From rongshenmd@gmail.com

perl6 rakudo 2016.11 match tries to assign to read-only variable, why not
in 2016.07?
<http://stackoverflow.com/questions/40970080/perl6-rakudo-2016-11-match-tries-to-assign-to-read-only-variable-why-not-in-201>
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up vote 2 down vote favorite
<http://stackoverflow.com/questions/40970080/perl6-rakudo-2016-11-match-tries-to-assign-to-read-only-variable-why-not-in-201?noredirect=1#>

I have the following method in an action class that worked well in Rakudo
2016.07, but I just installed 2016.11 and now the new Rakudo says my method
tries to assign to read-only varible, and I just don't see the problem​:

method ptName ($/) {
  my $nameStr = $/.Str, my $lastName, my $firstName;
  my $newMatch # this is line 182;
  # Cannot assign to a readonly variable or a value
  = $nameStr.match(/ \" (<alpha>+) .*? \, \s* (<alpha>+) .*? \" /);
  $lastName = $newMatch[0];
  $firstName = $newMatch[1];
  make "$lastName $firstName";
}

The whole error message is

Cannot assign to a readonly variable or a value
  in method ptName at /home/lisprog/Binary/grammar.pl line 182
  in regex ptName at /home/lisprog/Binary/grammar.pl line 151
  in regex TOP at /home/lisprog/Binary/grammar.pl line 137
  in block <unit> at /home/lisprog/Binary/grammar.pl line 217

What language spec has changed? Please help. Thanks.
match <http://stackoverflow.com/questions/tagged/match> readonly
<http://stackoverflow.com/questions/tagged/readonly> assign
<http://stackoverflow.com/questions/tagged/assign> perl6
<http://stackoverflow.com/questions/tagged/perl6> rakudo
<http://stackoverflow.com/questions/tagged/rakudo>
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asked 22 hours ago
<http://stackoverflow.com/users/4400590/lisprogtor>
lisprogtor <http://stackoverflow.com/users/4400590/lisprogtor>
1615

I vaguely recall something about this. What happens when you write method
ptName ($/ is copy) {? What about method ptName ($/ is rw) {? – raiph
<http://stackoverflow.com/users/1077672/raiph> 7 hours ago
<http://stackoverflow.com/questions/40970080/perl6-rakudo-2016-11-match-tries-to-assign-to-read-only-variable-why-not-in-201?noredirect=1#comment69180396_40970080>

Thank you raiph ! When I use ($/ is copy) on any $a=$someString.match(),
then the program runs, but fails to give meaningful $a[0] or $a[1]; when I
use ($/ is rw), then new error occurs and it says "Parameter '$/' expected
a writable container, but got Match value". I did not have this problem in
Rakudo 2016.07. I think something broke in 2016.11. Last time I tried to
report a bug, the email bounced back as undeliverable. Thanks. – lisprogtor
<http://stackoverflow.com/users/4400590/lisprogtor> 41 mins ago
<http://stackoverflow.com/questions/40970080/perl6-rakudo-2016-11-match-tries-to-assign-to-read-only-variable-why-not-in-201?noredirect=1#comment69186754_40970080>

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up vote 1 down vote accept

According to git blame src/core/Str.pm, lizmat worked on this in October.
Str.match will now fiddle with the lexical $/ of the calling block when it
apparently did not do so before.

As Str.match also returns a match object, there is no need to do so and
this might just be a bug. Either report it as such or ask in #perl6 on
Freenode about it.
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answered 22 hours ago
<http://stackoverflow.com/users/48015/christoph>
Christoph <http://stackoverflow.com/users/48015/christoph>
102k24123186

Thanks Christoph ! I am not sure what you mean by "no need to do so." –
lisprogtor <http://stackoverflow.com/users/4400590/lisprogtor> 35 mins ago
<http://stackoverflow.com/questions/40970080/perl6-rakudo-2016-11-match-tries-to-assign-to-read-only-variable-why-not-in-201?noredirect=1#comment69186901_40970413>

From @zoffixznet

Thank you for the report.

The current behaviour is correct. I wrote a more detailed answer on StackOverflow​:
http://stackoverflow.com/questions/40970080/perl6-rakudo-2016-11-match-tries-to-assign-to-read-only-variable-why-not-in-201/40998615#&#8203;40998615

P.S.​: in the future, please email bugs to rakudobug@​perl.org. I think the address you've used belongs to the Perl 5 queue.

Cheers,
ZZ

The RT System itself - Status changed from 'new' to 'open'

@zoffixznet - Status changed from 'open' to 'rejected'