Front page | perl.perl5.porters |
Postings from August 2016
On Mon Aug 29 10:21:32 2016, colonel@monmouth.com wrote:
> I am using Perl 5.22.2 on a Fedora 23 x64 system. I am getting
> anomalous results interpolating a string variable before an
> apostrophe.
>
> #!/usr/bin/perl
>
> $v = 1;
> ${v's} = 23; # Is this legal?
> print "$v is equal to one.\n";
> print "$v-s equal to one.\n";
> print "$v's equal to one.\n";
>
> Since apostrophes are not "word" characters, I would expect
> the print statements to print the same value. Instead I get
> this:
>
> 1 is equal to one.
> 1-s equal to one.
> 23 equal to one.
>
> I do not see anything about this behavior in Wall-Christansen-
> Orwant or at the Monks. It looks to me like a bug. Is it?
>
> --George Sicherman
> colonel@monmouth.com
This is the expected behavior. From `perldoc perlvar`:
Variable names in Perl can have several formats. Usually, they must begin with a letter or underscore, in which case they can be arbitrarily long (up to an internal limit of 251 characters) and may contain letters, digits, underscores, or the special sequence :: or '. In this case, the part before the last :: or ' is taken to be a package qualifier; see perlmod.
`'` is a valid part of an identifier, just as `::` is, so they are respected while interpolating variables within double-quoted strings. `-` is not a valid part of an identifier - `${v-s}` is a syntax error, and `"$v-s"` is equivalent to `$v . "-s"`.
--
Respectfully,
Dan Collins
Thread Previous