Attach

Wiki description

Triggered in an object when the object attaches or detaches from agent.

Specification

Triggered

When the object is attached to an avatar
- From the ground
- From inventory
- When the avatar wearing the object logs in
When object is detached (id == NULL_KEY)
- Dropped to the ground
- Derezzed to inventory
- ~~When the avatar wearing the object logs out~~ (does not occur with current versions, but scripters should anticipate the possibility)

Not Triggered

When the avatar wearing the object teleports
- Use CHANGED_TELEPORT to detect when the avatar teleports
When the avatar wearing the object moves from one region to another
- Use CHANGED_REGION to detect when the avatar changes region
When the attachment is detached after being attached with llAttachToAvatarTemp.
- There is no way to detect this at this moment.

Caveats

When detached to inventory, an object is only given limited time to execute its attach events. If these events are active when the script derezzes but have not completed, execution will finish when the object is next rezzed. ^{http://forums-archive.secondlife.com/54/8b/65518/1.html#post689314} If the script is busy handling a different event at detach time, an attach event with id=NULL_KEY can happen on the next rez, followed by one with the wearer's key. To verify a real detach, check that id == NULL_KEY AND llGetAttached() == 0.
If the script is busy with a complex event handler before it is taken to inventory, the event queue can overflow, leaving no room to capture new events. The queue is preserved, so attach and on_rez may not be triggered the next time the object is rezzed. To guard against this possibility, llGetAttached can be checked in other events.
When detaching an object, llGetAttached() returns 0, but the same happens when dropping an object from an attachment point to the ground. No other indicative event is triggered in the latter case; in particular, the on_rez event is not triggered for attachment drops. If you need to distinguish a drop from a detach, a possible hack is to check llGetObjectPrimCount(llGetKey()). If it's zero, it can be assumed that the object is being detached; otherwise, that it is being dropped.
There is a bug when an attach event is in a script in a child prim. When the object is attached, a detached event is first triggered, and then an attached event is triggered. When the object is detached, no event is triggered.

Examples

The following is a simplified example of the attach event. The variable id will be the key of the avatar the scripted object is attached to otherwise it will take on the value of NULL_KEY. The conditional if statement is used to determine the value of the variable id.

default
{
    attach(key id)
    {
        if (id)     // is a valid key and not NULL_KEY
        {
            llSay(0, "I have been attached!");
        }
        else
        {
            llSay(0, "I have been detached!");
        }
    }
}

Notes

on_rez & attach

on_rez will be triggered prior to attach when attaching from inventory or during login.

Shared wiki helpers

The original page also injects shared parameter notes, caveats or issue information through these helpers. Their conditional MediaWiki logic is not reproduced here; inspect the preserved helper source for additional material.

Template:Issues/SVC-6687

Original shared helper source (conditional wiki logic is not evaluated)

{{Issues|SVC-6687|[[Attach]] event doesn't trigger in a child-prim when detaching the object|type=bug|resolution=}}