity
      System.Activities.Statements.Switch<T>

Namespace:  System.Activities.Statements
Assembly:  System.Activities (in System.Activities.dll)

[ContentPropertyAttribute("Cases")]
public sealed class Switch<T> : NativeActivity

Type Parameters

T

The type of the values provided in the Cases collection.

The Switch<T> type exposes the following members.

  NameDescription
Public methodSwitch<T>()Creates a new instance of the Switch<T> class.
Public methodSwitch<T>(Activity<T>)Creates a new instance of the Switch<T> class with the specified expression.
Public methodSwitch<T>(Expression<Func<ActivityContext, T>>)Creates a new instance of the Switch<T> class with the specified expression.
Public methodSwitch<T>(InArgument<T>)Creates a new instance of the Switch<T> class with the specified expression.
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  NameDescription
Protected propertyCacheIdGets the identifier of the cache that is unique within the scope of the workflow definition. (Inherited from Activity.)
Protected propertyCanInduceIdleGets or sets a value that indicates whether the activity can cause the workflow to become idle. (Inherited from NativeActivity.)
Public propertyCasesRepresents the dictionary of potential execution paths. Each entry contains a key and an activity that is executed when the result of the expression matches the key.
Protected propertyConstraintsGets a collection of Constraint activities that can be configured to provide validation for the Activity. (Inherited from Activity.)
Public propertyDefaultRepresents the activity that is executed if no keys of entries in the Cases() collection match the Expression() property.
Public propertyDisplayNameGets or sets an optional friendly name that is used for debugging, validation, exception handling, and tracking. (Inherited from Activity.)
Public propertyExpressionGets the object to compare to the keys in the Cases() collection.
Public propertyIdGets an identifier that is unique in the scope of the workflow definition. (Inherited from Activity.)
Protected propertyImplementationThe execution logic of the activity. (Inherited from NativeActivity.)
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  NameDescription
Protected methodAbortWhen implemented in a derived class, takes actions in response to the activity being aborted. (Inherited from NativeActivity.)
Protected methodCacheMetadata(ActivityMetadata)Not implemented. Use the CacheMetadata(NativeActivityMetadata) method instead. (Inherited from NativeActivity.)
Protected methodCacheMetadata(NativeActivityMetadata)Creates and validates a description of the activity’s arguments, variables, child activities, and activity delegates. (Inherited from NativeActivity.)
Protected methodCancelWhen implemented in a derived class, runs logic to cause graceful early completion of the activity. (Inherited from NativeActivity.)
Public methodEquals(Object)Determines whether the specified Object is equal to the current Object. (Inherited from Object.)
Protected methodExecuteWhen implemented in a derived class, runs the activity’s execution logic. (Inherited from NativeActivity.)
Protected methodFinalizeAllows an object to try to free resources and perform other cleanup operations before it is reclaimed by garbage collection. (Inherited from Object.)
Public methodGetHashCodeServes as a hash function for a particular type. (Inherited from Object.)
Public methodGetTypeGets the Type of the current instance. (Inherited from Object.)
Protected methodMemberwiseCloneCreates a shallow copy of the current Object. (Inherited from Object.)
Public methodShouldSerializeDisplayNameIndicates whether the DisplayName property should be serialized. (Inherited from Activity.)
Public methodToStringReturns a String that contains the Id and DisplayName of the Activity. (Inherited from Activity.)
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Each case in the Cases dictionary consists of a value (serving as the key for the dictionary) and an activity (serving as the value for the dictionary). The Expression() is evaluated and compared against the keys in the Cases dictionary. If a match is found, the corresponding activity is executed. Every key in the Cases dictionary must be unique according to the dictionary’s equality comparer.

The following code sample demonstrates creating a Switch<T> activity. This example is from the Using Procedural Activities sample.


// check if the number is ok...
new Switch<int>()
{
    DisplayName = "Verify Value from User",
    Expression = ExpressionServices.Convert<int>( env => numberFromUser.Get(env).CompareTo(numberToGuess.Get(env)) ),
    Cases = 
    {
        { 0, new Assign<bool>()
            {
                To = new OutArgument<bool>(finished),
                Value = true
            }
        },
        {  1, new WriteLine() { Text = "    Try a lower number number..." } }, 
        { -1, new WriteLine() { Text = "    Try a higher number" } }
    }
}


.NET Framework

Supported in: 4

.NET Framework Client Profile

Supported in: 4

Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

Any public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.

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