The Sinclair QL Forum

Posted: **Tue Feb 15, 2022 7:06 pm**

Hi,

this might be an incredibly stupid question but for the life of me I can't figure out if it is possible to implement optional parameters in SuperBasic. What I mean is something along these lines:

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def proc foo(bar$,goo$)
  REM This I don't know how to do:
  if is_empty(goo$) then goo$="default value"
end def

And then being able to call foo with just one parameter:

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foo "val_for_bar$"

And since goo$ is passed in as empty/undefined then it would be set to the default value.

Toolkit II has PARSTR$ which lets me implement what I want this way:

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def proc foo(bar$,goo$)
  g$=PARSTR$(goo$,2)
  if g$='' then g$='default value'
  ....

BUT this will not work if I compile it since QLIb does not support PARSTR$ or PARNAM$

Are there any extensions or clever tricks in SuperBasic to check for undefined/empty parameter?

Thanks in advance for any tips or pointers to docs!

Posted: **Tue Feb 15, 2022 7:38 pm**

ppe wrote:this will not work if I compile it since QLIb does not support PARSTR$ or PARNAM$

As TT has written in the TK2 manual. You should read it!

Posted: **Tue Feb 15, 2022 7:47 pm**

RalfR wrote:
ppe wrote:this will not work if I compile it since QLIb does not support PARSTR$ or PARNAM$
As TT has written in the TK2 manual. You should read it!

I'm afraid I don't understand your comment. I have read both TK2 and QLiberator manuals. TK2 manual in my opinion does not address compiled code and PARSTR$. QLiberator manual does and it explicitly says it is not supported. That is why I'm asking if there is another way to do it using plain SuperBasic or some other SuperBasic extensions than TK2.

Posted: **Tue Feb 15, 2022 7:47 pm**

See here ...

https://www.theqlforum.com/viewtopic.php ... REX#p31714

EmmBee

Posted: **Tue Feb 15, 2022 7:50 pm**

EmmBee wrote:See here ...

https://www.theqlforum.com/viewtopic.php ... REX#p31714

EmmBee

Thank you very much for your help! I don't know why I didn't find that thread before.

Posted: **Tue Feb 15, 2022 7:55 pm**

ppe wrote:<>
Are there any extensions or clever tricks in SuperBasic to check for undefined/empty parameter?

The function VALID% from http://www.Knoware.no/htm/toolkits.htm#math can be useful in some cases. A very simple
demo:

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DEFine PROCedure test(t%)
PRINT HEX$(VALID%(-1, t%), 16)
END DEFine

test x%, with x% undefined will print 0003.
a$ = 'abc': test a$, prints 0201
test b$, with b$ undefined print 0001, etc
Sadly, test without any parameter at all doesnt help much.

Posted: **Tue Feb 15, 2022 8:00 pm**

pjw wrote: The function VALID% from http://www.Knoware.no/htm/toolkits.htm#math can be useful in some cases.

Thank you, Per! Will take a look!

The Sinclair QL Forum

SuperBasic: optional parameters that will work with QLiberator?

SuperBasic: optional parameters that will work with QLiberator?

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Re: SuperBasic: optional parameters that will work with QLiberator?

Re: SuperBasic: optional parameters that will work with QLiberator?

Re: SuperBasic: optional parameters that will work with QLiberator?

Re: SuperBasic: optional parameters that will work with QLiberator?