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  • F# return type coercion

    - by Alex
    Hi, In F# I have a function that returns System.Linq.Expression instances: and System.Object with member this.ToExpression() = match this with | :? System.Int32 -> Expression.Constant(this) :> Expression | :? System.Boolean -> Expression.Constant(this) :> Expression | :? Tml.Runtime.Seq as s -> s.ToExpression() | _ -> failwith "bad expression" If I omit the type coercions on the return values F# will infer the return type of the function to ConstantExpression. My first thought was to explicitly mark the return type as being : #Expression, but that didn't work. Is there a more elegant way of doing this that doesn't involve manually casting return types to the most generic type? Thanks.

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  • How To Get Type Info Without Using Generics?

    - by DaveDev
    Hi Guys I have an object obj that is passed into a helper method. public static MyTagGenerateTag<T>(this HtmlHelper htmlHelper, T obj /*, ... */) { Type t = typeof(T); foreach (PropertyInfo prop in t.GetProperties()) { object propValue = prop.GetValue(obj, null); string stringValue = propValue.ToString(); dictionary.Add(prop.Name, stringValue); } // implement GenerateTag } I've been told this is not a correct use of generics. Can somebody tell me if I can achieve the same result without specifying a generic type? If so, how? I would probably change the signature so it'd be like: public static MyTag GenerateTag(this HtmlHelper htmlHelper, object obj /*, ... */) { Type t = typeof(obj); // implement GenerateTag } but Type t = typeof(obj); is impossible. Any suggestions? Thanks Dave

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  • Problem compiling c++ in CodeGear

    - by Carlos
    I have written a C++ program for a University assignment. I used Netbeans 6.8 running on my Mac and the code runs smoothly, no warnings, errors or problems/bugs. However when compiling and running on a Windows computer using CodeGear RAD Studio 2009 (C++ Builder) am getting several errors. [BCC32 Error] main.cpp(51): E2094 'operator<<' not implemented in type 'ostream' for arguments of type 'string' [BCC32 Error] main.cpp(62): E2093 'operator==' not implemented in type 'string' for arguments of the same type [BCC32 Error] main.cpp(67): E2093 'operator==' not implemented in type 'string' for arguments of the same type [BCC32 Error] main.cpp(112): E2093 'operator==' not implemented in type 'string' for arguments of the same type [BCC32 Error] main.cpp(121): E2094 'operator<<' not implemented in type 'ostream' for arguments of type 'string' [BCC32 Error] main.cpp(130): E2093 'operator==' not implemented in type 'string' for arguments of the same type [BCC32 Error] main.cpp(133): E2094 'operator<<' not implemented in type 'ostream' for arguments of type 'string' [BCC32 Error] main.cpp(139): E2094 'operator<<' not implemented in type 'ostream' for arguments of type 'string' [BCC32 Error] main.cpp(153): E2094 'operator<<' not implemented in type 'fstream' for arguments of type 'string' [BCC32 Error] main.cpp(199): E2094 'operator>>' not implemented in type 'fstream' for arguments of type 'string' [BCC32 Error] main.cpp(219): E2094 'operator>>' not implemented in type 'istream' for arguments of type 'string' [BCC32 Error] main.cpp(231): E2094 'operator>>' not implemented in type 'istream' for arguments of type 'string' [BCC32 Error] main.cpp(240): E2094 'operator>>' not implemented in type 'istream' for arguments of type 'string' [BCC32 Error] main.cpp(262): E2094 'operator>>' not implemented in type 'istream' for arguments of type 'string' [BCC32 Error] main.cpp(264): E2094 'operator>>' not implemented in type 'istream' for arguments of type 'string' These are the header files am using #include <iostream> #include <fstream> #include <cmath> #include <stdio> #include <windows> //I added this one just to check and still does not work (I didnt have it on Netbeans/Mac) using namespace std; Any ideas what is producing the errors and how can I fix it?

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  • Create xml type with no body

    - by Pace
    Hopefully this is an easy question. How can I define an XML type such that the type doesn't have a body. As an example I can define the Foo type as follows... <xs:complexType name="Foo"> <xs:simpleContent> <xs:extension base="xs:string"> <xs:attribute name="id" type="xs:integer" use="required"/> </xs:extension> </xs:simpleContent> </xs:complexType> But that would allow the following... <Foo id="7">STUFF I DON'T WANT</Foo> Is there a way I can change the xsd so that the Foo element isn't allowed any body?

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  • C++/CLI com-Interop: Exposing a reference type property to VBA

    - by Adam
    After long hours of investigation on exposing C# property that accepts a reference type to VBA, I concluded that it was not possible. In brief, a C# property that is of type double[] or even an object cannot be consumed in VBA like this: ' Compile Error: Function or interface marked as restricted, ' or the function uses an Automation type not supported in Visual Basic oComExposedEarlyBinding.ObjectArray = VBArray ' Run-time error 424: Object required oComExposedEarlyBinding.PlainObject = VBArray Or for more details: C# property exposed to VBA (COM) : Run-time error '424': Object required I would like to know if C++/CLI would support such an option? i.e. Allowing a reference-type property to be exposed to VBA so that a syntax like the above is valid. N.B. You can achieve this by using late binding, but losing the intellisense is not an option.

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  • jQuery: get the file name selected from <input type="file" />

    - by ConNen
    This code should work in IE (don't even test it in Firefox), but it doesn't. What I want is to display the name of the attached file. Any help? <html> <head> <title>example</title> <script type="text/javascript" src="../js/jquery.js"></script> <script type="text/javascript"> $(document).ready( function(){ $("#attach").after("<input id='fakeAttach' type='button' value='attach a file' />"); $("#fakeAttach").click(function() { $("#attach").click(); $("#maxSize").after("<div id='temporary'><span id='attachedFile'></span><input id='remove' type='button' value='remove' /></div>"); $('#attach').change(function(){ $("#fakeAttach").attr("disabled","disabled"); $("#attachedFile").html($(this).val()); }); $("#remove").click(function(e){ e.preventDefault(); $("#attach").replaceWith($("#attach").clone()); $("#fakeAttach").attr("disabled",""); $("#temporary").remove(); }); }) }); </script> </head> <body> <input id="attach" type="file" /><span id="maxSize">(less than 1MB)</span> </body> </html>

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  • std::map default value for build-in type

    - by Qifa Zhao
    Recently, I was confused by the std::map operator[] function. In the MSDN library, it says: "If the argument key value is not found, then it is inserted along with the default value of the data type." I tryed to search much more exactly explanation for this issue. For example here: std::map default value In this page, Michael Anderson said that "the default value is constructed by the default constructor(zero parameter constructor)". Now my quest comes to this:"what the default value for the build-in type?". Was it compiler related? Or is there a standard for this issue by the c++ stardard committee? I did a test on visual studio 2008 for the "int" type, and found the "int" type is construted with the value 0.

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  • Replication - User defined table type not propogating to subscriber

    - by Aamod Thakur
    I created a User defined table type named tvp_Shipment with two columns (id and name) . generated a snapshot and the User defined table type was properly propogated to all the subscribers. I was using this tvp in a stored procedure and everything worked fine. Then I wanted to add one more column created_date to this table valued parameter.I dropped the stored procedure (from replication too) and also i dropped and recreated the User defined table type with 3 columns and then recreated the stored procedure and enabled it for publication When i generate a new snapshot, the changes in user defined table type are not propogated to the subscriber. The newly added column was not added to the subscription. the Error messages: The schema script 'usp_InsertAirSa95c0e23_218.sch' could not be propagated to the subscriber. (Source: MSSQL_REPL, Error number: MSSQL_REPL-2147201001) Get help: http://help/MSSQL_REPL-2147201001 Invalid column name 'created_date'. (Source: MSSQLServer, Error number: 207) Get help: http://help/207

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  • Possible form field types per model field type

    - by Jonathan
    Django's documentation specifies for each model field type the corresponding default form field type. Alas, I couldn't find in the documentation, or anywhere else, what form field types are possible per model field type. Not all combinations are possible, right? Same question for widgets...

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  • Haskell Type error

    - by Jon
    I am getting a Couldn't match expected type error on this code and am not sure why. Would appreciate it if someone could point me in the right direction as to fixing it. import qualified Data.ByteString.Lazy as S import Data.Binary.Get import Data.Word getBinary :: Get Word16 getBinary = do a <- getWord16be "Test.class" return (a) main :: IO () main = do contents <- S.getContents print getBinary contents Specifically it cannot match expected type 'S.ByteString - IO ()' to inferred type 'IO ()'

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  • Type patterns and generic classes in Haskell

    - by finnsson
    I'm trying to understand type patterns and generic classes in Haskell but can't seem to get it. Could someone explain it in laymen's terms? In [1] I've read that "To apply functions generically to all data types, we view data types in a uniform manner: except for basic predefined types such as Float, IO, and ?, every Haskell data type can be viewed as a labeled sum of possibly labeled products." and then Unit, :*: and :+: are mentioned. Are all data types in Haskell automatically versions of the above mentioned and if so how do I figure out how a specific data type is represented in terms of :*:, etc? The users guide for generic classes (ch. 7.16) at haskell.org doesn't mention the predefined types but shouldn't they be handled in every function if the type patterns should be exhaustive? [1] Comparing Approaches to Generic Programming in Haskell, Ralf Hinze, Johan Jeuring, and Andres Löh

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  • Using C# Type as generic

    - by I Clark
    I'm trying to create a generic list from a specific Type that is retrieved from elsewhere: Type listType; // Passed in to function, could be anything var list = _service.GetAll<listType>(); However I get a build error of: The type or namespace name 'listType' could not be found (are you missing a using directive or an assembly reference?) Is this even possible or am I setting foot onto C# 4 Dynamic territory? As a background: I want to automatically load all lists with data from the repository. The code below get's passed a Form Model whose properties are iterated for any IEnum (where T inherits from DomainEntity). I want to fill the list with objects of the Type the list made of from the repository. public void LoadLists(object model) { foreach (var property in model.GetType() .GetProperties(BindingFlags.Public | BindingFlags.Instance | BindingFlags.SetProperty)) { if (IsEnumerableOfNssEntities(property.PropertyType)) { var listType = property.PropertyType.GetGenericArguments()[0]; var list = _repository.Query<listType>().ToList(); property.SetValue(model, list, null); } } }

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  • .NET generic class instance - passing a variable data type

    - by FerretallicA
    As the title suggests, I'm tyring to pass a variable data type to a template class. Something like this: frmExample = New LookupForm(Of Models.MyClass) 'Works fine Dim SelectedType As Type = InstanceOfMyClass.GetType() 'Works fine frmExample = New LookupForm(Of SelectedType) 'Ba-bow! frmExample = New LookupForm(Of InstanceOfMyClass.GetType()) 'Ba-bow! LookupForm<Models.MyClass> frmExample; Type SelectedType = InstanceOfMyClass.GetType(); frmExample = new LookupForm<SelectedType.GetType()>(); //Ba-bow frmExample = new LookupForm<(Type)SelectedType>(); //Ba-bow I'm assuming it's something to do with the template being processed at compile time but even if I'm off the mark there, it wouldn't solve my problem anyway. I can't find any relevant information on using Reflection to instance template classes either. (How) can I create an instance of a dynamically typed repository at runtime?

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  • Error loading SQL_VARIANT data type using Python

    - by Brett D
    I am using Python and SQLAlchemy to query a database that I did not create. I have run into a problem querying a table that contains the SQL_VARIANT data type. I get the error: sqlalchemy.exc.DBAPIError: (Error) ('ODBC data type -150 is not supported. Cannot read column Value.', 'HY000') I confirmed with the database creator that the "Value" column is of type SQL_VARIANT. Does anyone know a way to load this data type using Python? I am currently using mssql with pyodbc. Thank you for any help you can offer! Versions: Python 2.7, SQLAlchemy 0.7.8

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  • 'Lexical' scoping of type parameters in C#

    - by leppie
    I have 2 scenarios. This fails: class F<X> { public X X { get; set; } } error CS0102: The type 'F' already contains a definition for 'X' This works: class F<X> { class G { public X X { get; set; } } } The only logical explanation is that in the second snippet the type parameter X is out of scope, which is not true... Why should a type parameter affect my definitions in a type? IMO, for consistency, either both should work or neither should work. Any other ideas? PS: I call it 'lexical', but it probably is not not the correct term.

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  • $_POST goes empty after adding a new input type "file"

    - by heldrida
    Hi, I'm not finding a way to understand and fix this and I've done a lot. I've got a script, wish is a simple form, that sends a file trough POST. The second file, process the info. By default, I give to the user a few fields, one of them being a input field of type "file" and there's also, a few "hidden" one's, that gives me values to work with on POST. I found that, when adding a new input of type "file", the $_POST returns array 0, even $_FILES returns nothing. I have no idea how to fix this, and it works just fine when keeping the default input box of type "file". This is the form http://pastie.org/872488 This only happens when: Exists! var_dump( $_POST ), or $_FILES, print_r(), etc Returns nothing. I've tryed to create a array on the input of type "files", like img_p_child[], but nothing. How to solve this ? Thanks for taking your time!

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  • Design Patterns: What is a type

    - by contactmatt
    A very basic question, but after reading the "Design Patterns: Elements of reusable OO Software" book, I'm a little confused. The book states, "An object's type only refers to its interface-the set of request to which it can respond. An object can have many types, and objects of different classes can have the same type." Could someone please better explain what a Type is? I also don't understand how one object can have multiple types...unless the book is speaking of polymorphism....

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  • mapping Field with variable type using Hibernate Annotaion

    - by Zahra
    Hi. how can I have a field with variable type in my class? I use hibernate annotation for mapping to DB. I tried to use java.io.Serializable as field's type, but it mapped to database as a 01 amount which is true if I get it's object and cast it to it's true type. but I need to run a query on this objects that needs true amount of field.(right now I can't compare an integer field with a number) Does anyone have any idea how can I do this? Thanks in advance.

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  • Type or namespace name could not be found

    - by Pandiya Chendur
    I use this: public IQueryable<MaterialsView> FindAllMaterials() { var materials = from m in db.Materials join Mt in db.MeasurementTypes on m.MeasurementTypeId equals Mt.Id select new MaterialsView { MatId = m.Mat_Name, MesName = Mt.Name, MesType = m.Mat_Type }; return materials; } It gives me the following errors: The type or namespace name MaterialsView could not be found (are you missing a using directive or an assembly reference?) Cannot implicitly convert type System.Collections.Generic.IEnumerable<MaterialsView> to System.Linq.IQueryable<MaterialsView>. An explicit conversion exists (are you missing a cast?) The type arguments for method System.Linq.Enumerable.ToList<TSource>(System.Collections.Generic.IEnumerable<TSource>) cannot be inferred from the usage. Try specifying the type arguments explicitly. I have googled it and found this SO question but it doesn't help. What's wrong?

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  • I can't change HTTP request header Content-Type value using jQuery

    - by Matt
    Hi I tried to override HTTP request header content by using jQuery's AJAX function. It looks like this $.ajax({ type : "POST", url : url, data : data, contentType: "application/x-www-form-urlencoded;charset=big5", beforeSend: function(xhr) { xhr.setRequestHeader("Accept-Charset","big5"); xhr.setRequestHeader("Content-Type","application/x-www-form-urlencoded;charset=big5"); }, success: function(rs) { target.html(rs); } }); Content-Type header is default to "application/x-www-form-urlencoded; charset=UTF-8", but it obviously I can't override its value no matter I use 'contentType' or 'beforeSend' approaches. Could anyone adivse me a hint that how do I or can I change the HTTP request's content-type value? thanks a lot. btw, is there any good documentation that I can study JavaScript's XMLHttpRequest's encoding handling?

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