Re^4: substitute characters in the RHS of a search & replace

[AnomalousMonk]

... a generic function to simulate /r ...

Defining functions that take 'naked' subroutine blocks is, IMHO, one of the few valid reasons for using prototypes. However, there's a subtle pitfall here that belies the word 'generic' in the description of the function. The use of the  $ prototype causes behavior that will almost certainly cause puzzlement in a wider, i.e., more generic, context by imposing scalar context on its argument. Better, I think, to use  @ instead.

>perl -wMstrict -le
"sub rx (&$) {
   my $c_regex = shift;
   local $_ = shift;
   $c_regex->();
   return $_;
   }
 ;;
 my $s = 'a b c';
 print rx { s/ /_/g } $s;
 ;;
 my @ra = 'p q r';
 print rx { s/ /_/g } @ra;
"
a_b_c
1

>perl -wMstrict -le
"sub rx (&@) {
   my $c_regex = shift;
   local $_ = shift;
   $c_regex->();
   return $_;
   }
 ;;
 my $s = 'a b c';
 print rx { s/ /_/g } $s;
 ;;
 my @ra = 'p q r';
 print rx { s/ /_/g } @ra;
"
a_b_c
p_q_r

[LanX]

I think a call on @something should rather generate a warning instead of trying DWIM.

But no (good) idea how to implement that.

Maybe better iterate over all arguments and returning a list? something called rxmap maybe?

[AnomalousMonk]

Hmmm...     This is the best I could do, but it's a bit icky for Anonymonk's OPed application:

>perl -wMstrict -le
"sub rx (&@) {
   return map { local $_ = $_;  ()= $_[0]->();  $_; } @_[1..$#_];
   }
 ;;
 my $s = 'a b c d';
 print rx { s/ /_/g } $s;
 ;;
 my @ra = ('p q r', 'x y z z y');
 print rx { s/ /_/g } @ra;
 ;;
 my $x =
   q{Here are [[a [[ variable]] number [[of ]words]] in brackets};
 print qq{'$x'};
 ;;
 $x =~ s( \[\[ (.*?) \]\] )( (rx {s/ /_/g} $1)[0] )xmsge;
 print qq{'$x'};
"
a_b_c_d
p_q_rx_y_z_z_y
'Here are [[a [[ variable]] number [[of ]words]] in brackets'
'Here are a_[[_variable number of_]words in brackets'

Bottom line:  s///r is a lot nicer. Thanks again to whoever thought of that one.