1 files changed, 59 insertions, 0 deletions
diff --git a/modules/shadow.m4 b/modules/shadow.m4
new file mode 100644
index 00000000..b55adbcb
--- /dev/null
+++ b/modules/shadow.m4
@@ -0,0 +1,59 @@
+# no modules loaded yet
+test
+shadow
+
+# define our own macros for `test' and `shadow'
+define(`test', `local::`test'')
+define(`shadow', `local::`shadow'')
+test
+shadow
+
+# save our local `shadow' macro until the Shadow module is unloaded
+pushdef(`shadow')
+
+# module Shadow defines `shadow' and `test' macros
+loadmodule(`shadow')
+dumpdef(`test')
+dumpdef(`shadow')
+test
+shadow
+
+# save the definition of `test' from the Shadow module
+define(`Shadow::test', defn(`test'))
+
+# module Test also defines a `test' macro
+loadmodule(`test') 
+dumpdef(`test')
+dumpdef(`shadow')
+test
+shadow
+
+# Reloading Shadow shouldn't affect anything
+loadmodule(`shadow')
+dumpdef(`test')
+dumpdef(`shadow')
+test
+shadow
+
+# Unloading Test will not unshadow the test definition in Shadow without
+# some macro magic
+unloadmodule(`test')
+define(`test', defn(`Shadow::test'))
+undefine(`Shadow::test')
+dumpdef(`test')
+dumpdef(`shadow')
+test
+shadow
+
+# Unloading Shadow once has no effect (we loaded it twice)
+unloadmodule(`shadow')
+dumpdef(`test')
+dumpdef(`shadow')
+test
+shadow
+
+# Unloading Shadow again will revert to copying `test' and the locally
+# pushed `shadow' macro.
+unloadmodule(`shadow')
+test
+shadow