Re^5: Hash/Array slice : how to exclude items?

if you shy away from the overhead to return a new hash,

yes, that's one of my fetishes. But as you and hv said: do the printing in the block. It sounds a bit excessive but it seems a good candidate now, along with the slice-with-grep-keys. Given that I may use a number of "printers" : print, say, Dumper, Mojo::Log, then I would not want a special sub which hardcodes the logger.

One purpose of this post was to nudge Perl language developers to consider exclude-slices, with maximum elegance and minimum overhead (Logging like this happens every few lines of code for me). Btw, the negation with ! looks nice.

Btw2, is anyone aware of another language implementing this? I googled pithon and did not see something.

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Re^6: Hash/Array slice : how to exclude items?
by LanX (Saint) on Jan 25, 2023 at 14:26 UTC

> Btw, the negation with ! looks nice.

I'm not sure about this anymore, it's already legal syntax and could conflict with older code.

  DB<33> $h{!A}=1

  DB<34> $h{!(A)}=1

  DB<35> $h{!("A")}=1

  DB<36> x \%h
0  HASH(0x32dad38)
   '' => 1
  DB<37>
[download]

One could consider something like @h!{LIST}

  DB<40> @h!{"A"} = (1)
syntax error at ...
[download]

But still, is adding another obscure operation to Perl worth it?

> One purpose of this post was to nudge Perl language developers to consider exclude-slices, with maximum elegance and minimum overhead (Logging like this happens every few lines of code for me).

I think we need a meta discuss, what "good" syntax is.

"Elegance" alone doesn't help if the use case is so obscure that you never use it.

For instance I saw delete local SLICE before, but didn't remember or ever used it till now.

I'm a fan of orthogonality, the combination of syntax should be productive and easily predictive instead of being limited to isolated edge-cases.

This special case interferes somehow with Perl's lacking abilities for set-operations.

Probably a combined approach would be a better return of investment.

edit

Furthermore:

IMHO A named "speaking" operator like ->excl would be a better choice than investing into a short symbol like '!'.

Don't forget that various parsers like perl-tidy need to be updated if ! was introduced.

Cheers Rolf
_{(addicted to the 𐍀𐌴𐍂𐌻 Programming Language :)

Wikisyntax for the Monastery}

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