View source for $List Global and $List Session

{{DISPLAYTITLE:$List_Global and $List_Session}}
<span class="pageSubtitle">$List_Global and $List_Session: Access/create global/session $list</span>

<p class="warning">Most Sirius $functions have been deprecated in favor of Object Oriented methods. There is no OO equivalent for the $List_Global and $List_Session functions because of the OO ability to declare any object Global or Session (that is, this function is part of Stringlist declaration).</p>

This function returns a $list identifier by which one may refer to a global or session $list in a request. The global or session $list may be one that already exists because of a previous $List_Global, $List_Session, or [[$ListSave]] function, or it may be created by the <var>$List_Global</var> or <var>$List_Session</var> function. 

<var>$List_Global</var> and <var>$List_Session</var> accept two arguments and return a numeric result. 

The first argument is the name of the global or session $list. This is a required argument. 

The second argument indicates the type of processing <var>$List_Global</var> or <var>$List_Session</var> is to perform. Valid values are the following:

<table class="syntaxTable">
<tr><th>ANY</th>
<td>If the global or session $list already exists, it is referenced with its current contents. If it does not exist, a new empty global or session $list is created.</td></tr>
<tr><th>OLD</th>
<td>The global or session $list must already exist, that is, it must have been created with a previous <var>$List_Global</var> or <var>$List_Session</var> or saved with a <var>$ListSave</var>.</td></tr>
<tr><th>NEW</th>
<td>The global or session $list must not already exist. If it does, it will be recreated.</td></tr>
<tr><th>PREP</th>
<td>Same as ANY but empties $list if it has data.</td></tr>
<tr><th>PREPANY</th>
<td>Same as ANY but empties $list if it has data.</td></tr>
<tr><th>PREPOLD</th>
<td>Same as OLD but empties $list if it has data.</td></tr>
<tr><th>PREPNEW</th>
<td>Same as NEW.</td></tr>
<tr><th>ANYPREP</th>
<td>Same as ANY but empties $list if it has data.</td></tr>
<tr><th>OLDPREP</th>
<td>Same as OLD but empties $list if it has data.</td></tr>
<tr><th>NEWPREP</th>
<td>Same as NEW.
</td></tr>
</table>

This is an optional argument and defaults to <tt>ANY</tt>.

==Syntax==
<p class="syntax"><section begin="syntax" /> %RESULT = $List_Global(name, type)
<section end="syntax" /></p>
<p class="caption">$List_Global Function
</p>
<p class="caption">%RESULT is set either to the identifier of the global $list, or to a negative error code if an error has occurred.</p>

<p class="code"> 
 %RESULT = $List_Session(name, type)
</p>
<p class="caption">$List_Session Function
</p>
<p class="caption">%RESULT is set either to the identifier of the session $list, or to a negative error code if an error has occurred.</p>

A particular instance of <var>$List_Global</var> or <var>$List_Session</var> always returns the same $list identifier so it cannot be called multiple times for different global or session $list names to allow simultaneous reference to these $lists. 

The scope of a <var>$List_Global</var> or <var>$List_Session</var> identifier is the evaluation of the <var class="product">User Language</var> request in which it was contained. When evaluation is over, global $list data appears exactly like a $ListSave'd (or $ListSav'ed) $list and, in fact, can be [[$ListRst]]'ed. For a different request to access that same global $list, it must issue a <var>$List_Global</var> or <var>$ListRst</var> with the same name. A <var>$List_Global</var> can also be issued against a $list that was $LISTSAVE'd, even in the same procedure, as in the following example.

<p class="code"> %RC = $ListSave(%LIST, 'NEW.NAME')
 %GLIST = $List_Global('NEW.NAME')
</p>

A <var>$List_Session</var> cannot access a $LISTSAVE'd $list, and <var>$ListRst</var> cannot access a session $list. 

Separate <var>$List_Global</var> or <var>$List_Session</var> statements can be issued against the same name. When this is done, each instance of <var>$List_Global</var> or <var>$List_Session</var> will return a separate $list identifier, but they will actually refer to the same underlying $list. For example, the result of the following <var>$List_Global</var> statements is a single global $list with name WHATEVER that contains two items: <tt>WASTE NOT</tt> is the first, and <tt>WANT NOT</tt> is the second.

<p class="code"> %LIST1 = $List_Global('WHATEVER', 'NEW')
 %LIST2 = $List_Global('WHATEVER')
 %RC = $ListAdd(%LIST1, 'WASTE NOT')
 %RC = $ListAdd(%LIST2, 'WANT NOT')
</p>


A <var>$ListImg</var> on a global $list identifier is associated with the $list identifier, not the underlying data, so in the case of multiple $LIST_GLOBALs or $LIST_SESSIONs for the same name, the <var>$ListImg</var> only applies to the $list identifier for which it was issued. For example, the first <var>$ListAddI</var> below adds data to the global $list from image MYIMAGE, while the second <var>$ListAddI</var> adds data from image YOURIMAGE:

<p class="code"> %LIST1 = $List_Global('WHATEVER', 'NEW')
 %LIST2 = $List_Global('WHATEVER')
 %RC = $ListImg(%LIST1, %MYIMAGE:COUNT)
 %RC = $ListImg(%LIST2, %YOURIMAGE:COUNT)
 %RC = $ListAddI(%LIST1)
 %RC = $ListAddI(%LIST2)
</p>

Global and session $list names are kept in CCATEMP. For every <var>$List_Global</var> or <var>$List_Session</var> call, logical I/O (and possibly physical I/O) must be performed to look up the name. As such, it is a good practice to avoid $LIST_GLOBALs or $LIST_SESSIONs for constant names inside a loop, and to make global and session $list identifier variables COMMON rather than letting each subroutine issue a <var>$List_Global</var> or <var>$List_Session</var> function. 

If it is uncertain whether the global or session list has been already declared inside a subroutine (or anywhere for that matter), code like the following can be used to ensure that the <var>$List_Global</var> or <var>$List_Session</var> statement is only issued once.

<p class="code"> IF NOT %MY.LIST THEN
 %MY.LIST = $List_Global('MY.LIST', 'ANY')
 END IF
</p>

The <tt>PREP</tt> prefix or suffix for all the types indicates that the returned $list should be cleared of its contents. For example, after

<p class="code"> %LIST1 = $List_Global('WHATEVER', 'NEW')
 %RC = $ListAdd(%LIST1, 'WASTE NOT')
 %LIST2 = $List_Global('WHATEVER', 'PREPOLD')
 %RC = $ListAdd(%LIST2, 'WANT NOT')
</p>

the global $list identified by <tt>WHATEVER</tt> would have a single item with content <tt>WANT NOT</tt>. Just as type <tt>ANY</tt> is the default for $LIST_GLOBAL, <tt>PREP</tt> is the same as <tt>PREPANY</tt>. 

Global $lists can only be restored with a <var>$ListRst</var> if they have not been accessed as <var>$List_Global</var> in the procedure that issues the <var>$ListRst</var>. You can clean up any global $lists with $LIST_GLOBAL_DEL, which can be issued whether or not a name was referenced in the current procedure with a <var>$List_Global</var>. You can clean up any session $lists with $LIST_SESSION_DEL, which can be issued whether or not a name was referenced in the current procedure with a <var>$List_Global</var>. 

<var>$List_Global</var> and <var>$List_Session</var> have independent namespaces. That is, the same name used for <var>$List_Global</var> and <var>$List_Session</var> reference different $lists. 

A <var>$List_Session</var> call when there is no session open causes a request cancellation. 

<p class="code">
  -3 - No room in CCATEMP to add global name
             (not possible with OLD)
 -14 - No global list for name (for type OLD)
             Already a global list for name (for type NOTOLD)
 -15 - Invalid type (second parameter)
</p>
<p class="caption">$List_Global and $List_Session Error Codes
</p>

<var>$List_Session</var> is new in Version 6.3 of the <var class="product">[[Sirius Mods]]</var>.<p>

<ul class="smallAndTightList">
<li>[[Sirius functions]]</li>
<li>[[Fast/Unload User Language Interface]]</li>
<li>[[Janus Open Client]]</li>
<li>[[Janus Open Server]]</li>
<li>[[Janus Sockets]]</li>
<li>[[Janus Web Server]]</li>
<li>[[Japanese functions]]</li>
<li>[[Sir2000 Field Migration Facility]]</li>

</ul>
 
</p>
<p class="caption">Products authorizing <var>$List_Global</var> and $List_Session
</p>


[[Category:$Functions|$List_Global and $List_Session]]