Guard - Revision history

163.1.231.194: reverted edit -- "DeepFrozen" is preferable to "Deep Frozen" since the former matches the name used in the language

2008-09-18T07:56:50Z

reverted edit -- "DeepFrozen" is preferable to "Deep Frozen" since the former matches the name used in the language

New page

A Guard will either coerce an input to a value that matches some condition, or it will fail.

A Guard is used in the E language to guard the definition of a variable or the return value of a method. Implementors of Guard should always override __printOn/1 to print a guard expression reflecting the guard's value.

It is planned but not yet implemented that all objects used as guards must be [[DeepFrozen]].

==Protocol==

{{instance msgdoc|coerce|2|<var>specimen</var>, <var>optEjector</var> :[[nullOk]]<nowiki>[</nowiki>[[OneArgFunc]]]|[[any]]}}

If <var>specimen</var> coerces to a reference that matches the condition represented by this guard, return that reference; otherwise fail (according to <var>[[optEjector]]</var>) with a [[problem]] explaining why not.

If optEjector is [[null]], then [[throw]] the problem. Otherwise, call optEjector with the problem. optEjector should perform a non-local exit, and so should not return. If optEjector returns anyway, then throw the problem after all.

(See also: the [[non-optional ejectors]] proposal.)

{{instance msgdoc|rangeSupersetOf|1|<var>other</var> :[[Guard]]|[[nullOk]]<nowiki>[</nowiki>[[Boolean]]]}}

Experimental. See [[guard-based auditing]].

[[Category:Protocols]]
[[Category:ELib specification]]

Zarutian: fixing it a bit better (replaced the underscore with an space)

2008-09-18T00:13:27Z

fixing it a bit better (replaced the underscore with an space)

←Older revision		Revision as of 00:13, 18 September 2008
Line 3:		Line 3:
	A Guard is used in the E language to guard the definition of a variable or the return value of a method. Implementors of Guard should always override __printOn/1 to print a guard expression reflecting the guard's value.		A Guard is used in the E language to guard the definition of a variable or the return value of a method. Implementors of Guard should always override __printOn/1 to print a guard expression reflecting the guard's value.

-	It is planned but not yet implemented that all objects used as guards must be [[~~Deep_Frozen~~]].	+	It is planned but not yet implemented that all objects used as guards must be [[Deep Frozen]].

	==Protocol==		==Protocol==

Zarutian: fixing an link

2008-09-18T00:12:27Z

fixing an link

←Older revision		Revision as of 00:12, 18 September 2008
Line 3:		Line 3:
	A Guard is used in the E language to guard the definition of a variable or the return value of a method. Implementors of Guard should always override __printOn/1 to print a guard expression reflecting the guard's value.		A Guard is used in the E language to guard the definition of a variable or the return value of a method. Implementors of Guard should always override __printOn/1 to print a guard expression reflecting the guard's value.

-	It is planned but not yet implemented that all objects used as guards must be [[~~DeepFrozen~~]].	+	It is planned but not yet implemented that all objects used as guards must be [[Deep_Frozen]].

	==Protocol==		==Protocol==

Kevin Reid: use instance msgdoc template

2008-07-02T02:22:20Z

use instance msgdoc template

←Older revision		Revision as of 02:22, 2 July 2008
Line 7:		Line 7:
	==Protocol==		==Protocol==

-	~~===~~coerce/2~~===~~	+	{{instance msgdoc\|coerce\|2\|<var>specimen</var>, <var>optEjector</var> :[[nullOk]]<nowiki>[</nowiki>[[OneArgFunc]]]\|[[any]]}}
-	~~to coerce(~~<var>specimen</var>, <var>optEjector</var> :[[nullOk]]<nowiki>[</nowiki>[[OneArgFunc]]]~~) :~~[[any]]	+

	If <var>specimen</var> coerces to a reference that matches the condition represented by this guard, return that reference; otherwise fail (according to <var>[[optEjector]]</var>) with a [[problem]] explaining why not.		If <var>specimen</var> coerces to a reference that matches the condition represented by this guard, return that reference; otherwise fail (according to <var>[[optEjector]]</var>) with a [[problem]] explaining why not.
Line 16:		Line 15:
	(See also: the [[non-optional ejectors]] proposal.)		(See also: the [[non-optional ejectors]] proposal.)

-	~~===~~rangeSupersetOf/1~~===~~	+	{{instance msgdoc\|rangeSupersetOf\|1\|<var>other</var> :[[Guard]]\|[[nullOk]]<nowiki>[</nowiki>[[Boolean]]]}}
-		+
-	~~to rangeSupersetOf(~~<var>other</var> :[[Guard]]~~) :~~[[nullOk]]<nowiki>[</nowiki>[[Boolean]]]	+

	Experimental. See [[guard-based auditing]].		Experimental. See [[guard-based auditing]].

Kevin Reid: copy in documentation from Guard.java in E-on-Java with permission

2008-06-20T19:02:04Z

copy in documentation from Guard.java in E-on-Java with permission

←Older revision		Revision as of 19:02, 20 June 2008
Line 1:		Line 1:
-	~~XXX explain what~~ a Guard is	+	A Guard will either coerce an input to a value that matches some condition, or it will fail.
		+
		+	A Guard is used in the E language to guard the definition of a variable or the return value of a method. Implementors of Guard should always override __printOn/1 to print a guard expression reflecting the guard's value.
		+
		+	It is planned but not yet implemented that all objects used as guards must be [[DeepFrozen]].

	==Protocol==		==Protocol==

	===coerce/2===		===coerce/2===
-	to coerce(<var>specimen</var>, <var>~~ejector~~</var> :[[OneArgFunc]]) :[[any]]	+	to coerce(<var>specimen</var>, <var>optEjector</var> :[[nullOk]]<nowiki>[</nowiki>[[OneArgFunc]]]) :[[any]]
		+
		+	If <var>specimen</var> coerces to a reference that matches the condition represented by this guard, return that reference; otherwise fail (according to <var>[[optEjector]]</var>) with a [[problem]] explaining why not.
		+
		+	If optEjector is [[null]], then [[throw]] the problem. Otherwise, call optEjector with the problem. optEjector should perform a non-local exit, and so should not return. If optEjector returns anyway, then throw the problem after all.

-	~~{{unspecified message}}~~	+	(See also: the [[non-optional ejectors]] proposal.)

	===rangeSupersetOf/1===		===rangeSupersetOf/1===

-	to rangeSupersetOf(<var>other</var> :[[Guard]]) :[[~~nullOK~~]][[[Boolean]]]	+	to rangeSupersetOf(<var>other</var> :[[Guard]]) :[[nullOk]]<nowiki>[</nowiki>[[Boolean]]]

	Experimental. See [[guard-based auditing]].		Experimental. See [[guard-based auditing]].

Kevin Reid at 18:56, 20 June 2008

2008-06-20T18:56:48Z

←Older revision		Revision as of 18:56, 20 June 2008
Line 1:		Line 1:
-	~~A Guard will either coerce an input to~~ a ~~value that matches some condition, or it will fail.~~	+	XXX explain what a Guard is
-		+
-	A Guard is used in the E language to guard the definition of a variable or the return value of a method. Implementors of Guard should always override __printOn/1 to print a guard expression reflecting the guard's value.	+
-		+
-	~~It is planned but not yet implemented that all objects used as guards must be [[DeepFrozen]].~~	+

	==Protocol==		==Protocol==

-	~~{{instance msgdoc\|~~coerce\|2\|<var>specimen</var>, <var>~~optEjector~~</var> :~~[[nullOk]]<nowiki>[</nowiki>~~[[OneArgFunc]]]\|[[any]]}}	+	===coerce/2===
-		+	to coerce(<var>specimen</var>, <var>ejector</var> :[[OneArgFunc]]) :[[any]]
-	If <var>specimen</var> coerces to a reference that matches the condition represented by this guard, return that reference; otherwise fail (according to <var>[[optEjector]]</var>) with a [[problem]] explaining why not.	+

-	If optEjector is [[null]], then [[throw]] the problem. Otherwise, call optEjector with the problem. optEjector should perform a non-local exit, and so should not return. If optEjector returns anyway, then throw the problem after all.	+	{{unspecified message}}

-	~~(See also: the [[non-optional ejectors]] proposal.)~~	+	===rangeSupersetOf/1===

-	~~{{instance msgdoc\|~~rangeSupersetOf~~\|1\|~~<var>other</var> :[[Guard]]\|[[~~nullOk~~]]~~<nowiki>~~[~~</nowiki>~~[[Boolean]]]}}	+	to rangeSupersetOf(<var>other</var> :[[Guard]]) :[[nullOK]][[[Boolean]]]

	Experimental. See [[guard-based auditing]].		Experimental. See [[guard-based auditing]].