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GTi
Maybe a very stupid question for an expert, but:

I have created a lib project in c# with some functions.
But how can I call this functions?

Functions libs:
namespace MyLib
{
class RegLib
{
public void WriteRegKey(string subKey, string name, string value)
{
RegistryKey key = Registry.LocalMachine.CreateSubKey(subKey);
key.SetValue(name, value, RegistryValueKind.String);
key.Close();
}
}
}
ref. files:

RegLib rl = new RegLib();
rl.WriteRegKey(...);
Why do I have to create a new RegLib() to call WriteRegKey?
How can I call this just by using:
RegLib.WriteRegKey(...);

Nov 17 '05 #1
8 1166
GTi wrote:
Maybe a very stupid question for an expert, but:

I have created a lib project in c# with some functions.
But how can I call this functions?
<snip>
Why do I have to create a new RegLib() to call WriteRegKey?
How can I call this just by using:
RegLib.WriteRegKey(...);


Your method is an instance method - it acts on an *instance* of the
class.

If you want to be able to call RegLib.WriteRegKey(...), just make it
static:
public static void WriteRegKey(string subKey, string name, string
value)
{
....
}

Jon

Nov 17 '05 #2
GTi wrote:
Maybe a very stupid question for an expert, but:

I have created a lib project in c# with some functions.
But how can I call this functions?

Functions libs:
namespace MyLib
{
class RegLib
{
public void WriteRegKey(string subKey, string name, string value)
{
RegistryKey key = Registry.LocalMachine.CreateSubKey(subKey);
key.SetValue(name, value, RegistryValueKind.String);
key.Close();
}
}
}
ref. files:

RegLib rl = new RegLib();
rl.WriteRegKey(...);

Why do I have to create a new RegLib() to call WriteRegKey?
How can I call this just by using:
RegLib.WriteRegKey(...);


You have defined your methods to be normal methods of a class, which
are called instance methods. So to use them, you first need to
instantiate the class to an object, then call the method on the object,
as the methods only live inside an instance of the class.

If you want to use them like RegLib.WriteRegKey(), you can define them
as static:
namespace MyLib
{
class RegLib
{
public static void WriteRegKey(string subKey, string name, string
value)
{
RegistryKey key = Registry.LocalMachine.CreateSubKey(subKey);
key.SetValue(name, value, RegistryValueKind.String);
key.Close();
}
}
}

and now you can do:
RegLib.WriteRegKey(....);

Keep in mind that static methods work on a single instance behind the
scenes. This means that local variables created INSIDE a method are
thread safe, but class wide variables (globals) aren't.

FB


--
------------------------------------------------------------------------
Get LLBLGen Pro, productive O/R mapping for .NET: http://www.llblgen.com
My .NET blog: http://weblogs.asp.net/fbouma
Microsoft MVP (C#)
------------------------------------------------------------------------
Nov 17 '05 #3
Frans Bouma [C# MVP] wrote:

<snip>
Keep in mind that static methods work on a single instance behind the
scenes.


No they don't - they don't work on *any* instance (of the class
involved). You may have meant that they work on a single instance of
Type, or something like that, but it's not terribly clear. One common
misconception (which I suspect you don't share, but which is worth
pointing out for the OP's sake) is that static variables are "shared
between all instances of the class". In fact, they are *independent* of
any instances of the class - meaning that you don't have to have any
instances of the class whatsoever in order to use them.

Jon

Nov 17 '05 #4
GTi
Thanks Jon :)
It was a very stupid question, but a exemplary answer...

Nov 17 '05 #5
Jon Skeet [C# MVP] wrote:
Frans Bouma [C# MVP] wrote:

<snip>
Keep in mind that static methods work on a single instance behind
the scenes.


No they don't - they don't work on any instance (of the class
involved). You may have meant that they work on a single instance of
Type, or something like that, but it's not terribly clear. One common
misconception (which I suspect you don't share, but which is worth
pointing out for the OP's sake) is that static variables are "shared
between all instances of the class". In fact, they are independent of
any instances of the class - meaning that you don't have to have any
instances of the class whatsoever in order to use them.


Thanks for formulating it more clearly than I did :). I used the
instance metaphore to illustrate the concept of thread insafety.

FB

--
------------------------------------------------------------------------
Get LLBLGen Pro, productive O/R mapping for .NET: http://www.llblgen.com
My .NET blog: http://weblogs.asp.net/fbouma
Microsoft MVP (C#)
------------------------------------------------------------------------
Nov 17 '05 #6
> <snip>
Keep in mind that static methods work on a single instance behind the
scenes.
No they don't - they don't work on *any* instance (of the class


Since you are such a stickler for picking out the right words, I thought I
might, too, in jest, of course:)
is that static variables are "shared
between all instances of the class". In fact, they are *independent* of
any instances of the class - meaning that you don't have to have any
instances of the class whatsoever in order to use them
You say "shared between all **instances** of the class" and then you go on
to say
"*independent* of any **instances** of the class " and "you don't have to
have any **instances** of the class whatsoever in order to use them".

So many **instances** being used, all in the same context, I guess?:)

Regards

Jv

"Jon Skeet [C# MVP]" wrote:
Frans Bouma [C# MVP] wrote:

<snip>
Keep in mind that static methods work on a single instance behind the
scenes.


No they don't - they don't work on *any* instance (of the class
involved). You may have meant that they work on a single instance of
Type, or something like that, but it's not terribly clear. One common
misconception (which I suspect you don't share, but which is worth
pointing out for the OP's sake) is that static variables are "shared
between all instances of the class". In fact, they are *independent* of
any instances of the class - meaning that you don't have to have any
instances of the class whatsoever in order to use them.

Jon

Nov 17 '05 #7
Ravichandran J.V. <Ra************@discussions.microsoft.com> wrote:
is that static variables are "shared
between all instances of the class". In fact, they are *independent* of
any instances of the class - meaning that you don't have to have any
instances of the class whatsoever in order to use them


You say "shared between all **instances** of the class" and then you go on
to say
"*independent* of any **instances** of the class " and "you don't have to
have any **instances** of the class whatsoever in order to use them".

So many **instances** being used, all in the same context, I guess?:)


There don't have to be any instances used. Note that I was saying that
*other people* talked about static variables being "shared between all
instances of the class" - I was arguing *against* that point of view.

--
Jon Skeet - <sk***@pobox.com>
http://www.pobox.com/~skeet Blog: http://www.msmvps.com/jon.skeet
If replying to the group, please do not mail me too
Nov 17 '05 #8
Thanks for the reply.

"Jon Skeet [C# MVP]" wrote:
Ravichandran J.V. <Ra************@discussions.microsoft.com> wrote:
is that static variables are "shared
between all instances of the class". In fact, they are *independent* of
any instances of the class - meaning that you don't have to have any
instances of the class whatsoever in order to use them


You say "shared between all **instances** of the class" and then you go on
to say
"*independent* of any **instances** of the class " and "you don't have to
have any **instances** of the class whatsoever in order to use them".

So many **instances** being used, all in the same context, I guess?:)


There don't have to be any instances used. Note that I was saying that
*other people* talked about static variables being "shared between all
instances of the class" - I was arguing *against* that point of view.

--
Jon Skeet - <sk***@pobox.com>
http://www.pobox.com/~skeet Blog: http://www.msmvps.com/jon.skeet
If replying to the group, please do not mail me too

Nov 17 '05 #9

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