you already got an explanation at your previous question, here: Re: Conditional initialization of my-variables (runtime)

concerning your code:

> 

    my $my_var = "default"
        unless defined $param;
    $my_var //= $param;

[download]

please try this instead

my $my_var = $param // "default";

Cheers Rolf
(addicted to the 𐍀𐌴𐍂𐌻 Programming Language :)
Wikisyntax for the Monastery

In reply to Re: Conditional initialization of lexical (my) variables by LanX
in thread Conditional initialization of lexical (my) variables by muthm

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