What is a software engineer?
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From: David Mark on 15 Nov 2009 03:13 On Nov 15, 2:41 am, Garrett Smith <dhtmlkitc...(a)gmail.com> wrote: > David Mark wrote: > > On Nov 15, 1:35 am, Garrett Smith <dhtmlkitc...(a)gmail.com> wrote: > >> Richard Cornford wrote: > >>> David Mark wrote: > >>>> On Nov 14, 11:55 pm, Richard Cornford wrote: > >>>>> Richard Cornford wrote: > >>>>>> ... After all, you can show them the environments where > >>>>>> objects result in 'undefined'... > >>>>> That 'undefined' should have been 'unknown', but you probably > >>>>> figured that out already. > >>>> Actually, I thought you meant document.all in FF quirks mode. ;) > >>> Fair enough, that will do as your third example of a host object - > >>> typeof - oddity that can be stated. (Which reminds me, there is (or was, > >>> as it has been criticised) something in Safari that claims to be > >>> 'undefined' even though it can be shown to exist (be an object or > >>> function). I don't recall the detail, but I think Garrett may be in a > >>> position to say what it is (without looking it up in the ES 4/3.1 > >>> mailing list archives.)) > >> Was an SVG "filter" style property, as a string value:- > > >> typeof el.style.filter > > >> "undefined". > > >> javascript:var s=document.body.style;alert([typeof s.filter,"filter"in s]); > > >> elerts "undefined, true" > > And: > > javascript:var s=document.body.style;prompt('',[typeof s.filter, s]); > > results: > > undefined,[object CSSStyleDeclaration] > > > Right. The collection item method is IE and "string". So to sum up, > > typeof for native objects is specified and all known implementations > > follow the specification in this regard (and would be broken as > > designed otherwise). > > Ah, not completely. > > We recently discussed callable regexp. > > In Spidermonkey typeof /a/ results "object" (where it should, by > following the typeof table, result "function". This is because RegExp is > callable in Spidermonkey, using Function Call syntax as: > > /a/("a");// results ["a"] > > javascript: alert( /a/("a") ) > > elerts "a" Fair enough, but it is still within the specified range for native types.
From: Thomas 'PointedEars' Lahn on 15 Nov 2009 06:50 Richard Cornford wrote: > Thomas 'PointedEars' Lahn wrote: >> David Mark wrote: > <snip> >>> How about this one:- >>> >>> if (typeof xyz == 'array' || xyz instanceof Array) { >>> ... >>> } >>> >>> First test is _never_ true in an ECMAScript implementation. >> >> That is not quite correct. The first test could result in `true' >> in a conforming implementation of ECMAScript if `xyz' referred to >> a host object. But I doubt the person writing it was aware of >> that or even intended to meet the case. > <snip> > > That "could result in 'true'" is very much a theoretical possibility; A possibility nonetheless, which disproves the "never". Nothing more, nothing less. > a host object may result in any string when - typeof - is applied to it, That was my point. > but it is extremely rare that they do result in anything that is not > already in the ECMAScript list, and the exception ('unknown' in IE when > testing ActiveX objects, methods and properties) is literally the only > one that I have ever encountered, or heard tell off. [...] You appear to think that I said it would be a likely case; I did not. PointedEars -- Use any version of Microsoft Frontpage to create your site. (This won't prevent people from viewing your source, but no one will want to steal it.) -- from <http://www.vortex-webdesign.com/help/hidesource.htm> (404-comp.)
From: RobG on 15 Nov 2009 07:49 On Nov 15, 6:38 am, David Mark <dmark.cins...(a)gmail.com> wrote: > What is a software engineer? To me, an engineer is a skilled technical professional who is able to apply scientific knowledge to solve practical problems. [...] > Would you hang your hat on this? I've been asked by these engineers > to "prove" that this is a bad idea (I say the proof is right there in > the code). They say they've never _seen_ it fail. Empirical evidence is used to develop and support a theory, however the theory itself must have a scientific basis - that is, it must have a rational explanation that will predict behaviour in similar circumstances. Simply observing that something happens is just an observation of a fact, an experiment. Being able to repeat an experiment and achieve the same outcome every time doesn't prove anything other than that the experiment is repeatable, it doesn't provide any explanation of why the experiment "works", nor predict the likely outcome if the parameters are changed, nor provide any bounds within which it "works" or "fails". Without the explanation, there is no theory. There is no application of scientific knowledge, no understanding of why the result occurs. It is no more than faith - it's always worked before in their limited experience, therefore they expect it to always work. Anyone who performs work using such methods should be categorised as a trades person. They are certainly not professionals applying scientific theories or methods. They are not engineers. > For this one, I > don't know what that means (it's obviously designed to fail). So when > did programming becomes a process of gathering empirical evidence, as > opposed to understanding logic? Seems like browser scripting would be > the worst discipline for such a change in strategy. It is an extremely common strategy, encouraged by modern programming environments that attempt to improve productivity by offering features like IntelliSense, I call it programming by feel. If you dare challenge the methodology, you'll be told they don't have time to learn the language thoroughly, that they don't need to understand it as long as it works. The only explanation I have for why such programmers get away with it is because their programs are compiled and very few ever get to see the awfulness of the raw code. It seems that passing user acceptance testing is the sole criterion of quality, that the source code totally sucks is likely seen as a good way to make money on maintenance. -- Rob
From: Asen Bozhilov on 15 Nov 2009 07:59 Richard Cornford wrote: > That "could result in 'true'" is very much a theoretical possibility; a > host object may result in any string when - typeof - is applied to it, > but it is extremely rare that they do result in anything that is not > already in the ECMAScript list, and the exception ('unknown' in IE when > testing ActiveX objects, methods and properties) is literally the only > one that I have ever encountered, or heard tell off. You are rioght, but that behavior of `typeof' is not the same for whole ActiveXObject instances in IE. window.alert(typeof document.nodeType == 'unknown'); //false - typeof number window.alert(document instanceof ActiveXObject); //true var XHR = new ActiveXObject('Microsoft.XMLHTTP'); window.alert(typeof XHR.open == 'unknown'); //true window.alert(XHR instanceof ActiveXObject); //true
From: The Natural Philosopher on 15 Nov 2009 08:07
RobG wrote: > Empirical evidence is used to develop and support a theory, however > the theory itself must have a scientific basis - that is, it must have > a rational explanation that will predict behaviour in similar > circumstances. Simply observing that something happens is just an > observation of a fact, an experiment. Being able to repeat an > experiment and achieve the same outcome every time doesn't prove > anything other than that the experiment is repeatable, it doesn't > provide any explanation of why the experiment "works", nor predict the > likely outcome if the parameters are changed, nor provide any bounds > within which it "works" or "fails". However most of science is, in the *final* analysis, precisely what you describe. a set of propositions that may (or may not!) reflect an underlying reality, whose predictions have failed to ever be falsified by experiment, and whose propositions CAN in principle be falsified. And which actually add some value that competing theories do not. Cf Kuhn, Popper, Instrumentalism, et al. > > Without the explanation, there is no theory. There is no application > of scientific knowledge, no understanding of why the result occurs. It > is no more than faith - it's always worked before in their limited > experience, therefore they expect it to always work. Anyone who > performs work using such methods should be categorised as a trades > person. They are certainly not professionals applying scientific > theories or methods. They are not engineers. > :-) sadly, there are no final explanations for anything. will the sun rise tomorrow? Can't say really. It always HAS...whether that's because it obeys certain immutable laws of physics that we BELIEVE to be universal true (nay DEFINE to be universally true) or whether its because the Ngongobongo tribe absolutely do a special tribal dance every sunset to make sure it does, is a very moot point. Oh, and an explanation is not a theory, and certainly not a scientific theory, nor is a scientific theory an explanation. It is if you like, the expression of the result of a lot of experimental data in terms of an algorithm. In the same way that the reality of our perceptions is a compressed representation of all the salient features of all the data we are subjected to. E=mc^2 is a shorthand algorithm for calculating mass-energy relationships. That is borne out by observation. I am not sure it explains anything at all. Not in any fundamental way. Its just the expression of a constancy of relationship between certain elements of a world we have defined in certain precise terms. 'Because God wills it' is the ultimately irrefutable explanation for everything. That doesn't make it a scientific theory in any sense. A professional engineer is one who makes his living out of designing engines. HOW he does it, is really no part of what he is. Professional is no guarantee of quality. |