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  • How to declare a generic constraint that is a generic type

    - by HackedByChinese
    I have a two generic abstract types: Entity and Association. Let's say Entity looks like this: public class Entity<TId> { //... } and Association looks like this: public class Association<TEntity, TEntity2> { //... } How do I constrain Association so they can be of any Entity? I can accomplish it by the following: public class Association<TEntity, TId, TEntity2, TId2> where TEntity : Entity<TId> where TEntity2: Entity<TId2> { //... } This gets very tedious as more types derive from Association, because I have to keep passing down TId and TId2. Is there a simpler way to do this, besides just removing the constraint?

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  • has_many association, nested models and callbacks

    - by fl00r
    Hi! I've got model A and model Attach. I'm editing my A form with nested attributes for :attaches. And when I am deleting all attaches from A via accepts_nested_attributes_for how can I get after_update/after_save callbacks for all of my nested models? Problem is that when I am executing callbacks in model A they are executed right AFTER model A is updated and BEFORE model Attach is updated, so I can't, for example, know if there is NO ANY attaches after I delete them all :). Look for example: my callback after_save :update_status won't work properly after I delete all of my attaches. model A after_save :update_status has_many :attaches accepts_nested_attributes_for :attaches, :reject_if => proc { |attributes| attributes['file'].blank? }, :allow_destroy => true def update_status print "\n\nOUPS! bag is empty!\n\n" if self.attaches.empty? end end model Attach belongs_to A end I am using rails 3 beta

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  • C#: Making sure parameter has attribute

    - by slayerIQ
    I have an attribute lets call it SomeAttribute and a class i need to make sure the class is passed a type which has SomeAttribute. So this is how i do it now: public class Test() { public Test(SomeType obj) { if(!obj.GetType().IsDefined(typeof(SomeAttribute), false)) { throw new ArgumentException("Errormessage"); } } } But this means that i don't get any errors at compile time but somewhere at runtime, if obj does not have the attribute. Is there a way to specify in the method declaration that the parameter must have some attribute ? So i get errors i compile time when using the wrong parameters.

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  • Force external function to be const

    - by vanna
    Here is my problem. I made a class with a member function declared as const that uses an external function that I cannot modify (declared in someone else's code) and that is not declared const. More precisely Someone else's code class B { public: void foo(); }; My code class A : public B { public: void bar() const { this->foo(); } }; I know that for member data we can force const-correctness by using mutable or const_cast. How can I 'hack' foo such that my compiler understands that I would like to use it as if it was const even if it is not declared in someone else's code ?

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  • Too many JavaScript and CSS files on my ASP.NET MVC 2 Master Page?

    - by Zack Peterson
    I'm using an EditorTemplate DateTime.ascx in my ASP.NET MVC 2 project. <%@ Control Language="C#" Inherits="System.Web.Mvc.ViewUserControl<DateTime>" %> <%: Html.TextBox(String.Empty, Model.ToString("M/dd/yyyy h:mm tt")) %> <script type="text/javascript"> $(function () { $('#<%: ViewData.TemplateInfo.GetFullHtmlFieldId(String.Empty) %>').AnyTime_picker({ format: "%c/%d/%Y %l:%i %p" }); }); </script> This uses the Any+Time™ JavaScript library for jQuery by Andrew M. Andrews III. I've added those library files (anytimec.js and anytimec.css) to the <head> section of my master page. Rather than include these JavaScript and Cascading Style Sheet files on every page of my web site, how can I instead include the .js and .css files only on pages that need them--pages that edit a DateTime type value?

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  • New to C# and trying to use a global variable

    - by Andrew G. Johnson
    Is it possible to use global variables in C#? I'm coming from mainly a PHP background so variables are either accessible everywhere or just a global definition away. My main issue is I have a User class that I built myself to wrap around the current users table on my company's database. I am defining it in the MasterPage but can't seem to access it from the actual pages (I don't know if there's a better word to describe them but they are the pages that inherit the styles and format from the MasterPage) Any general tips or implementation practices for me? EDIT: here's some code snippets of what I'm trying to do: Site.master.cs public partial class SiteMaster : System.Web.UI.MasterPage { public User user = new User(); } logout.aspx <%@ Page Title="" Language="C#" MasterPageFile="~/Site.master" AutoEventWireup="true" CodeFile="logout.aspx.cs" Inherits="logout" %> <%@ MasterType virtualPath="~/Site.master"%> logout.aspx.cs public partial class _Default : System.Web.UI.Page { protected void Page_Load(object sender, EventArgs e) { User user = Master.user; } }

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  • getting global name not defined error

    - by nashr rafeeg
    i have the following class class notify(): def __init__(self,server="localhost", port=23053): self.host = server self.port = port register = gntp.GNTPRegister() register.add_header('Application-Name',"SVN Monitor") register.add_notification("svnupdate",True) growl(register) def svn_update(self, author="Unknown", files=0): notice = gntp.GNTPNotice() notice.add_header('Application-Name',"SVN Monitor") notice.add_header('Notification-Name', "svnupdate") notice.add_header('Notification-Title',"SVN Commit") # notice.add_header('Notification-Icon',"") notice.add_header('Notification-Text',Msg) growl(notice) def growl(data): s = socket.socket(socket.AF_INET, socket.SOCK_STREAM) s.connect((self.host,self.port)) s.send(data) response = gntp.parse_gntp(s.recv(1024)) print response s.close() but when ever i try to use this class via the follwoing code i get 'NameError: global name 'growl' is not defined' from growlnotify import * n = notify() n.svn_update() any one has an idea what is going on here ? cheers nash

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  • Possible to use Tables of same type in Linq to SQL?

    - by Schneider
    Lets say I've got an object model, where I have many collections of the same type. For example something like class StockMarketData { List<SummaryData> WeeklySummary; List<SummaryData> MonthlySummary; } class SummaryData { DateTime DateTime {get; set;} double Value {get; set;} } Those lists will map onto database tables. If you actually use L2S to generate a model from the database you will get something like: class StockMarketData { List<WeeklySummaryData> WeeklySummary; List<MonthlySummaryData> MonthlySummary; } Even though WeeklySummaryData and MonthlySummaryData have the same shape. Is it possible for Linq to SQL to create tables from a database of summary data, but get each table to contain the same type (such as shown in the top example).

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  • Does a C++ destructor always or only sometimes call data member destructors?

    - by Magnus
    I'm trying to validate my understanding of C++ destructors. I've read many times that C++ supplies a default destructor if I don't write one myself. But does this mean that if I DO write a destructor that the compiler WON'T still provide the default cleanup of stack-allocated class fields? My hunch is that the only sane behavior would be that all class fields are destroyed no matter what, whether I provide my own destructor or not. In which case the statement I've read so many times is actually a little misleading and could be better stated as: "Whether or not you write your own destructor, the C++ compiler always writes a default destructor-like sequence to deallocate the member variables of your class. You may then specify additional deallocations or other tasks as needed by defining your own destructor" Is this correct?

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  • Sending an array of complex objects in the get string in C# ASP.NET MVC

    - by Mr Snuffle
    Hi, I want to send an array of objects in the get request string. I know this isn't the optimal solution, but I really just want to get this up and running. If I have a class, something like this public class Data { public int a { get; set; } public int b { get; set; } } public class RequestViewData { public IList<Data> MyData { get; set; } } I thought I could bind the MVC route to a web request like this http://localhost:8080/Request?MyData[0].a=1&MyData[0].b=2&MyData[1].a=3&[MyData[1].b=4 But all this does is create an array of two data objects without populating the values 1,2, 3 or 4. Is there a way to bind complex objects arrays?

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  • Exception while trying to deserialize JSON into EntityFramework using JavaScriptSerializer

    - by Barak
    I'm trying to deserialize JSON which I'm getting from an external source into an Entity Framework entity class using the following code: var serializer = new JavaScriptSerializer(); IList<Feature> obj = serializer.Deserialize<IList<Feature>>(json); The following exception is thrown: Object of type 'System.Collections.Generic.List1[JustTime.Task]' cannot be converted to type 'System.Data.Objects.DataClasses.EntityCollection1[JustTime.Task]'. My model is simple: The Feature class has a one-to-many relation to the Tasks class. The problem appears to be the deserializer is trying to create a generic List to hold the collection of tasks instead of an EntityCollection. I've tried implementing a JavaScriptConverted which would handle System.Collections.Generic.List but it didn't get called by the deserializer.

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  • Calling a method with getattr in Python

    - by brain_damage
    How to call a method using getattr? I want to create a metaclass, which can call non-existing methods of some other class that start with the word 'oposite_'. The method should have the same number of arguments, but to return the opposite result. def oposite(func): return lambda s, *args, **kw: not oposite(s, *args, **kw) class Negate(type): def __getattr__(self, name): if name.startswith('oposite_'): return oposite(self.__getattr__(name[8:])) def __init__(self,*args,**kwargs): self.__getattr__ = Negate.__getattr__ class P(metaclass=Negate): def yep(self): return True But the problem is that self.__getattr__(sth) returns a NoneType object. >>> p = P() >>> p.oposite_yep() Traceback (most recent call last): File "<pyshell#115>", line 1, in <module> p.oposite_yep() TypeError: <lambda>() takes at least 1 positional argument (0 given) How to deal with this?

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  • NoClassDefFound error - Spring JDBC

    - by glowcoder
    Right now, I'm compiling my .class files in eclipse and moving them over to my %tomcat_home%\webapps\myapp\WEB-INF\classes directory. They compile just fine. I also have in the ...\classes directory a org.springframework.jdbc-3.0.2.RELEASE.jar which I have verified has the org.springframework.jdbc.datasource.DriverManagerDataSource class inside it. However, I get a NoClassDefFound error when I run my class and it tries to DriverManagerDataSource source = new DriverManagerDataSource(); I don't understand why it wouldn't be finding that jar. Any help is appreciated!

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  • Grails: Querying Associations causes groovy.lang.MissingMethodException

    - by Paul
    Hi, I've got an issue with Grails where I have a test app with: class Artist { static constraints = { name() } static hasMany = [albums:Album] String name } class Album { static constraints = { name() } static hasMany = [ tracks : Track ] static belongsTo = [artist: Artist] String name } class Track { static constraints = { name() lyrics(nullable: true) } Lyrics lyrics static belongsTo = [album: Album] String name } The following query (and a more advanced, nested association query) works in the Grails Console but fails with a groovy.lang.MissingMethodException when running the app with 'run-app': def albumCriteria = tunehub.Album.createCriteria() def albumResults = albumCriteria.list { like("name", receivedAlbum) artist { like("name", receivedArtist) } // Fails here maxResults(1) } Stacktrace: groovy.lang.MissingMethodException: No signature of method: java.lang.String.call() is applicable for argument types: (tunehub.LyricsService$_getLyrics_closure1_closure2) values: [tunehub.LyricsService$_getLyrics_closure1_closure2@604106] Possible solutions: wait(), any(), wait(long), each(groovy.lang.Closure), any(groovy.lang.Closure), trim() at tunehub.LyricsService$_getLyrics_closure1.doCall(LyricsService.groovy:61) at tunehub.LyricsService$_getLyrics_closure1.doCall(LyricsService.groovy) (...truncated...) Any pointers?

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  • Show Alertdialog and use vibrator

    - by user1007522
    I'm having a class that implements RecognitionListener like this: public class listener implements RecognitionListener I wanted to show a alertdialog and use the vibrator but this isn't possible because I need to provide a context what I don't have. My alertdialog code was like this: new AlertDialog.Builder(this) .setTitle("dd") .setMessage("aa") .setNeutralButton("Ok", new DialogInterface.OnClickListener() { public void onClick(DialogInterface dialog, int which) { } }) .show(); But the AlertDialog.Builder(this) wants a context, the same problem with my vibrator code: v = (Vibrator) getSystemService(Context.VIBRATOR_SERVICE); The getSystemService method isn't available. My code that starts the class: sr = SpeechRecognizer.createSpeechRecognizer(this); sr.setRecognitionListener(new listener()); Intent intent = new Intent(RecognizerIntent.ACTION_RECOGNIZE_SPEECH); intent.putExtra(RecognizerIntent.EXTRA_LANGUAGE_MODEL,RecognizerIntent.LANGUAGE_MODEL_FREE_FORM); intent.putExtra(RecognizerIntent.EXTRA_CALLING_PACKAGE,"voice.recognition.test"); intent.putExtra(RecognizerIntent.EXTRA_MAX_RESULTS,5); sr.startListening(intent); Whats the best way to solve this?

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  • Django Admin: Many-to-Many listbox doesn't show up with a through parameter

    - by NP
    Hi All, I have the following models: class Message(models.Model): date = models.DateTimeField() user = models.ForeignKey(User) thread = models.ForeignKey('self', blank=True, null=True) ... class Forum(models.Model): name = models.CharField(max_length=24) messages = models.ManyToManyField(Message, through="Message_forum", blank=True, null=True) ... class Message_forum(models.Model): message = models.ForeignKey(Message) forum = models.ForeignKey(Forum) status = models.IntegerField() position = models.IntegerField(blank=True, null=True) tags = models.ManyToManyField(Tag, blank=True, null=True) In the admin site, when I go to add/change a forum, I don't see the messages listbox as you'd expect. However, it shows up if I remove the 'through' parameter in the ManyToManyField declaration. What's up with that? I've registered all three models (plus Tag) to the admin site in admin.py. TIA

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  • Is multi-level polymorphism possible in SQLAlchemy?

    - by Jace
    Is it possible to have multi-level polymorphism in SQLAlchemy? Here's an example: class Entity(Base): __tablename__ = 'entities' id = Column(Integer, primary_key=True) created_at = Column(DateTime, default=datetime.utcnow, nullable=False) entity_type = Column(Unicode(20), nullable=False) __mapper_args__ = {'polymorphic_on': entity_type} class File(Entity): __tablename__ = 'files' id = Column(None, ForeignKey('entities.id'), primary_key=True) filepath = Column(Unicode(255), nullable=False) file_type = Column(Unicode(20), nullable=False) __mapper_args__ = {'polymorphic_identity': u'file', 'polymorphic_on': file_type) class Image(File): __mapper_args__ = {'polymorphic_identity': u'image'} __tablename__ = 'images' id = Column(None, ForeignKey('files.id'), primary_key=True) width = Column(Integer) height = Column(Integer) When I call Base.metadata.create_all(), SQLAlchemy raises the following error: NotImplementedError: Can't generate DDL for the null type IntegrityError: (IntegrityError) entities.entity_type may not be NULL. This error goes away if I remove the Image model and the polymorphic_on key in File. What gives? (Edited: the exception raised was wrong.)

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  • Generic extension method returning IEnumerable<T> without using reflection

    - by roosteronacid
    Consider this snippet of code: public static class MatchCollectionExtensions { public static IEnumerable<T> AsEnumerable<T>(this MatchCollection mc) { return new T[mc.Count]; } } And this class: public class Ingredient { public String Name { get; set; } } Is there any way to magically transform a MatchCollection object to a collection of Ingredient? The use-case would look something like this: var matches = new Regex("([a-z])+,?").Matches("tomato,potato,carrot"); var ingredients = matches.AsEnumerable<Ingredient>();

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  • what is the programmatic parlance for this phenomenon?

    - by deostroll
    Here is javascript code (jquery) for adding a row of images: var tr = $('<tr>'); var td = '<td><img src="myimg.jpg"/></td>'; tr.append(td).append(td).append(td); $('#mytable tbody tr:eq(0)').before(tr); tr.empty(); //I really don't need this line... Technically tr.empty() shouldn't have worked. It actually does the opposite of what I want. What is the techinical term for this behaviour - You've added tr to the DOM, but any jquery function calls to that object still works, where as you'd normally not expect it to work i.e. make changes to the DOM?

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  • C++0x rvalue references - lvalues-rvalue binding

    - by Doug
    This is a follow-on question to http://stackoverflow.com/questions/2748866/c0x-rvalue-references-and-temporaries In the previous question, I asked how this code should work: void f(const std::string &); //less efficient void f(std::string &&); //more efficient void g(const char * arg) { f(arg); } It seems that the move overload should probably be called because of the implicit temporary, and this happens in GCC but not MSVC (or the EDG front-end used in MSVC's Intellisense). What about this code? void f(std::string &&); //NB: No const string & overload supplied void g1(const char * arg) { f(arg); } void g2(const std::string & arg) { f(arg); } It seems that, based on the answers to my previous question that function g1 is legal (and is accepted by GCC 4.3-4.5, but not by MSVC). However, GCC and MSVC both reject g2 because of clause 13.3.3.1.4/3, which prohibits lvalues from binding to rvalue ref arguments. I understand the rationale behind this - it is explained in N2831 "Fixing a safety problem with rvalue references". I also think that GCC is probably implementing this clause as intended by the authors of that paper, because the original patch to GCC was written by one of the authors (Doug Gregor). However, I don't this is quite intuitive. To me, (a) a const string & is conceptually closer to a string && than a const char *, and (b) the compiler could create a temporary string in g2, as if it were written like this: void g2(const std::string & arg) { f(std::string(arg)); } Indeed, sometimes the copy constructor is considered to be an implicit conversion operator. Syntactically, this is suggested by the form of a copy constructor, and the standard even mentions this specifically in clause 13.3.3.1.2/4, where the copy constructor for derived-base conversions is given a higher conversion rank than other implicit conversions: A conversion of an expression of class type to the same class type is given Exact Match rank, and a conversion of an expression of class type to a base class of that type is given Conversion rank, in spite of the fact that a copy/move constructor (i.e., a user-defined conversion function) is called for those cases. (I assume this is used when passing a derived class to a function like void h(Base), which takes a base class by value.) Motivation My motivation for asking this is something like the question asked in http://stackoverflow.com/questions/2696156/how-to-reduce-redundant-code-when-adding-new-c0x-rvalue-reference-operator-over ("How to reduce redundant code when adding new c++0x rvalue reference operator overloads"). If you have a function that accepts a number of potentially-moveable arguments, and would move them if it can (e.g. a factory function/constructor: Object create_object(string, vector<string>, string) or the like), and want to move or copy each argument as appropriate, you quickly start writing a lot of code. If the argument types are movable, then one could just write one version that accepts the arguments by value, as above. But if the arguments are (legacy) non-movable-but-swappable classes a la C++03, and you can't change them, then writing rvalue reference overloads is more efficient. So if lvalues did bind to rvalues via an implicit copy, then you could write just one overload like create_object(legacy_string &&, legacy_vector<legacy_string> &&, legacy_string &&) and it would more or less work like providing all the combinations of rvalue/lvalue reference overloads - actual arguments that were lvalues would get copied and then bound to the arguments, actual arguments that were rvalues would get directly bound. Questions My questions are then: Is this a valid interpretation of the standard? It seems that it's not the conventional or intended one, at any rate. Does it make intuitive sense? Is there a problem with this idea that I"m not seeing? It seems like you could get copies being quietly created when that's not exactly expected, but that's the status quo in places in C++03 anyway. Also, it would make some overloads viable when they're currently not, but I don't see it being a problem in practice. Is this a significant enough improvement that it would be worth making e.g. an experimental patch for GCC?

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  • Remapping design issue

    - by Sirupsen
    Hello, I'm currently developing a Ruby Gem and I'm a bit lost on the design currently. Basically, I'm remapping some APIs, so my skeleton is something like this: module MyApp module SomeApi class Function > Base::Function ... end class Function2 > Base::Function2 ... end ... end module SomeApi2 ... end class RemappedFunction def initalize # set some values and stuf ... end def remapped_method # Problem: # How would I know, if I should take contact to # SomeApi, or SomeApi2? end end def interact_with(api) # What would be the best way of letting RemappedFunction # know which API to use? end end someapi2 = MyApp.interact_with(:someapi2) someapi2.remapped_method Any ideas?

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  • Find all paths from root to leaves of tree in Scheme

    - by grifaton
    Given a tree, I want to find the paths from the root to each leaf. So, for this tree: D / B / \ A E \ C-F-G has the following paths from root (A) to leaves (D, E, G): (A B D), (A B E), (A C F G) If I represent the tree above as (A (B D E) (C (F G))) then the function g does the trick: (define (g tree) (cond ((empty? tree) '()) ((pair? tree) (map (lambda (path) (if (pair? path) (cons (car tree) path) (cons (car tree) (list path)))) (map2 g (cdr tree)))) (else (list tree)))) (define (map2 fn lst) (if (empty? lst) '() (append (fn (car lst)) (map2 fn (cdr lst))))) But this looks all wrong. I've not had to do this kind of thinking for a while, but I feel there should be a neater way of doing it. Any ideas for a better solution (in any language) would be appreciated.

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  • ActionScript: Determine wether superclass implements a particular interface?

    - by David Wolever
    Is there any non-hacky way to determine wether a class' superclass implements a particular interface? For example, assume I've got: class A extends EventDispatcher implements StuffHolder { private var myStuff = someKindOfStuff; public function getStuff():Array { if (super is StuffHolder) // <<< this doesn't work return super['getStuff']().concat([myStuf]); return [myStuff]; } class B extends A { private var myStuff = anotherKindOfStuff; } How could I perform that super is StuffHolder test in a way that, well, works? In this case, it always returns true.

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  • Does a PHP library exist to work with PRC/.mobi files?

    - by Chris Clarke
    I'm writing a WordPress plugin to create an eBook from a selected category in most major eBook formats. I would like to support MobiPocket since that's the format used by the Kindle but I'm not sure how to go about it. From what I've read .mobi files are actually Palm Resource Databases (PRC) but I haven't been able to find a PHP class to work with these. I thought about using exec along with KindleGen but that would be undesirable as it would complicate initial setup. I've also thought about hosting a web service somewhere and using XML-RPC to accomplish this but that also complicates things. My question is: is there a PHP class/library (PHP-only preferred) that can work with PRC or even better, a class that specialises in creating MobiPocket ebooks? (needs to be open source since I'm releasing under the GPL) I've tried searching but haven't been able to find anything.

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  • Giving 'TemplateError' can't convert String into Integer

    - by Gagan
    Hi, I recently transfered my app from Rails2 to Rails3. The code in 'app/views/distribution/index.html.erb' is like :- <div style="padding-bottom:10px; padding-left:0px;float:left;display:<%= (!session[:album][@artist.id.to_s].empty? && !session[:album][@artist.id.to_s].nil?)?'block' : 'none' %>" id = "make_payment_enabled"> <%= link_to 'Make Payments',{:action => 'pay', :album=>@album.id}, :class => "button" %> </div> It's giving me TemplateError on line :- <div style="padding-bottom:10px; padding-left:0px;float:left;display:<%= (!session[:album][@artist.id.to_s].empty? && !session[:album][@artist.id.to_s].nil?)?'block' : 'none' %>" id = "make_payment_enabled"> How to resolve the problem ?

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