Array pointer in function parameter

[Peter.Greulich]

This works:

FUNCTION zzz AS V (cList="" as C)
	msgbox("C")
End FUNCTION


zzz()

But how do I get this to work?

FUNCTION zzz AS V (pList as P)
	msgbox("P")
End FUNCTION


zzz()

[Sarah Mitchell]

Re: Array pointer in function parameter

This works:

FUNCTION zzz AS V (cList="" as C)
	msgbox("C")
End FUNCTION


zzz()

But how do I get this to work?

FUNCTION zzz AS V (pList as P)
	msgbox("P")
End FUNCTION


zzz()

See if null_value() works for you: http://documentation.alphasoftware.c...0Variables.xml

FUNCTION zzz AS  (pList = null_value() as P)
	msgbox("P")
end FUNCTION

zzz()

[Peter.Greulich]

Re: Array pointer in function parameter

null_value() that's what I was looking for.

I had tried null and of course it didn't work.

Thanks Sarah

[Peter.Greulich]

Re: Array pointer in function parameter

Actually that doesn't work Sarah.

This errors out:

FUNCTION zzz AS V (pList = null_value() as P)
	Dim pList.Test as C
	
end FUNCTION

zzz()

[Peter.Greulich]

Re: Array pointer in function parameter

This works, but I'm not sure I like it:

FUNCTION zzz AS V (pList = null_value() as P)
	if typeof(pList) = "Z"
		Delete pList
		Dim pList as P
		Dim pList.Test as C = "test"
	end if
	
	msgbox(pList.Test)
	
end FUNCTION

zzz()

[Sarah Mitchell]

Re: Array pointer in function parameter

Actually that doesn't work Sarah.

This errors out:

FUNCTION zzz AS V (pList = null_value() as P)
	Dim pList.Test as C
	
end FUNCTION

zzz()

If nothing is passed in, the type is 'Z', as you state in the second post. You'll have to check the type if you want to alter the parameter.

Instead of trying to use the parameter, use a local variable instead. EG:

FUNCTION zzz AS V (pL = null_value() as P)
	dim pList as p
	if (typeof(pL) = "P") then
		pList = pL
	end if
	
	pList.Test = "test"

	msgbox(pList.Test)
	
end FUNCTION

zzz()

[MoGrace]

Re: Array pointer in function parameter

This works if that is what you wanted:

FUNCTION zzz AS C (pList AS P = null_value() )
dim shared pList.test as c
pList.Test = "This is a test"
zzz = pList.Test
END FUNCTION

?zzz()
="This is a test"

[Peter.Greulich]

Re: Array pointer in function parameter

No Mo. Shared var = bad!

I'll use Sarah's suggestion. That's better.

[GGandhi]

Re: Array pointer in function parameter

http://wiki.alphasoftware.com/~alphafiv/Arrays
take a look at this page and this paragraph:

Passing Arrays to Functions
When you pass an array to a function, the receiving function defines the argument as a pointer.
Dim a[5] as C
a[1] = "a value"
my_function(a)
function my_function as V (arr as P)
ui_msg_box("Array Value", arr[1])
end function

ran a quick test and it works as described,
at least in the earlier posts i do not see you passing any array to the function.

[G Gabriel]

Re: Array pointer in function parameter

In you initial post you say you wrote a function:

FUNCTION zzz AS V (cList="" as C)
	msgbox("C")
End FUNCTION
zzz()

And you say it works.
"It does", really shouldn't but it does for the following reason:
The funtion has a C Parameter and you defaulted it to blank, actually null. So when you type zzz() in the IW, "It works".
When you wrote zzz() in the IW, you did not supply a value for that parameter. But since the function defaults that parameter to null, "It works", unwittingly, even though you did not supply a parameter, which amounted to the same thing as supplying a null.

But when you tried to do the same thing with a P parameter, it threw an error.
It did. BECAUSE YOU DID NOT SUPPLY A VALUE FOR THE PARAMETER. YOU JUST TYPED ZZZ() IN THE IW.
That wouldn't work unless you supply a value for that parameter OR you make this parameter optional. You did neither.

The function should have been written as follows:

FUNCTION zzz AS P (pList as P)
	zzz=plist
End FUNCTION

Now, in the IW try this:

dim mylist as p
dim mylist.name as c
dim mylist.age as n
mylist.name="Joe"
mylist.age=35
?zzz(mylist)
= age = 35
name = "Joe"

If you want the function as V instead of P, you could do that too. It will run as a script and acquires the values of mylist. It's up to you what you want to do with these values later. And you could write the function as follows:

FUNCTION zzz AS V (pList as P)
	msgbox("function ran")
End FUNCTION

Now run the function from the IW:

dim mylist as p
dim mylist.name as c
dim mylist.age as n
mylist.name="Joe"
mylist.age=35
?zzz(mylist)
= <Has no sub-properties>

The msg box will pop up but you will get the error <Has no sub-properties> because it doesn't. That error should not hamper what you are doing ( I don't think, but again I never write functions this way so I can't swear to it) if you acquire the values of plist and process them whichever way you want but you have to remember those values are local variables and you have to get a pointer to those local variables.
Alternatively, you could write it as V with no parameters since your objective would be to run it as an encapsulated script.
It's easier and much better to do it as a P instead of a V function.