attrwatch()

attrwatch(<attribute>)

Returns what @attribute/watch made of the standard attribute <attribute>: the pattern naming the event handler’s attributes that run when a copy of it changes, as @attribute <attribute> shows it. It returns nothing when <attribute> is in the attribute table but not watched, and #-1 NOT A STANDARD ATTRIBUTE when it is not in the table. See @attribute watch.

Code that sets up a watch of its own uses it to add the attribute to the table only when it is not there yet, and to leave alone a watch someone else set with another pattern.

> think attrwatch(HP)
#-1 NOT A STANDARD ATTRIBUTE
> @attribute/access HP=none
> think attrwatch(HP)
> @attribute/watch HP
> think attrwatch(HP)
WATCH`HP WATCH`HP`*

Output: HP is not in the table at first. Once it is, it is not watched, so the second think prints nothing. Watched with the default pattern, it returns the pattern.

::: seealso

@attribute
events :::