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Re^2: Modules to reduce syntax?

by LanX (Sage)
on Dec 22, 2021 at 14:44 UTC ( #11139833=note: print w/replies, xml ) Need Help??


in reply to Re: Modules to reduce syntax?
in thread Modules to reduce syntax?

It's not clear to me what you want, since your code is wrong.

Here the correct analogous:

$ref->{foo}{$bar}

(NB: autoquoting of key "foo" !)

is

demo in the JS console

>> ref={foo: {x:42}} Object { foo: {} } >> bar="x" "x" >> ref.foo[bar] 42 >> ref['foo'][bar] 42

as a side note, $ is a legal identifier in JS so you can also write

>> $ref={foo: {x:42}} Object { foo: {} } >> $ref['foo'][$bar] 42

update

demo in the Perl debugger

DB<3> $ref = {foo=> { x => 42 } } DB<4> $bar = "x" DB<5> p $ref->{foo}{$bar} 42 DB<6> p $$ref{foo}{$bar} 42

update

DB<11> use experimental 'refaliasing'; \%ref = $ref DB<12> p $ref{foo}{$bar} 42

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

Replies are listed 'Best First'.
Re^3: Modules to reduce syntax? (joining namespaces)
by LanX (Sage) on Dec 22, 2021 at 22:28 UTC
    You can't get rid of the sigils $%@ in Perl, because of conflicts with barewords which have many other meanings and the many bultin commands which depend on sigils.

    But this last example of aliasing a list-form and hashref-form \%hsh = $hsh could be simplified, such that the deref -> isn't needed anymore.

    use Keyword::Simple to define a new command like e.g. var or let and any

    var %hsh = LIST;

    is translated to

    my $hsh = \ my %hsh; %hsh = LIST;

    This is not too hard to implement, because you don't need to parse LIST in advance (which could be arbitrary Perl code)

    Like this explicit dereferencing with -> would be "simplified" away.

    Demo:

    DB<27> sub LIST { foo => { x => 42 } } DB<28> $bar ='x' DB<29> my $hsh = \ my %hsh; %hsh = LIST; \\ cont: say $hsh{foo}{$bar} 42

    Of course that way you'd loose the ability to have $ident and %ident in different namespaces, but that's often considered bad style anyway.

    And passing of hash-refs, like with function-parameters wouldn't be that easy without additional \ref-operation

    sub func { var (\%hsh,\@arr) = @_; }

    because otherwise var couldn't tell if a $scalar is meant to be aliased to a %hash or an @array

    sub func { var ($hsh,$arr) = @_; # ??? }

    tho you might be able simplify the syntax in many cases with

    sub func { var \(%hsh,@arr) = @_; }

    HTH! :)

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

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