You are also wrong about \%. \% means the sub requires a hash, not a hashref. 

>perl -le"sub f(\%) { print $_[0] }  f(\%h)"
Type of arg 1 to main::f must be hash (not reference constructor) at -
+e line 1, at end of line
Execution of -e aborted due to compilation errors.

>perl -le"sub f(\%) { print $_[0] }  f(%h)"
HASH(0x238be4)

[download]

A hashref is what the sub receives.

There is no prototype that will enforce what you desire (a scalar, an array and an optional hashref). Prototypes aren't good at validation.

In reply to Re^2: What's the better Perl style? Define parameters or not? by ikegami
in thread What's the better Perl style? Define parameters or not? by pureHeart

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