Beefy Boxes and Bandwidth Generously Provided by pair Networks
Do you know where your variables are?
 
PerlMonks  

Comment on

( #3333=superdoc: print w/ replies, xml ) Need Help??

If you want to know the name of a variable, you usually try to do something stupid. Most times, the answer is to use a hash instead. Also in this case, you can use a hash to get named parameters instead of positional parameters.

Something like this:

sub blah { my %args=(@_); foreach my $needed (qw( foo bar baz )) { exists $args{$needed} or die "blah() needs a $needed parameter +"; } # .... } blah(foo => 42, bar => "don't forget this", baz => 'oh!'); blah(foo => 42, baz => 'oh!'); # <-- will die()

Back to the "what's the name of the variable problem". What should a hypothetical nameThatVariable() function return for the following cases?

$foo=42; print nameThatVariable($foo); # '$foo', of course. $foo=[ 42 ]; print nameThatVariable($foo); # still '$foo'. @bar=( 42 ); print nameThatVariable(@bar); # '@bar', of course. $baz=$foo=\@bar; print nameThatVariable($foo); # 'reference to @bar' or '$foo'? print nameThatVariable($baz); # 'reference to @bar' or '$foo' or '$baz +' ? print nameThatVariable(\@bar); # 'reference to @bar'? print nameThatVariable(do { my $tmp=23 }); # '$tmp'? print nameThatVariable([ 23,45 ]); # ?

Alexander

--
Today I will gladly share my knowledge and experience, for there are no sweeter words than "I told you so". ;-)

In reply to Re: Can you find the name of a variable? by afoken
in thread Can you find the name of a variable? by pileofrogs

Title:
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!
  • 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
  • Outside of code tags, you may need to use entities for some characters:
            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?
    Username:
    Password:

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

    How do I use this? | Other CB clients
    Other Users?
    Others examining the Monastery: (6)
    As of 2014-11-29 00:38 GMT
    Sections?
    Information?
    Find Nodes?
    Leftovers?
      Voting Booth?

      My preferred Perl binaries come from:














      Results (200 votes), past polls