Hi Steve,
I think you may have hit the nail on the head...I found this in the top level CMakeLists.txt:
# It is a fatal error if no working C compiler is available to build
# the PLplot core C library and core C examples. All other compilers
# required by our bindings are optional in that if no working compiler
# of the kind needed is available, the associated bindings and
# examples are disabled.
enable_language(C)
The absence of a Lua compiler will cause exactly the symptom I describe, ie the <configure> process overwriting my choice to include Lua bindings on the basis that there is no Lua compiler.
I am undecided whether I should download and install a Lua compiler or if the Cmake condition would be satisfied if I pointed it to the Lua compiler embedded within Mach.
Are you aware of any differences between a 'real' Lua compiler verses the embedded version?
I have often said that a hobby is best judged by what you learn in the pursuit of it. I didn't anticipate delving into Cmake or compiler/linker setups...but I am learning.
Craig