Introduce helpers.setasyncall which simplifies calling of async wtype

Also add note about potential breakage on changing default symbol in volume_linux

Changes.md

@@ -1,12 +1,22 @@
-Feature:
+IMPORTANT:
 
-- Add `spawn.lua` as a fallback for `awful.spawn` in case Vicious is used as
+- `volume_linux` now uses 🔉 and 🔈 instead of ♫ and ♩ to show mute state.
+  This BREAKS backward compatibility if users substitute custom symbols
+  from these default.
+
+Added:
+
+- `spawn` as a fallback for `awful.spawn` in case Vicious is used as
   a stand-alone library. This wrapper, however, does NOT provide the facilities
   to asynchronously spawn new processes. It also lacks a few features such as
   parsing `stderr` and returning PID.
+- `helpers.setasyncall` to avoid writing redundant workers for asynchronous
+  widget types. Note that these workers are only needed in case Vicious is used
+  as a stand-alone library.
 
-Fixes:
+Fixed:
 
+- [volume_linux] Deprecate `io.popen`
 - [mpd] Lua 5.3 compatibility (for real this time); also correct a typo
 - [pkg,weather,contrib/btc] Allow function call without Awesome
 - [pkg] Use more updated front-ends for Debian/Ubuntu (apt) and Fedora (dnf)

helpers.lua

@@ -13,10 +13,7 @@ local rawget = rawget
 local require = require
 local tonumber = tonumber
 local tostring = tostring
-local io = { 
-    open = io.open, 
-    popen = io.popen 
-}
+local io = { open = io.open, popen = io.popen }
 local setmetatable = setmetatable
 local getmetatable = getmetatable
 local string = {
@@ -78,7 +75,7 @@ function helpers.wrequire(table, key)
             ret = value
             break
         end
-        not_found_msg = "module '"..name.."' not found"
+        local not_found_msg = "module '"..name.."' not found"
 
         -- ugly but there is afaik no other way to check if a module exists
         if value:sub(1, #not_found_msg) ~= not_found_msg then
@@ -93,6 +90,19 @@ function helpers.wrequire(table, key)
 end
 -- }}}
 
+-- {{{ Set __call metamethod to widget type table having async key
+function helpers.setasyncall(wtype)
+    local function worker(format, warg)
+        local ret
+        wtype.async(format, warg, function (data) ret = data end)
+        while ret == nil do end
+        return ret
+    end
+    local metatable = { __call = function (_, ...) return worker(...) end }
+    return setmetatable(wtype, metatable)
+end
+-- }}}
+
 -- {{{ Expose path as a Lua table
 function helpers.pathtotable(dir)
     return setmetatable({ _path = dir },

widgets/volume_linux.lua

@@ -5,7 +5,6 @@
 
 -- {{{ Grab environment
 local tonumber = tonumber
-local setmetatable = setmetatable
 local string = { match = string.match }
 local table  = { concat = table.concat }
 
@@ -25,7 +24,7 @@ local function parse(stdout, stderr, exitreason, exitcode)
     -- Capture mixer control state, e.g.        [  42    % ]   [  on    ]
     local volume, state = string.match(stdout, "%[([%d]+)%%%].*%[([%l]*)%]")
     -- Handle mixers without data
-    if volume == nil then return { 0, STATE.off } end
+    if volume == nil then return {} end
 
     if state == "" and volume == "0"    -- handle mixers without mute
        or state == "off" then           -- handle muted mixers
@@ -41,13 +40,6 @@ function volume_linux.async(format, warg, callback)
     spawn.easy_async("amixer -M get " .. table.concat(warg, " "),
                      function (...) callback(parse(...)) end)
 end
-
-local function worker(format, warg)
-    local ret
-    volume_linux.async(format, warg, function (volume) ret = volume end)
-    while ret == nil do end
-    return ret
-end
 -- }}}
 
-return setmetatable(volume_linux, { __call = function(_, ...) return worker(...) end })
+return helpers.setasyncall(volume_linux)