$ListAdj: Difference between revisions
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{{DISPLAYTITLE:$ListAdj}} | {{DISPLAYTITLE:$ListAdj}} | ||
<span class="pageSubtitle" | <span class="pageSubtitle">Adjust length of $list item</span> | ||
<p class=" | <p class="warn"><b>Note: </b>Many $functions have been deprecated in favor of Object Oriented methods. There is no OO equivalent for the $ListAdj function as the Stringlist replacement for $lists are natively longstring capable.</p> | ||
This function adjusts the length of a $list item. Generally, this $list would have been created with the [[$ListNew]] function. | This function adjusts the length of a $list item. Generally, this $list would have been created with the [[$ListNew]] function. | ||
The $ListAdj function accepts three arguments and returns a numeric result. It is a | The <var>$ListAdj</var> function accepts three arguments and returns a numeric result. It is a [[Calling Sirius Mods $functions|callable]] $function. | ||
The first argument is a $list identifier. This is a required argument. | The first argument is a $list identifier. This is a required argument. | ||
| Line 12: | Line 12: | ||
The second argument is a $list item number. This is a required argument. | The second argument is a $list item number. This is a required argument. | ||
The third argument is a number that indicates the new length of the $list item. This is a required argument. Its minimum valid value is 0; the maximum value is 6124 under | The third argument is a number that indicates the new length of the $list item. This is a required argument. Its minimum valid value is 0; the maximum value is 6124 under <var class="product">[[Sirius Mods]]</var> Version 6.5 and earlier, and it is 2**31-1 under <var class="product">[[Sirius Mods]]</var> Version 6.6 and later. If this value is smaller than the current length of the $list item, the $list item is truncated. If this value is larger than the current length of the $list item, the $list item is padded with blanks to the indicated length. | ||
==Syntax== | ==Syntax== | ||
<p class="syntax" | <p class="syntax">[%RESULT =] $ListAdj(list_identifier, itemnum, length) | ||
</p> | </p> | ||
<p class="code"> | <p><var class="term">%result</var> is set to 0 if the new item length is the same as the old item length, 1 if it is less, 2 if it is greater, or a negative number if an error has occurred.</p> | ||
===Error codes=== | |||
<p class="code">-3 - No room to add item | |||
(if LISTFC <var>$SirParm</var> parameter not set) | |||
All other errors cause request cancellation | |||
</p> | </p> | ||
==Usage notes== | |||
<ul> | |||
<li><var>$ListAdj</var> is extremely efficient if the $list item size is not being changed (return value for <var>$ListAdj</var> of 0), fairly efficient when a $list item is being shortened (return value of 1) and can be fairly expensive when a $list item is being lengthened (return value of 2). The latter case can be expensive because such a <var>$ListAdj</var> can result in the splitting of a $list leaf page. Once a leaf page is split, it will not be merged back together, even if subsequent $LISTREMs (or $LISTADJs) makes this possible. | |||
<p> | |||
Because split leaf pages remain split, heavy use of $LISADJ calls that increase $list item size (and <var>$ListIns</var> and $ListRem) can result in "sparse&CQ. $lists which place an unnecessary burden on the buffer pool and CCATEMP. It can also result in an inability to add an item to the end of the $list (via $ListAdd) because of a full pointer page, even though the $list is nowhere near the theoretical capacity for a $list. $List compression can be done using the <var>[[$List_Copy_Items]]</var> function. </p> | |||
</ul> | |||
The following example illustrates how $ListAdj can be used to add an asterisk to the end of a $list item: | ==Example== | ||
The following example illustrates how <var>$ListAdj</var> can be used to add an asterisk to the end of a $list item: | |||
<p class="code"> %LEN = $ListILn(%LIST, %NUM) | <p class="code">%LEN = $ListILn(%LIST, %NUM) | ||
%RC = $ListAdj(%LIST, %NUM, %LEN + 1) | |||
%RC = $ListOvl(%LIST, %NUM, %LEN + 1, '*') | |||
</p> | </p> | ||
==Products authorizing {{PAGENAMEE}}== | |||
<ul class="smallAndTightList"> | <ul class="smallAndTightList"> | ||
<li>[[Sirius functions]]</li> | <li>[[List of $functions|Sirius functions]]</li> | ||
<li>[[Fast/Unload User Language Interface]]</li> | <li>[[Fast/Unload User Language Interface]]</li> | ||
<li>[[Janus Open Client]]</li> | <li>[[Media:JoclrNew.pdf|Janus Open Client]]</li> | ||
<li>[[Janus Open Server]]</li> | <li>[[Media:JosrvrNew.pdf|Janus Open Server]]</li> | ||
<li>[[Janus Sockets]]</li> | <li>[[Janus Sockets]]</li> | ||
<li>[[Janus Web Server]]</li> | <li>[[Janus Web Server]]</li> | ||
<li> | <li>Japanese functions</li> | ||
<li>[[Sir2000 Field Migration Facility]]</li> | <li>[[Media:SirfieldNew.pdf|Sir2000 Field Migration Facility]]</li> | ||
</ul> | </ul> | ||
[[Category:$Functions|$ListAdj]] | [[Category:$Functions|$ListAdj]] | ||
Latest revision as of 22:51, 20 September 2018
Adjust length of $list item
Note: Many $functions have been deprecated in favor of Object Oriented methods. There is no OO equivalent for the $ListAdj function as the Stringlist replacement for $lists are natively longstring capable.
This function adjusts the length of a $list item. Generally, this $list would have been created with the $ListNew function.
The $ListAdj function accepts three arguments and returns a numeric result. It is a callable $function.
The first argument is a $list identifier. This is a required argument.
The second argument is a $list item number. This is a required argument.
The third argument is a number that indicates the new length of the $list item. This is a required argument. Its minimum valid value is 0; the maximum value is 6124 under Sirius Mods Version 6.5 and earlier, and it is 2**31-1 under Sirius Mods Version 6.6 and later. If this value is smaller than the current length of the $list item, the $list item is truncated. If this value is larger than the current length of the $list item, the $list item is padded with blanks to the indicated length.
Syntax
[%RESULT =] $ListAdj(list_identifier, itemnum, length)
%result is set to 0 if the new item length is the same as the old item length, 1 if it is less, 2 if it is greater, or a negative number if an error has occurred.
Error codes
-3 - No room to add item (if LISTFC $SirParm parameter not set) All other errors cause request cancellation
Usage notes
- $ListAdj is extremely efficient if the $list item size is not being changed (return value for $ListAdj of 0), fairly efficient when a $list item is being shortened (return value of 1) and can be fairly expensive when a $list item is being lengthened (return value of 2). The latter case can be expensive because such a $ListAdj can result in the splitting of a $list leaf page. Once a leaf page is split, it will not be merged back together, even if subsequent $LISTREMs (or $LISTADJs) makes this possible.
Because split leaf pages remain split, heavy use of $LISADJ calls that increase $list item size (and $ListIns and $ListRem) can result in "sparse&CQ. $lists which place an unnecessary burden on the buffer pool and CCATEMP. It can also result in an inability to add an item to the end of the $list (via $ListAdd) because of a full pointer page, even though the $list is nowhere near the theoretical capacity for a $list. $List compression can be done using the $List_Copy_Items function.
Example
The following example illustrates how $ListAdj can be used to add an asterisk to the end of a $list item:
%LEN = $ListILn(%LIST, %NUM) %RC = $ListAdj(%LIST, %NUM, %LEN + 1) %RC = $ListOvl(%LIST, %NUM, %LEN + 1, '*')