in reply to Re^2: Code Loop?
in thread Code Loop?

You could poison them with a tie to catch uses at runtime:

package Tie::Poison;
sub TIESCALAR {
...
}

sub TIEARRAY {
...
}

sub FETCH {
    my $var = tied $_[0];
    die "Prohibited variable '$$var' used";
}

package unusual_variable_names;
our @unusual = qw(
    @@
    @$
    ...    
);

sub unimport {
    for my $name (@unusual) {
        no strict 'refs';
        tie @{ $name }, 'Tie::Poison', $name;
    };
};

...

package main;
no unusual_variable_names;

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Re^4: Code Loop?
by LanX (Saint) on Aug 08, 2018 at 14:42 UTC
    yep but as you said it's only runtime.

    But it should be feasible to write a an op-code walker catching them at compile time in the UNITCHECK phase.

    D:\>perl -MO=Terse -E "use strict; say @@"
LISTOP (0x2820630) leave [1]
    OP (0x2820600) enter
    COP (0x2820670) nextstate
    LISTOP (0x2820700) say
        OP (0x28206d0) pushmark
        UNOP (0x2820740) rv2av [2]                      <-- array
            PADOP (0x2820778) gv  GV (0x1dede0) *@      <-- of glob *@
-e syntax OK

D:\>perl -MO=Concise -E "use strict; say @@"
7  <@> leave[1 ref] vKP/REFC ->(end)
1     <0> enter ->2
2     <;> nextstate(main 48 -e:1) v:%,*,&,{,x*,x&,x$,$,469764096 ->3
6     <@> say vK ->7
3        <0> pushmark s ->4
5        <1> rv2av[t2] lK/3 ->6                         <-- array
4           <#> gv[*@] s ->5                            <-- of glob *@
-e syntax OK

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

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