I for some very very odd reason thought that. Thing : IAuditableEntity Couch : Thing
if couch is IAuditableEntity would not work in this case, this is where isAssignableFrom from does, for some odd reason did not realise is, 'is' fine to use. We learn something every day. Cheers Stefan On Sat, Dec 20, 2008 at 2:52 AM, MAMMON <[email protected]> wrote: > > I am not an expert on this, but here is what I've found. > > Considering the line: > if (typeof(IAuditableEntity).IsAssignableFrom(entity.GetType())) > > versus > > if (entity is IAuditableEntity) > > I set up a test project, created an IAuditableEntity interface, a > class that implements it, and issues the 2 different "if" statements. > Then I opened the assembly with reflector, to see the MSIL code that > is generated. > > > Using "entity is IAuditableEntity" results in: > > L_008b: ldloc.1 // loads local var at index 1 ("entity") > onto the evaluation stack > > L_008c: isinst is_test.IAuditableEntity // pops the top > var off the evaluation stack, testing if it's an instance of > IAuditableEntity > > > > Using "typeof(IAuditableEntity).IsAssignableFrom(entity.GetType()) > results in: > > L_00b3: ldtoken is_test.IAuditableEntity // Converts a > metadata token to its runtime representation, pushing it onto the > evaluation stack > > L_00b8: call class [mscorlib]System.Type [mscorlib] > System.Type::GetTypeFromHandle(valuetype [mscorlib] > System.RuntimeTypeHandle) // Gets the type of IAuditableEntity > from the handle we just pushed onto the stack > > L_00bd: ldloc.1 // pushes "entity" onto the stack (local > var at index 1) > > L_00be: callvirt instance class [mscorlib]System.Type [mscorlib] > System.Object::GetType() > > L_00c3: callvirt instance bool [mscorlib] > System.Type::IsAssignableFrom(class [mscorlib]System.Type) > > > > So using the "is" operator issues a single IL instruction: isint. > > Using if (typeof(IAuditableEntity).IsAssignableFrom(entity.GetType())) > results in: > + ldtoken instruction > + function call (System.Type::GetTypeFromHandle) > + virtual call (System.Object::GetType()) > + virtual call (System.Type::IsAssignableFrom) > > > Keep in mind that virtual calls are more expensive than regular > function calls as well. > > > I would use the "is" operator. It's a built in operator that issues a > single IL instruction. > > > > > > > > > On Dec 18, 3:09 pm, "Stefan Sedich" <[email protected]> wrote: >> Heh what a post to wake upto, thanks guys, I will look into using the >> events look 100 times easier. >> >> Cheers >> Stefan >> >> >> >> On Fri, Dec 19, 2008 at 7:00 AM, Will Shaver <[email protected]> wrote: >> > Now you've just got me all confused and showing my ignorance. ;) >> >> > On Thu, Dec 18, 2008 at 1:55 PM, Tuna Toksöz <[email protected]> wrote: >> >> >> and assuming you are not talking about managed c++ >> >> >> On Thu, Dec 18, 2008 at 11:52 PM, Tuna Toksöz <[email protected]> wrote: >> >> >>> boxing in c++? >> >>> Are you sure that casting takes cycles? I think it doesn't, because it is >> >>> the cmpilers job to cast. >> >> >>> On Thu, Dec 18, 2008 at 11:25 PM, Will Shaver <[email protected]> >> >>> wrote: >> >> >>>> Yes, but with both Daniel and Tuna's examples are incomplete. >> >>>> if (typeof(IAuditableEntity).IsAssignableFrom(entity.GetType())) { >> >>>> ((IAuditableEntity) entity).Audit(); >> >>>> } >> >>>> or >> >>>> if (entity is IAuditableEntity) { >> >>>> ((IAuditableEntity) entity).Audit(); >> >>>> } >> >>>> In BOTH cases you have to do TWO casts. In mine you only have to do one. >> >>>> I learned in C++ where casting and boxing take cycles. >> >>>> -Will >> >> >>>> On Thu, Dec 18, 2008 at 1:17 PM, Tuna Toksöz <[email protected]> wrote: >> >> >>>>> or >> >> >>>>> if (entity is IAuditableEntity) >> >>>>> ? :) >> >> >>>>> On Thu, Dec 18, 2008 at 11:08 PM, Daniel Fernandes >> >>>>> <[email protected]> wrote: >> >> >>>>>> Beside the point I know but : >> >>>>>> if (typeof(IAuditableEntity).IsAssignableFrom(entity.GetType())) { >> >>>>>> to >> >>>>>> var auditable = entity as IAuditableEntity; >> >>>>>> if (auditable != null) { >> >> >>>>>> isn't easier to read ? >> >> >>>>>> On Dec 18, 6:35 am, "Stefan Sedich" <[email protected]> wrote: >> >>>>>> > Hello, >> >> >>>>>> > I am setting date last modified audit on an entity, I implement an >> >>>>>> > IAuditableEntity interface and use a helper to set the date >> >>>>>> > modified: >> >> >>>>>> > public override bool OnFlushDirty(object entity, object id, >> >>>>>> > object[] >> >>>>>> > currentState, object[] previousState, string[] propertyNames, >> >>>>>> > global::NHibernate.Type.IType[] types) { >> >> >>>>>> > if >> >>>>>> > (typeof(IAuditableEntity).IsAssignableFrom(entity.GetType())) { >> >> >>>>>> > // If entity is auditable as this is only an update >> >>>>>> > set the last modified date. >> >>>>>> > SetValue(propertyNames, currentState, item => >> >>>>>> > item.LastModified, DateTime.Now); >> >> >>>>>> > } >> >> >>>>>> > return false; >> >>>>>> > } >> >> >>>>>> > Type safe helper: >> >> >>>>>> > public void SetValue<T>(string[] propertyNames, object[] state, >> >>>>>> > Expression<System.Func<IAuditableEntity, T>> propertyExpression, T >> >>>>>> > value) { >> >> >>>>>> > var memberExpression = propertyExpression.Body as >> >>>>>> > MemberExpression; >> >>>>>> > if (memberExpression == null) >> >>>>>> > throw new ArgumentException("The member expression >> >>>>>> > was >> >>>>>> > not a valid member expression."); >> >> >>>>>> > string name = memberExpression.Member.Name; >> >>>>>> > int index = propertyNames.ToList().IndexOf(name); >> >> >>>>>> > if(index == -1) >> >>>>>> > throw new >> >>>>>> > InvalidOperationException(string.Format("Property {0} does no exist >> >>>>>> > on >> >>>>>> > entity.", name)); >> >> >>>>>> > state[index] = value; >> >> >>>>>> > } >> >> >>>>>> > Now the question is, I saw that you must set the current state and >> >>>>>> > not >> >>>>>> > the entity directly why would >> >> >>>>>> > var ent = entity as IAuditableEntity; >> >>>>>> > ent.LastModified = DateTime.Now; >> >> >>>>>> > Not work properly or will it be fine to do this? >> >> >>>>>> > Thanks >> >> >>>>>> > -- >> >>>>>> > Stefan Sedich >> >>>>>> > Software Developerhttp://weblogs.asp.net/stefansedich >> >> >>>>> -- >> >>>>> Tuna Toksöz >> >>>>>http://tunatoksoz.com >> >> >>>>> Typos included to enhance the readers attention! >> >> >>> -- >> >>> Tuna Toksöz >> >>>http://tunatoksoz.com >> >> >>> Typos included to enhance the readers attention! >> >> >> -- >> >> Tuna Toksöz >> >>http://tunatoksoz.com >> >> >> Typos included to enhance the readers attention! >> >> -- >> Stefan Sedich >> Software Developerhttp://weblogs.asp.net/stefansedich > > > -- Stefan Sedich Software Developer http://weblogs.asp.net/stefansedich --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "nhusers" group. 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