NetRexx bug: CONCAT null

[Jeff Hennick-3]

I have been running around with some unrepeatable errors while generating tests for pipe stages.

One seems in involve, or trigger, a problem with nulls in SAY.

In trying to see what is going on, I wrote this 3-liner, which is definitely causing a problem in CONCAT, before it gets to SAY. 

PS C:\Users\Jeff\documents\pipe tests> type test_say.nrx x = rexx null y = 'test' say y x PS C:\Users\Jeff\documents\pipe tests> java test_say Exception in thread "main" java.lang.NullPointerException at netrexx.lang.Rexx.concat(Rexx.java:2261) at netrexx.lang.Rexx.OpCcblank(Rexx.java:1593) at test_say.main(test_say.java:4) PS C:\Users\Jeff\documents\pipe tests>

[Note that it reports the error as being in line 4 of this 3-line program.]

I think that both CONCAT and SAY should handle nulls by quietly ignoring them.

Jeff Hennick

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[Jason Martin]

3 line NetRexx but generated Java is more lines.

Some new code added to RexxIO in last year that I have not used much or
looked over yet.

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[rvjansen]

’Say’ does handle nulls gracefully. But ‘concat’ does not. Do we want ‘concat’ to ignore them?

René.

> On 9 Dec 2019, at 16:39, Jason Martin <[hidden email]> wrote:
>
> 3 line NetRexx but generated Java is more lines.
>
> Some new code added to RexxIO in last year that I have not used much or looked over yet.
>
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[Jason Martin]

NetRexx Language Reference

chapter on Type conversions

My mind is not clear but obey the rules there?

Do not remember but 'Say' was designed with some thought on
terminal/device output.

I vaguely remember sending output to printer.

Leave the thing in there.

Send another doc to overlay and then form feed

Get just the one page.


On 2019-12-09 17:04, René Jansen wrote:
> ’Say’ does handle nulls gracefully. But ‘concat’ does not. Do we want ‘concat’ to ignore them?
>
> René.

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[ThSITC]

My personal opinion is that NULL Rexx Variables shall be reported as an
error in this case (as far as I do understand it).

Thomas.

===================================================================================

Am 10.12.2019 um 00:19 schrieb Jason Martin:

> NetRexx Language Reference
>
> chapter on Type conversions
>
> My mind is not clear but obey the rules there?
>
> Do not remember but 'Say' was designed with some thought on
> terminal/device output.
>
> I vaguely remember sending output to printer.
>
> Leave the thing in there.
>
> Send another doc to overlay and then form feed
>
> Get just the one page.
>
>
> On 2019-12-09 17:04, René Jansen wrote:
>> ’Say’ does handle nulls gracefully. But ‘concat’ does not. Do we want
>> ‘concat’ to ignore them?
>>
>> René.
>
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>

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[Jeff Hennick-3]

I have done some more reading and thinking on this.

My mistake: confusing a "null Rexx string," that is a zero length, empty one, with a "null value of an object," [NULL].  And expecting them to behave the same.  (Note to self: a declared Rexx string is an object, so it can have either a value of [NULL] or "" which is a null string.)

So, trying to concatenate a [NULL] value should be an error, and concatenating a null string to another string should just be the other string's value.

And SAYing a null value emits a null string.

Moral (for myself) when in doubt, use "catch NullPointerException" so [NULL]s don't get to CONCAT.

Thanks for all the help, and apologies for raising the word "bug."

Jeff

On 12/9/2019 5:04 PM, René Jansen wrote:

’Say’ does handle nulls gracefully. But ‘concat’ does not. Do we want ‘concat’ to ignore them?

René.

On 9 Dec 2019, at 16:39, Jason Martin [hidden email] wrote:

3 line NetRexx but generated Java is more lines.

Some new code added to RexxIO in last year that I have not used much or looked over yet.

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