Yes, interpolation means double quoted string, regex metacharacters are still regex metacharacters
m/.$/ and m'.$' match the same string
$ perl -Mre=debug -e " $_ = 1234; m/.$/ "
Compiling REx ".$"
Final program:
1: REG_ANY (2)
2: EOL (3)
3: END (0)
anchored ""$ at 1 minlen 1
Matching REx ".$" against "1234"
3 <123> <4> | 1:REG_ANY(2)
4 <1234> <> | 2:EOL(3)
4 <1234> <> | 3:END(0)
Match successful!
Freeing REx: ".$"
$ perl -Mre=debug -e " $_ = 1234; m'.$' "
Compiling REx ".$"
Final program:
1: REG_ANY (2)
2: EOL (3)
3: END (0)
anchored ""$ at 1 minlen 1
Matching REx ".$" against "1234"
3 <123> <4> | 1:REG_ANY(2)
4 <1234> <> | 2:EOL(3)
4 <1234> <> | 3:END(0)
Match successful!
Freeing REx: ".$"
variables interpolate in double quoted strings but metachars are still metachars
$ perl -Mre=debug -e " $x = q{\d}; $f = 1234; $f =~ q{$x} "
Compiling REx "$x"
Final program:
1: EOL (2)
2: EXACT <x> (4)
4: END (0)
anchored "x" at 0 (checking anchored) minlen 1
Guessing start of match in sv for REx "$x" against "1234"
Did not find anchored substr "x"...
Match rejected by optimizer
Freeing REx: "$x"
$ perl -Mre=debug -e " $x = q{\d}; $f = 1234; $f =~ qq{$x} "
Compiling REx "\d"
Final program:
1: DIGIT (2)
2: END (0)
stclass DIGIT minlen 1
Matching REx "\d" against "1234"
Matching stclass DIGIT against "1234" (4 bytes)
0 <> <1234> | 1:DIGIT(2)
1 <1> <234> | 2:END(0)
Match successful!
Freeing REx: "\d"
$ perl -Mre=debug -e " $x = q{\d}; $f = 1234; $f =~ qq{\$x} "
Compiling REx "$x"
Final program:
1: EOL (2)
2: EXACT <x> (4)
4: END (0)
anchored "x" at 0 (checking anchored) minlen 1
Guessing start of match in sv for REx "$x" against "1234"
Did not find anchored substr "x"...
Match rejected by optimizer
Freeing REx: "$x"
$ perl -Mre=debug -e " $x = q{\d}; $f = 1234; $f =~ q{\$x} "
Compiling REx "\$x"
Final program:
1: EXACT <$x> (3)
3: END (0)
anchored "$x" at 0 (checking anchored isall) minlen 2
Guessing start of match in sv for REx "\$x" against "1234"
Did not find anchored substr "$x"...
Match rejected by optimizer
Freeing REx: "\$x"
