Difference between revisions of "LSL 101/Functions That Return a Value"

From Second Life Wiki
Jump to navigation Jump to search
m (<lsl> tag to <source>)
 
(4 intermediate revisions by 3 users not shown)
Line 1: Line 1:
[[Category:LSL 101]]
[[Category:LSL 101]]
{{NavNextPrev|prev=Compile Time Errors|next=String Concatenation}}
{{NavNextPrev|prev=Functions|next=Creating a Script}}
{{LSL Wikibook Index}} 
 


The built-in functions we've seen so far, ''llSay'' and ''llOwnerSay'', act as commands, causing something to happen in SL.  But other built-in functions are used to ''retrieve'' information from SL and make it available to the script.  In this case, we say that the function ''returns'' the information.
The built-in functions we've seen so far, ''llSay'' and ''llOwnerSay'', act as commands, causing something to happen in SL.  But other built-in functions are used to ''retrieve'' information from SL and make it available to the script.  In this case, we say that the function ''returns'' the information.
Line 6: Line 8:
The built-in function ''llGetRegionName'' is an example of this.  When executed, it returns the name of whatever sim the script is executing in.  If the script is running in Ganymede, for example, executing ''llGetRegionName'' would return the string "Ganymede".
The built-in function ''llGetRegionName'' is an example of this.  When executed, it returns the name of whatever sim the script is executing in.  If the script is running in Ganymede, for example, executing ''llGetRegionName'' would return the string "Ganymede".


Here's how that would work in a sript.
Here's how that would work in a script.
<lsl>
<source lang="lsl2">default
default
{
{
     state_entry()
     state_entry()
Line 15: Line 16:
           llOwnerSay( llGetRegionName() );
           llOwnerSay( llGetRegionName() );
     }
     }
}
}</source>
</lsl>


Notice that ''llRegionSay'' does not take any parameters, but it still has to be followed by a pair of parentheses.  It is 'not' followed by a semicolon, because it is not, by itself, a statement.
Notice that ''llGetRegionName'' does not take any parameters, but it still has to be followed by a pair of parentheses.  It is ''not'' followed by a semicolon, because it is not, by itself, a statement.


When the SL sim server executes the line
When the SL sim server executes the line
Line 27: Line 27:


  llOwnerSay( "Ganymede" );
  llOwnerSay( "Ganymede" );
 
which chats the string "Ganymede" to the object's owner.
which chats the string "Ganymede" to the object's owner.


In the touch_start event handler, we see ''llGetRegionName()'', which looks like a built-in function with no parameters, which is exactly what it is.  But it doesn't stand by itself on a line with a semicolon after it, as did the previous built-in functions we've seen. That's because unlike ''llSay'' or ''llOwnerSay'', which cause something to happen in SL, ''llGetRegionName'' retrieves information from SL (in this case, a string containing the name of the current region) and returns it to the script.
Now let's make the output a little more meaningful by introducing [[LSL 101/String Concatenation|string concatenation]].
 
'''To continue this tutorial go forward to [[LSL 101/Creating a Script|Creating a Script]] or review the page before, to [[LSL 101/Functions| Functions]].'''

Latest revision as of 13:42, 24 January 2015

← Functions ↑̲  LSL 101  ̲↑ Creating a Script →


The built-in functions we've seen so far, llSay and llOwnerSay, act as commands, causing something to happen in SL. But other built-in functions are used to retrieve information from SL and make it available to the script. In this case, we say that the function returns the information.

The built-in function llGetRegionName is an example of this. When executed, it returns the name of whatever sim the script is executing in. If the script is running in Ganymede, for example, executing llGetRegionName would return the string "Ganymede".

Here's how that would work in a script. 

default
{
     state_entry()
     {
          // Announce the name of the current region
          llOwnerSay( llGetRegionName() );
     }
}

Notice that llGetRegionName does not take any parameters, but it still has to be followed by a pair of parentheses. It is not followed by a semicolon, because it is not, by itself, a statement.

When the SL sim server executes the line 

llOwnerSay( llGetRegionName() );

it first executes the llGetRegionName function and (in essence) replaces llGetRegionName() with the string that is returned. This results in something like 

llOwnerSay( "Ganymede" );

which chats the string "Ganymede" to the object's owner.

Now let's make the output a little more meaningful by introducing string concatenation.

To continue this tutorial go forward to Creating a Script or review the page before, to Functions.

Retrieved from "https://wiki.secondlife.com/w/index.php?title=LSL_101/Functions_That_Return_a_Value&oldid=1194757"