Inconsistent behavior under NetLogoWeb

[arcpaolo]

When running this code:

extensions [ table ]
globals [ $#table $t1 ]
to go
  set $#table table:make
  set $t1 table:get $#table "Test"
end

In the desktop version (6.3.0) you get an error: "Extension exception: No value for Test in table."

However, when running in NetLogoWeb, you don't get an error, $t1 is set to "undefined".

I have some code that checks to see if a certain table key already exists to avoid overwriting. I used "carefully [ ]" and then ignored the error if there was no such key. When I run on NLW this check no longer works.

As a stop-gap, is there a way to test if a variable is "undefined"? I could not figure out how to do this. It's not a boolean nor does it seem to be a primitive of any sort.

[CIVITAS-John]

Can you use `table:has-key?` for checking that?

…

On Wed, Jun 21, 2023 at 11:49 AM arcpaolo ***@***.***> wrote: When running this code: extensions [ table ] globals [ $#table $t1 ] to go set $#table table:make set $t1 table:get $#table "Test" end In the desktop version (6.3.0) you get and error: "Extension exception: No value for Test in table." However, when running in NetLogoWeb, you don't get an error, you get "undefined". I have some code that checks to see if a certain table key already exists to avoid overwriting. I used "carefully [ ]" and then ignored the error if there was no such key. When I run on NLW this check no longer works. As a stop-gap, is there a way to test if a variable is "undefined"? I could not figure out how to do this. It's not a boolean nor does it seem to be a primitive of any sort. — Reply to this email directly, view it on GitHub <#18>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AC523N3S2TCT4UPRLGNS46LXMMQ2ZANCNFSM6AAAAAAZPA3KDE> . You are receiving this because you are subscribed to this thread.Message ID: ***@***.***>

[arcpaolo]

Ah, of course. I should have thought of that, I just tried it and it works. Nonetheless it would be useful if the behavior were consistent.

I am also curious how one can check if a variable is undefined in NLW.

[LaCuneta]

Thanks for reporting this. I have a fix here and will merge it and close this issue once tests pass. There was a check for a missing key for a key with a list value, but no check for simple valued keys. There was a test for this here in the desktop repo, but somehow that test got dropped when the extension was ported to NetLogo Web. At some point we should get those tests back in sync, but for now I just added a new one to Tortoise.

I am also curious how one can check if a variable is undefined in NLW.

So, in theory this should never be necessary. NetLogo doesn't allow an undefined value, so NetLogo Web doesn't, either. The only time this would happen is with bugs (as in this case) or due to the lack of full runtime error checking. All NetLogo variables are initialized to 0 and the closest you see to undefined is the Nobody value for an agent that some reporters can produce.

[arcpaolo]

Thank you!