Thanks for the patch, but I don't think it makes sense:
> After numerous heated debates on comp.lang.perl.* here is my new
> improved answer for perlfaq4: expanding variables in strings.
I'm not sure it's "improved".
First, please adhere to the line wrapping used in the rest of the
document.
> -See also ``How can I expand variables in text strings?'' in this
> +See also ``How can I expand/interpolate variables in text strings?'' in this
> section of the FAQ.
I'm not sure the renaming makes sense.
> -=head2 How can I expand variables in text strings?
> -
> -Let's assume that you have a string like:
> +=head2 How can I expand/interpolate variables in text strings?
You've snipped the descriptive part.
> - $text = 'this has a $foo in it and a $bar';
> + $text = 'this has a $foo in it...\n ...and a $bar';
> + # Assume $text does not contain "\nEND\n"
> + chop ( $text = chop "<<END\n$text\nEND\n" );
> + die if $@;
What are you trying to do here?
> -If those were both global variables, then this would
> -suffice:
> +This is dangerous if the text comes form an untrusted source,
> +consider:
>
> - $text =~ s/\$(\w+)/${$1}/g; # no /e needed
> + $text = '@{[ system "rm -rf /" ]}';
Why did you remove the simple and safe example of inserting global
variables?
Also, the system example is overly complicated to use in the FAQ
without explaining it.
> -But since they are probably lexicals, or at least, they could
> -be, you'd have to do this:
> +If you only need to process simple scalars then you can do limit the
> +parts of the string that are passed to eval() like this:
>
> $text =~ s/(\$\w+)/$1/eeg;
> die if $@; # needed /ee, not /e
>
> -It's probably better in the general case to treat those
> -variables as entries in some special hash. For example:
> +This still gives unrestricted access to your scalar variables. It is
> +often better to use a hash:
I don't think this sentence is any clearer.
>
> %user_defs = (
> foo => 23,
> @@ -924,8 +928,8 @@
> );
> $text =~ s/\$(\w+)/$user_defs{$1}/g;
>
> -See also ``How do I expand function calls in a string?'' in this section
> -of the FAQ.
> +For other variations on the theme of text templates see the sprintf()
> +function and numerous modules on CPAN.
Why did you take out the reference?
