Re: "Safe" print?

[ambrus]

If you want undefined values printed as "undef", try

use 5.010;
print $somevalue // "undef";

[sundialsvc4]

... noting that the "//" operator is, IIRC, a relatively recent addition to the language.   You should have it, but you (or some backwater web-hosting companies who need not be named ...) conceivably might not.   See perldoc perlop on your system; look for the heading “C-style Logical Defined-Or.”

[ambrus]

See that first line in my the code? It says use 5.010;. The // operator was new in perl 5.10. It's not new anymore now.

[dd-b]

And that's right where I am (CENTOS 6 packaged Perl).

I know and heartily approve the "//" operator (except when I somehow get confused and use backslashes), but don't want to have to write special code each time I print something that I can't prove is defined quickly. However, the Dumper suggestion (and related) is useful, I'm just embarrassed I didn't think of it myself (that's for complex structures! In debugging!).

[LanX]

> ... noting that the "//" operator is, IIRC, a relatively recent addition to the language.

Googling perldelta defined-or quickly leads to http://perldoc.perl.org/5.10.0/perldelta.html#Defined-or-operator

(update: Perl 5.10.0 released Dec 2007)

So even if you ignore ambrus' use 5.010 there is no need to "IIRC" instead of checking!

> See perldoc perlop on your system; look for the heading “C-style Logical Defined-Or.”

see What shortcuts can I use for linking to other information?