Solid ops and subroutines

[James Murray]

I’m getting inconsistent results depending on whether ADDGROUP is used in a subroutine or in the main script. Example:

Version 1, add groups in main script, works:

GROUP ‘things’
	etc
ENDGROUP

GOSUB 100

foobar_ = ADDGROUP(‘foo’, ’bar’) !! NB, in main
final_ = SUBGROUP(foobar_, ‘things’) !! this works
PLACEGROUP final_

END

100:

GROUP ‘foo’
	stuff
ENDGROUP

GROUP ‘bar’
	more stuff
ENDGROUP

RETURN

Version 2, add groups in subroutine, doesn’t work:

GROUP ‘things’
	etc
ENDGROUP

GOSUB 100

final_ = SUBGROUP(foobar_, ‘things’) !! this gives error that foobar_ isn’t group name
PLACEGROUP final_

END

100:

GROUP ‘foo’
	stuff
ENDGROUP

GROUP ‘bar’
	more stuff
ENDGROUP

foobar_ = ADDGROUP(‘foo’, ’bar’) !! NB, in subroutine

RETURN

James M

[James Murray]

Wow that formatting looks great. Never mind. If you want to use an ADDGROUP result in a subsequent SUBGROUP operation, you can’t do the ADDGROUP in a subroutine. It would be nice to know why.

James M

[Péter Baksa]

Hi James,

the GDL interpreter runs some checks before executing the script. This check is done line-by line, not in execution order. In version 2 when it first comes to foobar_, that is an uninitialized variable, but it would expect string or group type. Sadly we can’t easily initialize a variable to be group type.
A solution:
– move the subgroup and placegroup commands to another subroutine, placed after subroutine 100
Less elegant solution if the above doesn’t work for your code structure:
– initialize group type variable: create an empty group and add it to itself, creating a group type variable

group “dummy”
endgroup
foobar_ = ADDGROUP(“dummy”, “dummy”)
killgroup “dummy”

GOSUB 100

Péter Baksa
Library Platform, Software Engineer
GRAPHISOFT SE

[Nader Belal]

My 2 cents,

This group structure is neither nice, nor clean, and it may cause a lot of confusion when the times arrives for code maintenance, all because the followed structure.

My solution

gosub 100

bla ... bla ... bla

end

100:

GROUP ‘things’
	etc
ENDGROUP

if something then
	GROUP ‘foo’
		etc
	ENDGROUP

	GROUP ‘bar’
		etc
	ENDGROUP
end

! -- Group placements --------------- 

if nothing then
	placegroup ‘things’

	killgroup ‘things’
end

if something then
	placegroup subgroup (addgroup (‘foo’, ’bar’), ‘things’)

	killgroup ‘things’
	killgroup ‘foo’
	killgroup ‘bar’
end

return

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