Beefy Boxes and Bandwidth Generously Provided by pair Networks
Pathologically Eclectic Rubbish Lister

Comment on

( #3333=superdoc: print w/ replies, xml ) Need Help??
I agree with others' design suggestions. However, it is worth noting that it is possible to do exactly what you requested:
use warnings; use strict; my ($thing,$foo,$blah) = (1,2,3); my $done=0; while (!$done) { print "What would you like to know? "; $_=<>; chomp; if (/^exit$/) { $done=1; } else { my $result = eval "\$$_"; if ($@) { print "bad variable name\n"; } else { print "\$$_=$result\n";; } } }
Generally speaking, eval is not "good design". Why not? Because the user could type this:
What would you like to know? foo;system("any malicious command here")

You could make this somewhat safer by sanitizing your input, but it is still better to avoid eval in production code. Besides the security issue, it also makes for confusing, hard to maintain code.

Nevertheless, I wanted to point this out because it can be very useful, especially for the quick-and-dirty tasks that Perl handles so well.

When's the last time you used duct tape on a duct? --Larry Wall

In reply to Re: Using user input to return variable typed. by ColonelPanic
in thread Using user input to return variable typed. by myelinviolin

Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post; it's "PerlMonks-approved HTML":

  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.
  • Log In?

    What's my password?
    Create A New User
    and the web crawler heard nothing...

    How do I use this? | Other CB clients
    Other Users?
    Others lurking in the Monastery: (3)
    As of 2015-11-28 20:25 GMT
    Find Nodes?
      Voting Booth?

      What would be the most significant thing to happen if a rope (or wire) tied the Earth and the Moon together?

      Results (744 votes), past polls