Contexts 3 4 2 – Fast Window Switcher App

1. Contexts 3 4 2 – Fast Window Switcher Approach
2. Contexts 3 4 2 – Fast Window Switcher Apps
3. Contexts 3 4 2 – Fast Window Switcher App Download
4. Contexts 3 4 2 – Fast Window Switcher Applications

Definition

Provides members for setting and retrieving data about an application's context.

CSwitch class.; 2 minutes to read; In this article. This class is the event type class for context switch events. The following syntax is simplified from MOF code. The switchName argument defines the switch name, and the isEnabled property defines the value of the switch. Because AppContext is a static class, it is available on a per-application domain basis. Calling the AppContext.SetSwitch(String, Boolean) has application scope; that is, it affects only the application.

Remarks

The AppContext class enables library writers to provide a uniform opt-out mechanism for new functionality for their users. It establishes a loosely-coupled contract between components in order to communicate an opt-out request. This capability is typically important when a change is made to existing functionality. Conversely, there is already an implicit opt-in for new functionality.

AppContext for library developers

Libraries use the AppContext class to define and expose compatibility switches, while library users can set those switches to affect the library behavior. By default, libraries provide the new functionality, and they only alter it (that is, they provide the previous functionality) if the switch is set. This allows libraries to provide new behavior for an existing API while continuing to support callers who depend on the previous behavior.

Define the switch name

The most common way to allow consumers of your library to opt out of a change of behavior is to define a named switch. Its value element is a name/value pair that consists of the name of a switch and its Boolean value. By default, the switch is always implicitly false, which provides the new behavior (and makes the new behavior opt-in by default). Setting the switch to true enables it, which provides the legacy behavior. Explicitly setting the switch to false also provides the new behavior.

It's beneficial to use a consistent format for switch names, since they are a formal contract exposed by a library. The following are two obvious formats.

• Switch.namespace.switchname

• Switch.library.switchname

Once you define and document the switch, callers can use it by using the registry, by adding an element to their application configuration file, or by calling the AppContext.SetSwitch(String, Boolean) method programmatically. See the AppContext for library consumers section for more information about how callers use and set the value of AppContext configuration switches.

When the common language runtime runs an application, it automatically reads the registry's compatibility settings and loads the application configuration file in order to populate the application's AppContext instance. Because the AppContext instance is populated either programmatically by the caller or by the runtime, you do not have to take any action, such as calling the SetSwitch method, to configure the AppContext instance.

Check the setting

You can then check if a consumer has declared the value of the switch and act appropriately by calling the AppContext.TryGetSwitch method. The method returns true if the switchName argument is found, and when the method returns, its isEnabled argument indicates the value of the switch. Otherwise, the method returns false.

Contexts 3 4 2 – Fast Window Switcher Approach

An example

The following example illustrates the use of the AppContext class to allow the customer to choose the original behavior of a library method. The following is version 1.0 of a library named StringLibrary. It defines a SubstringStartsAt method that performs an ordinal comparison to determine the starting index of a substring within a larger string.

The following example then uses the library to find the starting index of the substring 'archæ' in 'The archaeologist'. Because the method performs an ordinal comparison, the substring cannot be found.

Version 2 of the library, however, changes the SubstringStartsAt method to use culture-sensitive comparison.

When the app is recompiled to run against the new version of the library, it now reports that the substring 'archæ' is found at index 4 in 'The archaeologist'.

This change can be prevented from breaking the applications that depend on the original behavior by defining an switch. In this case, the switch is named StringLibrary.DoNotUseCultureSensitiveComparison. Its default value, false, indicates that the library should perform its version 2.0 culture-sensitive comparison. true indicates that the library should perform its version 1.0 ordinal comparison. A slight modification of the previous code allows the library consumer to set the switch to determine the kind of comparison the method performs.

If application can then use the following configuration file to restore the version 1.0 behavior.

When the application is run with the configuration file present, it produces the following output:

AppContext for library consumers

If you are the consumer of a library, the AppContext class allows you to take advantage of a library or library method's opt-out mechanism for new functionality. Individual methods of the class library that you are calling define particular switches that enable or disable a new behavior. The value of the switch is a Boolean. If it is false, which is typically the default value, the new behavior is enabled; if it is true, the new behavior is disabled, and the member behaves as it did previously.

Rapidclick 1 4 – auto mouse clicker. You can set the value of a switch in one of four ways:

• By calling the AppContext.SetSwitch(String, Boolean) method in your code. The switchName argument defines the switch name, and the isEnabled property defines the value of the switch. Because AppContext is a static class, it is available on a per-application domain basis.

  Calling the AppContext.SetSwitch(String, Boolean) has application scope; that is, it affects only the application.

• By adding an element to the section of your app.config file. The switch has a single attribute, value, whose value is a string that represents a key/value pair containing both the switch name and its value.

  To define multiple switches, separate each switch's key/value pair in the element's value attribute with a semicolon. In that case, the element has the following format:

  Using the element to define a configuration setting has application scope; that is, it affects only the application.

  Note

  For information on the switches defined by the .NET Framework, see the element.

• By adding an entry to the registry. Add a new string value to the HKLMSOFTWAREMicrosoft.NETFrameworkAppContext subkey. Set the name of the entry to the name of the switch. Set its value to one of the following options: True, true, False, or false. If the runtime encounters any other value, it ignores the switch.

  On a 64-bit operating system, you must also add the same entry to the HKLMSOFTWAREWow6432NodeMicrosoft.NETFrameworkAppContext subkey.

  Using the registry to define an AppContext switch has machine scope; that is, it affects every application running on the machine.

• For ASP.NET applications, you add an element to the section of the web.config file. For example:

If you set the same switch in more than one way, the order of precedence for determining which setting overrides the others is:

1. The programmatic setting.

2. The setting in the app config file or the web.config file.

3. The registry setting.

The following is a simple application that passes a file URI to the Path.GetDirectoryName method. When run under the .NET Framework 4.6, it throws an ArgumentException because file:// is no longer a valid part of a file path. Printworks 2 0 3 – all purpose desktop publishing workstation.

To restore the method's previous behavior and prevent the exception, you can add the Switch.System.IO.UseLegacyPathHandling switch to the application configuration file for the example:

See also

Properties

Methods

Contexts 3 4 2 – Fast Window Switcher Apps

Version 2 of the library, however, changes the SubstringStartsAt method to use culture-sensitive comparison.

When the app is recompiled to run against the new version of the library, it now reports that the substring 'archæ' is found at index 4 in 'The archaeologist'.

This change can be prevented from breaking the applications that depend on the original behavior by defining an switch. In this case, the switch is named StringLibrary.DoNotUseCultureSensitiveComparison. Its default value, false, indicates that the library should perform its version 2.0 culture-sensitive comparison. true indicates that the library should perform its version 1.0 ordinal comparison. A slight modification of the previous code allows the library consumer to set the switch to determine the kind of comparison the method performs.

If application can then use the following configuration file to restore the version 1.0 behavior.

When the application is run with the configuration file present, it produces the following output:

AppContext for library consumers

If you are the consumer of a library, the AppContext class allows you to take advantage of a library or library method's opt-out mechanism for new functionality. Individual methods of the class library that you are calling define particular switches that enable or disable a new behavior. The value of the switch is a Boolean. If it is false, which is typically the default value, the new behavior is enabled; if it is true, the new behavior is disabled, and the member behaves as it did previously.

Rapidclick 1 4 – auto mouse clicker. You can set the value of a switch in one of four ways:

• By calling the AppContext.SetSwitch(String, Boolean) method in your code. The switchName argument defines the switch name, and the isEnabled property defines the value of the switch. Because AppContext is a static class, it is available on a per-application domain basis.

  Calling the AppContext.SetSwitch(String, Boolean) has application scope; that is, it affects only the application.

• By adding an element to the section of your app.config file. The switch has a single attribute, value, whose value is a string that represents a key/value pair containing both the switch name and its value.

  To define multiple switches, separate each switch's key/value pair in the element's value attribute with a semicolon. In that case, the element has the following format:

  Using the element to define a configuration setting has application scope; that is, it affects only the application.

  Note

  For information on the switches defined by the .NET Framework, see the element.

• By adding an entry to the registry. Add a new string value to the HKLMSOFTWAREMicrosoft.NETFrameworkAppContext subkey. Set the name of the entry to the name of the switch. Set its value to one of the following options: True, true, False, or false. If the runtime encounters any other value, it ignores the switch.

  On a 64-bit operating system, you must also add the same entry to the HKLMSOFTWAREWow6432NodeMicrosoft.NETFrameworkAppContext subkey.

  Using the registry to define an AppContext switch has machine scope; that is, it affects every application running on the machine.

• For ASP.NET applications, you add an element to the section of the web.config file. For example:

If you set the same switch in more than one way, the order of precedence for determining which setting overrides the others is:

1. The programmatic setting.

2. The setting in the app config file or the web.config file.

3. The registry setting.

The following is a simple application that passes a file URI to the Path.GetDirectoryName method. When run under the .NET Framework 4.6, it throws an ArgumentException because file:// is no longer a valid part of a file path. Printworks 2 0 3 – all purpose desktop publishing workstation.

To restore the method's previous behavior and prevent the exception, you can add the Switch.System.IO.UseLegacyPathHandling switch to the application configuration file for the example:

See also

Properties

Methods

Contexts 3 4 2 – Fast Window Switcher Apps

Contexts 3 4 2 – Fast Window Switcher App Download

Contexts 3 4 2 – Fast Window Switcher Applications

Applies to

See also