revise the naming function

README.md

@@ -131,8 +131,7 @@ If `cycle` is true, it then moves the window by cycling all regions.
 
 ### `name` as a function in `machi.layout.create`
 
-When passed in as a function, `name` takes the tag `t` and a boolean flag `p` and returns a function for the tag-dependent name of the layout.
-Flag `p` is set true when the name is used for persisting the layout. If the layout is not intented to persist, returning `nil` when `p` is true to skip persisting.
+When passed in as a function, `name` takes the tag `t` and returns (1) a string for the tag-dependent name of the layout, and (2) a boolean indicating the persistence of the layout.
 
 The default layout, `machi.default_layout`, uses the screen geometry and the tag name for name, thus allows the actual layout to be tag- and screen-dependent.
 To differentiate tags with the same name, you may need a more advanced naming function.

editor.lua

@@ -653,8 +653,8 @@ local function create(data)
                         -- bring the current cmd to the front
                         data.cmds[#data.cmds + 1] = current_cmd
 
-                        local instance_name = layout.machi_get_instance_name(tag, true)
-                        if instance_name ~= nil then
+                        local instance_name, persistent = layout.machi_get_instance_name(tag)
+                        if persistent then
                            data.last_cmd[instance_name] = current_cmd
                            if data.history_file then
                               local file, err = io.open(data.history_file, "w")

init.lua

@@ -3,13 +3,13 @@ local editor = require(... .. ".editor")
 local switcher = require(... .. ".switcher")
 local default_editor = editor.create()
 local default_layout = layout.create(
-   function (tag, _persist)
+   function (tag)
       if tag.machi_name_cache == nil then
          tag.machi_name_cache =
             tostring(tag.screen.geometry.width) .. "x" .. tostring(tag.screen.geometry.height) .. "+" ..
             tostring(tag.screen.geometry.x) .. "+" .. tostring(tag.screen.geometry.y) .. '+' .. tag.name
       end
-      return tag.machi_name_cache
+      return tag.machi_name_cache, true
    end,
    default_editor)
 local gcolor = require("gears.color")

layout.lua

@@ -51,14 +51,14 @@ local function create(name, editor)
    if type(name) == "function" then
       get_instance_name = name
    else
-      get_instance_name = function () return name end
+      get_instance_name = function () return name, true end
    end
 
    local function get_instance(tag)
-      local name = get_instance_name(tag, false)
+      local name, persistent = get_instance_name(tag)
       if instances[name] == nil then
          instances[name] = {
-            cmd = editor.get_last_cmd(name),
+            cmd = persistent and editor.get_last_cmd(name) or nil,
             regions_cache = {},
          }
       end