Copy qualifier for subroutine parameters - Revision history

JAL at 22:49, 22 October 2013

2013-10-22T22:49:52Z

← Older revision		Revision as of 22:49, 22 October 2013
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	~~Leaving out the <var class="product">[[Janus SOAP User Language Interface\|Janus SOAP ULI]]</var>, there~~ are two types of parameters to ~~methods and~~ <var class="product">~~User Language~~</var> complex subroutines:		There are two types of parameters to <var class="product">SOUL</var> methods and complex subroutines:
	<ul>		<ul>
	<li>Input parameters		<li>Input parameters
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	directly sets <code>%common</code>.		directly sets <code>%common</code>.

	Unlike <var>Output</var> parameters, the <var>Input</var> parameters in ~~standard <var class="product">User Language</var>~~		Unlike <var>Output</var> parameters, the <var>Input</var> parameters in non-OO
	complex subroutines, and in method input parameters that are <var>Arrays</var>,		complex subroutines and in method input parameters that are <var>Arrays</var>
	are not allowed to be updated.		are not allowed to be updated.
	This is one of the two main problems with these <var>Input</var> parameters:		This is one of the two main problems with these <var>Input</var> parameters:
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	To circumvent these problems,		To circumvent these problems,
	~~the~~ <var class="product">~~Janus SOAP ULI~~</var> provides the '''Copy qualifier''' for complex subroutine and		<var class="product">SOUL</var> provides the '''Copy qualifier''' for complex subroutine and
	method array parameters.		method array parameters.
	The <var>Copy</var> qualifier indicates that:		The <var>Copy</var> qualifier indicates that:
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	The <var>Print</var> of <code>%message</code> would contain the called message without the time.		The <var>Print</var> of <code>%message</code> would contain the called message without the time.

	Implicitly, all <var class="product">~~Janus SOAP~~</var> non-array method input parameters are		Implicitly, all <var class="product">SOUL</var> non-array method input parameters are
	treated as if <var>Copy</var> were specified for them.		treated as if <var>Copy</var> were specified for them.
	This includes the input value for a property <var>Set</var> method:		This includes the input value for a property <var>Set</var> method:
	a copy is always made of the input value, and the input value		a copy is always made of the input value, and the input value
	variable may be updated inside the <var>Set</var> method.		variable may be updated inside the <var>Set</var> method.


	[[Category:User Language syntax enhancements]]		[[Category:User Language syntax enhancements]]

JALWiccan: 1 revision

2012-06-19T22:07:54Z

1 revision

← Older revision	Revision as of 22:07, 19 June 2012
(No difference)

JAL2 at 22:07, 19 June 2012

2012-06-19T22:07:45Z

← Older revision		Revision as of 22:07, 19 June 2012
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	Leaving out the <var class="product">[[Janus SOAP User Language Interface\|Janus SOAP ULI]]</var>, there are two types of parameters to methods and <var class="product>User Language</var> complex subroutines:		Leaving out the <var class="product">[[Janus SOAP User Language Interface\|Janus SOAP ULI]]</var>, there are two types of parameters to methods and <var class="product">User Language</var> complex subroutines:
	<ul>		<ul>
	<li>Input parameters		<li>Input parameters

JAL2 at 00:04, 7 September 2011

2011-09-07T00:04:43Z

← Older revision		Revision as of 00:04, 7 September 2011
Line 1:		Line 1:
	Leaving out the <var class="product">[[Janus SOAP User Language Interface\|Janus SOAP ULI]]</var>, there are two types of parameters to methods and complex subroutines:		Leaving out the <var class="product">[[Janus SOAP User Language Interface\|Janus SOAP ULI]]</var>, there are two types of parameters to methods and <var class="product>User Language</var> complex subroutines:
	<ul>		<ul>
	<li>Input parameters		<li>Input parameters

JAL2: Created page with "Leaving out the `Janus SOAP ULI`, there are two types of parameters to methods and complex subroutines:

I..."

2011-09-07T00:01:23Z

Created page with "Leaving out the <var class="product">Janus SOAP ULI</var>, there are two types of parameters to methods and complex subroutines: <ul> <li>I..."

New page

Leaving out the <var class="product">[[Janus SOAP User Language Interface|Janus SOAP ULI]]</var>, there are two types of parameters to methods and complex subroutines:
<ul>
<li>Input parameters
<li>Output parameters (also called <var>InOut</var>)
</ul>

The default parameter type is <var>Input</var>.

If <code>Output</code> is specified for a parameter,
references to the parameter in a method or
complex subroutine directly reference the corresponding parameter in
the <var>Call</var> statement.
As a result, changes to the output parameter are
immediately reflected in the <var>Call</var> variable, and vice versa.

For example, if a <var>Common</var> variable is passed to a <var class="product">User Language</var>
<var>Complex</var> subroutine,
all changes to the <var>Common</var> variable also affect the parameter:
%common is float common
...
%common = 7
call unusual(%common)
...
subroutine unusual(%parm is float output)
...
%common is float common
...
%common = 11
print %parm

In this example, when the indicated call is made to <code>Unusual</code>,
the subroutine would print <code>11</code>, because <code>%parm</code> is an
output parameter and thus a reference to the <var>Call</var> argument (<code>%common</code>).
As modifying the <var>Call</var> argument affects the output parameter, so does
modifying the output parameter affect the <var>Call</var> argument:
%common is float common
...
%common = 7
call unusual(%common)
...
subroutine unusual(%parm is float output)
...
%common is float common
...
%parm = 13
print %common

The print output here is <code>13</code>, because setting <code>%parm</code>
directly sets <code>%common</code>.

Unlike <var>Output</var> parameters, the <var>Input</var> parameters in standard <var class="product">User Language</var>
complex subroutines, and in method input parameters that are <var>Arrays</var>,
are not allowed to be updated.
This is one of the two main problems with these <var>Input</var> parameters:
<ol>
<li>It is often useful to be able to update an <var>Input</var> parameter as if
it were a local variable.
<li>Sometimes <var class="product">Model 204</var> passes <var>Input</var> parameters as references to the <var>Call</var>
argument.
This can cause strange behavior if the <var>Call</var> argument changes
(because the <var>Call</var> argument is a <var>Common</var> variable, for example).
</ol>

To circumvent these problems,
the <var class="product">Janus SOAP ULI</var> provides the '''Copy qualifier''' for complex subroutine and
method array parameters.
The <var>Copy</var> qualifier indicates that:
<ul>
<li>A copy of the input parameter is always made.
<li>The copy of the input parameter is updateable.
</ul>
The following example demonstrates a use of the <var>Copy</var> qualifier on a method
parameter:
subroutine log(%message is string len 255 copy)

%message = $time with ' ' with %message
%displayJournal(%message)

end subroutine
print %message


The <var>Print</var> of <code>%message</code> would contain the called message without the time.

Implicitly, all <var class="product">Janus SOAP</var> non-array method input parameters are
treated as if <var>Copy</var> were specified for them.
This includes the input value for a property <var>Set</var> method:
a copy is always made of the input value, and the input value
variable may be updated inside the <var>Set</var> method.

[[Category:User Language syntax enhancements]]

Copy qualifier for subroutine parameters - Revision history

JAL at 22:49, 22 October 2013

JALWiccan: 1 revision

JAL2 at 22:07, 19 June 2012

JAL2 at 00:04, 7 September 2011

JAL2: Created page with "Leaving out the Janus SOAP ULI, there are two types of parameters to methods and complex subroutines: I..."

JAL2: Created page with "Leaving out the `Janus SOAP ULI`, there are two types of parameters to methods and complex subroutines:

I..."