Difference between revisions of "NULL KEY"
(//corrected some language, cannot find where this typo is coming from: they should be store in a) |
|||
| Line 11: | Line 11: | ||
return (in == NULL_KEY); | return (in == NULL_KEY); | ||
}//returns 2 if it's a valid key, 1 if it's NULL_KEY</lsl> | }//returns 2 if it's a valid key, 1 if it's NULL_KEY</lsl> | ||
|notes=In most situations NULL_KEY isn't needed; an empty string ("") will suffice. To take advantage of this certain practices have to be avoided. In many applications keys are checked against NULL_KEY | |notes=In most situations NULL_KEY isn't needed; an empty string ("") will suffice. To take advantage of this certain practices have to be avoided. In many applications keys are checked against NULL_KEY to determine if they are valid; this is bad practice. | ||
LSL makes it easy to check if a key is valid. Simply use the key as the parameter for a conditional. | |||
That is, instead of <code>if(uuid != NULL_KEY)</code>, use <code>if(uuid)</code>. <code>if(uuid)</code> will only return true if it is a valid key and if it is not a NULL_KEY. | |||
|functions= | |functions= | ||
{{LSL DefineRow||[[llAvatarOnSitTarget]]|}} | {{LSL DefineRow||[[llAvatarOnSitTarget]]|}} | ||
Revision as of 09:33, 13 July 2008
| LSL Portal | Functions | Events | Types | Operators | Constants | Flow Control | Script Library | Categorized Library | Tutorials |
Description
Constant: string NULL_KEY = "00000000-0000-0000-0000-000000000000";The string constant NULL_KEY has the value "00000000-0000-0000-0000-000000000000"
While technically a string constant, it is only useful as a key.
Despite fitting the syntax criteria to be a valid key, when fed to a Conditional as a key it executes as false.
Caveats
Related Articles
Functions
| • | llAvatarOnSitTarget | |||
| • | llDetectedKey | |||
| • | llGetNotecardLine | |||
| • | llGetLandOwnerAt | |||
| • | llGetPermissionsKey | |||
| • | llGetTexture | |||
| • | llListen |
Events
| • | attach |
Examples
<lsl>integer isKey(key in) {
if(in) return 2; return (in == NULL_KEY);
}//returns 2 if it's a valid key, 1 if it's NULL_KEY</lsl>
Notes
Like any LSO string constants longer then 3 characters and used in multiple places in the code, they should be stored in a global variable. The result will be a considerable memory savings. This does not apply to scripts compiled with Mono. See LSL Constants vs Globals for more information about this and examples.
In most situations NULL_KEY isn't needed; an empty string ("") will suffice. To take advantage of this certain practices have to be avoided. In many applications keys are checked against NULL_KEY to determine if they are valid; this is bad practice.
LSL makes it easy to check if a key is valid. Simply use the key as the parameter for a conditional.
That is, instead of if(uuid != NULL_KEY), use if(uuid). if(uuid) will only return true if it is a valid key and if it is not a NULL_KEY.