From 2e815acb529159f5b6f0a4365a2eaf64d35330cc Mon Sep 17 00:00:00 2001
From: Nat Goodspeed <nat@lindenlab.com>
Date: Fri, 23 Aug 2024 21:28:03 -0400
Subject: Encapsulate the lazy submodule idiom as util.submoduledir().

---
 indra/newview/scripts/lua/require/UI.lua   |  9 +--------
 indra/newview/scripts/lua/require/util.lua | 19 +++++++++++++++++++
 2 files changed, 20 insertions(+), 8 deletions(-)

diff --git a/indra/newview/scripts/lua/require/UI.lua b/indra/newview/scripts/lua/require/UI.lua
index 2df70fd453..bbcae3514a 100644
--- a/indra/newview/scripts/lua/require/UI.lua
+++ b/indra/newview/scripts/lua/require/UI.lua
@@ -7,14 +7,7 @@ local util = require 'util'
 
 -- Allow lazily accessing UI submodules on demand, e.g. a reference to
 -- UI.Floater lazily loads the UI/Floater module.
-local UI = util.setmetamethods{
-    __index=function(t, key)
-        local mod = require('UI/' .. key)
-        -- cache the submodule
-        t[key] = mod
-        return mod
-    end
-}                               
+local UI = util.submoduledir({}, 'UI')
 
 -- ***************************************************************************
 --  registered menu actions
diff --git a/indra/newview/scripts/lua/require/util.lua b/indra/newview/scripts/lua/require/util.lua
index a000359226..40737a159a 100644
--- a/indra/newview/scripts/lua/require/util.lua
+++ b/indra/newview/scripts/lua/require/util.lua
@@ -92,4 +92,23 @@ function util.setmetamethods(specs)
     return t
 end
 
+-- On the passed module (i.e. table), set an __index metamethod such that
+-- referencing module.submodule lazily requires(path/submodule).
+-- The loaded submodule is cached in the module table so it need not be passed
+-- to require() again.
+-- 'path', like any require() string, can be relative to LuaRequirePath.
+-- Returns the enriched module, permitting e.g.
+-- mymod = util.submoduledir({}, 'mymod')
+function util.submoduledir(module, path)
+    return util.setmetamethods{
+        module,
+        __index=function(t, key)
+            local mod = require(`{path}/{key}`)
+            -- cache the submodule
+            t[key] = mod
+            return mod
+        end
+    }
+end
+
 return util
-- 
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