function returning an array in GAWK?

[Kenny McCormack]

I noticed today that you can't return an array as the value of a
function in GAWK. FWIW, this works in TAWK, but not GAWK:

function foo(s) {split(s,A);return A}
BEGIN { x = foo("the quick brown fox");for (i in x) print i,x[i] }

Error message in GAWK is "array used in scalar context" on the "return A"
line. I'm just curious - how intentional is this limitation?
Is there any particular reason for it to not work?

Tested in GAWK 3.1.4 - maybe fixed in later versions?

[Grant]

AFAIK it's not a bug (it's a gawk feature), so I treat array name as global
'cause the name is 'tainted' once used for array, no longer usable as scalar.

Grant.

[Ed Morton]

You could argue that returning an array is bad design since it overloads the
return from the function with the array contents plus an indication of
success/fail (which itself might be overloaded as a count of array entries). In
this specific case, a better design for the function might be:

awk 'function foo(s,A, c) {c=split(s,A); return c}
BEGIN { n = foo("the quick brown fox",x);for (i=1;i<=n;i++) print i,x[i] }'
1 the
2 quick
3 brown
4 fox

I think I could get behind the argument that any function you want to return an
array would actually be better designed as a function that populates the array
as a parameter and returns the number of elements in that array.

Ed.

[Anton Treuenfels]

"Ed Morton" <morto...@gmail.com> wrote in message
news:hndmu1$er4$1...@news.eternal-september.org...

Hey, I do that, even in TAWK! Not always, but this specific case is one
example. I have a custom split() that breaks up strings on whitespace, but
NOT if the whitespace is within a literal string or escaped. A passed-in
name is populated as an array, and the function itself returns the number of
items found.

However there are also plenty of times I return an array directly. You're
right in that this makes error conditions harder to detect. Sometimes I set
a global flag. Other times I return different types and rely on
run-time-type-identification (RTTI) to indicate what happened.

Although I've had minor problems with that in TAWK 5, which occasionally
seems to mess with types during function calls in ways that TAWK 4 never
does. Integers somehow becoming floats, IIRC.

- Anton Treuenfels

[Aharon Robbins]

In article <hndhg4$r1r$1...@news.xmission.com>,

Historical awk didn't have arrays as return values and so neither
does gawk. I don't see a major reason to add it; it's better
to pass in an array to be populated.

I also think that the gawk code is fragile enough that trying
to do this isn't a good idea in any case.

Thanks,

Arnold

P.S. You should move to 3.1.7 or CVS gawk-stable. 3.1.4 is pretty old.
--
Aharon (Arnold) Robbins arnold AT skeeve DOT com
P.O. Box 354 Home Phone: +972 8 979-0381
Nof Ayalon Cell Phone: +972 50 729-7545
D.N. Shimshon 99785 ISRAEL

[Kenny McCormack]

In article <hngt2t$gg8$1...@news.bytemine.net>,

Aharon Robbins <arn...@skeeve.com> wrote:
>In article <hndhg4$r1r$1...@news.xmission.com>,
>Kenny McCormack <gaz...@shell.xmission.com> wrote:
>>I noticed today that you can't return an array as the value of a
>>function in GAWK. FWIW, this works in TAWK, but not GAWK:
>>
>>function foo(s) {split(s,A);return A}
>>BEGIN { x = foo("the quick brown fox");for (i in x) print i,x[i] }
>>
>>Error message in GAWK is "array used in scalar context" on the "return A"
>>line. I'm just curious - how intentional is this limitation?
>>Is there any particular reason for it to not work?
>>
>>Tested in GAWK 3.1.4 - maybe fixed in later versions?
>
>Historical awk didn't have arrays as return values and so neither

>does gawk. I don't see a major reason to add it.

Good answer. That answers my basic question.

>It's better to pass in an array to be populated.

This comment belongs in the "alternatives" thread, not here.

>I also think that the gawk code is fragile enough that trying
>to do this isn't a good idea in any case.

Good point.

>Thanks,

Thank you (Miss Howe!)