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Re^8: Spot the bug

by Perl Mouse (Chaplain)
on Dec 22, 2005 at 01:50 UTC ( #518460=note: print w/replies, xml ) Need Help??


in reply to Re^7: Spot the bug
in thread Spot the bug

I think it would be better to bind lexically to the value myself.
What does "bind lexically to the value" mean?
Having some code you pulled in cause side effects is definitely not what most people think of as DWIW.
Well, perhaps not in a language like LISP or Haskell, but it's pretty hard to do something in Perl that doesn't have side-effects. Even looking at a value can change it (and hence, is a side-effect). Assignment is a side-effect. warn is a side-effect. Processing @ARGV is a side-effect. Reading from a handle is a side-effect.

People don't actually mind side-effects. In fact, most people will expect side-effects. What people don't like is unexpected side-effects. But I never advocated not telling what code does.

Perl --((8:>*

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Re^9: Spot the bug
by shotgunefx (Parson) on Dec 22, 2005 at 12:12 UTC
    I'm not agaist obvious and useful side effects (that's why I don't program in LISP, though I like some aspects of it).

    Personally, I don't consider your two examples as side effects (even though some would). The effect of warn and assigment is the intended effect. There could be other effects due to magic hanging off them, but that's another story.

    As far as lexically bound, I mean that it seems more intuitive to have the hash iterator block scoped.
      Personally, I don't consider your two examples as side effects
      I actually gave five examples of side effects (looking at a value, assignment, warn, processing @ARGV, reading from a handle).

      Now, you might not call them side-effects, but than you have a private definition of a side-effect. Using private definitions doesn't contribute to succesful communication.

      Perl --((8:>*
        I actually gave five examples of side effects (looking at a value, assignment, warn, processing @ARGV, reading from a handle).

        Well, you got me there. Shouldn't answer nodes right after rolling out of bed. Now, you might not call them side-effects, but than you have a private definition of a side-effect. Using private definitions doesn't contribute to succesful communication.

        I thought that was quite clear.
        Personally, I don't consider your two examples as side effects (even though some would)

        Yes from a language design standpoint, Perl is full of side effects. I'm talking about the expectations of people using Perl. Yes, it's a well know trap and easy to avoid.

        But it's non-intuitive and dare I say non-sensical. I'd be hard pressed to think of any situation were someone would want their loop iterations influenced transparently by code outside the current scope. Certainly that's what most people don't want the majority of the time. It doesn't follow expectation.


        -Lee

        perl digital dash (in progress)

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