Functions that return different datatypes

[Dennis]

Since .Net doesn't allow variants, how do you create a function that can
return different datatypes? Say we have a function that returns either a
recordset or an XML string based on a parameter, so it has to use Variant
for it's return type. Can we use this funciton in .Net somehow? Or would
we have to separate it into two functions?

Thanks,
Dennis

[Jonathan Wood]

How about returning an Object. Since all objects derive from Object, that
should work okay.

--
Jonathan Wood
SoftCircuits Programming
http://www.softcircuits.com
"Dennis" <dbronstein@brainranger.com> wrote in message
news:3a8c21a5@news.devx.com...
> Since .Net doesn't allow variants, how do you create a function that can
> return different datatypes? Say we have a function that returns either a
> recordset or an XML string based on a parameter, so it has to use Variant
> for it's return type. Can we use this funciton in .Net somehow? Or would
> we have to separate it into two functions?
>
> Thanks,
> Dennis
>
>

[Kenny Acock]

Dennis,

>Since .Net doesn't allow variants, how do you create a function that can
>return different datatypes? Say we have a function that returns either
a
>recordset or an XML string based on a parameter, so it has to use Variant
>for it's return type. Can we use this funciton in .Net somehow? Or would
>we have to separate it into two functions?

That is not entirely correct. In VB.Net you can think of Objects as SuperVariants.
They do everything a VB 6 Variant could do (AFAIK). They aren't recommended
unless you really need them, but they work.

--Kenny

[Dennis]

So how can we put a string into an object today?

Thanks,
Dennis

"Kenny Acock" <kennya@teacherspal.com> wrote in message
news:3a8c3165$2@news.devx.com...
>
> Dennis,
>
> >Since .Net doesn't allow variants, how do you create a function that can
> >return different datatypes? Say we have a function that returns either
> a
> >recordset or an XML string based on a parameter, so it has to use Variant
> >for it's return type. Can we use this funciton in .Net somehow? Or
would
> >we have to separate it into two functions?
>
> That is not entirely correct. In VB.Net you can think of Objects as
SuperVariants.
> They do everything a VB 6 Variant could do (AFAIK). They aren't
recommended
> unless you really need them, but they work.
>
> --Kenny

[Kevin P. Fleming]

In .NET, a string _IS_ an Object. You can assign any string to any generic
Object variable.

"Dennis" <dbronstein@brainranger.com> wrote in message
news:3a8c544b$1@news.devx.com...
> So how can we put a string into an object today?
>
> Thanks,
> Dennis
>
> "Kenny Acock" <kennya@teacherspal.com> wrote in message
> news:3a8c3165$2@news.devx.com...
> >
> > Dennis,
> >
> > >Since .Net doesn't allow variants, how do you create a function that
can
> > >return different datatypes? Say we have a function that returns either
> > a
> > >recordset or an XML string based on a parameter, so it has to use
Variant
> > >for it's return type. Can we use this funciton in .Net somehow? Or
> would
> > >we have to separate it into two functions?
> >
> > That is not entirely correct. In VB.Net you can think of Objects as
> SuperVariants.
> > They do everything a VB 6 Variant could do (AFAIK). They aren't
> recommended
> > unless you really need them, but they work.
> >
> > --Kenny
>
>

[J W Cooper]

Why not just overload the function so that there are two kinds of arguments
and two kinds of return types? Its far better programming practice and avoicd
unpleasant type cast failures.

Function getRecord(a as integer, b as integer) as RecordSet

Function getRecord(a as integer) as String

Jim Cooper

Dennis wrote:

> Since .Net doesn't allow variants, how do you create a function that can
> return different datatypes? Say we have a function that returns either a
> recordset or an XML string based on a parameter, so it has to use Variant
> for it's return type. Can we use this funciton in .Net somehow? Or would
> we have to separate it into two functions?
>
> Thanks,
> Dennis

[Dennis]

Again, how can we do that _today_, because a string is not an object in VB6?
Or are we going to have to change all the functions when we convert?

Dennis

"Kevin P. Fleming" <kevin@spam-labsysgrp-spam.com> wrote in message
news:96hne2$crj$1@localhost.localdomain...
> In .NET, a string _IS_ an Object. You can assign any string to any generic
> Object variable.
>
> "Dennis" <dbronstein@brainranger.com> wrote in message
> news:3a8c544b$1@news.devx.com...
> > So how can we put a string into an object today?
> >
> > Thanks,
> > Dennis
> >
> > "Kenny Acock" <kennya@teacherspal.com> wrote in message
> > news:3a8c3165$2@news.devx.com...
> > >
> > > Dennis,
> > >
> > > >Since .Net doesn't allow variants, how do you create a function that
> can
> > > >return different datatypes? Say we have a function that returns
either
> > > a
> > > >recordset or an XML string based on a parameter, so it has to use
> Variant
> > > >for it's return type. Can we use this funciton in .Net somehow? Or
> > would
> > > >we have to separate it into two functions?
> > >
> > > That is not entirely correct. In VB.Net you can think of Objects as
> > SuperVariants.
> > > They do everything a VB 6 Variant could do (AFAIK). They aren't
> > recommended
> > > unless you really need them, but they work.
> > >
> > > --Kenny
> >
> >
>
>

[Dennis]

We can't do that today, can we? And then we'd have a different set of
parameters for each, which we don't need.

Dennis

"J W Cooper" <ctswim@ctswim.org> wrote in message
news:3A8C9A87.F6E71BBA@ctswim.org...
> Why not just overload the function so that there are two kinds of
arguments
> and two kinds of return types? Its far better programming practice and
avoicd
> unpleasant type cast failures.
>
> Function getRecord(a as integer, b as integer) as RecordSet
>
> Function getRecord(a as integer) as String
>
> Jim Cooper
>
> Dennis wrote:
>
> > Since .Net doesn't allow variants, how do you create a function that can
> > return different datatypes? Say we have a function that returns either
a
> > recordset or an XML string based on a parameter, so it has to use
Variant
> > for it's return type. Can we use this funciton in .Net somehow? Or
would
> > we have to separate it into two functions?
> >
> > Thanks,
> > Dennis
>

[Dan Fergus]

No, you cannot do that today. I don't know of anyway that you can write
code, to do what you are asking, now in VB6 so that it will move smoothly
into VB.NET.

My own opinion, you will have a hard time moving anything except the most
basic code to VB.NET without major work.

Make sure that you comment well now in your VB6 code so that you can find
these problem spots later. I have even gone the the extreme of writing VB6
and VB.NET code next to each other in my VB6 code and commentoing out the
VB.NET code. When I port, I know exactly what I have to do.

Dan

"Dennis" <dbronstein@brainranger.com> wrote in message
news:3a8d58f9$1@news.devx.com...
> We can't do that today, can we? And then we'd have a different set of
> parameters for each, which we don't need.
>
> Dennis
>
> "J W Cooper" <ctswim@ctswim.org> wrote in message
> news:3A8C9A87.F6E71BBA@ctswim.org...
> > Why not just overload the function so that there are two kinds of
> arguments
> > and two kinds of return types? Its far better programming practice and
> avoicd
> > unpleasant type cast failures.
> >
> > Function getRecord(a as integer, b as integer) as RecordSet
> >
> > Function getRecord(a as integer) as String
> >
> > Jim Cooper
> >
> > Dennis wrote:
> >
> > > Since .Net doesn't allow variants, how do you create a function that
can
> > > return different datatypes? Say we have a function that returns
either
> a
> > > recordset or an XML string based on a parameter, so it has to use
> Variant
> > > for it's return type. Can we use this funciton in .Net somehow? Or
> would
> > > we have to separate it into two functions?
> > >
> > > Thanks,
> > > Dennis
> >
>
>

[Kenny Acock]

Dennis,

>Again, how can we do that _today_, because a string is not an object in
VB6?
>Or are we going to have to change all the functions when we convert?

VB.Net will automatically convert Variants to Objects. From a design standpoint,
however, I would limit the use of Variants.

--Kenny

[Dennis]

Sure we can. We can just have the function return a variant. The problem
is we want something we can use today that will convert easily to .Net.

"Dan Fergus" <dan@vbforest.com> wrote in message
news:3a8d5dd0$1@news.devx.com...
> No, you cannot do that today. I don't know of anyway that you can write
> code, to do what you are asking, now in VB6 so that it will move smoothly
> into VB.NET.
>
> My own opinion, you will have a hard time moving anything except the most
> basic code to VB.NET without major work.
>
> Make sure that you comment well now in your VB6 code so that you can find
> these problem spots later. I have even gone the the extreme of writing
VB6
> and VB.NET code next to each other in my VB6 code and commentoing out the
> VB.NET code. When I port, I know exactly what I have to do.
>
> Dan
>
> "Dennis" <dbronstein@brainranger.com> wrote in message
> news:3a8d58f9$1@news.devx.com...
> > We can't do that today, can we? And then we'd have a different set of
> > parameters for each, which we don't need.
> >
> > Dennis
> >
> > "J W Cooper" <ctswim@ctswim.org> wrote in message
> > news:3A8C9A87.F6E71BBA@ctswim.org...
> > > Why not just overload the function so that there are two kinds of
> > arguments
> > > and two kinds of return types? Its far better programming practice
and
> > avoicd
> > > unpleasant type cast failures.
> > >
> > > Function getRecord(a as integer, b as integer) as RecordSet
> > >
> > > Function getRecord(a as integer) as String
> > >
> > > Jim Cooper
> > >
> > > Dennis wrote:
> > >
> > > > Since .Net doesn't allow variants, how do you create a function that
> can
> > > > return different datatypes? Say we have a function that returns
> either
> > a
> > > > recordset or an XML string based on a parameter, so it has to use
> > Variant
> > > > for it's return type. Can we use this funciton in .Net somehow? Or
> > would
> > > > we have to separate it into two functions?
> > > >
> > > > Thanks,
> > > > Dennis
> > >
> >
> >
>
>

[Kenny Acock]

Dennis,

>Sure we can. We can just have the function return a variant. The problem
>is we want something we can use today that will convert easily to .Net.

Your problem will actually be with the Recordset. VB.Net has replaced it
with something else. (I forgot the exact name.) If you use a Variant, VB.Net
has no information on which to do a conversion. You can use a variant to
pass data, but be sure not to access the variant as a recordset directly:

VariantVariable.SomeMethod <---Not a good idea (Even if it works)

(VB.Net will *not* know how to handle the method because it is late bound.)

Do this instead:

Dim rs As ADODB.Recordset
set rs = VariantVariable
rs.SomeMethod

(VB.Net *will* know how to handle the method because it is early bound.)
When VB.Net converts the project, the Variant will become an Object, which
will be able to do what VB6 Variants and VB6 Objects can do. (AFAIK)

--Kenny

[Tim Romano]

It would be cleaner to separate these functions into separate methods of a
VB6 class:

myXMLString = myClass.GetXML( )
Set myRecordset = myClass.GetRS( )

Tim Romano



"Dennis" <dbronstein@brainranger.com> wrote in message
news:3a8c21a5@news.devx.com...
> Since .Net doesn't allow variants, how do you create a function that can
> return different datatypes? Say we have a function that returns either a
> recordset or an XML string based on a parameter, so it has to use Variant
> for it's return type. Can we use this funciton in .Net somehow? Or would
> we have to separate it into two functions?
>
> Thanks,
> Dennis
>
>