Function to pass array

[danh]

Can a Function pass an array (loaded) back to the calling script? I've tried but cannot get it to work.

ie.

dim va[0] as p
va = udfGVList()

for i = 1 to va.size()
	trace.WriteLn("Element: " + va[i].gvName)
next

FUNCTION udfGVList AS P ()

dim gvlst as c
gvlst = <<%lst%
gvCompanyName,c,Setup
gvCompanyAddr1,c,Setup
gvCompanyAddr2,c,Setup
gvCompanyCity,c,Setup
gvCompanyState,c,Setup
gvCompanyZip,c,Setup
gvCompanyCountry,c,Setup
gvCompanyPhone,c,Setup
gvCompanyFax,c,Setup
gvCompanyWeb,c,Setup
gvCompanyEMail,c,Setup
gvCompanyEIN,c,Setup
gvInvoiceNum,c,Setup
%lst%

dim aray[0] as P
dim aray[0].gvName as c
dim aray[0].gvType as c
dim aray[0].gvClase as c

for each foo in gvlst
	aray[].gvName = word(foo.value,1,",",1)
	aray[..].gvType = word(foo.value,2,",",1)
	aray[..].gvClass = word(foo.value,3,",",1)
next

udfGVList = aray

END FUNCTION

The function runs fine, but it will not pass the array back correctly.

Thanks, Dan

[jaryder]

Re: Function to pass array

Dan,

Any variables defined within a function are destroyed when you exit the function so you can not return a pointer to a variable defined within a function. My suggestion to try is define the array outside the function and pass the array by reference to the function and then the function will actually affect the array from within the function. Search the help for for passing by reference to a function.

[G Gabriel]

Re: Function to pass array

Can a Function pass an array (loaded) back to the calling script? I've tried but cannot get it to work.

ie.

dim va[0] as p
va = udfGVList()

for i = 1 to va.size()
    trace.WriteLn("Element: " + va[i].gvName)
next

Nice try!.. Not a chance.
you can't make an array inherit another array (equal it) by simply saying:
this array=that array.
Negative.
Arrays live in a rough neighborhood. Array's world is tough. Before you become an array, you have to be intiated (or initialized). To the contrary, dot variables like to play nice. You could do this with dot variables instead, BUT why? you don't even need a UDF:

dim gvlst as c
gvlst = <<%lst%
#gvCompanyName,c,Setup
#gvCompanyAddr1,c,Setup
#gvCompanyAddr2,c,Setup
#gvCompanyCity,c,Setup
#gvCompanyState,c,Setup
#gvCompanyZip,c,Setup
#gvCompanyCountry,c,Setup
#gvCompanyPhone,c,Setup
#gvCompanyFax,c,Setup
#gvCompanyWeb,c,Setup
#gvCompanyEMail,c,Setup
#gvCompanyEIN,c,Setup
#gvInvoiceNum,c,Setup%lst%
ct=line_count(gvlst)
?ct
= 13
dim ar[ct] as p
ar.initialize_properties("gvName,gvType,gvClase",gvlst)
?ar[1].gvname
= "gvCompanyName"

?ar[3].gvclase
= "Setup"

And you could make a function out of the above, something like:

Function udfgvlst as p(list as c)
x=line_count(list)
format=("gvName,gvType,gvClase")
dim udfgvlst[x] as p
udfgvlst.initialize_properties(format,list)
End Function

If the object of your function primarily is to pass one array to another, you need to populate the second array either by:
1-Dumping the first array into a list then populating the second array from the list, or
2-iterating over the first one, or
3-create a dummy empty array and append the first array to the empty one to create the second array
And yes you could make a UDF out of that as well, which begs the question:
If the first array is initialized from a list, why not just initialize the second array from the same list?

[csda1]

Re: Function to pass array

Hi Jeff,

Any variables defined within a function are destroyed when you exit the function so you can not return a pointer to a variable defined within a function.

Actually, you can.

Create this function

FUNCTION testptr AS P ( )
dim testptr.varname as c
testptr.varname="abc"

END FUNCTION

Then in the interactive window
ptr=testptr()
?ptr
= varname = "abc"
?ptr.varname
= "abc"

Arrays and collections are essentially special versions of pointers within Alpha, and arrays, collections and pointers are all automatically passed by reference. Even though there are by reference, it's best to make local copy of values if you want to modify values to allow easier debugging, unless the intent is to modify those values for returning results.

And Dan,

Modifying your code slightly to this

FUNCTION udfGVList AS P ()

dim gvlst as c
gvlst = <<%lst%
gvCompanyName,c,Setup
gvCompanyAddr1,c,Setup
gvCompanyAddr2,c,Setup
gvCompanyCity,c,Setup
gvCompanyState,c,Setup
gvCompanyZip,c,Setup
gvCompanyCountry,c,Setup
gvCompanyPhone,c,Setup
gvCompanyFax,c,Setup
gvCompanyWeb,c,Setup
gvCompanyEMail,c,Setup
gvCompanyEIN,c,Setup
gvInvoiceNum,c,Setup
%lst%

dim ptr as p
dim ptr.aray[0] as P
dim ptr.aray[0].gvName as c
dim ptr.aray[0].gvType as c
dim ptr.aray[0].gvClase as c

for each foo in gvlst
    ptr.aray[].gvName = word(foo.value,1,",",1)
    ptr.aray[..].gvType = word(foo.value,2,",",1)
    ptr.aray[..].gvClass = word(foo.value,3,",",1)
next

udfGVList = ptr

END FUNCTION

then in the interactive window
ptr=udfGVList()
?ptr.aray
= +[1].
+[2].
+[3].
+[4].
+[5].
+[6].
+[7].
+[8].
+[9].
+[10].
+[11].
+[12].
+[13].
?ptr.aray[1]
= gvClass = "Setup"
gvName = "gvCompanyName"
gvType = "c"
?ptr.aray[2]
= gvClass = "Setup"
gvName = "gvCompanyAddr1"
gvType = "c"

But an array, Property type or regular, can't be just referenced by assigning one pointer to another (but it makes sense that you might think it does). There are methods to copy and append arrays to each other should you need them.

Pointers are more like a space where a bunch of other variables are stored, and that's why you can pass that space back (and all the variables that are properties of that pointer), but not the variables themselves as a group.

Hopefully this "points" you in the right direction! :)

[danh]

Re: Function to pass array

Got something else to work, but this looks interesting and might be simpler. Heading home for today, but will definitely experiment some more. I figured someone would have some ideas. Thanks everyone!
Dan

[Tim Kiebert]

Re: Function to pass array

Hopefully others will comment on the pros and cons of this idea.

Which is to pass the pointer to the array into the function like so:

dim va[0] as p
'probably should dim the elements as below but seems to work without doing so
'would just be good and consistent practice to do so I guess
dim va[0].gvName as c
dim va[0].gvType as c
dim va[0].gvClase as c

udfGVList(va)

trace.Clear()
for i = 1 to va.size()
    trace.WriteLn("Element: " + va[i].gvName)
next


FUNCTION udfGVList AS V (aray as p)

dim gvlst as c
gvlst = <<%lst%
gvCompanyName,c,Setup
gvCompanyAddr1,c,Setup
gvCompanyAddr2,c,Setup
gvCompanyCity,c,Setup
gvCompanyState,c,Setup
gvCompanyZip,c,Setup
gvCompanyCountry,c,Setup
gvCompanyPhone,c,Setup
gvCompanyFax,c,Setup
gvCompanyWeb,c,Setup
gvCompanyEMail,c,Setup
gvCompanyEIN,c,Setup
gvInvoiceNum,c,Setup
%lst%


for each foo in gvlst
    aray[].gvName = word(foo.value,1,",",1)
    aray[..].gvType = word(foo.value,2,",",1)
    aray[..].gvClass = word(foo.value,3,",",1)
next

END FUNCTION

[csda1]

Re: Function to pass array

Hi Tim,

It's perfectly valid to do as you have done. What you don't have, is a "Pure Function", which I always strive for (although not always succeed). You can read about it here