These variables are read-only ...

I suspect that statement can be found at least back to 5.10 and maybe to 5.8.

I checked my local perlvar for the versions I have in captivity, 5.8-14, and this assertion is in each one. (I didn't bother to check all the on-line perlvar versions; I assume it's in all those as well.)

For all my initial shock at seeing an old, dear friend abused in this way, I'm not so sure | I do not think it's classifiable as a bug. After all,  $1 is just a symbol, and aliasing is supposed to enable one to treat one symbol exactly like another. That's what's going on in the for-loop: the perfectly mutable  @line array elements are successively aliased to the  $1 symbol, to which one can do anything it's kosher to do to an element of the array. One can see this here: 

c:\@Work\Perl>perl -wMstrict -le
"my @lines = (qq{foo\n}, qq{bar\n});
 print qq{[[@lines]]};
 ;;
 for $1 (@lines) {
   chomp $1;
   print qq{'$1'};
   }
 ;;
 print qq{[[@lines]]};
"
[[foo
 bar
]]
'foo'
'bar'
[[foo bar]]

[download]
Everything you would expect to happen to  @lines does happen. Similar code that does not alias  $1 still causes the compiler to barf as expected: 
c:\@Work\Perl>perl -wMstrict -le
"my @lines = (qq{foo\n}, qq{bar\n});
 ;;
 for my $ln (@lines) {
   $1 = $ln;
   chomp $1;
   print qq{'$1'};
   }
"
Modification of a read-only value attempted at -e line 1.

[download]
So I guess I have to say I'm happy with things as they are. (Update: Some men see things as they are and say "Well... Ok, then!")

Update: See "alias" in perlglossary.

Give a man a fish:  <%-(-(-(-<

In reply to Re^4: Getting an unknown error by AnomalousMonk
in thread Getting an unknown error by andybshaker

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