20731 2013-01-22 11:51:16 +0000 Sequence algorithm seems incorrect 2013-01-22 17:24:20 +0000 1 1 1 Unclassified WebAppsWG WebIDL unspecified PC All RESOLVED INVALID P2 normal --- 1 w3c cam bzbarsky mike public-script-coord w3c public-webapps-bugzilla oldest_to_newest 81925 0 w3c 2013-01-22 11:51:16 +0000 Reading http://dev.w3.org/2006/webapi/WebIDL/#es-sequence Where the algorithm goes: " Let n be the result of calling ToUint32(length). Initialize S0..n−1 to be an IDL sequence with elements of type T, where each element is uninitialized. While i < n: Let P be the result of calling ToString(i). Let E be the result of calling [[Get]] on V with property name P. " P will just be "1", "2", "3", and so on, but not the actual property name. And hence E will just be undefined. 81931 1 bzbarsky 2013-01-22 13:07:56 +0000 What do you mean by "actual property name"? In ECMAScript, all property names are strings. So for example the array [ "a", "b" ] has properties named "0" and "1" (as well as "length"). 81932 2 w3c 2013-01-22 13:21:25 +0000 You are correct, but how does this work if the object passed is: {foo: "x", bar: "y"} 81933 3 bzbarsky 2013-01-22 13:25:13 +0000 Then it doesn't have indexed properties, right? And no length, either. So in terms of conversion to a sequence it's exactly the same as passing in the empty array []. 81938 4 w3c 2013-01-22 16:26:04 +0000 (In reply to comment #3) > Then it doesn't have indexed properties, right? And no length, either. So > in terms of conversion to a sequence it's exactly the same as passing in the > empty array []. ah, ok. In the case of [[Get]] length being ``undefined`` calling `ToUint32(length)` converts it to a +0. Thanks for clarifying, Boris. Closing as invalid. 81939 5 w3c 2013-01-22 16:49:45 +0000 Just one more minor thing (which may be JS implementation specific)... calling new Array(-1) causes Array to throw a "RangeError: Invalid array length", as happens in the following case: length = undefined; //Let n be the result of calling ToUint32(length). n = ToUint32(length); //0 //Initialize S[0..n−1] to be an IDL sequence with elements of type T, //where each element is uninitialized. S = new Array(n - 1); Does that matter? 81942 6 bzbarsky 2013-01-22 17:05:03 +0000 > S = new Array(n - 1); That line of code is just wrong, no? 81944 7 w3c 2013-01-22 17:08:43 +0000 (In reply to comment #6) > > S = new Array(n - 1); > > That line of code is just wrong, no? Dunno. I'm just doing what the spec says. 81947 8 bzbarsky 2013-01-22 17:12:30 +0000 No, you're not. You're passing in the wrong length. The correct thing to pass in is "n". 81950 9 w3c 2013-01-22 17:20:29 +0000 (In reply to comment #8) > No, you're not. You're passing in the wrong length. The correct thing to > pass in is "n". ah, got thrown by the "..n−1" bit. 81951 10 bzbarsky 2013-01-22 17:24:20 +0000 Right, the indices range from 0 to n-1.