Language Reference/Terms/Try-catch-finally - Revision history

Thomas Linder Puls: subarticle

2013-02-12T09:39:05Z

subarticle

← Older revision		Revision as of 11:39, 12 February 2013
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	The <vp>Stmt</vp> is <vp>free</vp>'d also if <vp>fetch</vp> fails, or if something terminates with an exception.		The <vp>Stmt</vp> is <vp>free</vp>'d also if <vp>fetch</vp> fails, or if something terminates with an exception.
	}}		}}
	<noinclude>~~[[Category:Language Reference Subarticle]]~~</noinclude>		<noinclude>{{LanguageReferenceSubarticle\|Terms/Try-catch-finally}}</noinclude>

Thomas Linder Puls: line

2012-10-25T15:50:36Z

line

← Older revision		Revision as of 17:50, 25 October 2012
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	The <vp>Stmt</vp> is <vp>free</vp>'d also if <vp>fetch</vp> fails, or if something terminates with an exception.		The <vp>Stmt</vp> is <vp>free</vp>'d also if <vp>fetch</vp> fails, or if something terminates with an exception.
	}}		}}

	<noinclude>[[Category:Language Reference Subarticle]]</noinclude>		<noinclude>[[Category:Language Reference Subarticle]]</noinclude>

Thomas Linder Puls: Example Template

2008-11-05T09:51:31Z

Example Template

← Older revision		Revision as of 11:51, 5 November 2008
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	Notice, that no bindings are made by <vpbnf><Body></vpbnf> if it terminates with an exception.		Notice, that no bindings are made by <vpbnf><Body></vpbnf> if it terminates with an exception.

	~~'''~~Example~~'''~~ Handle the situation where a file cannot be read:		{{Example\| Handle the situation where a file cannot be read:

	<vip>clauses		<vip>clauses
Line 76:		Line 76:

	If it raises an exception the handler is evaluated with <vp>TraceId</vp> bound to the exception. So in this case a message is written to <vp>stdio</vp> and then the exception is dumped to <vp>stdio</vp>, and finally <vp>Contents</vp> is set to the empty string which is returned as result.		If it raises an exception the handler is evaluated with <vp>TraceId</vp> bound to the exception. So in this case a message is written to <vp>stdio</vp> and then the exception is dumped to <vp>stdio</vp>, and finally <vp>Contents</vp> is set to the empty string which is returned as result.
			}}

	==== try-finally ====		==== try-finally ====
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	* If <vpbnf><Body></vpbnf> terminates with an exception <vpbnf><Exn></vpbnf>: <vpbnf><Handler></vpbnf> is executed and the try-finally construction terminates with the exception <vpbnf><Exn></vpbnf>.		* If <vpbnf><Body></vpbnf> terminates with an exception <vpbnf><Exn></vpbnf>: <vpbnf><Handler></vpbnf> is executed and the try-finally construction terminates with the exception <vpbnf><Exn></vpbnf>.

	~~'''~~Example~~'''~~ Ensure that an <vp>odbcStatement</vp> is <vp>free</vp>'d after use:		{{Example\| Ensure that an <vp>odbcStatement</vp> is <vp>free</vp>'d after use:

	<vip>clauses		<vip>clauses
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	The <vp>Stmt</vp> is <vp>free</vp>'d also if <vp>fetch</vp> fails, or if something terminates with an exception.		The <vp>Stmt</vp> is <vp>free</vp>'d also if <vp>fetch</vp> fails, or if something terminates with an exception.
			}}

	<noinclude>[[Category:Language Reference Subarticle]]</noinclude>		<noinclude>[[Category:Language Reference Subarticle]]</noinclude>

Thomas Linder Puls: Categorized

2008-10-29T20:02:25Z

Categorized

← Older revision		Revision as of 22:02, 29 October 2008
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	The <vp>Stmt</vp> is <vp>free</vp>'d also if <vp>fetch</vp> fails, or if something terminates with an exception.		The <vp>Stmt</vp> is <vp>free</vp>'d also if <vp>fetch</vp> fails, or if something terminates with an exception.

			<noinclude>[[Category:Language Reference Subarticle]]</noinclude>

Thomas Linder Puls: /* try-finally */ spelling

2008-10-20T13:26:41Z

try-finally: spelling

← Older revision		Revision as of 15:26, 20 October 2008
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	* If <vpbnf><Body></vpbnf> terminates with an exception <vpbnf><Exn></vpbnf>: <vpbnf><Handler></vpbnf> is executed and the try-finally construction terminates with the exception <vpbnf><Exn></vpbnf>.		* If <vpbnf><Body></vpbnf> terminates with an exception <vpbnf><Exn></vpbnf>: <vpbnf><Handler></vpbnf> is executed and the try-finally construction terminates with the exception <vpbnf><Exn></vpbnf>.

	'''Example''' Ensure that an <vp>odbcStatement</vp> is <vp>free</vp>'ed after use:		'''Example''' Ensure that an <vp>odbcStatement</vp> is <vp>free</vp>'d after use:

	<vip>clauses		<vip>clauses
Line 111:		Line 111:
	end try.</vip>		end try.</vip>

	The <vp>Stmt</vp> is <vp>free</vp>'ed also if <vp>fetch</vp> fails, or if something terminates with an exception.		The <vp>Stmt</vp> is <vp>free</vp>'d also if <vp>fetch</vp> fails, or if something terminates with an exception.

Thomas Linder Puls: /* try-finally */ example

2008-10-20T13:25:34Z

try-finally: example

@@ Line 87: / Line 87: @@
 end try</vipbnf>
-The purpose of the construction is to evaluate the <vpbnf><Handler></vpbnf> after the <vpbnf><Body></vpbnf> no matter how the <vpbnf><Body></vpbnf> terminates, i.e. whether it succeeds, fails or terminates with an exception (it cannot leave backtrackpoints).
+The purpose of the construction is to evaluate the <vpbnf><Handler></vpbnf> after the <vpbnf><Body></vpbnf> no matter how the <vpbnf><Body></vpbnf> terminates, i.e. whether it succeeds, fails or terminates with an exception (it cannot leave backtrack points).
 The evaluation is like this
@@ Line 96: / Line 96: @@
 * If <vpbnf><Body></vpbnf> fails: <vpbnf><Handler></vpbnf> is executed and the try-finally construction fails.
 * If <vpbnf><Body></vpbnf> terminates with an exception <vpbnf><Exn></vpbnf>: <vpbnf><Handler></vpbnf> is executed and the try-finally construction terminates with the exception <vpbnf><Exn></vpbnf>.

Thomas Linder Puls: /* try-finally */ description

2008-10-20T13:06:51Z

try-finally: description

← Older revision		Revision as of 15:06, 20 October 2008
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	==== try-finally ====		==== try-finally ====

			Consider the try-finally construction:

			<vipbnf>try
			<Body>
			finally
			<Handler>
			end try</vipbnf>

			The purpose of the construction is to evaluate the <vpbnf><Handler></vpbnf> after the <vpbnf><Body></vpbnf> no matter how the <vpbnf><Body></vpbnf> terminates, i.e. whether it succeeds, fails or terminates with an exception (it cannot leave backtrackpoints).

			The evaluation is like this

			First <vpbnf><Body></vpbnf> is evaluated.

			* If <vpbnf><Body></vpbnf> succeeds: <vpbnf><Handler></vpbnf> is executed and the try-finally construction succeeds.
			* If <vpbnf><Body></vpbnf> fails: <vpbnf><Handler></vpbnf> is executed and the try-finally construction fails.
			* If <vpbnf><Body></vpbnf> terminates with an exception <vpbnf><Exn></vpbnf>: <vpbnf><Handler></vpbnf> is executed and the try-finally construction terminates with the exception <vpbnf><Exn></vpbnf>.

Thomas Linder Puls: spelling

2008-10-20T12:47:01Z

spelling

← Older revision		Revision as of 14:47, 20 October 2008
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	The <vpbnf><Term></vpbnf> and the handlers are not allowed to leave backtrack points (i.e. they cannot have mode <vp>multi</vp> or <vp>nondeterm</vp>).		The <vpbnf><Term></vpbnf> and the handlers are not allowed to leave backtrack points (i.e. they cannot have mode <vp>multi</vp> or <vp>nondeterm</vp>).

	A try-construction with more than one handler is ~~equivivalent~~ to nesting several try-constructions with one handler each. I.e. the following term:		A try-construction with more than one handler is equivalent to nesting several try-constructions with one handler each. I.e. the following term:

	<vipbnf>try		<vipbnf>try
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	First <vpbnf><Body></vpbnf> is evaluated.		First <vpbnf><Body></vpbnf> is evaluated.

	If <vpbnf><Body></vpbnf> fails or ~~succeds~~ the whole try construction fails or succeeds, respectively. I.e. if <vpbnf><Body></vpbnf> does not terminate with an exception the try construction ~~correcponds~~ to evaluating <vpbnf><Body></vpbnf>.		If <vpbnf><Body></vpbnf> fails or succeeds the whole try construction fails or succeeds, respectively. I.e. if <vpbnf><Body></vpbnf> does not terminate with an exception the try construction corresponds to evaluating <vpbnf><Body></vpbnf>.

	If <vpbnf><Body></vpbnf> terminates with an exception, then the exception is caught by the catch handler. Meaning that first <vpbnf><Var></vpbnf> is bound to the exception (in PFC context the exception will be a <vp>traceId</vp>) and then <vpbnf><Handler></vpbnf> is evaluated. In this case the construction behaves as if <vpbnf><Handler></vpbnf> is evaluated with <vpbnf><Var></vpbnf> bound to the caught exception.		If <vpbnf><Body></vpbnf> terminates with an exception, then the exception is caught by the catch handler. Meaning that first <vpbnf><Var></vpbnf> is bound to the exception (in PFC context the exception will be a <vp>traceId</vp>) and then <vpbnf><Handler></vpbnf> is evaluated. In this case the construction behaves as if <vpbnf><Handler></vpbnf> is evaluated with <vpbnf><Var></vpbnf> bound to the caught exception.

Thomas Linder Puls: update

2008-10-20T12:46:04Z

update

@@ Line 1: / Line 1: @@
-The try-catch-finally statement provides a way to handle possible errors that may occur in a given block of code.
+The try-catch-finally statement provides means for dealing with exceptions that may occur in a given block of code.
 <vipbnf><TryCatchTerm>:
@@ Line 11: / Line 11: @@
      <Term></vipbnf>
-The following two terms are equivalent:
+A try-construction thus have a <vpbnf>Term</vpbnf> and a list of catch and finally handlers.
 <vipbnf>try
     <Body>
-catch <Var> do
+catch <Var1> do
     <Handler1>
 finally
     <Handler2>
 end try</vipbnf>
 <vipbnf>try
-   try
+    try
-       <Body>
+        try
-   catch <Var> do
+            <Body>
-       <Handler1>
+        catch <Var1> do
-   end try
+            <Handler1>
-finally
+        end try
-   <Handler2>
+    finally
 end try</vipbnf>

Thomas Linder Puls: 1 revision(s)

2008-09-15T14:22:23Z

1 revision(s)

← Older revision	Revision as of 16:22, 15 September 2008
(No difference)