what is the use of derefernce in substitution?

tej has asked for the wisdom of the Perl Monks concerning the following question:

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Re: what is the use of derefernce in substitution? by moritz (Cardinal) on Sep 22, 2011 at 11:48 UTC
`${var}` and `$var` are the same thing in an interpolation. People use the first form if the next thing after it is an identifier: `say "${var}foo"; # interpolates $var, adds literal foo say "$varfoo"; # interpolates $varfoo` [download] So in your case there's no reason to write it, but it seems the author deemed the form with curlies safer. Perl 6 - second systems done right	[reply] [d/l] [select]
Re: what is the use of derefernce in substitution? by jwkrahn (Abbot) on Sep 22, 2011 at 11:45 UTC
In that example there is no difference between `${1}` or `${2}` and `$1` or `$2`. It could just as well be written as: `$text =~ s/(<jrnl;\d+;)[^>]*(>)/$1$annualIssue;$first\\N$last$2/gs;` [download]	[reply] [d/l] [select]
Re: what is the use of derefernce in substitution? by Kc12349 (Monk) on Sep 22, 2011 at 18:12 UTC
I, on occasion, do this in my code when adding a characters to an interpolated string, but generally there is a better way to do it. My preference is to concatenate variables individually instead of wrapping in double quotes. `my $string1 = 'test'; my $string2 = "${string1}append"; # my preference my $string3 = $string1 . 'append';` [download] In the case of replacements this approach could be replicated with the `/e` modifier. Which again is just my preference, but is what I would do in this case.	[reply] [d/l] [select]