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Re: Interactive scripting with DB

by perrin (Chancellor)
on May 26, 2005 at 02:44 UTC ( [id://460491]=note: print w/replies, xml ) Need Help??


in reply to Interactive scripting with debugger

In my experience, most Perl programmers (in fact, most programmers) don't use the debugger at all.

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Re^2: Interactive scripting with DB
by tlm (Prior) on May 26, 2005 at 04:30 UTC

    It sure looks that way. I find it inexplicable... It's like writing Perl programs without ever using hashes: it is certainly possible, but why forgo the benefits of such a powerful tool?

    the lowliest monk

      You can count me in the "rarely use the debugger" school. I've always found using the Perl debugger is a process of frustration, I use win32 so it tends not to play nicely, but even when it isn't playing silly-buggers I still find it annoying. Its like inspecting a house through a keyhole, you never quite know how what you are looking at fits into the big picture. Ive also had far to much experience with code that has been "patched" from the debugger, and not well.

      I think the issue is that the debugger tells us "what" and usually the real problem involves a lot of "why". Debugging with print statements IMO tends to promote a holistic view of the program. Its necessary to have a good understanding of the program flow and processes to debug this way, and I think overall this promotes a better quality of programming. If you need to step through your code in a debugger to understand why it isnt doing the right thing then I think its not unreasonable to argue that your code is too complex and needs to be rethought. And such rethinking wont happen while you are in the debugger.

      I leave you with a quote by a famous programmer about why he doest much like debuggers. Admittedly the debugger/debugging he is talking about is kernal debugging, which is a somewhat specialized area but i think the points are valid nonetheless.

      I happen to believe that not having a kernel debugger forces people to think about their problem on a different level than with a debugger. I think that without a debugger, you don't get into that mindset where you know how it behaves, and then you fix it from there. Without a debugger, you tend to think about problems another way. You want to understand things on a different _level_.

      It's partly "source vs binary", but it's more than that. It's not that you have to look at the sources (of course you have to - and any good debugger will make that _easy_). It's that you have to look at the level _above_ sources. At the meaning of things. Without a debugger, you basically have to go the next step: understand what the program does. Not just that particular line.

      which is an excerpt from this posting by Linus Torvalds.

      ---
      $world=~s/war/peace/g

        You can count me in the "rarely use the debugger" school.

        Me too, but for entirely different reaons. I work with a number of different languages and environments. Not all of them will have debuggers (eg: javascript on AvantGo browser). Even if a debugger is available, each language will have its own debugger model with its own quirks and idiosynchrancies. I found that using print statements and conditional statements (eg: print $foo if $DEBUG>3 ) to be good enough in most cases, and more importantly cross platform and cross language (ie. the technique is, the syntax will not be).

      It's like writing Perl programs without ever using hashes: it is certainly possible, but why forgo the benefits of such a powerful tool?

      Because some people find they get more benefit using other techniques. See Are debuggers good? for a long vitriolic thread on this very topic :-)

      For example I personally find doing TDD a far more effective use of my time than spending time in the debugger. The mere fact that I need to drop into the debugger is a sign that I've fouled up earlier since I've obviously written code that is too hard for me to understand. The incidence of me using the debugger on my own code is as close to zero as makes no difference.

      About the only time I use the debugger now is when poking at other peoples code and doing exploratory testing, or maybe trying out a one liner.

        Snips from three notes above, with emphasis adjusted by me:

        In my experience, most Perl programmers (in fact, most programmers) don't use the debugger at all.
        but why forgo the benefits of such a powerful tool?
        Because some people find they get more benefit using other techniques.

        the debugger is a sign that I've fouled up earlier

        About the only time I use the debugger now is when poking at other peoples code and doing exploratory testing

        Do you see how you contradict your own argument and/or misunderstood the original point?

        Using the debugger need not be a sign that one doesn't know how to write code well. I guess there are people who use the debugger as a crutch and spend hours single-stepping through code aimlessly hoping to understand what they did wrong. I assume that because I've heard several people complain about such. I've never seen that. What I have often seen is someone wasting a lot of time trying to track down a problem when I can tell that this type of problem is likely easy to explore in a debugger and I would have found the problem quickly using a debugger.

        There are certainly stupid ways to try to use a debugger. And I still find that people who dislike debuggers are those who don't know how to use a debugger effectively. I like debuggers. I don't use them that often. But when I've used them, they were often invaluable. There are many bugs and non-bug problems that debuggers are not well suited for trying to solve. And sometimes it is hard to predict whether you've got a problem that a debugger will be useful against.

        But the debugger is a powerful tool and there are a lot of people (in my experience, the majority of programmers) who have never learned how to use this tool well (or even at all).

        - tye        

      There are no benefits. You're a dyslexic wondering why everyone isn't dyslexic.

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