title: Is there a way to test if a scalar has been stringified or not?
body: <p>I am writing a thing to output something similar to JSON, from a perl structure.  I want the quoting to behave like this:</p>
  
  <pre><code>"string" outputs "string"
  "05" outputs "05"
  "5" outputs "5"
  5 outputs 5
  05 outputs 5, or 05 would be acceptable
  </code></pre>
  
  <p>JSON::XS handles this by testing if a scalar has been "stringified" or not, which I think is very cool.  But I can't find a way to do this test myself without writing XS, which I'd rather avoid.  Is this possible?  I can't find this anywhere on CPAN without finding vast pedantry about Scalar::Util::looks_like_number, etc which completely isn't what I want.  The only stopgap I can find is Devel::Peek, which feels evil.  And also, just like JSON::XS, I'm fine with this secenario:</p>
  
  <pre><code>my $a = 5;
  print $a."\n";
  # now $a outputs "5" instead of 5)
  </code></pre>