llMessageLinked
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Summary
Function: llMessageLinked( integer linknum, integer num, string str, key id );| 0.0 | Forced Delay |
| 10.0 | Energy |
Triggers a link_message event with the parameters num, str, and id in the group or link linknum.
| • integer | linknum | – | Link number or a LINK_* flag. | |
| • integer | num | |||
| • string | str | |||
| • key | id |
You can use id as a second string field (in LSL the key type is implemented as a string with just custom operators). Typecasting between string and key types has no effect on the data contained.
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Caveats
- A script can hear its own linked messages if linknum is set to LINK_SET or LINK_THIS. This creates the possibility of an infinite loop (a bad thing); be very careful about how messages are handled and passed along.
- Some users have noted occasional failures of linked messages when sending a message to a large number of recieving scripts in different prims using LINK_SET, LINK_ALL_OTHERS, & LINK_ALL_CHILDREN (ie. not all prims recieve the message). If you encounter this problem, a workaround is to place all child prim scripts in a single prim, using targeted functions like llSetLinkPrimitiveParams to modify the prim in which the script previously resided, and use a single link message to address them Void Singer
Examples
default{ // assumptions // object name: LSLWiki // script name: _lslwiki
state_entry() {
llMessageLinked(LINK_THIS, 0, llGetScriptName(), NULL_KEY);
}
link_message(integer sender_num, integer num, string msg, key id) {
llOwnerSay(msg);
// the owner of object LSLWiki will hear
// LSLWiki:_lslwiki
}
}
Useful Snippets
default
{ // Quick and dirty debugging link_messages
link_message(integer sender_num, integer num, string msg, key id) {
llSay(DEBUG_CHANNEL, llList2CSV([sender_num, num, msg, id]));
}
}
// This is just an example script, you shouldn't handle link message within single script this way.
default{ // To propagate an unlimted number of arguments of any type.
// Presumed, the separator string isn't used in any source string!
state_entry() {
list my_list = [1, 2.0, "a string", <1, 2, 3>, <1, 2, 3, 4>, llGetOwner()];
string list_parameter = llDumpList2String(my_list, "|"); // Typecast list to a string
llMessageLinked(LINK_THIS, 0, list_parameter, NULL_KEY)
}
link_message(integer sender_num, integer num, string list_argument, key id) {
list re_list = llParseString2List(list_argument, ["|"], [""]); // Typecast string back to a list
}
}
Notes
Link Numbers
Each prim that makes up an object has an address, a link number. To access a specific prim in the object, the prim's link number must be known. In addition to prims having link numbers, avatars seated upon the object do as well.
- If an object consists of only one prim, and there are no avatars seated upon it, the (root) prim's link number is zero.
- However, if the object is made up of multiple prims or there is an avatar seated upon the object, the root prim's link number is one.
When an avatar sits on an object, it is added to the end of the link set and will have the largest link number. In addition to this, while an avatar is seated upon an object, the object is unable to link or unlink prims without unseating all avatars first.
Counting Prims & Avatars
There are two functions of interest when trying to find the number of prims and avatars on an object.
llGetNumberOfPrims()- Returns the number of prims and seated avatars.llGetObjectPrimCount(llGetKey())- Returns only the number of prims in the object but will return zero for attachments.
integer GetPrimCount() { //always returns only the number of prims
if(llGetAttached())//Is it attached?
return llGetNumberOfPrims();//returns avatars and prims but attachments can't be sat on.
return llGetObjectPrimCount(llGetKey());//returns only prims but won't work on attachments.
}
Errata
If a script located in a child prim erroneously attempts to access link 0, it will get or set the property of the linkset's root prim. This bug (BUG-5049) is preserved for broken legacy scripts.
- Using llMessageLinked in a single prim object allows developers to mitigate some LSL limits by breaking up functionality between cooperating scripts and synchronizing actions. When you do this, be extremely careful not to create infinite loops as mentioned above.
- The sizes of str and id are only limited by available script memory, I believe.--RJ Thibaud 13:27, 23 December 2007 (PST)