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Re: New feature proposal : <<>> to disable magic open of ARGV

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July 24, 2014 20:15
Re: New feature proposal : <<>> to disable magic open of ARGV
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On Fri, Jul 25, 2014 at 07:27:34AM +1200, Kent Fredric wrote:
> On 25 July 2014 05:13, Ricardo Signes <> wrote:
> > I like the feature, but I think it might be too small a change to pick up
> > a new
> > operator.  What about a pragma/feature?
> >
> +1 on pragma/featurizing it.
> I'm half of the mind that <> allowing pipe opens constitutes a kind of bug
> in itself.
> So a lexical pragma that turns on/off that behavior seems more sensible
> than new syntax, and once we do that, we can discuss whether or not the
> pragma should default on/off somehow in a future perl.

-1 here.

People don't like magic open because you can't see what you're getting.

Disabling this with a feature means, you're disabling it with something
you don't see.

   while (<>) {
       ...  # Magic open or not?

Whether or not it's a magic open is something you can't see locally. 
You'd have to scroll the file to see whether a feature is active or not.

   while (<<>>) {
       ... # Obvious

Note 1: I'm well aware this is not something specific about <>/<<>>, but
        that it's general uneasyness I have with features (or pragmas)
        controlling behaviour. It's often too much "action in a distance"
        for my liking. (Pragmas also means that whenever you explain something
        about a construct, you always have to put a disclaimer there about
        the pragmas affecting the construct -- it doesn't make it easier
        to learn or teach the language).

Note 2: Having said that, to eliminate the magicness of open(), we got 
        3-arg open(), instead of controlling it with a pragma.

Note 3: (To ease the feeling of the pumpkin): Instead of seeing '<<>>' as
        a new operator, just see it as the '<>' operator with a special
        cased operand.


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