Programming Reference:EnvironmentExtension Class - Revision history

Mellinger: /* Events */

2026-02-20T14:06:36Z

Events

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	</pre>		</pre>
	There, BEGIN/END macros enclose lists of comma-separated C strings representing [[Technical_Reference:Parameter_Definition\|parameter]] or [[Technical_Reference:State_Definition\|state definition lines]], respectively.		There, BEGIN/END macros enclose lists of comma-separated C strings representing [[Technical_Reference:Parameter_Definition\|parameter]] or [[Technical_Reference:State_Definition\|state definition lines]], respectively.

			===AutoConfig===
			Called during the [[Technical_Reference:States_of_Operation#Initialization_Phase\|system initialization phase]].
			In this event handler, the extension component is supposed to automatically configure itself according to sensible defaults, or hardware properties.
			Using the <tt>Parameter()</tt> function (see below), the event handler can write to all parameters defined during the <tt>Publish</tt> event.
			Only parameters set to "auto" will be modified, though. This way, the user can decide whether a certain parameter should be auto-configured or not.

	===Preflight===		===Preflight===
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	===Resting===		===Resting===
	Called while the system is suspended. Typically, <tt>Resting</tt> is called repeatedly inside source modules; in the remaining modules, <tt>Resting</tt> is called once when the system enters suspended state. Except that it is called at least once in suspended state, you should not make any assumption how often <tt>Resting</tt> is called.		Called while the system is suspended. Typically, <tt>Resting</tt> is called repeatedly inside source modules; in the remaining modules, <tt>Resting</tt> is called once when the system enters suspended state. Except that it is called at least once in suspended state, you should not make any assumption how often <tt>Resting</tt> is called.


	==Methods==		==Methods==

Mellinger: /* Instantiation */

2026-02-20T14:01:16Z

Instantiation

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	==Instantiation==		==Instantiation==
	<tt>EnvironmentExtension</tt> components may be used freely as members or ancestors of any other class in a BCI2000 module. When writing an extension component that is independent of existing classes, it may be instantiated from its own source code file by putting a		<tt>EnvironmentExtension</tt> components may be used freely as members or ancestors of any other class in a BCI2000 module. When writing an extension component that is independent of existing classes, it may be instantiated from its own source code file by putting a
	Extension( ClassName );		Extension(ClassName);
	statement at the top of that file.		statement at the top of that file.

			For <tt>EnvironmentExtension</tt> components that use command line parameters for enabling, the constructor should contain one <tt>PublishEnabler()</tt> call for each enabler parameter.
			For example, the Keylogger extension allows to log from keyboard, mouse, or both:
			Keylogger::Keylogger()
			{
			PublishEnabler("LogKeyboard");
			PublishEnabler("LogMouse");
			}
			These calls help the BCI2000Launcher program to identify extensions present in BCI2000 modules, and they tell it how to enable features provided by extensions.

	==See also==		==See also==

Mellinger: /* Publish */

2026-02-20T13:55:37Z

Publish

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	END_PARAMETER_DEFINITIONS		END_PARAMETER_DEFINITIONS

	~~BEGIN_EVENT_DEFINITIONS~~		BEGIN_STREAM_DEFINITIONS
	"MyState 1 0",		"MyState 1 0",
	... // any number of state definition lines may follow here		... // any number of stream state definition lines may follow here
	~~END_EVENT_DEFINITIONS~~		END_STREAM_DEFINITIONS

	BEGIN_EVENT_DEFINITIONS		BEGIN_EVENT_DEFINITIONS

Mellinger: /* Publish */

2026-02-18T15:36:27Z

Publish

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	END_PARAMETER_DEFINITIONS		END_PARAMETER_DEFINITIONS

	~~BEGIN_STATE_DEFINITIONS~~		BEGIN_EVENT_DEFINITIONS
	"MyState 1 0",		"MyState 1 0",
	... // any number of state definition lines may follow here		... // any number of state definition lines may follow here
	~~END_STATE_DEFINITIONS~~		END_EVENT_DEFINITIONS

	BEGIN_EVENT_DEFINITIONS		BEGIN_EVENT_DEFINITIONS

Mellinger: /* Location */

2026-02-18T15:35:59Z

Location

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	==Location==		==Location==
	<tt>~~BCI200~~/src/shared/accessors</tt>		<tt>BCI2000/src/shared/accessors</tt>

	==Synopsis==		==Synopsis==

Mellinger: /* Publish */

2022-08-12T14:28:17Z

Publish

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	BEGIN_STATE_DEFINITIONS		BEGIN_STATE_DEFINITIONS
	"",		"MyState 1 0",
	... // any number of state definition lines may follow here		... // any number of state definition lines may follow here
	END_STATE_DEFINITIONS		END_STATE_DEFINITIONS

			BEGIN_EVENT_DEFINITIONS
			"MyEvent 16 0",
			... // any number of event definition lines may follow here
			END_EVENT_DEFINITIONS
	</pre>		</pre>
	There, BEGIN/END macros enclose lists of comma-separated C strings representing [[Technical_Reference:Parameter_Definition\|parameter]] or [[Technical_Reference:State_Definition\|state definition lines]], respectively.		There, BEGIN/END macros enclose lists of comma-separated C strings representing [[Technical_Reference:Parameter_Definition\|parameter]] or [[Technical_Reference:State_Definition\|state definition lines]], respectively.

Mellinger: /* Synopsis */

2011-08-17T12:23:42Z

Synopsis

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	==Synopsis==		==Synopsis==
	The EnvironmentExtension class ~~is a base class~~ for BCI2000 components (''"extensions"'') that are not [[Programming Reference:GenericFilter Class\|filters]]. Such extensions do not process signals but still have access to [[BCI2000 Glossary#Parameter\|BCI2000 parameters]] and [[BCI2000 Glossary#State\|state variables]], and are notified of system events such as ''Preflight'', ''Initialize'', and ''StartRun''.		The EnvironmentExtension class defines an interface for BCI2000 components (''"extensions"'') that are not [[Programming Reference:GenericFilter Class\|filters]]. Such extensions do not process signals but still have access to [[BCI2000 Glossary#Parameter\|BCI2000 parameters]] and [[BCI2000 Glossary#State\|state variables]], and are notified of system events such as ''Preflight'', ''Initialize'', and ''StartRun''.

	Components that don't need to handle system events may inherit from the [[Programming Reference:Environment Class\|Environment class]] directly rather than indirectly via EnvironmentExtension.		Components that don't need to handle system events may inherit from the [[Programming Reference:Environment Class\|Environment class]] directly rather than indirectly via EnvironmentExtension.

Mellinger: /* Synopsis */

2011-08-17T12:20:28Z

Synopsis

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	==Synopsis==		==Synopsis==
	The EnvironmentExtension class is a base class for BCI2000 components (''"extensions"'') that are not [[Programming Reference:GenericFilter Class\|filters]]. Such extensions do not process signals but still have access to [[BCI2000 Glossary#Parameter\|BCI2000 parameters]] and [[BCI2000 Glossary#State\|state variables]], and are notified of system events such as ''Preflight'', ''Initialize'', and ''StartRun''.		The EnvironmentExtension class is a base class for BCI2000 components (''"extensions"'') that are not [[Programming Reference:GenericFilter Class\|filters]]. Such extensions do not process signals but still have access to [[BCI2000 Glossary#Parameter\|BCI2000 parameters]] and [[BCI2000 Glossary#State\|state variables]], and are notified of system events such as ''Preflight'', ''Initialize'', and ''StartRun''.

			Components that don't need to handle system events may inherit from the [[Programming Reference:Environment Class\|Environment class]] directly rather than indirectly via EnvironmentExtension.

	==Events==		==Events==

Mellinger: /* See also */

2008-09-08T16:12:53Z

Mellinger: /* StateRef State(string Name) */

2008-09-08T16:12:26Z

StateRef State(string Name)

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	===StateRef State(string Name)===		===StateRef State(string Name)===
	The <tt>State()</tt> method returns a reference to a state variable that may be used for reading and writing states. When there is no state variable with the specified name available in the system, an error message is displayed. For details, see [[Programming Reference:Error Handling#Accessing Environment Objects]].		The <tt>State()</tt> method returns a reference to a state variable that may be used for reading and writing states. When there is no state variable with the specified name available in the system, an error message is displayed. For details, see [[Programming Reference:Error Handling#Accessing Environment Objects\|Accessing Environment Objects]].

	===StateRef OptionalState(string Name)===		===StateRef OptionalState(string Name)===

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	==See also==		==See also==
	[[Programming Reference:GenericFilter Class]],[[Technical Reference:States of Operation]],[[Technical Reference:Parameter Definition]],[[Technical Reference:State Definition]],[[Programming Reference:Error Handling#Accessing Environment Objects]]		[[Programming Reference:GenericFilter Class]], [[Technical Reference:States of Operation]], [[Technical Reference:Parameter Definition]], [[Technical Reference:State Definition]], [[Programming Reference:Error Handling#Accessing Environment Objects]]

	[[Category:Development]][[Category:Framework API]]		[[Category:Development]][[Category:Framework API]]