Difference between revisions of "NULL KEY"
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|desc=While technically a string constant, it is only useful as a [[key]]. | |desc=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 {{LSLGC|Conditional}} as a key it executes as | Despite fitting the syntax criteria to be a valid [[key]], when fed to a {{LSLGC|Conditional}} as a key it executes as [[FALSE]]. | ||
|examples= | |examples= | ||
<lsl>integer isKey(key in) { | <lsl>integer isKey(key in) { | ||
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LSL makes it easy to check if a key is valid. Simply use the key as the parameter for a conditional. | 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 | 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 that is also not a null key. | ||
|functions= | |functions= | ||
{{LSL DefineRow||[[llAvatarOnSitTarget]]|}} | {{LSL DefineRow||[[llAvatarOnSitTarget]]|}} | ||
Revision as of 15:58, 23 November 2008
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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.
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 that is also not a null key.