X-Git-Url: https://git.madduck.net/etc/awesome.git/blobdiff_plain/2d6b75a796ed12acc8aecf427d2eda1ba9b53b7d..8cde629906fd8d8e571fd519b3ca5ab3496ebbc1:/luatz/timetable.lua?ds=inline

diff --git a/luatz/timetable.lua b/luatz/timetable.lua
index 318bb63..f096372 100644
--- a/luatz/timetable.lua
+++ b/luatz/timetable.lua
@@ -1,3 +1,4 @@
+local strftime = require "luatz.strftime".strftime
 local strformat = string.format
 local floor = math.floor
 local function idiv ( n , d )
@@ -143,12 +144,20 @@ function timetable_methods:rfc_3339 ( )
 	return strformat ( "%04u-%02u-%02uT%02u:%02u:%06.3f" , self:unpack ( ) )
 end
 
-local strftime = require "luatz.strftime".strftime
 function timetable_methods:strftime ( format_string )
 	return strftime ( format_string , self )
 end
 
-local timetable_mt = {
+local timetable_mt
+
+local function coerce_arg ( t )
+	if getmetatable ( t ) == timetable_mt then
+		return t:timestamp ( )
+	end
+	return t
+end
+
+timetable_mt = {
 	__index    = timetable_methods ;
 	__tostring = timetable_methods.rfc_3339 ;
 	__eq = function ( a , b )
@@ -157,6 +166,9 @@ local timetable_mt = {
 	__lt = function ( a , b )
 		return a:timestamp ( ) < b:timestamp ( )
 	end ;
+	__sub = function ( a , b )
+		return coerce_arg ( a ) - coerce_arg ( b )
+	end ;
 }
 
 local function cast_timetable ( tm )
@@ -181,6 +193,9 @@ function timetable_methods:clone ( )
 end
 
 local function new_from_timestamp ( ts )
+	if type ( ts ) ~= "number" then
+		error ( "bad argument #1 to 'new_from_timestamp' (number expected, got " .. type ( ts ) .. ")" , 2 )
+	end
 	return new_timetable ( 1970 , 1 , 1 , 0 , 0 , ts )
 end