Exceptions - Revision history

Dme: /* Rethrow */

2020-03-23T21:58:53Z

Rethrow

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	===<b id="Rethrow statement"></b>Rethrow===		===<b id="Rethrow statement"></b>Rethrow===
			====Syntax====
			{{template:Rethrow statement syntax}}
			====Description====
	<var class="product">Sirius Mods</var> 8.1 introduced the <var>Rethrow</var> clause in a <var>Try</var> block. <var>Rethrow</var> lets you propagate an exception without having to assign it to a local variable, probably eliminating the need to declare a local exception class object for the sole purpose of propagating an exception.		<var class="product">Sirius Mods</var> 8.1 introduced the <var>Rethrow</var> clause in a <var>Try</var> block. <var>Rethrow</var> lets you propagate an exception without having to assign it to a local variable, probably eliminating the need to declare a local exception class object for the sole purpose of propagating an exception.

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	<li>The class or classes specified on a <var>Rethrow</var> clause must be declared as being thrown by that method.		<li>The class or classes specified on a <var>Rethrow</var> clause must be declared as being thrown by that method.
	</ul>		</ul>
			====Example====
	The following local subroutine illustrates a <var>Rethrow</var> of an <var>InvalidHexdata</var> exception. This subroutine sends a string converted from hex to binary on a socket.		The following local subroutine illustrates a <var>Rethrow</var> of an <var>InvalidHexdata</var> exception. This subroutine sends a string converted from hex to binary on a socket.
	<p class="code">local subroutine (socket):sendHex(%hexdata is longstring) throws invalidHexData		<p class="code">local subroutine (socket):sendHex(%hexdata is longstring) throws invalidHexData
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	end subroutine		end subroutine
	</p>		</p>
			<!--SOUL.DME.290.QA is an example. It differs from the above
			example. My feeling is that it would be a better doc example,
			although it should be simplified & just do a single (failing)
			invocation of the local function (i.e., remove the For loop).
			It's a bit more complete in that it shows the caller handling
			the exception (strictly speaking, the reader should understand
			this, but I think it's nice to be explicit). Also, I think the
			HexToString method is nice because it's so simple and the user
			could clip and play with it, without the "baggage" of Sockets.
			Dave Evans, 23 March 2020.
			-->

	===Mutiple classes on a Catch or Rethrow statement===		===Mutiple classes on a Catch or Rethrow statement===

Dme: /* Rethrow */

2020-03-23T21:42:59Z

Rethrow

← Older revision		Revision as of 21:42, 23 March 2020
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	Presumably, this block would be useful in diagnosing the problem or even correcting it.		Presumably, this block would be useful in diagnosing the problem or even correcting it.

	===Rethrow===		===<b id="Rethrow statement"></b>Rethrow===
	<var class="product">Sirius Mods</var> 8.1 introduced the <var>Rethrow</var> clause in a <var>Try</var> block. <var>Rethrow</var> lets you propagate an exception without having to assign it to a local variable, probably eliminating the need to declare a local exception class object for the sole purpose of propagating an exception.		<var class="product">Sirius Mods</var> 8.1 introduced the <var>Rethrow</var> clause in a <var>Try</var> block. <var>Rethrow</var> lets you propagate an exception without having to assign it to a local variable, probably eliminating the need to declare a local exception class object for the sole purpose of propagating an exception.

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	end subroutine		end subroutine
	</p>		</p>

	===Mutiple classes on a Catch or Rethrow statement===		===Mutiple classes on a Catch or Rethrow statement===
	<var class="product">Sirius Mods</var> 8.0 introduced the ability to specify multiple exception classes on a single <var>Catch</var> statement. The class names are separated from each other by the <var>And</var> keyword. However, in <var class="product">Sirius Mods</var> 8.0, no <var>To</var> clause could be specified on a <var>Catch</var> statement with multiple classes.		<var class="product">Sirius Mods</var> 8.0 introduced the ability to specify multiple exception classes on a single <var>Catch</var> statement. The class names are separated from each other by the <var>And</var> keyword. However, in <var class="product">Sirius Mods</var> 8.0, no <var>To</var> clause could be specified on a <var>Catch</var> statement with multiple classes.

Dme: /* Exception class definitions */

2017-06-03T17:07:52Z

Exception class definitions

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	can have variables, methods, and the same <var>Allow</var> and <var>Disallow</var> rules		can have variables, methods, and the same <var>Allow</var> and <var>Disallow</var> rules
	as any other class.		as any other class.
	<li>There can be system exception classes,		<li>There can be [[List of system exception classes\|system exception classes]],
	which are provided as part of the <var class="product">Model 204</var> installation, and there can be		which are provided as part of the <var class="product">Model 204</var> installation, and there can be
	exception classes which are defined and maintained by <var class="product">SOUL</var> code.		exception classes which are defined and maintained by <var class="product">SOUL</var> code.
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	For links to the descriptions of the individual system exception classes, see the		For links to the descriptions of the individual system exception classes, see the
	[[Lists of classes and methods#except\|"Lists of classes and methods"]].		[[Lists of classes and methods#except\|"Lists of classes and methods"]].

	==Throwing exceptions==		==Throwing exceptions==
	When an error situation occurs, the code that detects the situation can do		When an error situation occurs, the code that detects the situation can do

JAL: /* Try block syntax */

2014-09-23T22:19:46Z

Try block syntax

← Older revision		Revision as of 22:19, 23 September 2014
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	===Try block syntax===		===Try block syntax===
	<p class="syntax">		<p class="syntax"><span class="literal">Try</span>
	<span class="literal">Try</span>
	<span class="term">tStmt1</span> ; * Exceptions can		<span class="term">tStmt1</span> ; * Exceptions can
	<span class="squareb">[</span> <span class="term">tStmt2</span> <span class="squareb">]</span> ; * be caught in		<span class="squareb">[</span> <span class="term">tStmt2</span> <span class="squareb">]</span> ; * be caught in
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	<span class="squareb">]</span>		<span class="squareb">]</span>

	<span class="literal">End Try</span>		<span class="literal">End Try</span>

	</p>		</p>

	====Syntax terms====		====Syntax terms====

	The <var>Try</var> block is divided into two or more sections, which are separated by		The <var>Try</var> block is divided into two or more sections, which are separated by
	<var>[[#Rethrow\|Rethrow]]</var>, <var>Catch</var>, and <var>[[#Success blocks\|Success]]</var> statements. Multiple		<var>[[#Rethrow\|Rethrow]]</var>, <var>Catch</var>, and <var>[[#Success blocks\|Success]]</var> statements. Multiple
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	There must be either one <var>Rethrow</var> or <var>Catch</var> statement in a <var>Try</var> block.		There must be either one <var>Rethrow</var> or <var>Catch</var> statement in a <var>Try</var> block.

	<table ~~class="syntaxTable"~~>		<table>

	<tr><th>tStmt1 [tStmt2...]</th>		<tr><th>tStmt1 [tStmt2...]</th>
	<td>The first section in the <var>Try</var> block must contain one or more <var class="product">SOUL</var> statements. These statements are executed in turn, and if an exception is thrown within them, execution resumes at the <var>Rethrow</var> or <var>Catch</var> statement specifying that exception; if there are none, the request is cancelled. If no exceptions are thrown, execution resumes with the <var>Success</var> block statements, if any, and then after the <var>End Try</var> statement.</td></tr>		<td>The first section in the <var>Try</var> block must contain one or more <var class="product">SOUL</var> statements. These statements are executed in turn, and if an exception is thrown within them, execution resumes at the <var>Rethrow</var> or <var>Catch</var> statement specifying that exception; if there are none, the request is cancelled. If no exceptions are thrown, execution resumes with the <var>Success</var> block statements, if any, and then after the <var>End Try</var> statement.</td></tr>

	<tr><th><var>Rethrow</var> rethClassA ...</th>		<tr><th nowrap><var>Rethrow</var> rethClassA ...</th>
	<td>The <var>Rethrow</var> <b>statement</b> (not block) specifies one or more exception classes; if one of them is thrown, then the method containing the <var>Try</var> block throws that exception. Hence a <var>Rethrow</var> statement can only occur within a method which declares all of the <var class="term">rethClass</var> exceptions in its <var>Throws</var> clause.		<td>The <var>Rethrow</var> <b>statement</b> (not block) specifies one or more exception classes; if one of them is thrown, then the method containing the <var>Try</var> block throws that exception. Hence a <var>Rethrow</var> statement can only occur within a method which declares all of the <var class="term">rethClass</var> exceptions in its <var>Throws</var> clause.
	<p></p>		<p></p>
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	<tr><th><var>Success</var></th>		<tr><th><var>Success</var></th>
	<td>If no exceptions are thrown in the <var class="term">tStmt</var> statements, the (optional) <var class="term">sStmt</var> statements in the <var>Success</var> block are executed in turn, and then execution resumes after the <var>End Try</var> statement.</td></tr>		<td>If no exceptions are thrown in the <var class="term">tStmt</var> statements, the (optional) <var class="term">sStmt</var> statements in the <var>Success</var> block are executed in turn, and then execution resumes after the <var>End Try</var> statement.</td></tr>

	</table>		</table>

	===Try block considerations===		===Try block considerations===
	A <var>Try</var> block can contain more than one statement:		A <var>Try</var> block can contain more than one statement:

JAL: /* Background */

2014-07-02T20:03:59Z

Background

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	program at the earliest point that the error was detected so that		program at the earliest point that the error was detected so that
	the program does not do damage because of the error.		the program does not do damage because of the error.
	In addition, if <var class="product">[~~http://sirius-software.com/maint/download/factr.pdf~~ SirFact]</var> is being used, the request cancelling error		In addition, if <var class="product">[[SirFact]]</var> is being used, the request cancelling error
	will produce a <var class="product">SirFact</var> dump at the time the error was first detected		will produce a <var class="product">SirFact</var> dump at the time the error was first detected
	(or at the very least, indicate the procedure and line number where the error was first detected).		(or at the very least, indicate the procedure and line number where the error was first detected).
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	</ul>		</ul>

	~~<var class="product">Sirius Mods</var> 7.2 introduced an~~ alternative to output parameters to handle unusual		An alternative to output parameters to handle unusual
	cases in method calls.		cases in method calls is called '''exception handling'''.
	~~This alternative~~ is called '''exception handling'''.

	==Errors unsuitable for exception handling==		==Errors unsuitable for exception handling==
	Exception handling consists of three parts:		Exception handling consists of three parts:

Dme at 15:18, 18 October 2013

2013-10-18T15:18:15Z

Show changes

JALWiccan: Automatically generated page update

2013-10-14T20:05:23Z

Automatically generated page update

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	exception class or any of its base classes.		exception class or any of its base classes.

	[[Category:~~Janus SOAP ULI~~ topics]]		[[Category:SOUL object-oriented programming topics]]

Dme: /* Try block syntax */

2013-10-13T03:22:01Z

Try block syntax

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	<td>The <var>Rethrow</var> <b>statement</b> (not block) specifies one or more exception classes; if one of them is thrown, then the method containing the <var>Try</var> block throws that exception. Hence a <var>Rethrow</var> statement can only occur within a method which declares all of the <var class="term">rethClass</var> exceptions in its <var>Throws</var> clause.		<td>The <var>Rethrow</var> <b>statement</b> (not block) specifies one or more exception classes; if one of them is thrown, then the method containing the <var>Try</var> block throws that exception. Hence a <var>Rethrow</var> statement can only occur within a method which declares all of the <var class="term">rethClass</var> exceptions in its <var>Throws</var> clause.
	<p></p>		<p></p>
	Each <var class="term">rethClass</var> ~~must~~ be ~~different from all~~ of the ~~other exception classes specified~~ on ~~any~~ <var>Rethrow</var> and <var>Catch</var> ~~statement~~ in the <var>Try</var> block.</td></tr>		Each <var class="term">rethClass</var> may not be the same as, nor an extension of, any exception class preceding it on the statement or on preceding <var>Rethrow</var> and <var>Catch</var> statements in the <var>Try</var> block.</td></tr>

	<tr><th><var>Catch</var> catClassC ...</th>		<tr><th><var>Catch</var> catClassC ...</th>
	<td>The <var>Catch</var> statement specifies one or more exception classes; if one of them is thrown, then the (optional) <var class="term">cStmt</var> statements in the <var>Catch</var> block are executed in turn, and then execution resumes after the <var>End Try</var> statement.		<td>The <var>Catch</var> statement specifies one or more exception classes; if one of them is thrown, then the (optional) <var class="term">cStmt</var> statements in the <var>Catch</var> block are executed in turn, and then execution resumes after the <var>End Try</var> statement.
	<p></p>		<p></p>
	Each <var class="term">catClass</var> ~~must~~ be ~~different from all~~ of the ~~other exception classes specified~~ on ~~any~~ <var>Rethrow</var> and <var>Catch</var> ~~statement~~ in the <var>Try</var> block.</td></tr>		Each <var class="term">catClass</var> may not be the same as, nor an extension of, any exception class preceding it on the statement or on preceding <var>Rethrow</var> and <var>Catch</var> statements in the <var>Try</var> block.</td></tr>

	<tr><th><var>Success</var></th>		<tr><th><var>Success</var></th>

Dme: /* Try block syntax */

2013-10-13T02:33:40Z

Try block syntax

← Older revision		Revision as of 02:33, 13 October 2013
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	The <var>Try</var> block is divided into two or more sections, which are separated by		The <var>Try</var> block is divided into two or more sections, which are separated by
	<var>[[#Rethrow\|Rethrow]]</var>, <var>Catch</var>, and <var>[[#Success\|Success]]</var> statements. Multiple		<var>[[#Rethrow\|Rethrow]]</var>, <var>Catch</var>, and <var>[[#Success blocks\|Success]]</var> statements. Multiple
	<var>Rethrow</var> and <var>Catch</var> statements can be mixed		<var>Rethrow</var> and <var>Catch</var> statements can be mixed
	with each other and with the <var>Success</var> statement, in any order.		with each other and with the <var>Success</var> statement, in any order.

Dme: /* Try block syntax */

2013-10-13T02:31:54Z

Try block syntax

← Older revision		Revision as of 02:31, 13 October 2013
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	The <var>Try</var> block is divided into two or more sections, which are separated by		The <var>Try</var> block is divided into two or more sections, which are separated by
	<var>Rethrow</var>, <var>Catch</var>, and <var>Success</var> statements. Multiple		<var>[[#Rethrow\|Rethrow]]</var>, <var>Catch</var>, and <var>[[#Success\|Success]]</var> statements. Multiple
	<var>Rethrow</var> and <var>Catch</var> statements can be mixed		<var>Rethrow</var> and <var>Catch</var> statements can be mixed
	with each other and with the <var>Success</var> statement, in any order.		with each other and with the <var>Success</var> statement, in any order.