in reply to Re^3: Passing argument by reference (for a scalar)
in thread Passing argument by reference (for a scalar)

Same thing would happen if you did my $STRING = ${ +shift }; if you had passed a reference. If you don't want a copy, don't make a copy! (Also, don't use a 20 year old version of the language!) This was already all covered in detail. Including how what you claim happens hasn't been true for 10 years.

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Re^5: Passing argument by reference (for a scalar)
by Danny (Chaplain) on Sep 10, 2024 at 14:53 UTC
    I'm not familiar with ${ +shift }; syntax. It looks like the + is a way to interpret 'shift' as a command inside ${}. I'm not readily finding documentation for this. Where should I look?
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        Thanks!
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      > I'm not familiar with

      That's why I prefer

      ${ shift() }

      even if it needs one letter more.

      Cheers Rolf
      (addicted to the Perl Programming Language :)
      see Wikisyntax for the Monastery

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      + is the unary-+ operator. It does absolutely nothing but evaluate to the same thing its operand does. It even provides the same context as the one in which it's evaluated. 

      +5        # Same as `5`
+"abc"    # Same as `"abc"`
+@a       # Same as `@a`, in both scalar and list context

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      ${ shift } is just a weird undocumented way of writing $shift. I didn't want that. I wanted to use the shift operator. ${ +shift } can't be parsed as a scalar named +shift, so it has the desired effect.

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        A truly useful use of + is for constructing hashes with map: 
        my %hash = map +($_=>undef), @list;

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        Without the +, Perl would think you wanted to call map with 2 args, not over @list.
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