Shawn Corey am Montag, 16. Januar 2006 16.55:
> John Doe wrote:
> > The Ghost am Montag, 16. Januar 2006 06.34:
> >>I am storing text stings in a database. when I have the string:
> >>
> >>'some perl $variable'
> >>
> >>which would print as:
> >>
> >>some perl $variable
> >>
> >>how can I force interpolation of '$variable'?
> >>
> >>one idea I thought of was:
> >>#!/usr/bin/perl
> >>my $var='variable';
> >>$string='some $var';
> >>$string=~s/\$(\w+)/${$1}/gi;
> >>print "$string\n";
> >>
> >>But it doesn't work. I want it to print "some variable".
> >
> > One way is to change the regex a bit:
> >
> > #!/usr/bin/perl
> > use strict;
> > use warnings;
> >
> > my $var='variable';
> > my $other_var='another';
> > my ($string1, $string2, $string3)=map 'some $var $other_var', 1..3;
> >
> > # test1, test2, final version:
> > #
> > $string1=~s/(\$\w+)/$1/g;
> > $string2=~s/(\$\w+)/$1/ge;
> > $string3=~s/(\$\w+)/$1/gee;
> >
> > print join "\n", $string1, $string2, $string3;
> >
> >
> > greetings
> > joe
>
> Usually it is considered a bad idea to interpolate external strings. You
> could have your users printing any variable. Consider using sprintf
> instead (see `perldoc -f sprintf`).
>
> my $format = 'some perl %s';
> my $string = sprintf $format, $variable;
> print "$string\n";
As I understood "The Ghost", the starting point string already contains a
literal '$variable': 'some perl $variable'.
I do not know the bigger picture of his problem, but I think an extensible way
to replace a set of known names within a string by values would be (mirco
templating system):
===
#!/usr/bin/perl
use strict;
use warnings;
my %lookup=(
var=>'variable',
other_var=>'another',
);
sub err {warn q(Unkown name '), shift, qq(' found\n)}
my $string='some $var $other_var $unknown';
$string=~s
{ \$([a-zA-Z_]+) }
{ exists $lookup{$1} ? $lookup{$1} : do {err($1), ''} }gxe;
print $string;
===
# prints:
Unkown name 'unknown' found
some variable another
No interpolation involved, and the '$' sign preceding the names could be
another one.
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