Global variables in a project.

[UJ]

How do I create an instance of a class that is accessible to all
classes/forms in my project? I already have a startup module and I was
thinking putting stuff in there and then accessing it through there.

I need it for things like db connections, security manager, general db
functions, .....

Any help would be appreciated.... .

UJ.

[Bob Powell [MVP]]

Re: Global variables in a project.

You can create a class that uses the Singleton Pattern.
Something like...

public class DBCentral

private _theInstance as DBCentral

public readonly shared property TheInstance() as DBCentral
get()
if _theInstance is nothing then
_theInstance=ne w DBCentral()
end if
return _theInstance
end get
end property

end class

I didn't check the exact syntax but you get the picture....

--
Bob Powell [MVP]
Visual C#, System.Drawing

Find great Windows Forms articles in Windows Forms Tips and Tricks

http://www.bobpowell.net/tipstricks.htm

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"UJ" <UJ@nowhere.com > wrote in message
news:O9JQkMQFFH A.3376@TK2MSFTN GP12.phx.gbl...[color=blue]
> How do I create an instance of a class that is accessible to all
> classes/forms in my project? I already have a startup module and I was
> thinking putting stuff in there and then accessing it through there.
>
> I need it for things like db connections, security manager, general db
> functions, .....
>
> Any help would be appreciated.... .
>
> UJ.
>
>[/color]

[chanmmn]

Re: Global variables in a project.

http://msdn.microsoft.com/architecture

chanmm

"UJ" <UJ@nowhere.com > wrote in message
news:O9JQkMQFFH A.3376@TK2MSFTN GP12.phx.gbl...[color=blue]
> How do I create an instance of a class that is accessible to all
> classes/forms in my project? I already have a startup module and I was
> thinking putting stuff in there and then accessing it through there.
>
> I need it for things like db connections, security manager, general db
> functions, .....
>
> Any help would be appreciated.... .
>
> UJ.
>
>[/color]

[UJ]

Re: Global variables in a project.

Chanmm,

Can you point me in the correct direction? This is a general architecture
page. I don't see anything specific to globals.

UJ.

"chanmmn" <chanmmn@hotmai l.com> wrote in message
news:OgttB1QFFH A.3596@TK2MSFTN GP12.phx.gbl...[color=blue]
> http://msdn.microsoft.com/architecture
>
> chanmm
>
> "UJ" <UJ@nowhere.com > wrote in message
> news:O9JQkMQFFH A.3376@TK2MSFTN GP12.phx.gbl...[color=green]
>> How do I create an instance of a class that is accessible to all
>> classes/forms in my project? I already have a startup module and I was
>> thinking putting stuff in there and then accessing it through there.
>>
>> I need it for things like db connections, security manager, general db
>> functions, .....
>>
>> Any help would be appreciated.... .
>>
>> UJ.
>>
>>[/color]
>
>[/color]

[Samuel R. Neff]

Re: Global variables in a project.


The .NET recommended practice for creating singletons is to use a
single line..

Public Shared ReadOnly Instance As New [ClassName]

For example..

Public NotInheritable Class DBCentral

Public Shared ReadOnly Instance As New DBCentral

Private Sub New()
End Sub

End Class


Sam


On Thu, 17 Feb 2005 17:09:03 +0100, "Bob Powell [MVP]"
<bob@_spamkille r_bobpowell.net > wrote:
[color=blue]
>You can create a class that uses the Singleton Pattern.
>Something like...
>
>public class DBCentral
>
>private _theInstance as DBCentral
>
>public readonly shared property TheInstance() as DBCentral
>get()
> if _theInstance is nothing then
> _theInstance=ne w DBCentral()
> end if
> return _theInstance
>end get
>end property
>
>end class
>
>I didn't check the exact syntax but you get the picture....[/color]

B-Line is now hiring one VB.NET developer for
WinForms + WebServices position with ASPX in future.
Seaking mid to senior level developer. For
information or to apply e-mail sam_blinex_com.

[UJ]

Re: Global variables in a project.

OK I'm completely lost. I think I didn't explain myself correctly. I want to
be able define somewhere a user object called SecurityManager (which I
wrote). I want to be able to define it somewhere so I can reference it from
all kinds of objects. I have found so far that what I can do is create a
startup module (let's call it StartItUp), and create the instance of the
class as public in there. But then I always need to reference my Security
Manager as StartItUp.SecMa nager.

Is there an easier way?

TIA - UJ

"Samuel R. Neff" <blinex@newsgro up.nospam> wrote in message
news:b4v911d8ia 0kjqhkb1pjcooui o87nh5gtd@4ax.c om...[color=blue]
>
> The .NET recommended practice for creating singletons is to use a
> single line..
>
> Public Shared ReadOnly Instance As New [ClassName]
>
> For example..
>
> Public NotInheritable Class DBCentral
>
> Public Shared ReadOnly Instance As New DBCentral
>
> Private Sub New()
> End Sub
>
> End Class
>
>
> Sam
>
>
> On Thu, 17 Feb 2005 17:09:03 +0100, "Bob Powell [MVP]"
> <bob@_spamkille r_bobpowell.net > wrote:
>[color=green]
>>You can create a class that uses the Singleton Pattern.
>>Something like...
>>
>>public class DBCentral
>>
>>private _theInstance as DBCentral
>>
>>public readonly shared property TheInstance() as DBCentral
>>get()
>> if _theInstance is nothing then
>> _theInstance=ne w DBCentral()
>> end if
>> return _theInstance
>>end get
>>end property
>>
>>end class
>>
>>I didn't check the exact syntax but you get the picture....[/color]
>
> B-Line is now hiring one VB.NET developer for
> WinForms + WebServices position with ASPX in future.
> Seaking mid to senior level developer. For
> information or to apply e-mail sam_blinex_com.[/color]

[Dennis]

RE: Global variables in a project.

In your start-up module, you can just create a public instance and use it
throughout your applciation:

PUblic myClassInstance as myClass = new myclass

You can then referr to myClassInstance throughout your applicaiton. Hope I
understood your question correctly.

"UJ" wrote:
[color=blue]
> How do I create an instance of a class that is accessible to all
> classes/forms in my project? I already have a startup module and I was
> thinking putting stuff in there and then accessing it through there.
>
> I need it for things like db connections, security manager, general db
> functions, .....
>
> Any help would be appreciated.... .
>
> UJ.
>
>
>[/color]

[Bob Powell [MVP]]

Re: Global variables in a project.

Thats rubbish. This gives you a new instance of the class every time you ask
for it. Not a single persistent instance that can store instance data.

--
Bob Powell [MVP]
Visual C#, System.Drawing

Find great Windows Forms articles in Windows Forms Tips and Tricks

http://www.bobpowell.net/tipstricks.htm

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"Samuel R. Neff" <blinex@newsgro up.nospam> wrote in message
news:b4v911d8ia 0kjqhkb1pjcooui o87nh5gtd@4ax.c om...[color=blue]
>
> The .NET recommended practice for creating singletons is to use a
> single line..
>
> Public Shared ReadOnly Instance As New [ClassName]
>
> For example..
>
> Public NotInheritable Class DBCentral
>
> Public Shared ReadOnly Instance As New DBCentral
>
> Private Sub New()
> End Sub
>
> End Class
>
>
> Sam
>
>
> On Thu, 17 Feb 2005 17:09:03 +0100, "Bob Powell [MVP]"
> <bob@_spamkille r_bobpowell.net > wrote:
>[color=green]
>>You can create a class that uses the Singleton Pattern.
>>Something like...
>>
>>public class DBCentral
>>
>>private _theInstance as DBCentral
>>
>>public readonly shared property TheInstance() as DBCentral
>>get()
>> if _theInstance is nothing then
>> _theInstance=ne w DBCentral()
>> end if
>> return _theInstance
>>end get
>>end property
>>
>>end class
>>
>>I didn't check the exact syntax but you get the picture....[/color]
>
> B-Line is now hiring one VB.NET developer for
> WinForms + WebServices position with ASPX in future.
> Seaking mid to senior level developer. For
> information or to apply e-mail sam_blinex_com.[/color]

[Bob Powell [MVP]]

Re: Global variables in a project.

What's easier than....

public class SecurityManager

private _sm As new SecurityManager

public readonly shared TheSecurityMana ger() as SecurityManager
get
return _sm
end get
end property



end class

Now whenever you need to access your security manager you use...

SecurityManager .TheSecurityMan ager.SomeMethor OrOther()

--
Bob Powell [MVP]
Visual C#, System.Drawing

Find great Windows Forms articles in Windows Forms Tips and Tricks

http://www.bobpowell.net/tipstricks.htm

Answer those GDI+ questions with the GDI+ FAQ

http://www.bobpowell.net/faqmain.htm

All new articles provide code in C# and VB.NET.
Subscribe to the RSS feeds provided and never miss a new article.





"UJ" <UJ@nowhere.com > wrote in message
news:%23ZzMi$TF FHA.3068@TK2MSF TNGP10.phx.gbl. ..[color=blue]
> OK I'm completely lost. I think I didn't explain myself correctly. I want
> to be able define somewhere a user object called SecurityManager (which I
> wrote). I want to be able to define it somewhere so I can reference it
> from all kinds of objects. I have found so far that what I can do is
> create a startup module (let's call it StartItUp), and create the instance
> of the class as public in there. But then I always need to reference my
> Security Manager as StartItUp.SecMa nager.
>
> Is there an easier way?
>
> TIA - UJ
>
> "Samuel R. Neff" <blinex@newsgro up.nospam> wrote in message
> news:b4v911d8ia 0kjqhkb1pjcooui o87nh5gtd@4ax.c om...[color=green]
>>
>> The .NET recommended practice for creating singletons is to use a
>> single line..
>>
>> Public Shared ReadOnly Instance As New [ClassName]
>>
>> For example..
>>
>> Public NotInheritable Class DBCentral
>>
>> Public Shared ReadOnly Instance As New DBCentral
>>
>> Private Sub New()
>> End Sub
>>
>> End Class
>>
>>
>> Sam
>>
>>
>> On Thu, 17 Feb 2005 17:09:03 +0100, "Bob Powell [MVP]"
>> <bob@_spamkille r_bobpowell.net > wrote:
>>[color=darkred]
>>>You can create a class that uses the Singleton Pattern.
>>>Something like...
>>>
>>>public class DBCentral
>>>
>>>private _theInstance as DBCentral
>>>
>>>public readonly shared property TheInstance() as DBCentral
>>>get()
>>> if _theInstance is nothing then
>>> _theInstance=ne w DBCentral()
>>> end if
>>> return _theInstance
>>>end get
>>>end property
>>>
>>>end class
>>>
>>>I didn't check the exact syntax but you get the picture....[/color]
>>
>> B-Line is now hiring one VB.NET developer for
>> WinForms + WebServices position with ASPX in future.
>> Seaking mid to senior level developer. For
>> information or to apply e-mail sam_blinex_com.[/color]
>
>[/color]

[Bob Powell [MVP]]

Re: Global variables in a project.

Global variable usage is a very poor architectural choice. If you use them,
and global methods then you go back to the dark-ages of unstructured non
object oriented programming and create horrible spaghetti code. That's why
there is no mention of them in the architecture guidelines.

Of course, if you're moving over from VB6 you will be used to the concept of
spaghetti and feel quite at home with it but VB6 wasn't ever a real
programming language ;-).

--
Bob Powell [MVP]
Visual C#, System.Drawing

Find great Windows Forms articles in Windows Forms Tips and Tricks

http://www.bobpowell.net/tipstricks.htm

Answer those GDI+ questions with the GDI+ FAQ

http://www.bobpowell.net/faqmain.htm

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Subscribe to the RSS feeds provided and never miss a new article.





"UJ" <UJ@nowhere.com > wrote in message
news:e$qKk8QFFH A.3120@TK2MSFTN GP12.phx.gbl...[color=blue]
> Chanmm,
>
> Can you point me in the correct direction? This is a general architecture
> page. I don't see anything specific to globals.
>
> UJ.
>
> "chanmmn" <chanmmn@hotmai l.com> wrote in message
> news:OgttB1QFFH A.3596@TK2MSFTN GP12.phx.gbl...[color=green]
>> http://msdn.microsoft.com/architecture
>>
>> chanmm
>>
>> "UJ" <UJ@nowhere.com > wrote in message
>> news:O9JQkMQFFH A.3376@TK2MSFTN GP12.phx.gbl...[color=darkred]
>>> How do I create an instance of a class that is accessible to all
>>> classes/forms in my project? I already have a startup module and I was
>>> thinking putting stuff in there and then accessing it through there.
>>>
>>> I need it for things like db connections, security manager, general db
>>> functions, .....
>>>
>>> Any help would be appreciated.... .
>>>
>>> UJ.
>>>
>>>[/color]
>>
>>[/color]
>
>[/color]

[Cor Ligthert]

Re: Global variables in a project.

Bob,

Good morning,
[color=blue]
> Of course, if you're moving over from VB6 you will be used to the concept
> of spaghetti and feel quite at home with it but VB6 wasn't ever a real
> programming language ;-).
>[/color]
You need some coffee

:-)

Cor

[Bob Powell [MVP]]

Re: Global variables in a project.

Nah, never drink the stuff. It makes me all hyper :-))

--
Bob Powell [MVP]
Visual C#, System.Drawing

Find great Windows Forms articles in Windows Forms Tips and Tricks

http://www.bobpowell.net/tipstricks.htm

Answer those GDI+ questions with the GDI+ FAQ

http://www.bobpowell.net/faqmain.htm

All new articles provide code in C# and VB.NET.
Subscribe to the RSS feeds provided and never miss a new article.





"Cor Ligthert" <notmyfirstname @planet.nl> wrote in message
news:O$oKXPbFFH A.464@TK2MSFTNG P09.phx.gbl...[color=blue]
> Bob,
>
> Good morning,
>[color=green]
>> Of course, if you're moving over from VB6 you will be used to the concept
>> of spaghetti and feel quite at home with it but VB6 wasn't ever a real
>> programming language ;-).
>>[/color]
> You need some coffee
>
> :-)
>
> Cor
>
>[/color]

[UJ]

Re: Global variables in a project.

Bob,
It's all fine and good to say you don't need globals. But then how do you do
something like a security manager class where every class is going to need
to access it? Do you spend you life passing references around for it?

Currently I am going to put references in my startup module and then make
references to it by startup.securit ymanager

I can't think of any other way. Remember - the whole point is to have only
one instance of the variable around. I don't want to have many instances.

I supposed in a really good world, I would make it a property of the startup
(and I may do that).

Thanks for the help.

UJ.


"Bob Powell [MVP]" <bob@_spamkille r_bobpowell.net > wrote in message
news:OYF9zBbFFH A.464@TK2MSFTNG P09.phx.gbl...[color=blue]
> Global variable usage is a very poor architectural choice. If you use
> them, and global methods then you go back to the dark-ages of unstructured
> non object oriented programming and create horrible spaghetti code. That's
> why there is no mention of them in the architecture guidelines.
>
> Of course, if you're moving over from VB6 you will be used to the concept
> of spaghetti and feel quite at home with it but VB6 wasn't ever a real
> programming language ;-).
>
> --
> Bob Powell [MVP]
> Visual C#, System.Drawing
>
> Find great Windows Forms articles in Windows Forms Tips and Tricks
> http://www.bobpowell.net/tipstricks.htm
>
> Answer those GDI+ questions with the GDI+ FAQ
> http://www.bobpowell.net/faqmain.htm
>
> All new articles provide code in C# and VB.NET.
> Subscribe to the RSS feeds provided and never miss a new article.
>
>
>
>
>
> "UJ" <UJ@nowhere.com > wrote in message
> news:e$qKk8QFFH A.3120@TK2MSFTN GP12.phx.gbl...[color=green]
>> Chanmm,
>>
>> Can you point me in the correct direction? This is a general architecture
>> page. I don't see anything specific to globals.
>>
>> UJ.
>>
>> "chanmmn" <chanmmn@hotmai l.com> wrote in message
>> news:OgttB1QFFH A.3596@TK2MSFTN GP12.phx.gbl...[color=darkred]
>>> http://msdn.microsoft.com/architecture
>>>
>>> chanmm
>>>
>>> "UJ" <UJ@nowhere.com > wrote in message
>>> news:O9JQkMQFFH A.3376@TK2MSFTN GP12.phx.gbl...
>>>> How do I create an instance of a class that is accessible to all
>>>> classes/forms in my project? I already have a startup module and I was
>>>> thinking putting stuff in there and then accessing it through there.
>>>>
>>>> I need it for things like db connections, security manager, general db
>>>> functions, .....
>>>>
>>>> Any help would be appreciated.... .
>>>>
>>>> UJ.
>>>>
>>>>
>>>
>>>[/color]
>>
>>[/color]
>
>[/color]

[Cor Ligthert]

Re: Global variables in a project.

UJ,

The simplest you can do is to pass the variables in the constructor.

Cor

[Jay B. Harlow [MVP - Outlook]]

Re: Global variables in a project.

Bob,[color=blue]
> Thats rubbish. This gives you a new instance of the class every time you
> ask for it. Not a single persistent instance that can store instance data.[/color]
Huh?

Looking at Samual's code, he has a readonly shared field. That shared field
will be initialized when the class itself is initialized (when the Shared
Sub New runs).
[color=blue][color=green]
>> Public Shared ReadOnly Instance As New DBCentral[/color][/color]

How does it give a new instance each time you ask for it?

Very curious
Jay

"Bob Powell [MVP]" <bob@_spamkille r_bobpowell.net > wrote in message
news:%231Snv8aF FHA.2608@TK2MSF TNGP10.phx.gbl. ..[color=blue]
> Thats rubbish. This gives you a new instance of the class every time you
> ask for it. Not a single persistent instance that can store instance data.
>
> --
> Bob Powell [MVP]
> Visual C#, System.Drawing
>
> Find great Windows Forms articles in Windows Forms Tips and Tricks
> http://www.bobpowell.net/tipstricks.htm
>
> Answer those GDI+ questions with the GDI+ FAQ
> http://www.bobpowell.net/faqmain.htm
>
> All new articles provide code in C# and VB.NET.
> Subscribe to the RSS feeds provided and never miss a new article.
>
>
>
>
>
> "Samuel R. Neff" <blinex@newsgro up.nospam> wrote in message
> news:b4v911d8ia 0kjqhkb1pjcooui o87nh5gtd@4ax.c om...[color=green]
>>
>> The .NET recommended practice for creating singletons is to use a
>> single line..
>>
>> Public Shared ReadOnly Instance As New [ClassName]
>>
>> For example..
>>
>> Public NotInheritable Class DBCentral
>>
>> Public Shared ReadOnly Instance As New DBCentral
>>
>> Private Sub New()
>> End Sub
>>
>> End Class
>>
>>
>> Sam
>>
>>
>> On Thu, 17 Feb 2005 17:09:03 +0100, "Bob Powell [MVP]"
>> <bob@_spamkille r_bobpowell.net > wrote:
>>[color=darkred]
>>>You can create a class that uses the Singleton Pattern.
>>>Something like...
>>>
>>>public class DBCentral
>>>
>>>private _theInstance as DBCentral
>>>
>>>public readonly shared property TheInstance() as DBCentral
>>>get()
>>> if _theInstance is nothing then
>>> _theInstance=ne w DBCentral()
>>> end if
>>> return _theInstance
>>>end get
>>>end property
>>>
>>>end class
>>>
>>>I didn't check the exact syntax but you get the picture....[/color]
>>
>> B-Line is now hiring one VB.NET developer for
>> WinForms + WebServices position with ASPX in future.
>> Seaking mid to senior level developer. For
>> information or to apply e-mail sam_blinex_com.[/color]
>
>[/color]