Re^2: Perl Code Changes Behavior if Two Subroutine definitions are swapped

Hi Athanasius,

Thanks for your response.

Regarding the empty string. I tried running your example code using perl 5.10.1 and got following output:

OUTPUT WITH EXAMPLE CODE:

abc: matches 'bc'
def: matches 'de'
ghi: no match found
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So, somehow we get different outputs. Not sure why. Since in my case it tries to match with $_ when nothing is specified in switch(), I could not identify any issue with such use of switch and therefore I continued using it.

Thanks for mentioning things to take care as best practice about using empty arguments and next statements. I will try your suggestions and get back if the main issue persists. For now I am not going to use switch as it is not necessary for my code.

Best Regards,
Abhishek

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Re^3: Perl Code Changes Behavior if Two Subroutine definitions are swapped
by Athanasius (Archbishop) on Jul 28, 2016 at 09:57 UTC

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
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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,

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Re^4: Perl Code Changes Behavior if Two Subroutine definitions are swapped

by Anonymous Monk on Jul 28, 2016 at 10:22 UTC

Isnt switch noncore? I doubt perl version plays any part, aside from deparse version

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Re^3: Perl Code Changes Behavior if Two Subroutine definitions are swapped
by Cow1337killr (Monk) on Aug 02, 2016 at 00:44 UTC

Welcome, rkabhi.

Is there any particular reason why you are not running the latest version of Perl?

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