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RCCService2021/ExtraContent/LuaPackages/AppTempCommon/Common/Action.lua

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+--[[
+    A helper function to define a Rodux action creator with an associated name.
+
+    Normally when creating a Rodux action, you can just create a function:
+
+        return function(value)
+            return {
+                type = "MyAction",
+                value = value,
+            }
+        end
+
+    And then when you check for it in your reducer, you either use a constant,
+    or type out the string name:
+
+        if action.type == "MyAction" then
+            -- change some state
+        end
+
+    Typos here are a remarkably common bug. We also have the issue that there's
+    no link between reducers and the actions that they respond to!
+
+    `Action` (this helper) provides a utility that makes this a bit cleaner.
+
+    Instead, define your Rodux action like this:
+
+        return Action("MyAction", function(value)
+            return {
+                value = value,
+            }
+        end)
+
+    We no longer need to add the `type` field manually.
+
+    Additionally, the returned action creator now has a 'name' property that can
+    be checked by your reducer:
+
+        local MyAction = require(Reducers.MyAction)
+
+        ...
+
+        if action.type == MyAction.name then
+            -- change some state!
+        end
+
+    Now we have a clear link between our reducers and the actions they use, and
+    if we ever typo a name, we'll get a warning in LuaCheck as well as an error
+    at runtime!
+]]
+
+return function(name, fn)
+    assert(type(name) == "string", "A name must be provided to create an Action")
+    assert(type(fn) == "function", "A function must be provided to create an Action")
+
+    return setmetatable({
+        name = name,
+    }, {
+        __call = function(self, ...)
+            local result = fn(...)
+
+            assert(type(result) == "table", "An action must return a table")
+
+            result.type = name
+
+            return result
+        end
+    })
+end