creating a new instance of an object XXX type

[jernej goricki]

Hi,
Is it possible to do this in vb.net :

1.)To make a function that would have a string parameter ClassName
2.)This function would return an object of the same type as the ClassName
parameter was.

For example, in my project a have this classes : ClassPerson, ClassCar,
ClassXXX....... ....

Dim objectA as Object = GetNewObject(Cl assPerson)
' ObjectA would be of a type ClassPeron

Public function GetNewObject(Cl assName as string)
return new object instance of a type ClassName
End function

Thanks for your help!

[One Handed Man [ OHM# ]]

Re: creating a new instance of an object XXX type




Can see why you want to do this but !


(Untested )

Class CGetter

public FunctionGetObje ct( cname as String ) return Object

Select Case case cname

case "ClassPerso n"
return New ClassPerson()
case "ClassCar"
return New ClassCar()
case Else
return Nothing
End Select

End Function

End Class





jernej goricki wrote:[color=blue]
> Hi,
> Is it possible to do this in vb.net :
>
> 1.)To make a function that would have a string parameter ClassName
> 2.)This function would return an object of the same type as the
> ClassName parameter was.
>
> For example, in my project a have this classes : ClassPerson,
> ClassCar, ClassXXX....... ....
>
> Dim objectA as Object = GetNewObject(Cl assPerson)
> ' ObjectA would be of a type ClassPeron
>
> Public function GetNewObject(Cl assName as string)
> return new object instance of a type ClassName
> End function
>
> Thanks for your help![/color]

Regards - OHM# OneHandedMan{at }BTInternet{dot }com

[Scott M.]

Re: creating a new instance of an object XXX type

So you are saying that you want a function to return a dynamically
determined class.

You can't do what you have below unless you plan on returning a string
because that's what the function says it returns. In your example below,
you don't indicate what the return type from the function is.

You need to know up front what type your function will return. You could do
this I suppose:

Public Function Test(x as object) as Object
some code
Dim x as new x.GetType
return x
End Function


"jernej goricki" <ph-enom@obmocje51. net> wrote in message
news:%23nnV1axx DHA.1740@TK2MSF TNGP09.phx.gbl. ..[color=blue]
> Hi,
> Is it possible to do this in vb.net :
>
> 1.)To make a function that would have a string parameter ClassName
> 2.)This function would return an object of the same type as the ClassName
> parameter was.
>
> For example, in my project a have this classes : ClassPerson, ClassCar,
> ClassXXX....... ....
>
> Dim objectA as Object = GetNewObject(Cl assPerson)
> ' ObjectA would be of a type ClassPeron
>
> Public function GetNewObject(Cl assName as string)
> return new object instance of a type ClassName
> End function
>
> Thanks for your help!
>
>[/color]

[One Handed Man [ OHM# ]]

TYPO


Class CGetter

public FunctionGetObje ct( cname as String ) As Object ( Not return object as
f*&ked up in above post )

Select Case case cname

case "ClassPerso n"
return New ClassPerson()
case "ClassCar"
return New ClassCar()
case Else
return Nothing
End Select

End Function

End Class

[Blumidoo]

Re: creating a new instance of an object XXX type

> Hi,[color=blue]
> Is it possible to do this in vb.net :
>
> 1.)To make a function that would have a string parameter ClassName
> 2.)This function would return an object of the same type as the ClassName
> parameter was.[/color]

What you are trying to do is dirty, very dirty. You should rather design and
implement an AbstractFactory design pattern class. AbstractFactory design
pattern allows you to returns an instance of one of several possible classes
depending on the data provided to it.
Read http://www.dotnetextreme.com/code/SimpleFactory.asp for more
information about simple AbstractFactory design pattern implementations .

sincerely,
--
Sebastian Zaklada
Skilled Software

http://www.skilledsoftware.com

*************** *************** ******
SQL Source Control 2003 - for
SQL Server Source Safe integration
and custom databases documentation

[jernej goricki]

Re: creating a new instance of an object XXX type

yes this with select case would probably work, but I want to do this without
writing a new "select case" line for every ne class I will create.

Is possible to do this dynamically something like this:

return new object.Gettype( "Class Name")




"One Handed Man [ OHM# ]" <OneHandedMan{a t}BTInternet{do t}com> wrote in
message news:uCBxpixxDH A.3416@tk2msftn gp13.phx.gbl...[color=blue]
>
>
>
> Can see why you want to do this but !
>
>
> (Untested )
>
> Class CGetter
>
> public FunctionGetObje ct( cname as String ) return Object
>
> Select Case case cname
>
> case "ClassPerso n"
> return New ClassPerson()
> case "ClassCar"
> return New ClassCar()
> case Else
> return Nothing
> End Select
>
> End Function
>
> End Class
>
>
>
>
>
> jernej goricki wrote:[color=green]
> > Hi,
> > Is it possible to do this in vb.net :
> >
> > 1.)To make a function that would have a string parameter ClassName
> > 2.)This function would return an object of the same type as the
> > ClassName parameter was.
> >
> > For example, in my project a have this classes : ClassPerson,
> > ClassCar, ClassXXX....... ....
> >
> > Dim objectA as Object = GetNewObject(Cl assPerson)
> > ' ObjectA would be of a type ClassPeron
> >
> > Public function GetNewObject(Cl assName as string)
> > return new object instance of a type ClassName
> > End function
> >
> > Thanks for your help![/color]
>
> Regards - OHM# OneHandedMan{at }BTInternet{dot }com
>
>[/color]

[One Handed Man [ OHM# ]]

Re: creating a new instance of an object XXX type

There may well be some obscure way to achieve this, but It does not sound
very structured because. What you imply is that your factory class does not
need to validate if a class exists before it tries to create it.

IMHO This is not good sense.

Regards - OHM


jernej goricki wrote:[color=blue]
> yes this with select case would probably work, but I want to do this
> without writing a new "select case" line for every ne class I will
> create.
>
> Is possible to do this dynamically something like this:
>
> return new object.Gettype( "Class Name")
>
>
>
>
> "One Handed Man [ OHM# ]" <OneHandedMan{a t}BTInternet{do t}com> wrote
> in message news:uCBxpixxDH A.3416@tk2msftn gp13.phx.gbl...[color=green]
>>
>>
>>
>> Can see why you want to do this but !
>>
>>
>> (Untested )
>>
>> Class CGetter
>>
>> public FunctionGetObje ct( cname as String ) return Object
>>
>> Select Case case cname
>>
>> case "ClassPerso n"
>> return New ClassPerson()
>> case "ClassCar"
>> return New ClassCar()
>> case Else
>> return Nothing
>> End Select
>>
>> End Function
>>
>> End Class
>>
>>
>>
>>
>>
>> jernej goricki wrote:[color=darkred]
>>> Hi,
>>> Is it possible to do this in vb.net :
>>>
>>> 1.)To make a function that would have a string parameter ClassName
>>> 2.)This function would return an object of the same type as the
>>> ClassName parameter was.
>>>
>>> For example, in my project a have this classes : ClassPerson,
>>> ClassCar, ClassXXX....... ....
>>>
>>> Dim objectA as Object = GetNewObject(Cl assPerson)
>>> ' ObjectA would be of a type ClassPeron
>>>
>>> Public function GetNewObject(Cl assName as string)
>>> return new object instance of a type ClassName
>>> End function
>>>
>>> Thanks for your help![/color]
>>
>> Regards - OHM# OneHandedMan{at }BTInternet{dot }com[/color][/color]

Regards - OHM# OneHandedMan{at }BTInternet{dot }com

[Herfried K. Wagner [MVP]]

Re: creating a new instance of an object XXX type

* "jernej goricki" <ph-enom@obmocje51. net> scripsit:[color=blue]
> Is it possible to do this in vb.net :
>
> 1.)To make a function that would have a string parameter ClassName
> 2.)This function would return an object of the same type as the ClassName
> parameter was.[/color]

<http://groups.google.c om/groups?selm=bqn s3k%2424ghqf%24 2%40ID-208219.news.uni-berlin.de>

--
Herfried K. Wagner [MVP]
<http://www.mvps.org/dotnet>

[jernej goricki]

Re: creating a new instance of an object XXX type

that is just the thing im looking for, thanks
"Herfried K. Wagner [MVP]" <hirf-spam-me-here@gmx.at> wrote in message
news:OP6tg9xxDH A.2156@TK2MSFTN GP09.phx.gbl...[color=blue]
> * "jernej goricki" <ph-enom@obmocje51. net> scripsit:[color=green]
> > Is it possible to do this in vb.net :
> >
> > 1.)To make a function that would have a string parameter ClassName
> > 2.)This function would return an object of the same type as the[/color][/color]
ClassName[color=blue][color=green]
> > parameter was.[/color]
>
>[/color]
<http://groups.google.com/groups?selm...-208219.news.u
ni-berlin.de>[color=blue]
>
> --
> Herfried K. Wagner [MVP]
> <http://www.mvps.org/dotnet>[/color]

[One Handed Man [ OHM# ]]

Re: creating a new instance of an object XXX type

I knew this would not be something simple, well done for finding it.

Regards - OHM


Herfried K. Wagner [MVP] wrote:[color=blue]
> * "jernej goricki" <ph-enom@obmocje51. net> scripsit:[color=green]
>> Is it possible to do this in vb.net :
>>
>> 1.)To make a function that would have a string parameter ClassName
>> 2.)This function would return an object of the same type as the
>> ClassName parameter was.[/color]
>
>[/color]
<http://groups.google.com/groups?selm...-208219.news.u
ni-berlin.de>

Regards - OHM# OneHandedMan{at }BTInternet{dot }com

[Blumidoo]

Re: creating a new instance of an object XXX type

>
<http://groups.google.com/groups?selm...-208219.news.u
ni-berlin.de>

What a beautiful way to make a total mess in the code... :-/
Not that I do not like the solution, but I don't like to promote bad
programming habits.

sincerely,
--
Sebastian Zaklada
Skilled Software

http://www.skilledsoftware.com

*************** *************** ******
SQL Source Control 2003 - for
SQL Server Source Safe integration
and custom databases documentation

[One Handed Man [ OHM# ]]

Re: creating a new instance of an object XXX type

I agree. The principal itself is poor.

Regards

Blumidoo wrote:[color=blue]
>[/color]
<http://groups.google.com/groups?selm...-208219.news.u[color=blue]
> ni-berlin.de>
>
> What a beautiful way to make a total mess in the code... :-/
> Not that I do not like the solution, but I don't like to promote bad
> programming habits.
>
> sincerely,[/color]

Regards - OHM# OneHandedMan{at }BTInternet{dot }com

[Herfried K. Wagner [MVP]]

Re: creating a new instance of an object XXX type

* "Blumidoo" <szaklada-dont-like-spam@skilledsof tware.com> scripsit:[color=blue]
> <http://groups.google.com/groups?selm...-208219.news.u
> ni-berlin.de>
>
> What a beautiful way to make a total mess in the code... :-/
> Not that I do not like the solution, but I don't like to promote bad
> programming habits.[/color]

Why should this code promote "bad programming habits"?

--
Herfried K. Wagner [MVP]
<http://www.mvps.org/dotnet>

[Herfried K. Wagner [MVP]]

Re: creating a new instance of an object XXX type

* "One Handed Man [ OHM# ]" <OneHandedMan{a t}BTInternet{do t}com> scripsit:[color=blue]
> I knew this would not be something simple, well done for finding it.[/color]

;-)

It's easy for me to find messages I have written previously...

--
Herfried K. Wagner [MVP]
<http://www.mvps.org/dotnet>

[Blumidoo]

Re: creating a new instance of an object XXX type

> > What a beautiful way to make a total mess in the code... :-/[color=blue][color=green]
> > Not that I do not like the solution, but I don't like to promote bad
> > programming habits.[/color]
>
> Why should this code promote "bad programming habits"?[/color]

Not the code itself, I wrote I like it. But the idea is wrong - Jernej
should should rather design and implement an AbstractFactory design pattern
class, not create objects of any type whenever he wants and wherever in the
code. It is messy. Development is design, than design even more, and after
that you may code... And even than you will always end up refactoring what
you have written before... :-)

sincerely,
--
Sebastian Zaklada
Skilled Software

http://www.skilledsoftware.com

*************** *************** ******
SQL Source Control 2003 - for
SQL Server Source Safe integration
and custom databases documentation