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.NET Forum / Languages / C# / June 2007Logging Class - Instance or Static
I have a logging component that I will access in other assemblies. So it was brought up to me that I should pass an instance around to these components instead of just making the logging class static. If I make it static I wouldn't need to pass an instance around. What is your take on this? > I have a logging component that I will access in other assemblies. So it > was brought up to me that I should pass an instance around to these > components instead of just making the logging class static. If I make it > static I wouldn't need to > pass an instance around. What is your take on this? Hi, An important decision, and it depends on your needs. Does your class need to retain state? How complicated is it? How memory-hungry is it?  SignatureTom Spink University of Edinburgh Its a pretty simple class that will send emails, write to eventlog or to a file. My thinking is if I pass an instance around and it gets passed down a chain of about 3 classes then I will have multiple refs to my logging class and I am wondering if that is the proper coding technique to be using here? > Does your class need > to retain state? No my class doesn't need to retain state but if I make it static I can just refer to directly from any where without having refs to it. > > I have a logging component that I will access in other assemblies. So it > > was brought up to me that I should pass an instance around to these [quoted text clipped - 6 lines] > An important decision, and it depends on your needs. Does your class need > to retain state? How complicated is it? How memory-hungry is it? Hi, > Its a pretty simple class that will send emails, write to eventlog or to a > file. My thinking is if I pass an instance around and it gets passed down [quoted text clipped - 3 lines] > and I am wondering if that is the proper coding technique to be using > here? I will definetely will not pass an instance around. A logging class makes sense to have it accesible from all over the app, I would select either a static class or a Singleton > I have a logging component that I will access in other assemblies. So it was > brought up to me that I should pass an instance around to these components > instead of just making the logging class static. If I make it static I > wouldn't need to > pass an instance around. What is your take on this? Have you seen the Microsoft Enterprise ApplicationBlocks? There is a logging block that should meet your needs. You might want to either use this instead or model your component after it (the source code is provided). http://msdn2.microsoft.com/en-us/library/aa480464.aspx I would recomend to use a Singleton class here. This means a static GetInstance method which only instanciates the class once and gives this instance back. > I have a logging component that I will access in other assemblies. So it was > brought up to me that I should pass an instance around to these components > instead of just making the logging class static. If I make it static I > wouldn't need to > pass an instance around. What is your take on this? I would check out the Microsoft Enterprise Application Block first. If it doesn't suit your needs, or you don't have time to study it, then I would side with Martin: create a logging instance class, then create a static method that returns a (singleton) instance of it. I would also create a logging interface and have the static method return that type. The logic behind this is that you can then (if you want to) create other logging classes that implement the same interface but log in different ways, and swap them out with a minimum of fuss. > I would recomend to use a Singleton class here. > This means a static GetInstance method which only instanciates the class [quoted text clipped - 7 lines] > > - Show quoted text - So in using a singleton I am going to call it directly like so, singletonClass.Instance().method; and with using a singleton I don't have to pass it around from class to class, I can just call it as above, correct? > I would recomend to use a Singleton class here. > This means a static GetInstance method which only instanciates the class [quoted text clipped - 5 lines] > > wouldn't need to > > pass an instance around. What is your take on this? Hello, A singleton method looks normaly like this. private static MyClass instance = null; public static MyClass GetInstance() { if(instance==null) { instance = new MyClass(); //Only done once } // You can do other stuff here // For example calling some Init methods return instance; } And will be called like this: Your.Full.Namespace.MyClass myreferencetomyclass = Your.Full.Namespace.MyClass.GetInstance(); Hop it helps! All the best, Martin > So in using a singleton I am going to call it directly like so, > singletonClass.Instance().method; [quoted text clipped - 10 lines] > > > wouldn't need to > > > pass an instance around. What is your take on this? > A singleton method looks normaly like this. > [quoted text clipped - 9 lines] > return instance; > } Except that's not thread-safe. It's simpler to use a static initializer. See http://pobox.com/~skeet/csharp/singleton.html SignatureJon Skeet - <skeet@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 Good point for the concept! But what I meant was alittle more custom specific. For example if the sender is passed as a parameter, there would be the write place to forward it to the accurate method. All the best, Martin > > A singleton method looks normaly like this. > > [quoted text clipped - 15 lines] > See http://pobox.com/~skeet/csharp/singleton.html > You wouldn't necessarily create one ref to singleton and pass it around to the different classes. I figure I would get a ref to getInstance whenever I would need it and destroy it after I am done using it in each class. Is that how you guys would use it? > Hello, > [quoted text clipped - 36 lines] > > > > wouldn't need to > > > > pass an instance around. What is your take on this? Hello, Yes, you don't have to pass around it, cause every class can call the GetInstance(). "destroy" as you sayed, is only a "null" set . All the best, Martin > You wouldn't necessarily create one ref to singleton and pass it around to > the different classes. I figure I would get a ref to getInstance whenever I [quoted text clipped - 41 lines] > > > > > wouldn't need to > > > > > pass an instance around. What is your take on this? Thank you all! > Hello, > [quoted text clipped - 51 lines] > > > > > > wouldn't need to > > > > > > pass an instance around. What is your take on this? Oh, and GetInstance() might be better implemented in C# as an Instance property. I think it reads better: Logger.Instance.Log(...); versus Logger.GetInstance().Log(...); > Hello, > [quoted text clipped - 53 lines] > > - Show quoted text - > Oh, and GetInstance() might be better implemented in C# as an Instance > property. I think it reads better: [quoted text clipped - 64 lines] > > - Show quoted text - Why don't you use a simple static method in a static class (if you are using .NET Framework 2.0)? I think the singleton instance, in this case, is completely useless. Regards, Fernando Hi, >> Oh, and GetInstance() might be better implemented in C# as an Instance >> property. I think it reads better: [quoted text clipped - 77 lines] > using .NET Framework 2.0)? > I think the singleton instance, in this case, is completely useless. Not really, if the logging facility change dynamically (file, eventlog, email, SMS, etc) you will want a Factory that build the concrete class according some parameters: class Log { ILog current; static public ILog GetLogger{ get{return current;}} static Log() { switch ( flag) { case Email: current = new EmailLogger();break; case Eventlog: current = new EL_Logger();break; case textl: current = new FileLogger();break; } } } interface ILog{ void Log(......);} class EmailLogger:ILog{} .... On Jun 29, 12:22 pm, "Ignacio Machin \( .NET/ C# MVP \)" <machin TA laceupsolutions.com> wrote: > Hi, > [quoted text clipped - 103 lines] > > - Show quoted text - Hi Ignacio, .NET 2.0 have some facilities to work with logging, based on configuration files (*.config's). You don't need to switch which logging class use based on a flag passed from client classes. Instead, .NET Framework 2.0 have classes (namespace System.Diagnostics) that abstract this job for us. For more information, take a look at http://msdn2.microsoft.com/en-us/library/system.diagnostics.aspx What I want to say, is that your (static) class can abstract the BLC methods to do this kind of job, instead of create instance class (the unique advantage from this is that you can decide, based on an commom interface, which class to use) and verify other things about log source etc. ps.: sorry by my poor english. my natural language is another one. Hi, >I would recomend to use a Singleton class here. > This means a static GetInstance method which only instanciates the class > once and gives this instance back. Why singleton over a static class? The only reason I can think of is if you want to be able to change the logging tool under need, let's say from EventLog to a file. Hi, >I have a logging component that I will access in other assemblies. So it >was > brought up to me that I should pass an instance around to these components > instead of just making the logging class static. If I make it static I > wouldn't need to > pass an instance around. What is your take on this? If you use it in different assemblies you will have to place it in a separate assembly that all other projects will need to add a reference to. Regarding your question, I have a similar situation, I decided to use a static class and based on a flag I use either the EventLog or dump it to a file. Agreed, my environment is simple, if you have a dynamic environment you should implement something more fancy like a Factory. Free MagazinesGet these publications absolutely FREE for up to 12 months. There are no hidden fees and no obligation. Simply choose a title, complete the application form and submit it. Read more ...
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