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  • Does `throw` cause stack variables (full types) to be freed from memory in C++?

    - by nbolton
    I'm pondering a question on Brainbench. I actually realised that I could answer my question easily by compiling the code, but it's an interesting question nonetheless, so I'll ask the question anyway and answer it myself shortly. Take a look at this snippet: The question considers what happens when we throw from a destructor (which causes terminate() to be called). It's become clear to me by asking the question that the memory is indeed freed and the destructor is called, but, is this before or after throw is called from foo? Perhaps the issue here is that throw is used while the stack is unwinding that is the problem... Actually this is slightly confusing.

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  • XNA Class Design with Structs as Properties and issues because they are value types and not referenc

    - by Nate Bross
    I'm wondering how you'd recommend designin a class, given the fact that XNA Framework uses Struct all over the place? For example, a spite class, which may require a Vector2 and a Rectangle (both defined as Struct) to be accessed outside of the class. The issue come in when you try to write code like this: class Item { public Vetor2 Position {get; set;} public Item() { Position = new Vector2(5,5); } } Item i = new Item(); i.Positon.X = 20; // fails with error 'Cannot modify the return value of Item because it is not a variable.' // you must write code like this var pos = i.Position; pos.X++; i.Position = pos; The second option compiles and works, but it is just butt ugly. Is there a better way?

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  • Declare 2 types inside using statement gives compile error?

    - by citronas
    I want to use this line of code: using (ADataContext _dc = new ADataContext(ConnectionString), BDataContext _dc2 = new BrDataContext(ConnectionString)){ // ...} This gives a compile error: Cannot use more than one type in a for, using, fixed or declartion statement. I thought this was possible? MSDN says it is: http://msdn.microsoft.com/en-us/library/yh598w02%28VS.80%29.aspx In the MSDN sample code Font is used, which is class and thereby a reference type as well as my two DataContext classes. What went wrong here? How does my attempt differ from the MSDN sample?

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  • How does Python differentiate between the different data types?

    - by wrongusername
    Sorry if this is quite noobish to you, but I'm just starting out to learn Python after learning C++ & Java, and I am wondering how in the world I could just declare variables like id = 0 and name = 'John' without any int's or string's in front! I figured out that perhaps it's because there are no ''s in a number, but how would Python figure that out in something like def increase(first, second) instead of something like int increase(int first, int second) in C++?!

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  • Is there a way to achieve covariance of generic types in C# 3.5?

    - by nullDev
    This has been introduced in C# 4.0, but is there a way to achieve this in c# 3.5? For e.g., consider the following code: class Base { } class Derived1 : Base { } class Derived2 : Base { } class User<T> where T : Base { } class User1 : User<Derived1> { } Now, I would like to have a list of User<T>, in which I can store User<Derived1> as well as User<Derived2>, but the following code fails to compile in C# 3.5: List<User<Base>> users = new List<User<Base>>(); users.Add(new User1()); Any ideas?

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  • does mysql stored procedures support data types like array, hash,etc?

    - by Yang
    i am creating a mysql function which takes in a varchar and change it to a int based on a mapping table. select name, convert_to_code(country) from users where sex = 'male' here, the convert_to_code() function takes in a country name (e.g. Japan, Finland..) and change it to country code which is an integer (e.g. 1001, 2310..) based on a mapping table called country_maping like below: country_name (varchar) | country_code (int) Japan | 1001 Finland | 2310 Canada | 8756 currently, the stored function need to select country_code from country_mapping where country_name = country_name and return the query result. is that possible to create a hash data struct in SP to optimize the process so that it will not need to perform the query for each row matches the where clause. thanks in advance!

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  • How to replace all id attributes of a child collection of complex types using jQuery in ASP.net MVC

    - by TJB
    Here's my situation: I'm writing an ASP.net MVC 1 website and I have a create/edit form that uses the default model binding to parse the form into a strongly typed complex object. The object I'm posting has a child collection of another complex type and the way I format my id's for the model binder is as follows: <div class="childContainer" > <!-- There's one of these for each property for each child collection item --> <%= Html.TextBox("ChildCollectionName[0].ChildPropertyName", /* blah blah */ ) %> <%= Html.TextBox("ChildCollectionName[0].OtherChildPropertyName", /* blah blah */ ) %> <!-- ... --> </div> This gets rendered as <div class="childContainer" > <input id="ChildCollectionName[0]_ChildPropertyName" ... /> <input id="ChildCollectionName[0]_OtherChildPropertyName" ... /> ... </div> <div class="childContainer" > <input id="ChildCollectionName[1]_ChildPropertyName" ... /> <input id="ChildCollectionName[1]_OtherChildPropertyName" ... /> ... </div> For each entry in the chlid collection. This collection is dynamically created in the form using jQuery, so entries can be added, removed etc. and whenever there's an operation on the collection I need to update the indexes so that it's bound correctly on the server side. What's the best way to replace all the html input id's when I'm updating the index within the child e.g. replace all [*] -- [N] where N is the correct index. using jQuery / JavaScript ? I have something coded now, but its buggy and I think there is a simpler solution. Also, if you have an easier way to identify the child collection I'll take any advice on that as well. Thanx!

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  • How do polymorphic inline caches work with mutable types?

    - by kingkilr
    A polymorphic inline cache works by caching the actual method by the type of the object, in order to avoid the expensive lookup procedures (usually a hashtable lookup). How does one handle the type comparison if the type objects are mutable (i.e. the method might be monkey patched into something different at run time). The one idea I've come up with would be a "class counter" that gets incremented each time a method is adjusted, however this seems like it would be exceptionally expensive in a heavily monkey patched environ since it would kill all the PICs for that class, even if the methods for them weren't altered. I'm sure there must be a good solution to this, as this issue is directly applicable to Javascript and AFAIK all 3 of the big JS VMs have PICs (wow acronym ahoy).

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  • What's the difference between these two calls to a function taking a collection of structural types?

    - by James Moore
    Why does the call to fn(Iterator("foo") compile, but the call to fn(fooIterator) fail with an error "type mismatch; found : Iterator[java.lang.String] required: scala.Iterator[com.banshee.Qx.HasLength]" object Qx { type HasLength = {def length: Int} def fn(xs: Iterator[HasLength]) = 3 var tn = fn(Iterator("foo")) var fooIterator = Iterator("foo") var tnFails = fn(fooIterator) //doesn't compile } Aren't they the same thing?

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  • How do I handle editing of custom types in a C# datagridview?

    - by Ian Hopkinson
    I have a datagridview in which one column contains a custom class, which I have set using: dgvPeriods.Columns[1].ValueType = typeof(ExDateTime); It is rigged up to display correctly by handling the CellFormatting event, but I'm unsure what event to handle for cell editing. In the absence of doing anything I get a FormatException as the datagridview tries to convert String to ExDateTime as I try to move focus out of the edited cell. I tried adding type conversion to my ExDateTime custom class: public static implicit operator ExDateTime(string b) { return new ExDateTime(b); } But this this didn't work. I also tried handling the DataError event, but this seems to fire too late. The datagridview is not databound.

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  • When using a HiLo ID generation strategy, what types should be used to hold Ids?

    - by UpTheCreek
    I'm asking this from a c#/NHibnernate perspective, but it's generally applicable. The concern is that the HiLo strategy goes though id's pretty quickly, and for example a low record-count table (Such as Users) is sharing from the same set of id's as a high record-count table (Such as comments). So you can potentially get to high numbers quicker that with other strategies. So what do people recommend? Code side: int/uint/long/ulong? DBSide: int/bigint? My feeling is to go with longs and bigingts, but would like a sanity check :)

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  • Drupal 6: getting particular fields from Node Reference types...

    - by artmania
    Hi friends, I'm a drupal newbie... <?php print $node->field_date[0]['view']; ?> I can get the custom created CCK fields' value and display in tpl.php files as above... that's fine. my question is how can I get the Node reference fields' in-fields? for example, I have an event content type, and I have defined Node Reference for Location (title, address, img, etc.). When I write the code below, it displays all location content; <?php print $node->field_location[0]['view']; ?> but I need to get only address field from this location content type. sth like below would be great :D but not working; <?php print $node->field_location[0]['field_address']['view']; ?> so how can get that? appreciate helps so much! thanks a lot!

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  • Why doesn't C# allow for global inferred types i.e. using var?

    - by BritishDeveloper
    I know it can't be done since using var can only be done for local variables. I'm just wondering if anyone has a theory why the C# team thought this should be so. e.g. what would be wrong with this: public class SomeClass { var someString = "hello"; //not cool public SomeClass() { var someOtherString = "hello"; //cool } } If someString is initialised then it is obviously a string just like someOtherString. Why is there one rule for local variables and another for globals?

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  • How should I return different types in a method based on the value of a string in Java?

    - by Siracuse
    I'm new to Java and I have come to having the following problem: I have created several classes which all implement the interface "Parser". I have a JavaParser, PythonParser, CParser and finally a TextParser. I'm trying to write a method so it will take either a File or a String (representing a filename) and return the appropriate parser given the extension of the file. Here is some psuedo-code of what I'm basically attempting to do: public Parser getParser(String filename) { String extension = filename.substring(filename.lastIndexOf(".")); switch(extension) { case "py": return new PythonParser(); case "java": return new JavaParser(); case "c": return new CParser(); default: return new TextParser(); } } In general, is this the right way to handle this situation? Also, how should I handle the fact that Java doesn't allow switching on strings? Should I use the .hashcode() value of the strings? I feel like there is some design pattern or something for handling this but it eludes me. Is this how you would do it?

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  • Can I change class types in a setter with an object-oriented language?

    - by user214626
    Hello, Here is the problem statement : Calling a setter on the object should result in the object to change to an object of a different class, which language can support this ? Ex. I have a class called "Man" (Parent Class), and two children namely "Toddler" and "Old Man", they are its children because they override a behaviour in Man called as walk.( i.e Toddler sometimes walks using both his hands and legs kneeled down and the Old man uses a stick to support himself). The Man class has a attribute called age, I have a setter on Man,say it is called setAge(int ageValue). I have 3 objects, 2 toddlers, 1 old-Man. (The system is up and running,i guess when we say objects it is obvious) .I will make this call, toddler.setAge(80), I expect the toddler to change to an object of type Old Man. Is this possible.Please suggest. Thanks,

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  • How can I build an app with multiple types of controllers?

    - by Sheehan Alam
    How can I accomplish the following: When my app loads a UIView will show 4 buttons Clicking on a button will load a UITabBarController (not a UIView with a UITabBar) that can display multiple views. This seems challenging to me, because in order for me to use the UITabBarController I need to add this to the window's subview in my appDelegate. By doing so, my app automatically will load with the UITabbarController in the root view.

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  • How do I put all types implementing a certain generic interface in a dictionary?

    - by James Wenday
    Given a particular interface ITarget<T> and a particular type myType, here's how you would determine T if myType implements ITarget<T>. (This code snippet is taken from the answer to an earlier question.) foreach (var i in myType.GetInterfaces ()) if (i.IsGenericType && i.GetGenericTypeDefinition() == typeof(ITarget<>)) return i.GetGenericArguments ()[0] ; However, this only checks a single type, myType. How would I create a dictionary of all such type parameters, where the key is T and the value is myType? I think it would look something like this: var searchTarget = typeof(ITarget<>); var dict = Assembly.GetExecutingAssembly().[???] .Where(t => t.IsGenericType && t.GetGenericTypeDefinition() == searchTarget) .[???]; What goes in the blanks?

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  • Using typedefs (or #defines) on built in types - any sensible reason?

    - by jb
    Well I'm doing some Java - C integration, and throught C library werid type mappings are used (theres more of them;)): #define CHAR char /* 8 bit signed int */ #define SHORT short /* 16 bit signed int */ #define INT int /* "natural" length signed int */ #define LONG long /* 32 bit signed int */ typedef unsigned char BYTE; /* 8 bit unsigned int */ typedef unsigned char UCHAR; /* 8 bit unsigned int */ typedef unsigned short USHORT; /* 16 bit unsigned int */ typedef unsigned int UINT; /* "natural" length unsigned int*/ Is there any legitimate reason not to use them? It's not like char is going to be redefined anytime soon. I can think of: Writing platform/compiler portable code (size of type is underspecified in C/C++) Saving space and time on embedded systems - if you loop over array shorter than 255 on 8bit microprocessor writing: for(uint8_t ii = 0; ii < len; ii++) will give meaureable speedup.

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  • How do you compare using .NET types in an NHibernate ICriteria query for an ICompositeUserType?

    - by gabe
    I have an answered StackOverflow question about how to combine to legacy CHAR database date and time fields into one .NET DateTime property in my POCO here (thanks much Berryl!). Now i am trying to get a custom ICritera query to work against that very DateTime property to no avail. here's my query: ICriteria criteria = Session.CreateCriteria<InputFileLog>() .Add(Expression.Gt(MembersOf<InputFileLog>.GetName(x => x.FileCreationDateTime), DateTime.Now.AddDays(-14))) .AddOrder(Order.Desc(Projections.Id())) .CreateCriteria(typeof(InputFile).Name) .Add(Expression.Eq(MembersOf<InputFile>.GetName(x => x.Id), inputFileName)); IList<InputFileLog> list = criteria.List<InputFileLog>(); And here's the query it's generating: SELECT this_.input_file_token as input1_9_2_, this_.file_creation_date as file2_9_2_, this_.file_creation_time as file3_9_2_, this_.approval_ind as approval4_9_2_, this_.file_id as file5_9_2_, this_.process_name as process6_9_2_, this_.process_status as process7_9_2_, this_.input_file_name as input8_9_2_, gonogo3_.input_file_token as input1_6_0_, gonogo3_.go_nogo_ind as go2_6_0_, inputfile1_.input_file_name as input1_3_1_, inputfile1_.src_code as src2_3_1_, inputfile1_.process_cat_code as process3_3_1_ FROM input_file_log this_ left outer join go_nogo gonogo3_ on this_.input_file_token=gonogo3_.input_file_token inner join input_file inputfile1_ on this_.input_file_name=inputfile1_.input_file_name WHERE this_.file_creation_date > :p0 and this_.file_creation_time > :p1 and inputfile1_.input_file_name = :p2 ORDER BY this_.input_file_token desc; :p0 = '20100401', :p1 = '15:15:27', :p2 = 'LMCONV_JR' The query is exactly what i would expect, actually, except it doesn't actually give me what i want (all the rows in the last 2 weeks) because in the DB it's doing a greater than comparison using CHARs instead of DATEs. I have no idea how to get the query to convert the CHAR values into a DATE in the query without doing a CreateSQLQuery(), which I would like to avoid. Anyone know how to do this?

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  • What types of objects should the ViewModel reference in the MVVM pattern?

    - by Blanthor
    I've seen quite a few examples of MVVM. I can see that the View should reference the ViewModel. I've seen recently an example of a ViewModel referencing a View, which seems wrong to me, as it would result in tighter coupling. Given that ViewModel is often described as an intermediary between the View and the Model, is there more to the ViewModel than a facade to domain objects? I hope I used the term "facade" correctly here.

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  • How to get global access to enum types in C#?

    - by lala
    This is probably a stupid question, but I can't seem to do it. I want to set up some enums in one class like this: public enum Direction { north, east, south, west }; Then have that enum type accessible to all classes so that some other class could for instance have: Direction dir = north; and be able to pass the enum type between classes: public void changeDirection(Direction direction) { dir = direction; } I thought that setting the enum to public would make this automatically possible, but it doesn't seem to be visible outside of the class I declared the enum in.

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