create command environments

init.lua

@@ -1,22 +1,106 @@
+local MODNAME = core.get_current_modname()
+
+local api = {}
+_G[MODNAME] = api
+
+-- per-player persistent environments
+api.e = {}
+
+
+local function create_global_environment(player_name)
+    local me = core.get_player_by_name(player_name)
+    local magic_keys = {
+        me = function()
+            return core.get_player_by_name(player_name)
+        end,
+        my_pos = function()
+            local pos = here
+            if me:is_player() then
+                pos = me:get_pos()
+            end
+            return pos
+        end,
+        this_obj = function()
+        end,
+        this_node = function()
+        end,
+    }
+
+    local g = {}
+    local eval_env = setmetatable(
+        {
+            my_name = player_name,
+            here = here,
+        },
+        {
+            __index = function(self, key)
+                local res = rawget(_G, key)
+                if res == nil then
+                    local magic = magic_keys[key]
+                    if magic then
+                        return magic()
+                    elseif not g[key] then
+                        core.chat_send_player(player_name, string.format("* Accessing undeclared variable: '%s'", key))
+                        g[key] = true
+                    end
+                end
+                return res
+            end
+        }
+    )
+    return eval_env
+end
+
+
+local function create_command_environment(player_name)
+    local global_env = api.e[player_name]
+    if not global_env then
+        global_env = create_global_environment(player_name)
+        api.e[player_name] = global_env
+    end
+
+    local me = core.get_player_by_name(player_name)
+    local here = me:get_pos()
+    local cmd_env = {
+        here = here,
+    }
+    setmetatable(
+        cmd_env,
+        {
+            __index = global_env,
+            __newindex = global_env,
+        }
+    )
+    return cmd_env
+end
+
+
 core.register_chatcommand("eval",
     {
         params = "<code>",
         description = "Execute and dump value into chat",
         privs = { server = true },
-        func = function(name, param)
+        func = function(player_name, param)
             if param == "" then
                 return false, "Gib code pls"
             end
-            local code = "return " .. param
+            local code = param
+            if code:sub(1, 1) == "=" then
+                code = "return " .. code:sub(2)
+            end
 
             -- echo input back
-            core.chat_send_player(name, "> " .. code)
+            core.chat_send_player(player_name, "> " .. code)
 
             local func, err = loadstring(code, "code")
             if not func then
                 return false, err
             end
 
+            local env = create_command_environment(player_name)
+
+            setfenv(func, env)
+
             local coro = coroutine.create(func)
 
             local ok