Use Proto for Moments app

[liangwang0734]

Two changes:

• Allow attaching __gc to the "object" returned by the newmember method. This object, not the "class", is the one holding the resources.
• Use Proto to make Moments app
  • The first step 1a59589 does the conversion but keeps most codes unchanged in order to see the changes clearly.
  • The second step 7021cf4 properly indents the codes.
• Tested on gem challenge.

The changes to allow attaching __gc is a Lua 5.1 hack (Luajit uses 5.1). Note that presently, other g2 codes that implement __gc all rely on a C type (through xsys or luajit metatype ), but the new changes to Proto work for pure Lua tables.

In principle, this should have no impact on all codes except Moments.lua since __gc is attached only when the class carries one, and no existing Proto children have __gc.

[ammarhakim]

@liangwang-phys can you put some print statements into the Proto code to see if the GC is actually being called. I remember trying this and there was some funky stuff and GC was never called explicitly. Do this in the unit tests for Proto. Once you determine that we can merge

[ammarhakim]

One other thing to do is see if the GC method is called in the Moment App. It should be simple to check.

[liangwang0734]

Diff:

diff --git a/App/Moments/Moments.lua b/App/Moments/Moments.lua
index ba9ad3e4..5a9b993e 100644
--- a/App/Moments/Moments.lua
+++ b/App/Moments/Moments.lua
@@ -1149,7 +1149,9 @@ App.init = function(self, tbl)
 end

 function App:__gc()
+   print("calling __gc on", self.app)
    C.gkyl_moment_app_release(self.app)
+   print("calling __gc done")
 end
 App.apply_ic = function(self)
    C.gkyl_moment_app_apply_ic(self.app, self.t0)

Results:

Main loop took 1.97284 secs to complete
calling __gc on cdata<struct gkyl_moment_app *>: 0x55f715c93240
calling __gc done