$ListRem: Difference between revisions
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<span class="pageSubtitle">Remove item from $list</span> | <span class="pageSubtitle">Remove item from $list</span> | ||
<p class=" | <p class="warn"><b>Note: </b>Many $functions have been deprecated in favor of Object Oriented methods. The OO equivalent for the $ListRem function is <var>[[RemoveItem (Stringlist function)|RemoveItem]]</var>.</p> | ||
This function removes an item from a $list, decrementing the item numbers of all items which follow. | This function removes an item from a $list, decrementing the item numbers of all items which follow. | ||
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<p class="syntax">[%RESULT =] $ListRem(list_identifier, item_num) | <p class="syntax">[%RESULT =] $ListRem(list_identifier, item_num) | ||
</p> | </p> | ||
<p class="code"> | <p><var class="term">%result</var> is the number of items remaining in the $list after the removal, or is a negative number if an error has occurred.</p> | ||
===Error codes=== | |||
<p class="code">-5 - Required argument not specified | |||
-6 - $List identifier invalid | |||
-7 - Item number not found in $list | |||
</p> | </p> | ||
Consecutive $list leaf pages that are made relatively empty with <var>$ListRem</var> will not be merged together. Because of this, heavy use of [[$ListIns]] and <var>$ListRem</var> can result in "sparse" $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 $list. To make matters worse, <var>$ListCpy</var> does a page-for-page copy of a $list so does not result in any compression of the resultant $list. $List compression can be done using the [[$List_Copy_Items]] function.< | ==Usage notes== | ||
<ul> | |||
<li>Consecutive $list leaf pages that are made relatively empty with <var>$ListRem</var> will not be merged together. Because of this, heavy use of [[$ListIns]] and <var>$ListRem</var> can result in "sparse" $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 $list. To make matters worse, <var>$ListCpy</var> does a page-for-page copy of a $list so does not result in any compression of the resultant $list. $List compression can be done using the [[$List_Copy_Items]] function. | |||
</ul> | |||
==Products authorizing {{PAGENAMEE}}== | ==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|$ListRem]] | [[Category:$Functions|$ListRem]] | ||
Latest revision as of 22:51, 20 September 2018
Remove item from $list
Note: Many $functions have been deprecated in favor of Object Oriented methods. The OO equivalent for the $ListRem function is RemoveItem.
This function removes an item from a $list, decrementing the item numbers of all items which follow.
The $ListRem function accepts two 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 number that specifies the item number in the $list. This is a required argument. The number of items remaining in the $list after the removal is returned as the result of this function. If removal of an item makes a CCATEMP $list page empty, that page is removed from use by the $list. Except for sorted lists which are only one page in size, space taken up by the removed item is made available on the $list page. If there are no items remaining after the removal, the $list is deleted.
Syntax
[%RESULT =] $ListRem(list_identifier, item_num)
%result is the number of items remaining in the $list after the removal, or is a negative number if an error has occurred.
Error codes
-5 - Required argument not specified -6 - $List identifier invalid -7 - Item number not found in $list
Usage notes
- Consecutive $list leaf pages that are made relatively empty with $ListRem will not be merged together. Because of this, heavy use of $ListIns and $ListRem can result in "sparse" $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. To make matters worse, $ListCpy does a page-for-page copy of a $list so does not result in any compression of the resultant $list. $List compression can be done using the $List_Copy_Items function.