Clean up spawn and widget types using it

Changes.md

@@ -1,3 +1,16 @@
+Feature:
+
+- Add `spawn.lua` 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.
+
+Fixes:
+
+- [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)
+
 # Changes in 2.3.3
 
 Feature: Add battery widget type for OpenBSD

spawn.lua

@@ -52,7 +52,9 @@ local spawn = {}
 -- @treturn boolean|nil true if cmd terminated successfully, or nil otherwise
 function spawn.with_line_callback_with_shell(cmd, callbacks)
     local stdout_callback, stdout = callbacks.stdout, io.popen(cmd)
-    for line in stdout:lines() do stdout_callback(line) end
+    if stdout_callback then
+        for line in stdout:lines() do stdout_callback(line) end
+    end
     if callbacks.output_done then callbacks.output_done() end
 
     local success, reason, code = stdout:close()    -- this requires Lua 5.2

widgets/pkg_all.lua

@@ -4,8 +4,6 @@
 ---------------------------------------------------
 
 -- {{{ Grab environment
-local io = { popen = io.popen }
-local math = { max = math.max }
 local setmetatable = setmetatable
 local spawn = require("vicious.spawn")
 -- }}}

widgets/weather_all.lua

@@ -5,15 +5,12 @@
 
 -- {{{ Grab environment
 local tonumber = tonumber
-local io = { popen = io.popen }
 local setmetatable = setmetatable
 local math = { ceil = math.ceil }
 local string = { match = string.match }
 
--- Awesome library for spawning programs
 local spawn = require"vicious.spawn"
-
-local helpers = require("vicious.helpers")
+local helpers = require"vicious.helpers"
 -- }}}
 
 
@@ -23,7 +20,7 @@ local weather_all = {}
 
 
 -- {{{ Weather widget type
-local function parse(ws)
+local function parse(stdout, stderr, exitreason, exitcode)
     -- Initialize function tables
     local _weather = {
         ["{city}"]    = "N/A",
@@ -41,26 +38,26 @@ local function parse(ws)
     }
 
     -- Check if there was a timeout or a problem with the station
-    if ws == '' then return _weather end
+    if stdout == '' then return _weather end
 
     _weather["{city}"]    = -- City and/or area
-       string.match(ws, "^(.+)%,.*%([%u]+%)") or _weather["{city}"]
+       string.match(stdout, "^(.+)%,.*%([%u]+%)") or _weather["{city}"]
     _weather["{wind}"]    = -- Wind direction and degrees if available
-       string.match(ws, "Wind:[%s][%a]+[%s][%a]+[%s](.+)[%s]at.+$") or _weather["{wind}"]
+       string.match(stdout, "Wind:[%s][%a]+[%s][%a]+[%s](.+)[%s]at.+$") or _weather["{wind}"]
     _weather["{windmph}"] = -- Wind speed in MPH if available
-       string.match(ws, "Wind:[%s].+[%s]at[%s]([%d]+)[%s]MPH") or _weather["{windmph}"]
+       string.match(stdout, "Wind:[%s].+[%s]at[%s]([%d]+)[%s]MPH") or _weather["{windmph}"]
     _weather["{sky}"]     = -- Sky conditions if available
-       string.match(ws, "Sky[%s]conditions:[%s](.-)[%c]") or _weather["{sky}"]
+       string.match(stdout, "Sky[%s]conditions:[%s](.-)[%c]") or _weather["{sky}"]
     _weather["{weather}"] = -- Weather conditions if available
-       string.match(ws, "Weather:[%s](.-)[%c]") or _weather["{weather}"]
+       string.match(stdout, "Weather:[%s](.-)[%c]") or _weather["{weather}"]
     _weather["{tempf}"]   = -- Temperature in fahrenheit
-       string.match(ws, "Temperature:[%s]([%-]?[%d%.]+).*[%c]") or _weather["{tempf}"]
+       string.match(stdout, "Temperature:[%s]([%-]?[%d%.]+).*[%c]") or _weather["{tempf}"]
     _weather["{dewf}"]    = -- Dew Point in fahrenheit
-       string.match(ws, "Dew[%s]Point:[%s]([%-]?[%d%.]+).*[%c]") or _weather["{dewf}"]
+       string.match(stdout, "Dew[%s]Point:[%s]([%-]?[%d%.]+).*[%c]") or _weather["{dewf}"]
     _weather["{humid}"]   = -- Relative humidity in percent
-       string.match(ws, "Relative[%s]Humidity:[%s]([%d]+)%%") or _weather["{humid}"]
+       string.match(stdout, "Relative[%s]Humidity:[%s]([%d]+)%%") or _weather["{humid}"]
     _weather["{press}"]   = -- Pressure in hPa
-       string.match(ws, "Pressure[%s].+%((.+)[%s]hPa%)") or _weather["{press}"]
+       string.match(stdout, "Pressure[%s].+%((.+)[%s]hPa%)") or _weather["{press}"]
 
     -- Wind speed in km/h if MPH was available
     if _weather["{windmph}"] ~= "N/A" then
@@ -91,8 +88,8 @@ function weather_all.async(format, warg, callback)
     -- Get weather forceast by the station ICAO code, from:
     -- * US National Oceanic and Atmospheric Administration
     local url = ("https://tgftp.nws.noaa.gov/data/observations/metar/decoded/%s.TXT"):format(warg)
-    local cmd = "curl -fs " .. url
-    spawn.easy_async(cmd, function (stdout) callback(parse(stdout)) end)
+    spawn.easy_async("curl -fs " .. url,
+                     function (...) callback(parse(...)) end)
 end
 
 local function worker(format, warg)