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Re^5: What operator should perl5porters use for safe dereferencing?

by BrowserUk (Pope)
on Jun 25, 2012 at 19:07 UTC ( #978244=note: print w/ replies, xml ) Need Help??


in reply to Re^4: What operator should perl5porters use for safe dereferencing?
in thread What operator should perl5porters use for safe dereferencing?

Your theory about skimming it seems to be dependent on the previous developer doing everything right. What if ~> was used by accident? What if it's in the wrong place of the expression?

I do not believe so.

In every accidental mis-usage scenario I can imagine, if the reference is undef, the result of the dereference expression will be undef, and so will trigger an undefined value warning the first time it is used.

Of course, the first usage my be remote from its generation, but tracing undefs back to their source is a common enough procedure in Perl now, and is hardly rocket science. I do not see the shape of the operator being a major factor either way.

I think the only way I can counter your premise, is to respond to example usage in-situ. And producing examples realistic enough to form the basis of serious discussion is very difficult.

You inevitably end up arguing about the validity of the example, rather than the merits of the case being presented.

In the end, I can only express my opinion along with everyone else's and counter what I see as bad arguments, in the hope of influencing those making the decision. Assuming it hasn't already been made.


With the rise and rise of 'Social' network sites: 'Computers are making people easier to use everyday'
Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error.
"Science is about questioning the status quo. Questioning authority".
In the absence of evidence, opinion is indistinguishable from prejudice.

The start of some sanity?


Comment on Re^5: What operator should perl5porters use for safe dereferencing?
Re^6: What operator should perl5porters use for safe dereferencing?
by phaylon (Curate) on Jun 25, 2012 at 19:30 UTC

    Oh, I didn't mean to counter all of your arguments with that point. It was more geared towards the visibility during scanning larger bodies of code. Especially that the general need to deal with the different behaviour would give a visual clue. This is what I would regard depending on that visual clue being there.

    With regard to undef hunting, I assume our typical day-to-day problems are just different. This is where I would really welcome a separate clue like a more distinguished operator. After all, undefined can also mean false, so a (remote) expression involving "~>" could very well result in valid, but unwanted behavior. At this point one might not even know that one is hunting undefined values.

    An additional scenario would be code reviews: I'd have to look much more closely to make sure nobody sneaks in a "~>" where it shouldn't be. This would even be for reviewing my own code. If I refactor a piece of code I have to pay more attention to the arrows.

    Just want to note that I don't regard your opinions as wrong, they just differ from mine. I hope I'm doing a half-way decent job at explaining why I hold these views :) Do you have anything against "?->" visually itself, or do you simply prefer "~>" for being more concise (or something else)?


    Ordinary morality is for ordinary people. -- Aleister Crowley
      I'd have to look much more closely to make sure nobody sneaks in a "~>" where it shouldn't be.

      Sorry, but that is a bit of a crock.

      ~> versus ->, is certainly no harder to "detect" than . versus ',', (or $l .v. $1, O .v. 0 etc.) and the results can be equally mysterious and damaging.

      If your font is unclear, use a proper programming font.

      If your eyesight is poor -- as mine is -- use a bigger font.

      Just want to note that I don't regard your opinions as wrong, they just differ from mine. I hope I'm doing a half-way decent job at explaining why I hold these views :)

      Ditto! (And you have:)

      Do you have anything against "?->" visually itself, or do you simply prefer "~>" for being more concise (or something else)?

      My eyes/brain have become used over the past 30 years or so to translating -> into points at, without conscious effort.

      In the smae way as you can raed tihs snetnce wihtupt dicffiluty dsetite the tpyos, I believe that I will be able to read $ref~>meth( $arg ) equally easily.

      However, I think that every time I encountered $ref?->meth( $arg ), that ? is going to stand out like a sore thumb, ring an alarm bell, and throw a brake on my flow.

      And given that the vast majority of the time, $ref~>meth( $arg ) will act exactly like $ref->meth( $arg ), that would be giving it a prominence that it simply does deserve or warrant. (IMO:)

      Stated the other way, I think that when you need to notice it, ~> is sufficiently different; but when you don't need to notice, it is sufficiently similar to ->, as to not cry wolf in your subconsciousness.


      With the rise and rise of 'Social' network sites: 'Computers are making people easier to use everyday'
      Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error.
      "Science is about questioning the status quo. Questioning authority".
      In the absence of evidence, opinion is indistinguishable from prejudice.

      The start of some sanity?

        As has been said earlier, it's very unpractical to change the font of every website, every editor, every email client, every IM, and so on, just to have the closeness not be a problem. Eyesight doesn't even come into it for me at this point :)

        And those examples you posted can be very problematic. They are exactly the cases why you need a good programming font that dashes the 0, gives "," bigger mass, and uses clever serifs. And I'd feel like this would just add another case. Maybe I read too much prose with inline code that isn't monospaced (and that I can easily slap my font on).

        I can see your point about the mental "points to" equivalency. I guess the "standing out like a sore thumb" is actually what I like about it. In my head "?->" reads as "(if possible (do what -> does))". So my mind basically wraps the "?" around the "->" (which is why I'd prefer the prefixed version over a postfixed one). And I'd like my brain to have it easy enough to always do that expansion quickly. It being a three-char operator helps me with that.

        Too bad we don't have something like a double-squiggly line in ASCII. That might be a good middle-ground.


        Ordinary morality is for ordinary people. -- Aleister Crowley

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