- (echo 'native_methods = """' ; cd PLC/Methods; ls -1 *.py system/*.py | grep -v __init__ | sed -e 's,.py$$,,' -e 's,system/,system.,' ; echo '""".split()') > $@
+ (echo '## Please use make index to update this file' ; echo 'native_methods = """' ; cd PLC/Methods; ls -1 *.py system/*.py | grep -v __init__ | sed -e 's,.py$$,,' -e 's,system/,system.,' ; echo '""".split()') > $@
+
+########## Legacy/
+# the current content of __init__.py
+LEGACY_now := $(sort $(shell fgrep -v '"' PLC/Legacy/__init__.py 2>/dev/null))
+# what should be declared
+LEGACY_paths := $(filter-out %/__init__.py, $(wildcard PLC/Legacy/*.py))
+LEGACY_files := $(sort $(notdir $(LEGACY_paths:.py=)))
+
+ifneq ($(LEGACY_now),$(LEGACY_files))
+PLC/Legacy/__init__.py: force
+endif
+PLC/Legacy/__init__.py:
+ (echo '## Please use make index to update this file' ; echo 'native_methods = """' ; cd PLC/Legacy; ls -1 *.py | grep -v __init__ | sed -e 's,.py$$,,' -e 's,system/,system.,' ; echo '""".split()') > $@