The default patterns used for variable naming convention is chosen to match
the dominant convention of the listfiles distributed with cmake itself. The
tool analyze_naming.py was used to classify each variable assignment in
all modules from cmake 3.10 yielding the following counts:
PARENT
======
other: 237
'[A-Z][A-Z0-9_]+' 335
'[a-z][a-z0-9_]+' 146
'_[A-Z0-9_]+' 62
'_[a-z0-9_]+' 236
LOCAL
=====
other: 375
'[A-Z][A-Z0-9_]+' 646
'[a-z][a-z0-9_]+' 1220
'_[A-Z0-9_]+' 375
'_[a-z0-9_]+' 450
DIRECTORY
=========
other: 235
'[A-Z][A-Z0-9_]+' 2140
'[a-z][a-z0-9_]+' 111
'_[A-Z0-9_]+' 515
'_[a-z0-9_]+' 182
LOOP
====
other: 72
'[A-Z][A-Z0-9_]+' 98
'[a-z][a-z0-9_]+' 288
'_[A-Z0-9_]+' 79
'_[a-z0-9_]+' 114
ARGUMENT
========
other: 17
'[A-Z][A-Z0-9_]+' 159
'[a-z][a-z0-9_]+' 512
'_[A-Z0-9_]+' 60
'_[a-z0-9_]+' 184