Redefine data structures?

[mike]

I suspect the answer is "no," but I thought I'd throw this out anyway.
My background is in languages that support redefintion in
datastructures, something that I've yet to figure out in VBA.

Is it possible redefine variables something like this in VBA:

Type BatchHeader1
RecType As String * 1
ServiceClassCd As String * 3
CompanyName As String * 16
end type

dim bh as BatchHeader1
dim strBig as string redefines bh

bh.Rectype = "A"
bh.ServiceClassCd = "BBB"
bh.CompanyName ="CCCCCCCCCCCCCCCC"

At this point, strBig would contain
"ABBBCCCCCCCCCCCCCCCC"
Thanks,
Mike
..

[Wayne Gillespie]

On 9 Mar 2006 14:11:13 -0800, "mike" <mi**********@gmail.com> wrote:

I suspect the answer is "no," but I thought I'd throw this out anyway.
My background is in languages that support redefintion in
datastructures, something that I've yet to figure out in VBA.

Is it possible redefine variables something like this in VBA:

Type BatchHeader1
RecType As String * 1
ServiceClassCd As String * 3
CompanyName As String * 16
end type

dim bh as BatchHeader1
dim strBig as string redefines bh

bh.Rectype = "A"
bh.ServiceClassCd = "BBB"
bh.CompanyName ="CCCCCCCCCCCCCCCC"

At this point, strBig would contain
"ABBBCCCCCCCCCCCCCCCC"

strBig = bh.Rectype & bh.ServiceClassCd & bh.CompanyName
Wayne Gillespie
Gosford NSW Australia

[Rich P]

The simplest thing you could do is to write a function (which I suspect
is what your redifinition thing is) to concatenate the elements of your
data structure:

bh.Rectype = "A"
bh.ServiceClassCd = "BBB"
bh.CompanyName ="CCCCCCCCCCCCCCCC"

Function concatElements(bh As BatchHeader1) As String
concatElements = bh.RectType & bh.ServiceClassCD & bh.CompanyName
End Function

strBig = concatElements(bh)

If you want to do something like

Dim strBig As String = bh

then you need to use an Object oriented version of VB like VB.Net. VBA
is not object oriented - does not support polymorphism, overloading, or
inheritance

HTH
Rich

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[mike]

Thanks for your replies. I suspected there was no such thing, it's
just kind of surprising. I realize that the VB way is to concatenate
the individual components of the defined type to arrive at one large
string, but that kind of cripples its functionality.

There are a number of non-object traditional languages that support
redefinition, I've worked primarily with COBOL, Powerhouse and VAX
BAsic, so I suspect it's a limitation of VBA, rather than being an OE
vs non-OE thing.

Another data structure that seems to be "missing" in Access from my
perspective is the ability to sub-define items in table design. Both
COBOL and Powerhouse let you define a table item like this for example

TRANS-DATE ZONED UNSIGNED 8
_TRANS-DATE-ASCII CHARACTER 8
.TRANS-DATE-YEAR CHARACTER 4
.TRANS-DATE-MONTH CHARACTER 2
.TRANS-DATE-DAY CHARACTER 2

Zoned decimal is essentially ASCII, so a date defined as zoned
(TRANS-DATE) can be redefined as ASCII (TRANS-DATE-ASCII), which can be
broken into sub-items, indicated by the dot notation in Powerhouse.
COBOL is similar, and I seem to remember doing this is C as well. We
would typically define a date like this in Powerhouse to be able to
assign a numeric value, e.g. the system date, to TRANS-DATE, and be
able to reference it or it's components as ASCII. Alternately, computed
values, e.g., a date in an ensuing month or fiscal year, could be
assigned to the year, month, and day sub-items and referenced as a
numeric via TRANS-DATE, or as an entire ASCII date via
TRANS-DATE-ASCII.

Oh well, enough reminiscing about the past, back to the task at
hand....

Thanks again.
Rich P wrote:

The simplest thing you could do is to write a function (which I suspect
is what your redifinition thing is) to concatenate the elements of your
data structure:

bh.Rectype = "A"
bh.ServiceClassCd = "BBB"
bh.CompanyName ="CCCCCCCCCCCCCCCC"

Function concatElements(bh As BatchHeader1) As String
concatElements = bh.RectType & bh.ServiceClassCD & bh.CompanyName
End Function

strBig = concatElements(bh)

If you want to do something like

Dim strBig As String = bh

then you need to use an Object oriented version of VB like VB.Net. VBA
is not object oriented - does not support polymorphism, overloading, or
inheritance

HTH
Rich

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