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  • Using type passed as a template in C++

    - by MeDiCS
    Is it possible to actually use the type passed as a template for control flow? I'd like to write a function that uses templates, which in turn calls another function based on the type passed: template <class T> void test_function (T var) { //Do stuff if (T == char) { bar (var); } else { foo (var); } //Do even more stuff } If not, I'll have to fallback to enums...

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  • storing characters in char data type C language

    - by iSight
    Hi, I can store string of few length in char data type. But when it exceeds its capacity what can be the alternative way to store string. I am using char data type. void setString(char* inPoints) { if (strcmp(mPoints, inPoints)!= ZERO) { if (mPoints) { free(mPoints); } mPoints = (char*)malloc((strlen(inPoints) + 1) * sizeof(char)); strcpy(mPoints, inPoints); } }

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  • C++ function dynamic data type definition

    - by user330352
    Hi all, in C++, when you define a function which takes one argument, you have to define the data type of that variable: void makeProccess(int request) However, I want to implement a function which takes different data types rather taking statically defined integer type. void makeProccess(anyType request) How can I design a proccess like this, any idea? Thanks.

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  • Restrict a generic type

    - by Water Cooler v2
    I want to restrict the generic type parameter to: 1) either that of a certain user defined reference type; OR 2) any of the primitive types in the CLR; How do I say something to the effect of: interface IDataManager<T>: IDataManager where T: IDataObject, T: ValueType

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  • Swap partition not recognized (The disk drive with UUID=... is not ready yet or not present)

    - by ladaghini
    I think I had an encrypted swap partition, because I chose to encrypt my home directory during the installation. I believe that's what the line with /dev/mapper/cryptswap1 ... in my /etc/fstab is all about. I did something to bork my swap because on the next boot, I got a message (paraphrased): The disk drive for /dev/mapper/cryptswap1 is not ready yet or not present. Wait to continue. Press S to skip or M to manually recover. (As a side note, pressing S or M seemed to do nothing different from just waiting.) Here's what I've tried: This tutorial on how to fix the swap partition not mounting. However, in the above, the mkswap command fails because the device is busy. So I booted from a live USB, ran GParted to reformat the swap partition (which showed up as an unknown fs type), and chrooted into the broken system to try that tutorial again. I also adjusted /etc/initramfs-tools/conf.d/resume and /etc/fstab to reflect the new UUID generated from formatting the partition as a swap. That still didn't work; instead of /dev/mapper/cryptswap1 not present, "The disk drive with UUID=[swap partition's UUID] is not ready yet or not present..." So I decided to start afresh as though I never had created a swap partition in the first place. From the Live USB, I deleted the swap partition altogether (which, again showed up in GParted as an unknown fs type), removed the swap and cryptswap entries in /etc/fstab as well as removed /etc/initramfs-tools/conf.d/resume and /etc/crypttab. At this point the main system shouldn't be considered broken because there is no swap partition and no instructions to mount one, right? I didn't get any errors during startup. I followed the same instructions to create and encrypt the swap partition, starting with creating a partition for the swap, though I think fdisk said a reboot was necessary to see changes. I was confident the 3rd process above would work, but the problem yet persists. Some relevant info (/dev/sda8 is the swap partition): /etc/fstab file: # /etc/fstab: static file system information. # # Use 'blkid' to print the universally unique identifier for a # device; this may be used with UUID= as a more robust way to name devices # that works even if disks are added and removed. See fstab(5). # # <file system> <mount point> <type> <options> <dump> <pass> proc /proc proc nodev,noexec,nosuid 0 0 # / was on /dev/sda6 during installation UUID=4c11e82c-5fe9-49d5-92d9-cdaa6865c991 / ext4 errors=remount-ro 0 1 # /boot was on /dev/sda5 during installation UUID=4031413e-e89f-49a9-b54c-e887286bb15e /boot ext4 defaults 0 2 # /home was on /dev/sda7 during installation UUID=d5bbfc6f-482a-464e-9f26-fd213230ae84 /home ext4 defaults 0 2 # swap was on /dev/sda8 during installation UUID=5da2c720-8787-4332-9317-7d96cf1e9b80 none swap sw 0 0 /dev/mapper/cryptswap1 none swap sw 0 0 output of sudo mount: /dev/sda6 on / type ext4 (rw,errors=remount-ro) proc on /proc type proc (rw,noexec,nosuid,nodev) sysfs on /sys type sysfs (rw,noexec,nosuid,nodev) none on /sys/fs/fuse/connections type fusectl (rw) none on /sys/kernel/debug type debugfs (rw) none on /sys/kernel/security type securityfs (rw) udev on /dev type devtmpfs (rw,mode=0755) devpts on /dev/pts type devpts (rw,noexec,nosuid,gid=5,mode=0620) tmpfs on /run type tmpfs (rw,noexec,nosuid,size=10%,mode=0755) none on /run/lock type tmpfs (rw,noexec,nosuid,nodev,size=5242880) none on /run/shm type tmpfs (rw,nosuid,nodev) /dev/sda5 on /boot type ext4 (rw) /dev/sda7 on /home type ext4 (rw) /home/undisclosed/.Private on /home/undisclosed type ecryptfs (ecryptfs_check_dev_ruid,ecryptfs_cipher=aes,ecryptfs_key_bytes=16,ecryptfs_unlink_sigs,ecryptfs_sig=cbae1771abd34009,ecryptfs_fnek_sig=7cefe2f59aab8e58) gvfs-fuse-daemon on /home/undisclosed/.gvfs type fuse.gvfs-fuse-daemon (rw,nosuid,nodev,user=undisclosed) output of sudo blkid (note that /dev/sda8 is missing): /dev/sda1: LABEL="SYSTEM" UUID="960490E80490CC9D" TYPE="ntfs" /dev/sda2: UUID="D4043140043126C0" TYPE="ntfs" /dev/sda3: LABEL="Shared" UUID="80F613E1F613D5EE" TYPE="ntfs" /dev/sda5: UUID="4031413e-e89f-49a9-b54c-e887286bb15e" TYPE="ext4" /dev/sda6: UUID="4c11e82c-5fe9-49d5-92d9-cdaa6865c991" TYPE="ext4" /dev/sda7: UUID="d5bbfc6f-482a-464e-9f26-fd213230ae84" TYPE="ext4" /dev/mapper/cryptswap1: UUID="41fa147a-3e2c-4e61-b29b-3f240fffbba0" TYPE="swap" output of sudo fdisk -l: Disk /dev/mapper/cryptswap1 doesn't contain a valid partition table Disk /dev/sda: 320.1 GB, 320072933376 bytes 255 heads, 63 sectors/track, 38913 cylinders, total 625142448 sectors Units = sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0xdec3fed2 Device Boot Start End Blocks Id System /dev/sda1 * 2048 409599 203776 7 HPFS/NTFS/exFAT /dev/sda2 409600 210135039 104862720 7 HPFS/NTFS/exFAT /dev/sda3 210135040 415422463 102643712 7 HPFS/NTFS/exFAT /dev/sda4 415424510 625141759 104858625 5 Extended /dev/sda5 415424512 415922175 248832 83 Linux /dev/sda6 415924224 515921919 49998848 83 Linux /dev/sda7 515923968 621389823 52732928 83 Linux /dev/sda8 621391872 625141759 1874944 82 Linux swap / Solaris Disk /dev/mapper/cryptswap1: 1919 MB, 1919942656 bytes 255 heads, 63 sectors/track, 233 cylinders, total 3749888 sectors Units = sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0xaf5321b5 /etc/initramfs-tools/conf.d/resume file: RESUME=UUID=5da2c720-8787-4332-9317-7d96cf1e9b80 /etc/crypttab file: cryptswap1 /dev/sda8 /dev/urandom swap,cipher=aes-cbc-essiv:sha256 output of sudo swapon -as: Filename Type Size Used Priority /dev/mapper/cryptswap1 partition 1874940 0 -1 output of sudo free -m: total used free shared buffers cached Mem: 1476 1296 179 0 35 671 -/+ buffers/cache: 590 886 Swap: 1830 0 1830 So, how can this be fixed?

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  • post xml to Spring REST server returns Unsupported Media Type

    - by Mayra
    I'm trying to create a simple spring based webservice that supports a "post" with xml content. In spring, I define an AnnotationMethodHandler: <bean id="inboundMessageAdapter" class="org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerAdapter"> <property name="messageConverters"> <util:list> <bean class="org.springframework.http.converter.xml.MarshallingHttpMessageConverter"> <property name="marshaller" ref="xmlMarshaller"/> <property name="unmarshaller" ref="xmlMarshaller"/> </bean> </util:list> </property> </bean> And a jaxb based xml marshaller: <bean id="xmlMarshaller" class="org.springframework.oxm.jaxb.Jaxb2Marshaller"> <property name="contextPaths"> <array> <value>com.company.schema</value> </array> </property> <property name="schemas"> <array> <value>classpath:core.xsd</value> </array> </property> </bean> My controller is annotated as follows, where "Resource" is a class autogenerated by jaxb: @RequestMapping(method = POST, value = "/resource") public Resource createResource(@RequestBody Resource resource) { // do work } The result of a webservice call is always "HTTP/1.1 415 Unsupported Media Type". Here is an example service call: HttpPost post = new HttpPost(uri); post.addHeader("Accept", "application/xml"); post.addHeader("Content-Type", "application/xml"); StringEntity entity = new StringEntity(request, "UTF-8"); entity.setContentType("application/xml"); post.setEntity(entity); It seems to me that I am setting the correct media type everywhere possible. Anyone have an ideas?

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  • InvalidCastException for two Objects of the same type

    - by LLEA
    hi, I have this weird problem that I cannot handle myself. A class in the model of my mvp-project designed as singleton causes an InvalidCastException. The source of error is found in this code line where the deserialised object is assigned to the instance variable of the class: engineObject = (ENGINE)xSerializer.Deserialize(str); It occurs whenever I try to add one of my UserControls to a Form or to a different UC. All of my UCs have a special presenter that access the above mentioned instance variable of the singleton class. This is what I get when trying to add a UC somewhere: 'System.TypeInitializationException: The type initializer for 'MVP.Model.EngineData' threw an exception. ---- System.InvalidCastException: [A]Engine cannot be cast to [B]Engine. Type A originates from 'MVP.Model, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null' in the context 'LoadNeither' at location '[...]\AppData\Roaming\Microsoft\VisualStudio\9.0\ProjectAssemblies\uankw1hh01\MVP.Model.dll'. Type B originates from 'MVP.Model, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null' in the context 'LoadNeither' at location '[...]\AppData\Roaming\Microsoft\VisualStudio\9.0\ProjectAssemblies\u_hge2de01\MVP.Model.dll'... So I somehow have two assemblies and they are not accessed from my project folder, but from a VS temp folder? I googled a lot and only found this: IronPython Exception: [A]Person cannot be cast to [B]Person. There is a solution offered, but first it concerns IronPhyton and second I don't know where to use it within my project? It would be just great, if u could help me out here :-) thx

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  • javascript removeChild(this) from input[type="submit"] onclick breaks future use of form.submit() un

    - by maximumduncan
    I have come across some strange behaviour, and I'm assuming a bug in firefox, when removing a input submit element from the DOM from within the click event. The following code reproduces the issue: <form name="test_form"> <input type="submit" value="remove me" onclick="this.parentNode.removeChild(this);" /> <input type="submit" value="submit normally" /> <input type="button" value="submit via js" onclick="document.test_form.submit();" /> </form> To reproduce: Click "remove me" Click "submit via js". Note that the form does not get submitted, this is the problem. Click "submit normally". Note that the form still gets submitted normally. It appears that, under Firefox, if you remove a submit button from within the click event it puts the form in an invalid state so that any future calls to form.submit() are simply ignored. But it is a javascript-specific issue as normal submit buttons within this form still function fine. To be honest, this is such a simple example of this issue that I was expecting the internet to be awash with other people exeriencing it, but so far searching has yealded nothing useful. Has anyone else experienced this and if so, did you get to the bottom of it? Many thanks

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  • Exporting non-public type through public API

    - by feelgood
    What if I have few factory methods returning non-public type and pairing set of methods which gives variables of this non-public type? This results with titled warning message in NetBeans. In result public API will contain only two pairing sets of methods. The reason is to make my type hierarchy sealed (like seald classes in Scala) and allow users only instantiate these types through factory methods. So we get DSL in some sense. For example, Schedule class represented by calendar fields' contraints. There are some types of contraints - Range, Singleton, List, FullSet - with NumberSet interface as a root. We don't want to expose these types and how Schedule interact with them. We just want the specification from the user. So we make NumberSet package-private. In class Schedule we create few factory-methods for constraints: NumberSet singleton(int value); NumberSet range(int form, int to); NumberSet list(NumberSet ... components); and some methods for creating Schedule object: Schedule everyHour(NumberSet minutes); Schedule everyDay(NumberSet minutes, NumberSet hours); User can only use them in the manner: Schedule s = Schedule.everyDay( singleton(0), list(range(10-15), singleton(8)) ); Is it bad idea?

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  • XMLBeans - xsi:type stripped using Axis2 and Tomcat?

    - by Matthew Gamble
    I’m new to XMLBeans and have been trying to use it to create an XML document as part of an axis2 web service. When I run my code as a standard Java application or as a standard servlet, the XML is correctly generated: <?xml version="1.0" encoding="UTF-8"?> <c:BroadsoftDocument protocol="OCI" xmlns:c="C"> <sessionId>000000001</sessionId> <command xsi:type="AuthenticationRequest" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"> <userId>admin</userId></command> </c:BroadsoftDocument> However, when the exact same code is run under Axis2 & Tomcat in a servlet I get: <?xml version="1.0" encoding="UTF-8"?> <c:BroadsoftDocument protocol="OCI" xmlns:c="C"> <sessionId>000000001</sessionId> <command> <userId>admin</userId></command> </c:BroadsoftDocument> This of course isn’t valid – the xsi:type of the “command” element is stripped when the code is run under Tomcat. Does anyone have any suggestions of what I could be doing wrong that would cause this type of issue only when running under Axis2? At first I thought it was a Tomcat issue, but after creating a generic servlet and running the exact same code I don't have any issues. I've tried playing with the XMLOptions for XMLBeans, but couldn't seem to resolve the problem. The options I'm currently using are: xmlOptions = new XmlOptions(); xmlOptions.setCharacterEncoding("UTF-8"); xmlOptions.setUseDefaultNamespace(); xmlOptions.setSaveAggressiveNamespaces(); xmlOptions.setSavePrettyPrint();

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  • boost lambda::bind return type selection

    - by psaghelyi
    I would like to call a member through lambda::bind. Unfortunately I have got to members with the same name but different return type. Is there a way to help the lambda::bind to deduce the right return type for a member function call? #include <vector> #include <iostream> #include <algorithm> #include <boost/bind.hpp> #include <boost/lambda/lambda.hpp> #include <boost/lambda/bind.hpp> using namespace std; using namespace boost; struct A { A (const string & name) : m_name(name) {} string & name () { return m_name; } const string & name () const { return m_name; } string m_name; }; vector<A> av; int main () { av.push_back (A ("some name")); // compiles fine find_if(av.begin(), av.end(), bind<const string &>(&A::name, _1) == "some name"); // error: call of overloaded 'bind(<unresolved overloaded function type>, const boost::lambda::lambda_functor<boost::lambda::placeholder<1> >&)' is ambiguous find_if(av.begin(), av.end(), lambda::bind(&A::name, lambda::_1) == "some name"); return 0; }

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  • Facebook app submit action type

    - by Axel
    I've been reading about this on StackOverflow and facebook doc, yet I dont seem to be able to submit my action type. I have the following code from the FB doc <script type="text/javascript"> console.log("Function begins"); function postForm() { console.log(FB); FB.api( '/me/concoursvelirium:form', 'post', { recipe: 'http://concours.gestev.com/fbvel2012/form.php' }, function(response) { console.log("Stay"); if (!response || response.error) { console.log("error: " + response); } else { console.log('Cook was successful! Action ID: ' + response.id); } }); } </script> I have added my values from FB autogenerated values: <head prefix="og: http://ogp.me/ns# fb: http://ogp.me/ns/fb# concoursvelirium: http://ogp.me/ns/fb/concoursvelirium#"> <meta property="fb:app_id" content="194081877384051" /> <meta property="og:type" content="concoursvelirium:form" /> <meta property="og:url" content="Put your own URL to the object here" /> <meta property="og:title" content="Sample Form" /> <meta property="og:image" content="https://s-static.ak.fbcdn.net/images/devsite/attachment_blank.png" /> And yet I see no output in the console past the console.log(FB); I have no idea what I'm doing wrong. I'm also getting the Unsafe JavaScript attempt to access frame with URL error, but I have read here that I should just ignore it. Ty, Axel

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  • XML Schema and element with type string

    - by svick
    I'm trying to create an XML Schema and I'm stuck. It seems I can't define an element with string content. What am I doing wrong? Schema: <?xml version="1.0"?> <xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema" xmlns="http://ponderka.wz.cz/MusicLibrary0" targetNamespace="http://ponderka.wz.cz/MusicLibrary0"> <xs:element name="music-library"> <xs:complexType> <xs:sequence> <xs:element name="artist" type="xs:string"/> </xs:sequence> </xs:complexType> </xs:element> </xs:schema> Document: <?xml version="1.0"?> <music-library xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://ponderka.wz.cz/MusicLibrary0 data0.xsd" xmlns="http://ponderka.wz.cz/MusicLibrary0"> <artist>a</artist> </music-library> The validator says: Element <artist> is not allowed under element <music-library>. Reason: The following elements are expected at this location (see below) <artist> Error location: music-library / artist Details cvc-model-group: Element <artist> unexpected by type '{anonymous}' of element <music-library>. cvc-elt.5.2.1: The element <music-library> is not valid with respect to the actual type definition '{anonymous}'.

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  • Instantiate type variable in Haskell

    - by danportin
    EDIT: Solved. I was unware that enabling a language extension in the source file did not enable the language extension in GHCi. The solution was to :set FlexibleContexts in GHCi. I recently discovered that type declarations in classes and instances in Haskell are Horn clauses. So I encoded the arithmetic operations from The Art of Prolog, Chapter 3, into Haskell. For instance: fac(0,s(0)). fac(s(N),F) :- fac(N,X), mult(s(N),X,F). class Fac x y | x -> y instance Fac Z (S Z) instance (Fac n x, Mult (S n) x f) => Fac (S n) f pow(s(X),0,0) :- nat(X). pow(0,s(X),s(0)) :- nat(X). pow(s(N),X,Y) :- pow(N,X,Z), mult(Z,X,Y). class Pow x y z | x y -> z instance (N n) => Pow (S n) Z Z instance (N n) => Pow Z (S n) (S Z) instance (Pow n x z, Mult z x y) => Pow (S n) x y In Prolog, values are insantiated for (logic) variable in a proof. However, I don't understand how to instantiate type variables in Haskell. That is, I don't understand what the Haskell equivalent of a Prolog query ?-f(X1,X2,...,Xn) is. I assume that :t undefined :: (f x1 x2 ... xn) => xi would cause Haskell to instantiate xi, but this gives a Non type-variable argument in the constraint error, even with FlexibleContexts enabled.

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  • Create an anonymous type object from an arbitrary text file

    - by Robert Harvey
    I need a sensible way to draw arbitrary text files into a C# program, and produce an arbitrary anonymous type object, or perhaps a composite dictionary of some sort. I have a representative text file that looks like this: adapter 1: LPe11002 Factory IEEE: 10000000 C97A83FC Non-Volatile WWPN: 10000000 C93D6A8A , WWNN: 20000000 C93D6A8A adapter 2: LPe11002 Factory IEEE: 10000000 C97A83FD Non-Volatile WWPN: 10000000 C93D6A8B , WWNN: 20000000 C93D6A8B Is there a way to get this information into an anonymous type object or some similar structure? The final anonymous type might look something like this, if it were composed in C# by hand: new { adapter1 = new { FactoryIEEE = "10000000 C97A83FC", Non-VolatileWWPN = "10000000 C93D6A8A", WWNN = "20000000 C93D6A8A" } adapter2 = new { FactoryIEEE = "10000000 C97A83FD", Non-VolatileWWPN = "10000000 C93D6A8B", WWNN = "20000000 C93D6A8B" } } Note that, as the text file's content is arbitrary (i.e. the keys could be anything), a specialized solution (e.g. that looks for names like "FactoryIEEE") won't work. However, the structure of the file will always be the same (i.e. indentation for groups, colons and commas as delimiters, etc). Or maybe I'm going about this the wrong way, and you have a better idea?

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  • How to Debug an exception: Type is not marked as serializable... when the type is marked as serializ

    - by rism
    I'm trying to: ((Request.Params["crmid"] != null)) in a web page. But it keeps throwing a serialzation exception: Type 'QC.Security.SL.SiteUser' in assembly 'QC.Security, Version=1.0.0.1, Culture=neutral, PublicKeyToken=null' is not marked as serializable. The type is however marked as serializable as follows: [Serializable()] public class SiteUser : IIdentity { private long _userId; public long UserId { get { return _userId; } set { _userId = value; } } private string _name; public string Name { get { return _name; } } private bool _isAuthenticated; public bool IsAuthenticated { get { return _isAuthenticated; } } private string _authenticationType; public string AuthenticationType { get { return _authenticationType; } } I've no idea how to debug this as I cant step into the serializer code to find out why its falling over. The call stack is only one frame deep before it hits [External Code]. And the error message is next to useless given that type is clearly marked as serializable. It was working fine. But now "all of a sudden" it doesn't which typically means some dumb bug in Visual Studio but rebooting doesn't help "this" time. So now I dont know if it's a stupid VS bug or a completely unrelated error for which Im getting a serialization exception or something I'm doing wrong. The truth is I just dont trust VS anymore given the number of wild goose chases Ive been on over the last several months which were "fixed" by rebooting VS 2008 or some other rediculous workaround.

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  • Type-conditional controls in Haskell

    - by estanford
    I'm going through the 99 Haskell problems to build my proficiency with the language. On problem 7 ("Flatten a nested list structure"), I found myself wanting to define a conditional behavior based on the type of argument passed to a function. That is, since *Main> :t 1 1 :: (Num t) => t *Main> :t [1,2] [1,2] :: (Num t) => [t] *Main> :t [[1],[2]] [[1],[2]] :: (Num t) => [[t]] (i.e. lists nested at different levels have different data types) it seems like I should be able to write a function that can read the type of the argument, and then behave accordingly. My first attempt was along these lines: listflatten l = do if (:t l) /= ((Num t) => [t]) then listflatten (foldl (++) [] l) else id l But when I try to do that, Haskell returns a parse error. Is Haskell flexible enough to allow this sort of type manipulation, do I need to find another way?

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  • Full Text Index type column is empty

    - by RemotecUk
    I am trying to create an index on a VarBinary(max) field in my SQL Server 2008 database. The steps I am taking are as follows: Table: dbo.Records Right click on table and select "Full Text Index" Then select "Define Index..." I choose the primary key which is the PK of my table (field name Id, type UniqueIndentifier). I then get the screen with the options Available Columns, Language for Word Breaker and Type Column I select my VarBinary(max) field called Chart as the Available Column by ticking the box. I select "English" as the Language for Word Breaker field. Then... I try to select the Type Column but there are no entries in here. I cannot proceed by clicking "Next" until this column is populated. Why are there no entries in this column for selection and what should be in there? Note 1: The VarBinary(max) field is linked to a file group if that makes any difference. Note 2: Also noticed that in the table designer I cannot set the full text option on that same field to "Yes" - its permanently stuck on "No". Thanks.

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  • "Pattern matching" of algebraic type data constructors

    - by jetxee
    Let's consider a data type with many constructors: data T = Alpha Int | Beta Int | Gamma Int Int | Delta Int I want to write a function to check if two values are produced with the same constructor: sameK (Alpha _) (Alpha _) = True sameK (Beta _) (Beta _) = True sameK (Gamma _ _) (Gamma _ _) = True sameK _ _ = False Maintaining sameK is not much fun, it is potentially buggy. For example, when new constructors are added to T, it's easy to forget to update sameK. I omitted one line to give an example: -- it’s easy to forget: -- sameK (Delta _) (Delta _) = True The question is how to avoid boilerplate in sameK? Or how to make sure it checks for all T constructors? The workaround I found is to use separate data types for each of the constructors, deriving Data.Typeable, and declaring a common type class, but I don't like this solution, because it is much less readable and otherwise just a simple algebraic type works for me: {-# LANGUAGE DeriveDataTypeable #-} import Data.Typeable class Tlike t where value :: t -> t value = id data Alpha = Alpha Int deriving Typeable data Beta = Beta Int deriving Typeable data Gamma = Gamma Int Int deriving Typeable data Delta = Delta Int deriving Typeable instance Tlike Alpha instance Tlike Beta instance Tlike Gamma instance Tlike Delta sameK :: (Tlike t, Typeable t, Tlike t', Typeable t') => t -> t' -> Bool sameK a b = typeOf a == typeOf b

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  • Java - Class type from inside static initialization block

    - by DutrowLLC
    Is it possible to get the class type from inside the static initialization block? This is a simplified version of what I currently have:: class Person extends SuperClass { String firstName; static{ // This function is on the "SuperClass": // I'd for this function to be able to get "Person.class" without me // having to explicitly type it in but "this.class" does not work in // a static context. doSomeReflectionStuff(Person.class); // IN "SuperClass" } } This is closer to what I am doing, which is to initialize a data structure that holds information about the object and its annotations, etc... Perhaps I am using the wrong pattern? public abstract SuperClass{ static void doSomeReflectionStuff( Class<?> classType, List<FieldData> fieldDataList ){ Field[] fields = classType.getDeclaredFields(); for( Field field : fields ){ // Initialize fieldDataList } } } public abstract class Person { @SomeAnnotation String firstName; // Holds information on each of the fields, I used a Map<String, FieldData> // in my actual implementation to map strings to the field information, but that // seemed a little wordy for this example static List<FieldData> fieldDataList = new List<FieldData>(); static{ // Again, it seems dangerous to have to type in the "Person.class" // (or Address.class, PhoneNumber.class, etc...) every time. // Ideally, I'd liken to eliminate all this code from the Sub class // since now I have to copy and paste it into each Sub class. doSomeReflectionStuff(Person.class, fieldDataList); } }

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