It is the defined-or-equals operator. It assigns the RHS to the LHS only if the LHS is undefined. It is listed in perlop along with all the other operators.

Thanks, I was reading it wrong. I wouldn't say the documentation is particularly thick about it:

$ perldoc perlop | grep '//='
               .=    %=    ^=    ^.=           //=
$

[download]

, but I see why bliako uses it, and think I'll borrow the scheme.

In reply to Re^7: a *working* JSON module (Perl's Debugger), related issues by Aldebaran
in thread Can someone please write a *working* JSON module by cnd

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