NULL KEY

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Revision as of 09:33, 13 July 2008 by Chaz Longstaff (Talk | contribs)

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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.

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.

Deep Notes

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Signature

string NULL_KEY = "00000000-0000-0000-0000-000000000000";