Re: Missing NullPointerException

[Konrad Bucheli via perl6-users]

The returned Nil aka bug was from my side. But when debugging it took me a while to find the culprit because when the statement with the chained methods was executed I expected all of them being executed...

So that was a bit of a surprise.

Thanks for the insights!

On 03.12.20 23:25, Elizabeth Mattijsen wrote:

Nil is really a Failure that doesn't throw.  It indicates the absence of a 
value where there is one expected.

That is why Nil doesn't throw.  If you want to indicate a soft failure, you 
should use fail().

If the chain of methods you mention are core methods, and one of them is 
returning Nil, then perhaps we have a bug.  Could you elaborate on the 
situation where you encountered this?

On 3 Dec 2020, at 15:22, Konrad Bucheli via perl6-users <perl6-us...@perl.org> 
wrote:



On 02.12.20 15:55, Ralph Mellor wrote:

On Wed, Dec 2, 2020 at 7:08 AM Patrick R. Michaud <pmich...@pobox.com> wrote:

Nil.any_non_existent method always seems to return Nil.  I'm not sure where 
this is documented

It's near the top of the `Nil` doc page you linked:

Any method call on `Nil` of a method that does not exist ... will succeed and 
return `Nil`.

OK, that is intentional and documented then. What is actually the rationale for 
such a behaviour?

For me it was an unexpected trap as I had a chain of methods which should do 
some side effect. It all went fine only the side effect was not there. I then 
figured out after some time that one of methods returned Nil and somehow 
silently it did not do what I expected.

Thanks

Konrad

--
Konrad Bucheli
Systems Engineering Fellow

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W.  open-systems.com

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