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Re^7: Thx, St. Larry, for the Beauty of Sigils

by LanX (Cardinal)
on Jul 27, 2019 at 14:36 UTC ( #11103508=note: print w/replies, xml ) Need Help??


in reply to Re^6: Thx, St. Larry, for the Beauty of Sigils
in thread Thx, St. Larry, for the Beauty of Sigils

blah

Cheers Rolf
(addicted to the Perl Programming Language :)
Wikisyntax for the Monastery FootballPerl is like chess, only without the dice

  • Comment on Re^7: Thx, St. Larry, for the Beauty of Sigils

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Re^8: Thx, St. Larry, for the Beauty of Sigils
by shmem (Chancellor) on Jul 27, 2019 at 14:52 UTC
    blah

    sigh... "plain variables" are "named variables".

    $var = "Hello world!"; # \ @ary = qw(foo bar baz); # - plain %hash = qw(foo 1 bar 2 baz 3); # / $sref = \$var; # \ $aref = \@ary; # - references $href = \%hash; # /

    References which aren't references of plain (or named) variables are anonymous.

    E.g. we speak of $ary = [] as of an anonymous array which happens to be stored in the plain (or named) scalar variable $ary, be that stored in a symbol table or a pad.

    perl -le'print map{pack c,($-++?1:13)+ord}split//,ESEL'
      Well yes that's how it's implemented in Perl - and other languages like Python or JS too - but doesn't help comparing languages.

      They all store references into their "namespaces" or "lexical pads"

      Perl for instance does a *array= [1,2,3] to create a package variable accessible as @array

      Python and JS do essentially* the same thing!!!

      Only the syntax to access and operate those variables is different.

      the following is legal▓ JS code │

      >> $a = [1,2,3] Array(3) [ 1, 2, 3 ] >> $a[0] // Perl: $a->[0] 1 >> $b = $a Array(3) [ 1, 2, 3 ] >> $b[0]=666 // Perl $b->[0] = 666 666 >> $a Array(3) [ 666, 2, 3 ]

      and "anonymous" only refers to the literal [array] or {hash} constructors not to the scalar on the LHS of an assignment.

      The difference is not "named" or "unnamed", but explicit or implicit dereferencing.

      If anything, references are the "plain" fundamental thing..

      Cheers Rolf
      (addicted to the Perl Programming Language :)
      Wikisyntax for the Monastery FootballPerl is like chess, only without the dice

      ░) or scalars, but this can't be easily written *scalar = \1 is not the same thing

      *) JS has primitive values (read scalar) and objects (read blessed references), there is no explicit referencing only implicit.

      ▓) JS has no sigils $ is a legal part of an identifier to allow "machine translations", jQuery is messing with that.

      │) updated and extended

        Well yes that's how it's implemented in Perl - and other languages like Python or JS too - but doesn't help comparing languages.

        They all store references into their "namespaces" or "lexical pads"

        ...

        and anonymous" only refers to the literal array or {hash} constructors not to the scalar on the LHS of an assignment.

        perldata states:

        Values are usually referred to by name, or through a named reference.

        So the LHS in $ary = [1,2,3] is a named reference; it is a named variable. The RHS is an anonymous array, at least that is what is called throughout the perl documentation. So let's stick to that to avoid confusion.

        The difference is not "named" or "unnamed", but explicit or implicit dereferencing.

        Difference between languages, but not in perl.

        In perl, the scalar $ary may hold an anonymous array. But @ary is a named array. Perl does no implicit derefrencing, and so the syntax to access slots of the named array @ary necessarily has to be distinct from the one to access a slot of the anonymous array stored in the named scalar variable $ary - or of any anonymous array:

        my $result = [ func(@args) ]->[2];

        So in perl - at least that is how I understand perl for a couple of decades now - the difference is between named and anonymous variables. To get hold of an anonymous variable beyond a single statement, its reference has to be stored in a named scalar variable.

        But I'm not going on telling you stuff you know as well as I do, only to get reverse 'halb' back, and I won't argue any more, since there is no point but frustration. Let's close this sub-thread. Thank you.

        update

        ░) or scalars, but this can't be easily written *scalar = \1 is not the same thing

        Of course not, because that makes a reference from a constant. A variable reference is needed to make it variable:

        *scalar = \do { my $x = 1 };

        The expression *scalar = \"foo bar" creates a package constant (readonly package variable) $scalar (but *scalar = \"Hello $world" doesn't, it's r/w :-).

        perl -le'print map{pack c,($-++?1:13)+ord}split//,ESEL'

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