The use of global names like #<_line:len>,
#<_move:phi> is just a convention used for
communication of results in some of the provided
ngcgui examples and for handling of entry boxes.
From the docs:
Code:
While input global named parameters are
discouraged, linuxCNC subroutines must use global
named parameters for returning results. Since
ngcgui-compatible subfiles are aimed at gui usage,
return values are not a common requirement.
However, ngcgui is useful as a testing tool for
subroutines which do return global named
parameters and it is common for ngcgui-compatible
subfiles to call utility subroutine files that
return results with global named parameters.
To support these usages, ngcgui ignores global
named parameters that include a colon (:)
character in their name. Use of the colon (:) in
the name prevents ngcgui from making entryboxes
for these parameters.
Ref:
linuxcnc.org/docs/2.7/html/gui/ngcgui.html
The source file text gives some more background:
Code:
# The linuxcnc gcode language does not provide a
# mechanism for returning results so subroutines
# must set global parameters for results. Within
# ngcgui, _globals with names that contain a colon
# (:) character are ignored in the creation of
# entry boxes. For example, a subroutine called
# from a Subfile named o<line> returns results in
# globals like: #<_line:theta>, $<_line:length>,
# etc. This feature can be used to hide globals
# from entry boxes for any purpose or for
# communication between routines
Ref:
github.com/LinuxCNC/linuxcnc/blob/2.7/tcl/ngcgui.tcl#L89
