2.3.13. - Cleanup Macros
On keyboard interrupts (and command and syntax errors), if macros named
cleanup_once
or
cleanup_always have been defined,
their definitions are read as input.
Typical uses of the
cleanup_once macro are to return motors to starting positions on
an interrupted delta scan or to display
counter contents if counting is interrupted.
After running the
cleanup_once and/or
cleanup_always macros, spec gives the standard prompt and waits for the next
command from the keyboard.
The
cleanup_once macro is removed before the next main prompt is issued,
whether or not it was triggered.
Definitions for these macros should be constructed using the
cdef()
(chained macro) function (described
2.4.4.1
in order to allow various clean-up actions to
be added and removed during the flow of arbitrary statement blocks.
The legacy cleanup macros
cleanup and
cleanup1 remain supported.
Like
cleanup_always, the macros remain defined across the standard prompt.
However, unlike
cleanup_always, both
cleanup and
cleanup1 are deleted if they generate an error or the commands contained therein are
interruped by
^C.