$ListSav and $ListSave: Difference between revisions
m (misc cleanup) |
m (minor formatting) |
||
Line 78: | Line 78: | ||
<code>MY.GLOBAL.LIST</code> would still be a valid global $list, but it would be empty. | <code>MY.GLOBAL.LIST</code> would still be a valid global $list, but it would be empty. | ||
<li>The only difference between <var>$ListSav</var> and <var>$ListSave</var> is that <var>$ListSav</var> will not allow the saving of an empty $list while <var>$ListSave</var> will and that <var>$ListSave</var> will replace an existing saved $list by the same name as long as the existing list is not active as a <var>$List_Global</var> list in the current procedure. For example, in | <li>The only difference between <var>$ListSav</var> and <var>$ListSave</var> is that <var>$ListSav</var> will not allow the saving of an empty $list while <var>$ListSave</var> will and that <var>$ListSave</var> will replace an existing saved $list by the same name as long as the existing list is not active as a <var>$List_Global</var> list in the current procedure. For example, in the following the second <var>$ListSav</var> would fail because a $list is already saved under the name <code>A.LITTLE.LIST</code>: | ||
<p class="code">%RESULT = $ListSav(%ALIST, 'A.LITTLE.LIST') | <p class="code">%RESULT = $ListSav(%ALIST, 'A.LITTLE.LIST') | ||
Line 84: | Line 84: | ||
</p> | </p> | ||
the second <var>$ | While the second <var>$ListSave</var> below would succeed: | ||
<p class="code">%RESULT = $ListSave(%ALIST, 'A.LITTLE.LIST') | <p class="code">%RESULT = $ListSave(%ALIST, 'A.LITTLE.LIST') | ||
%RESULT = $ListSave(%BLIST, 'A.LITTLE.LIST') | %RESULT = $ListSave(%BLIST, 'A.LITTLE.LIST') | ||
</p> | </p> | ||
</ul> | </ul> | ||
Latest revision as of 21:56, 6 June 2018
$ListSav and $ListSave: Save global $list
Note: Many $functions have been deprecated in favor of Object Oriented methods. There is no direct OO equivalent for the $ListSav and $ListSave functions because Stringlists can, more naturally, be declared as "Global".
These callable $functions are used to save a $list to be later retrieved with the $ListRst function or the $List_Global and $List_Session functions. $ListSav and $ListSave are used with $ListRst or $List_Global to pass a $list between separate requests.
Syntax
[%result =] $ListSav(list_identifier, [name]) [%result =] $ListSave(list_identifier, [name])
Syntax terms
%result | A numeric value that is set to 0, or if an error has occurred, to a negative number. |
---|---|
list_identifier | The identifier of the $list to be saved. This is a required argument. |
name | A string that is the name under which to save the $list. If this argument is omitted, the name is the null string.
The $ListRst function can be given the name under which the $list was saved. |
Usage notes
- A $list "saved" via $ListSav or $ListSave will be cleaned up at user logoff. After a $list has been "saved" via $ListSav or $ListSave it is no longer accessible in the current request, but will not be cleaned up at request termination or Release All Records processing. The $list is effectively "hidden" until restored via $ListRst or $List_Global.
- Only one $list can be saved at a time under a given name. For example:
B FOR %I FROM 1 TO 4 %LIST1 = $ListNew %RESULT = $ListAdd(%LIST1 , $WORD('HE SHE WE IT', , %I) WITH ' ATE') %RESULT = $ListSave(%LIST1, $WORD('A', , %I)) END FOR END
The request above produces three $lists, as follows:
HE ATE
, successfully saved via $ListSave under nameA
SHE ATE
, successfully saved via $ListSave under name ''IT ATE
, not saved, but accessible under $list identifier%RESULT
for the duration of the request
The string
WE ATE
is not saved (a list was already saved with the name ''), and since each invocation of $ListNew deletes the list associated with it, the list containingWE ATE
was deleted in the last iteration of the FOR loop. - If $ListSav or $ListSave is invoked only with a null name argument, CCATEMP is not used and processing is very efficient. Because many Sirius Software products use $ListSav/$ListRst with the null global $list name, care should be taken of the interaction between global $list names used by your applications and the null $list name.
- To ensure that a $ListSav or $ListSave is not blocked by a previously "saved" list under a given name, you can simply issue a $ListRst to restore any previously saved list under that name, as in
%result = $ListDel($ListRst) %result = $ListSave(%list)
Another way to address the problem of a global $list name already in use is to use the $List_Global function.
- $Lists saved with $ListSave can also be accessed with $List_Global. For example, this is a valid program:
%result = $ListSave(%alist, 'MY.GLOBAL.LIST') %list = $List_Global('MY.GLOBAL.LIST')
While a name is accessed as a global, however, it is not possible to save another list to the same name. This $ListSave would fail with a return code of -13:
%LIST = $List_Global('MY.GLOBAL.LIST') %RESULT = $ListSave(%ALIST, 'MY.GLOBAL.LIST')
It is possible to $ListSave a global $list to a separate name. In the following, the contents of global list
MY.GLOBAL.LIST
are saved under the nameOTHER.GLOBAL.LIST
:%LIST = $List_Global('MY.GLOBAL.LIST') %RESULT = $ListSave(%LIST, 'OTHER.GLOBAL.LIST')
MY.GLOBAL.LIST
would still be a valid global $list, but it would be empty. - The only difference between $ListSav and $ListSave is that $ListSav will not allow the saving of an empty $list while $ListSave will and that $ListSave will replace an existing saved $list by the same name as long as the existing list is not active as a $List_Global list in the current procedure. For example, in the following the second $ListSav would fail because a $list is already saved under the name
A.LITTLE.LIST
:%RESULT = $ListSav(%ALIST, 'A.LITTLE.LIST') %RESULT = $ListSav(%BLIST, 'A.LITTLE.LIST')
While the second $ListSave below would succeed:
%RESULT = $ListSave(%ALIST, 'A.LITTLE.LIST') %RESULT = $ListSave(%BLIST, 'A.LITTLE.LIST')
$ListSav and $ListSave completion codes
0 — $list successfully saved -3 — No room to add list name (if LISTFC $SirParm parameter not set) -5 — Required argument not specified -6 — $List identifier invalid -13 — Another $list has already been saved with the specified name -14 — $list is null, is not saved ($ListSav only)