Re: delete of nested array is in consistent

[Peng Yu]

I think the main problem is that "delete" should not be used for
initialisation an array. Once you try to mix up two things into one
keyword, it becomes confusing.

If there were a keyword like `inita`, it becomes clearer what it
means. Hence, the awk implementation should be cleaner as well because
it will not have a conflict with the existing "delete" implementation.

inita a[""]
inita a[""][""]
inita a[""][""][""]

On 4/19/20, address@hidden <address@hidden> wrote:
> You are, of course, welcome to your opinion.  But simply stating
> it on the bug list is not actually going to effect any changes.
>
> Here is an incomplete list of possible things you might do to change
> things:
>
> A. Switch from gawk to Python for all your programming. This is
> recommended.
>
> B. Failing (A), learn C, read the gawk code, and develop a patch to
> submit for review.
>
> C. Failing (B), find someone else to do that for you.
>
> D. Failing (C), talk to me offline about my consulting rates.
>
> Arnold
>
> Peng Yu <address@hidden> wrote:
>
>> I feel if `delete a[“”]` can initialize the array, it should be intuitive
>> to support `delete a[1][“”]` as well. The definition of the language
>> should
>> be separated from the difficulties in the implementation.
>>
>> On Fri, Apr 17, 2020 at 8:46 AM <address@hidden> wrote:
>>
>> > I poked at this in a debugger. Basically for
>> >
>> >         BEGIN { delete a[1][""]; print typeof(a[1]) }
>> >
>> > a[1] never existed as a defined array, just as a[1][""] doesn't have
>> > any
>> > value associated with it.  Thus the delete effectively does nothing.
>> >
>> > So, when typeof() is called on a[1], it reports undefined, since no
>> > direct
>> > assignment was ever made to it.
>> >
>> > Andy's suggestion:
>> >
>> >         BEGIN { a[1][""]; delete a[1][""]; print typeof(a[1]) }
>> >
>> > is the right way to go to force gawk to create a[1] and make it
>> > into an array.
>> >
>> > Forcing that creation from within the delete statement is way too
>> > hard to do, and definitely much less clear at the awk level as to
>> > what's going on anyway.
>> >
>> > Arnold
>> >
>> > "Andrew J. Schorr" <address@hidden> wrote:
>> >
>> > > On Fri, Apr 17, 2020 at 01:26:17AM -0600, address@hidden wrote:
>> > > > Peng Yu <address@hidden> wrote:
>> > > >
>> > > > > See below. I'd expect the second one should also print array. Is
>> > > > > it
>> > a bug?
>> > > > >
>> > > > > $ awk -e 'BEGIN { delete a[""]; print typeof(a) }'
>> > > > > array
>> > > > > $ awk -e 'BEGIN { delete a[1][""]; print typeof(a[1]) }'
>> > > > > unassigned
>> > > > >
>> > > > > --
>> > > > > Regards,
>> > > > > Peng
>> > > >
>> > > > Upgrade your version of gawk:
>> > > >
>> > > > $ ./gawk --version | sed 2q
>> > > > GNU Awk 5.1.0, API: 3.0 (GNU MPFR 4.0.1, GNU MP 6.1.2)
>> > > > Copyright (C) 1989, 1991-2020 Free Software Foundation.
>> > > > $ ./gawk 'BEGIN { delete a[""]; print typeof(a) }'
>> > > > array
>> > > > $ ./gawk 'BEGIN { delete a[1][""]; print typeof(a) }'
>> > > > array
>> > >
>> > > Actually, in latest gawk, his second example still says unassigned:
>> > >
>> > > bash-4.2$ ./gawk --version | head -1
>> > > GNU Awk 5.1.0, API: 3.0 (GNU MPFR 3.1.1, GNU MP 6.0.0)
>> > > bash-4.2$ ./gawk 'BEGIN { delete a[1][""]; print typeof(a[1]) }'
>> > > unassigned
>> > >
>> > > This gives the desired outcome:
>> > > bash-4.2$ ./gawk 'BEGIN { a[1][""]; delete a[1][""]; print
>> > > typeof(a[1])
>> > }'
>> > > array
>> > >
>> > > Regards,
>> > > Andy
>> >
>> > --
>> Regards,
>> Peng
>


-- 
Regards,
Peng