In addition to the 'pram' operator (also known as the Baby Cart From Hell operator), there's something like:

c:\@Work\Perl\monks>perl -wMstrict -le
"sub stars { return \ ('*' x $_[0]); }
 ;;
 my $str = qq{foo-${ stars(5) }-bar};
 print qq{'$str'};
"
'foo-*****-bar'
[download]

But why bother? Just use good old sprintf; that's what it's there for.

c:\@Work\Perl\monks>perl -wMstrict -le
"sub stars { return '*' x $_[0]; }
 ;;
 my $str = sprintf 'foo%s%sbar', stars(5), '=' x 7;
 print qq{'$str'};
"
'foo*****=======bar'
[download]

Update: Added sprintf example, Baby Cart WP link.