I actually would have expected it to interpolate as you describe :)

If you have a newline in $deCommafied, there certainly will be an effect; anything after the newline isn't part of the comment: 

$ perl -wle'use re "debug"; $x = "foo\nbar"; qr/(?x)hullo #there $x/'
Compiling REx `(?x)hullo #there foo
bar'
size 4 Got 36 bytes for offset annotations.
first at 1
   1: EXACT <hullobar>(4)
   4: END(0)
anchored `hullobar' at 0 (checking anchored isall) minlen 8
Offsets: [4]
        5[20] 0[0] 0[0] 25[0]
Freeing REx: `"(?x)hullo #there foo)\nbar"'

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FWIW, using qr{ ... }x; instead of qr{(?x) ... }; seems to do what you expect. But I'd try to avoid relying on that. Also watch out for having your end-quote character ('}' in your example) in the comment.

In reply to Re: A variable name in a regex comment triggers a warning by ysth
in thread A variable name in a regex comment triggers a warning by johngg

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