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.NET Forum / Languages / C# / February 2008Casting problem
I am trying to do this in one statement; This works: PropertyType pt1 = propertyTypesList.Find(delegate(PropertyType pt) {return pt.Description == "Sales"; }); cmd.Parameters.Add(new SqlParameter("@" + "PropertyTypeID", pt1)); But I can't seem to get this to work: cmd.Parameters.Add(new SqlParameter("@" + "PropertyTypeID", (PropertyType)(propertyTypesList.Find(delegate(PropertyType pt) {return pt.Description == "Listing"; }).PropertyTypeID))); break; I get an error: Cannot convert type 'int' to 'PropertyType' If I put an (int) in front of it I get the same error. cmd.Parameters.Add(new SqlParameter("@" + "PropertyTypeID", (int)(PropertyType)(propertyTypesList.Find(delegate(PropertyType pt) {return pt.Description == "Listing"; }).PropertyTypeID))); break; I have also tried putting parens after the (int) and before the .PropertyTypeID with same error: cmd.Parameters.Add(new SqlParameter("@" + "PropertyTypeID", (int)((PropertyType)(propertyTypesList.Find(delegate(PropertyType pt) {return pt.Description == "Listing"; })).PropertyTypeID))); break; Does it have to be created as an object before? Intellisense knows that the return is a PropertType as it gives me the list of properties when I put the "." in - so I would assume that it should be able to know that I am passing back an int. Thanks, Tom > I am trying to do this in one statement; > [quoted text clipped - 40 lines] > > Tom tshad, The problem is because you are trying to cast an int to PropertyType. Try this instead: cmd.Parameters.Add(new SqlParameter("@PropertyTypeID", propertyTypesList.Find(delegate(PropertyType pt) { return pt.Description == "Listing"; }).PropertyTypeID)); >> I am trying to do this in one statement; >> [quoted text clipped - 52 lines] > propertyTypesList.Find(delegate(PropertyType pt) > { return pt.Description == "Listing"; }).PropertyTypeID)); It works fine. I was puting the (PropertyType) in front of the delegate since the delegate was passing back a PropertyType object. I assumed that I would have to tell it what type of object it was before I could use the property. Obviously, I was wrong. Thanks, Tom > I am trying to do this in one statement; (see also previous thread) Why do you keep trying to do everything in one statement? This aim is often detrimental to code quality... >> I am trying to do this in one statement; > > (see also previous thread) Why do you keep trying to do everything in > one statement? This aim is often detrimental to code quality... Probably true. I like to consolidate where possible. For the same reason to use anonymous functions (at least one of the reasons). Why create a function name I am going to call only once, where I would create the function and then call the function. Why not just do it in one call. Why is it detrimental to code quality? It could be that in some cases it is harder to follow by putting 2 anonymous delegates in one method call. Not incorrect, just hard to follow. Is that what you mean? Thanks, Tom > I like to consolidate where possible. > > For the same reason to use anonymous functions (at least one of the > reasons). Actually I'm all-up for anonymous methods for delegates; agree with you strongly. Even better in C# 3 where you can use the much abbreviated lambda syntax. But there's a line smoewhere, between simpy consolidating, vs deliberately banging your code out of shape to make it into one line/ statement; the fact that you have to ask how to do it in one statement probably means you're on the far side of the line. It isn't helping you, and it can *only* complicate the code. Fine if throwaway, but most of the longterm cost of code is support/maintenance - which means (in a typical corporate setupt) that you might not be the person editing the code next time. If the next person has to stop and think "what does this do?" then you've achieved an own goal; there are times when simple code, and meaningful variable names go a long way towards creating maintainable code. > It could be that in some cases it is harder to follow by putting 2 anonymous > delegates in one method call. Not incorrect, just hard to follow. I agree - not incorrect (see LINQ...) - but I would advocate using lambdas if possible; they make such things a lot easier to follow; regardless of the body of the anon/lambda, the human eye/brain can only see so much at once; a lambda takes only a fraction as much effort to understand as an anon-method. Marc >> I like to consolidate where possible. >> [quoted text clipped - 16 lines] > when simple code, and meaningful variable names go a long way towards > creating maintainable code. Sounds reasonable. If it costs more to put it together and even more to maintain, then it probably wasn't the best way to go. >> It could be that in some cases it is harder to follow by putting 2 >> anonymous [quoted text clipped - 5 lines] > only see so much at once; a lambda takes only a fraction as much > effort to understand as an anon-method. I haven't really done much with lambdas yet, but heard it was pretty neat. Looking forward to playing with it. Thanks, Tom > Marc > This works: > [quoted text clipped - 9 lines] > {return pt.Description == "Listing"; }).PropertyTypeID))); > break; This is not the same as above. Why did you add PropertyTypeID? In the first statement you implicitly cast the result of Find to PropertyType. In the second statement you cast the PropertyTypeID to PropertyType. > I get an error: > > Cannot convert type 'int' to 'PropertyType' I guess PropertyType is int and can't be cast to PropertyType Christof >> This works: >> [quoted text clipped - 13 lines] > first statement you implicitly cast the result of Find to PropertyType. In > the second statement you cast the PropertyTypeID to PropertyType. Your right, that was my mistake. It should have been: cmd.Parameters.Add(new SqlParameter("@" + "PropertyTypeID", pt1.PropertyTypeID)); but that wasn't causing the problem. The casting to (PropertyType) was the problem. PropertyTypeID is an int property in PropertyType. And by adding the (PropertyType) cast I was, apparently, trying to cast the PropertyTypeID (which is an int) to a PropertyType object. I just had to take the cast off to make it work. I was under the assumption that I needed to say what type of object I was dealing with before I could add the property (.PropertyTypeID). Thanks, Tom >> I get an error: >> [quoted text clipped - 3 lines] > > Christof 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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