From a77e650c5fbbaf1c625a2616b7880529648e69b6 Mon Sep 17 00:00:00 2001
From: Emmanuel Lepage Vallee <elv1313@gmail.com>
Date: Sun, 13 Mar 2016 03:42:57 -0400
Subject: [PATCH] gears.object: Add a new "property fallback" object type

---
 lib/gears/object.lua            |   3 +-
 lib/gears/object/properties.lua | 103 ++++++++++++++++++++++++++++++++
 2 files changed, 105 insertions(+), 1 deletion(-)
 create mode 100644 lib/gears/object/properties.lua

diff --git a/lib/gears/object.lua b/lib/gears/object.lua
index 2eb230cd..9c21e681 100644
--- a/lib/gears/object.lua
+++ b/lib/gears/object.lua
@@ -9,8 +9,9 @@ local setmetatable = setmetatable
 local pairs = pairs
 local type = type
 local error = error
+local properties = require("gears.object.properties")
 
-local object = { mt = {} }
+local object = { properties = properties, mt = {} }
 
 --- Verify that obj is indeed a valid object as returned by new()
 local function check(obj)
diff --git a/lib/gears/object/properties.lua b/lib/gears/object/properties.lua
new file mode 100644
index 00000000..7d05ca86
--- /dev/null
+++ b/lib/gears/object/properties.lua
@@ -0,0 +1,103 @@
+---------------------------------------------------------------------------
+--- An helper module to map userdata __index and __newindex entries to
+-- lua classes.
+--
+-- @author Emmanuel Lepage-Vallee &lt;elv1313@gmail.com&gt;
+-- @copyright 2016 Emmanuel Lepage-Vallee
+-- @release @AWESOME_VERSION@
+-- @module gears.object.properties
+---------------------------------------------------------------------------
+
+local object = {}
+
+local properties = setmetatable({}, { __mode = 'k' })
+
+local function cobj_register(cobj)
+    local fallback = {}
+
+    function fallback:rawset(_, prop, val)
+        fallback[prop] = val
+    end
+
+    function fallback:rawget(_, prop)
+        return fallback[prop]
+    end
+
+    properties[cobj] = fallback
+    return fallback
+end
+
+--- Add the missing properties handler to a CAPI object such as client/tag/screen
+-- Valid args:
+--
+-- * **getter**: A smart getter (handle property getter itself)
+-- * **getter_fallback**: A dumb getter method (don't handle individual property getter)
+-- * **getter_class**: A module with individual property getter/setter
+-- * **getter_prefix**: A special getter prefix (like "get" or "get_" (default))
+-- * **setter**: A smart setter (handle property setter itself)
+-- * **setter_fallback**: A dumb setter method (don't handle individual property setter)
+-- * **setter_class**: A module with individual property getter/setter
+-- * **setter_prefix**: A special setter prefix (like "set" or "set_" (default))
+-- * **auto_emit**: Emit "property::___" automatically (default: false). This is
+--     ignored when setter_fallback is set or a setter is found
+--
+-- @param class A standard luaobject derived object
+-- @tparam[opt={}] table args A set of accessors configuration parameters
+function object.capi_index_fallback(class, args)
+    args = args or {}
+
+    local getter_prefix = args.getter_prefix or "get_"
+    local setter_prefix = args.setter_prefix or "set_"
+
+    local getter = args.getter or function(cobj, prop)
+        -- Look for a getter method
+        if args.getter_class and args.getter_class[getter_prefix..prop] then
+            return args.getter_class[getter_prefix..prop](cobj)
+        end
+
+        -- Make sure something like c:a_mutator() works
+        if args.getter_class and args.getter_class[prop] then
+            return args.getter_class[prop]
+        end
+
+        -- In case there is already a "dumb" getter like `awful.tag.getproperty'
+        if args.getter_fallback then
+            return args.getter_fallback(cobj, prop)
+        end
+
+        local fallback = properties[cobj] or cobj_register(cobj)
+
+        -- Use the fallback property table
+        return fallback[prop]
+    end
+
+    local setter = args.setter or function(cobj, prop, value)
+        -- Look for a setter method
+        if args.setter_class and args.setter_class[setter_prefix..prop] then
+            return args.setter_class[setter_prefix..prop](cobj, value)
+        end
+
+        -- In case there is already a "dumb" setter like `awful.client.property.set'
+        if args.setter_fallback then
+            return args.setter_fallback(cobj, prop, value)
+        end
+
+        local fallback = properties[cobj] or cobj_register(cobj)
+
+        -- Use the fallback property table
+        fallback[prop] = value
+
+        -- Emit the signal
+        if args.auto_emit then
+            cobj:emit_signal("property::"..prop, value)
+        end
+    end
+
+    -- Attach the accessor methods
+    class.set_index_miss_handler(getter)
+    class.set_newindex_miss_handler(setter)
+end
+
+return setmetatable( object, {__call = function(_,...) object.capi_index_fallback(...) end})
+
+-- vim: filetype=lua:expandtab:shiftwidth=4:tabstop=8:softtabstop=4:textwidth=80