I tried running your example code using perl 5.10.1 and got following output...

Interesting. Experimenting with the Strawberry Perl versions I have on my system, it appears the change occurred between Perl 5.12.3 and 5.14.4. Running with -MO=Deparse reveals only one difference:

&Switch::switch();    # v5.12.3
vs.
&Switch::switch(());  # v5.14.4

[download]

And calling switch explicitly with an empty list — switch(()) — under 5.12.3 gives the same result as calling switch() under 5.14.4.

I’ve skimmed through the deltas, but so far haven’t found a plausible explanation. Possibly related to the change in handling the (;$) prototype,1 since that is the prototype of sub switch in the Switch module, but I don’t see how that would account for the observed behaviour. :-/

1See “Change in parsing of certain prototypes” in perl5140delta.

Cheers,

Athanasius <°(((>< contra mundum Iustus alius egestas vitae, eros Piratica,

In reply to Re^3: Perl Code Changes Behavior if Two Subroutine definitions are swapped by Athanasius
in thread Perl Code Changes Behavior if Two Subroutine definitions are swapped by rkabhi

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