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ville56
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Joined: 08/06/2022
Location: Austria
Posts: 242

Posted: 07:11pm 09 Oct 2025

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I've a strange problem with a GOSUB within a FUNCTION. In the following example the scope of the variable in_param gets lost in the GOSUB, no matter where I place the code for the gosub.

OPTION EXPLICIT
OPTION DEFAULT NONE

dim integer stat

stat=test_f(22)

end

function test_f (in_param as integer) as integer
gosub print_param
exit function

print_param:
print "in funct ";in_param
return

end function

it throws "Error : IN_PARAM is not declared"

Are there any restrictions of using GOSUB within a FUNCTION?

Version is PicoMite MMBasic RP2350A V6.01.00b20

Thanks for any hints ....

Gerald
Edited 2025-10-10 05:12 by ville56

73 de OE1HGA, Gerald

Nimue

Guru

Joined: 06/08/2020
Location: United Kingdom
Posts: 423

Posted: 08:25pm 09 Oct 2025

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Hi

P116 of the manual:

"You must not jump into or out of a function using commands like GOTO.
Doing so will have undefined side effects including ruining your day."

Solution: Don't do it ;-)

Got caught by that one a few times...

Entropy is not what it used to be

phil99

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Joined: 11/02/2018
Location: Australia
Posts: 2765

Posted: 09:49pm 09 Oct 2025

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Although "gosub print_param" and "print_param:" are both within the Function so is not jumping out, I think it has been mentioned that nesting a Sub within a Function is not supported.
However I can't find it in the manual.
Edited 2025-10-10 07:57 by phil99

disco4now

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Joined: 18/12/2014
Location: Australia
Posts: 1033

Posted: 01:31am 10 Oct 2025

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GOSUB, SUB and FUNCTION all increment the LocalIndex pointer when called, so they are only aware of Global variables and any Local variables created at their own level.
In the function test_f the variable in_param is created as a Local variable as it is passed BYVAL. The GOSUB code cannot see this Local variable as the LocalIndex pointer has been incremented, it must be passed.
GOSUB is obsolete and I don't think you can pass it parameters.

Embedding the GOSUB within the Function as above does not put it at the same level. The Function tolerates it being there but never really sees it as part of the function because of Exit Function. The GOSUB is happy to go and find the label and execute its code and return, but it can't see any of the Functions variables.

OPTION EXPLICIT
OPTION DEFAULT NONE

dim integer stat

stat=test_f(22)

end

function test_f (in_param as integer) as integer
gosub print_param
end function

print_param:
print "in funct ";in_param
return

Use the more modern SUB allows passing the parameter

Option EXPLICIT
Option DEFAULT NONE

Dim integer stat

stat=test_f(22)

End

Function test_f(in_param As integer) As integer
print_param in_param
End Function

Sub print_param(in_param As integer)
Print "in funct ";in_param
End Sub

Edited 2025-10-10 11:32 by disco4now

F4 H7 FotS F4xGT

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