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• Passing session data to ModelForm inside of ModelAdmin

  - by theactiveactor

  I'm trying to initialize the form attribute for MyModelAdmin class inside an instance method, as follows: class MyModelAdmin(admin.ModelAdmin): def queryset(self, request): MyModelAdmin.form = MyModelForm(request.user) My goal is to customize the editing form of MyModelForm based on the current session. When I try this however, I keep getting an error (shown below). Is this the proper place to pass session data to ModelForm? If so, then what may be causing this error? TypeError at ... Exception Type: TypeError Exception Value: issubclass() arg 1 must be a class Exception Location: /usr/lib/pymodules/python2.6/django/forms/models.py in new, line 185

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• Joining a one-to-many association with a many-to-many association in Rails 3

  - by Maz

  Hi all, I have a many-to-many association between a User class and a Table class. Additionally, i have a one-to-many association between the User and the Table (one User ultimately owns the table). I am trying to access all of the tables which the user may access (essintally joining both associations). Additionally, it would be nice to do this this with named_scope (now scope) Here's what I have so far: class User < ActiveRecord::Base acts_as_authentic attr_accessible :email, :password, :password_confirmation has_many :feedbacks has_many :tables has_many :user_table_permissions has_many :editableTables, :class_name => "Table", :through => :user_table_permissions def allTables editableTables.merge(tables) end end Thanks.

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• How to build the ViewModel in MVVM not to violate the Single Responsibility Principle?

  - by Przemek

  Robert Martin says: "There should never be more than one reason for a class to change". Let's consider the ViewModel class which is bound to a View. It is possible (or even probable) that the ViewModel consists of properties that are not really related to each other. For small views the ViewModel may be quite coherent, but while the application gets more complex the ViewModel will expose data that will be subject to change for different and unrelated reasons. Should we worry about the SRP principle in the case of ViewModel class or not?

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• Uses for static generic classes?

  - by Hightechrider

  What are the key uses of a Static Generic Class in C#? When should they be used? What examples best illustrate their usage? e.g. public static class Example<T> { public static ... } Since you can't define extension methods in them they appear to be somewhat limited in their utility. Web references on the topic are scarce so clearly there aren't a lot of people using them. Here's a couple:- http://ayende.com/Blog/archive/2005/10/05/StaticGenericClass.aspx http://stackoverflow.com/questions/686630/static-generic-class-as-dictionary

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• Java newbie problem: package with private access

  - by HH

  Pack.java imports pack.TestPack; but it cannot access it. I cannot understand why it cannot access the class despite the import. Error Pack.java:7: TestPack() is not public in pack.TestPack; cannot be accessed from outside package System.out.println(new TestPack().getHello()); ^ 1 error Pack.java import pack.TestPack; import java.io.*; public class Pack { public static void main(String[] args){ System.out.println(new TestPack().getHello()); } } TestPack.java package pack; import java.util.*; import java.io.*; public class TestPack { private String hello="if you see me, you ar inside class TestPack"; public String getHello(){return hello;} TestPack(){} }

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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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• How to specify a different column for a @Inheritance JPA annotation

  - by Cue

  @Entity @Inheritance(strategy = InheritanceType.JOINED) public class Foo @Entity @Inheritance(strategy = InheritanceType.JOINED) public class BarFoo extends Foo mysql> desc foo; +---------------+-------------+ | Field | Type | +---------------+-------------+ | id | int | +---------------+-------------+ mysql> desc barfoo; +---------------+-------------+ | Field | Type | +---------------+-------------+ | id | int | | foo_id | int | | bar_id | int | +---------------+-------------+ mysql> desc bar; +---------------+-------------+ | Field | Type | +---------------+-------------+ | id | int | +---------------+-------------+ Is it possible to specify column barfo.foo_id as the joined column? Are you allowed to specify barfoo.id as BarFoo's @Id since you are overriding the getter/seeter of class Foo? I understand the schematics behind this relationship (or at least I think I do) and I'm ok with them. The reason I want an explicit id field for BarFoo is exactly because I want to avoid using a joined key (foo _id, bar _id) when querying for BarFoo(s) or when used in a "stronger" constraint. (as Ruben put it)

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• NullPointerException Java help

  - by KP65

  Hello guys. I've been tearing my hair out the past few hours trying to solve this problem. Every time I click on a JButton which should open a JFrame(And it does), i get a stacktrace saying I have a null point exception at these bits of code: In class A i have: aButton.addActionListener(new ActionListener() { public void actionPerformed(ActionEvent e) { B instanceofB = new B(userSession.getBalance()); }); and Class B super.getSomeBtn().setVisible(false); This is where the stacktrace says the errors are in the two above sections. I have a line exactly the same as the one above in Class B and it works fine? Really stuck here!

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• hasErrors with indexed property

  - by Micor

  I am having hard time getting hasErrors to work with indexed properties. For example class Order { String prop1 String prop2 static hasMany = [items: Item] } class Item { String name static constraints = { name(blank:false) } } Validation works properly and on item.name being blank I do get an error with <g:renderErrors bean="${orderInstance}"/> However, I am trying to have input box highlighted using hasErrors : <g:each in="${orderIntsance.items}" status="i" var="item"> <span class="field ${hasErrors(bean: orderInstance, field: ????????? , 'errors')}"> <g:textField name="items[${i}].name" value="${item?.name}"/> </span> </g:each> Not sure how to get to it with a field: property, any ideas? Thanks

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• IntelliJ: Including jars in a jar artifact

  - by skiaddict1

  Developing on the Mac with IntelliJ 9.0.2. I have a program which depends on two library jars. I have figured out how to get IntelliJ to make me a jar of my source (with the Artifact tab), and even to include the two jars in it. However, if I get a listing of the jar file it produces, it looks like this: com/acme/MyClass1.class com/acme/MyClass2.class ... mylib1.jar myLib2.jar And, no surprises, if I double-click the jar file, it gets a NoClassDefFoundError the first time it tries to access a class in one or other library jar. How do I get IntelliJ to include the two library jars such that the classes are visible?

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• Reverse Expression.Like criterion

  - by Joel Potter

  How should I go about writing a backwards like statement using NHibernate criteria? WHERE 'somestring' LIKE [Property] + '%' Sub Question: Can you access the abstract root alias in a SQLCriterion expression? This is somewhat achievable using the SQLCriterion expression Expression.Sql("? like {alias}.[Property] + '.%'", value, NHibernateUtil.String); However, in the case of class inheritance, {alias} is replaced with the incorrect alias for the column. Example (these classes are stored in separate tables): public abstract class Parent { public virtual string Property { get; set; } } public class Child : Parent { } The above query executed with Child as the root type will replace {alias} with the alias to the Child table rather than the Parent table. This results in an invalid column exception. I need to execute a like statement as above where the property exists on the parent table rather than on the root type table.

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• Get the entire string of a jquery DOM object

  - by Scozzard

  Hi, I have had a bit of a look around and am having some difficulty solving a wee issue I am having. I basically have a string of HTML, I convert that to a JQuery DOM object so that I can easily remove all elements that have a certain class using JQuery's .remove(). I.e., var radHtml = editor.get_html(); var jqDom = $(radHtml); $(".thickbox", jqDom).remove(); editor.set_html(jqDom.html()); The only problem is that .html() only gets the first element, not the entire DOM. In reference to my code I am basically wanting radHhtml - elements with class "thickbox" (returned as string). I was wondering if there was an easy way to do this - have some html and remove all elements (in this case divs) that have a certain class (but leaving their contents). JQuery doesnt have to used, but I would like to. Any help would be much appreicated. Thanks.

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• PHP Doxygen Collaboration Diagrams

  - by Shabbyrobe

  I've started playing around with doxygen to generate documentation from my PHP code. I notice there are two diagrams in the generated output - inheritance and collaboration. I know about the inheritance one, but the collaboration one has piqued my interest since reading the manual: If the COLLABORATION_GRAPH and HAVE_DOT tags are set to YES then doxygen will generate a graph for each documented class showing the direct and indirect implementation dependencies (inheritance, containment, and class references variables) of the class with other documented classes. The impression I get from that description is that composition relationships should be represented by the collaboration diagram as well, but it always seems to just be identical to the inheritance one. Is there something I can do to hint to Doxygen the things I would like to appear in this diagram? Does it just not work with PHP?

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• Singleton constructor question

  - by gillyb

  Hi, I created a Singleton class in c#, with a public property that I want to initialize when the Singleton is first called. This is the code I wrote : public class BL { private ISessionFactory _sessionFactory; public ISessionFactory SessionFactory { get { return _sessionFactory; } set { _sessionFactory = value; } } private BL() { SessionFactory = Dal.SessionFactory.CreateSessionFactory(); } private object thisLock = new object(); private BL _instance = null; public BL Instance { get { lock (thisLock) { if (_instance == null) { _instance = new BL(); } return _instance; } } } } As far as I know, when I address the Instance BL object in the BL class for the first time, it should load the constructor and that should initialize the SessionFactory object. But when I try : BL.Instance.SessionFactory.OpenSession(); I get a Null Reference Exception, and I see that SessionFactory is null... why?

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• open iphone Mail from Actionsheet..

  - by totato

  hi .. I want to open Mail app from my app when the one button in actionsheet is pressed, I know this way : -(IBAtion)openClick:(id)sender { [[UIApplication sharedApplication] openURL:[NSURL URLWithString:@”mailto:[email protected]”]]; } but can I write this method inside if statement or switch case?(in ControlView class NOT NSObject class , because I use actionsheet for this propose) like this: - (void)actionSheet:(UIActionSheet *)modalView clickedButtonAtIndex:(NSInteger)buttonIndex { switch (buttonIndex) { case 0: { [[UIApplication sharedApplication] openURL:[NSURL URLWithString:@”mailto:[email protected]”]]; break; } I can't test my code because simulator doesn't have the Mail app.. So I need to know is this will work in controlView or must write it in NSObject class ? + seconde question : I want to open Mail app from my app and copy the content in the view to mail body,then the user choice the contact from his contacts list ! Is this way achieve my goal?

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• C++ interface inheritance problem

  - by james t

  Hey, i'm trying to create a c++ stomp client, my client constructor is : Client(std::string &server, short port, std::string &login, std::string &pass, Listener &listener); it gets a listener object which when Listener is the following interface : class Listener { virtual void message(StmpMessage message) =0; }; now i attempt to instantiate a client in a test class : class test : public virtual Listener { public: void message(StmpMessage message) { message.prettyPrint(); } int main(int argc, char* argv[]) { Client client("127.0.0.1", 61613, *this); return 0; } }; i'm sending this to the client because this is a listener object, i get the following error : /Users/mzruya/Documents/STOMPCPP/main.cpp:18: error: no matching function for call to 'Client::Client(const char [10], int, test&)' /Users/mzruya/Documents/STOMPCPP/Client.h:43: note: candidates are: Client::Client(std::string&, short int, std::string&, std::string&, Listener&) /Users/mzruya/Documents/STOMPCPP/Client.h:37: note: Client::Client(const Client&)

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• When to use the Flyweight Pattern

  - by elmt

  So I've just gotten on the boost train and was checking out the flyweight pattern and was interested in implementing it in my project. Obviously, it doesn't make sense to use it on any class that has only has one instance of it. However, say I have 5 instances of an class. Should I be using the flyweight pattern or should it be only used for a class that has at least N instances. I realize that many factors will influence this answer (how many fields there are, the size of the fields, etc.).

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• RIA Services and multiple/dynamic "Include" strategies

  - by user326526

  As an example, assume the following simple model: public class Order { public List<LineItem> LineItems { get; set; } public List<Fee> Fees { get; set; } } public class LineItem { } public class Fee { } With RIA Services, if I want to retrieve an Order and include all of it's line items in the same network call, I can statically place an [Include] attribute on the above LineItems collection. This works great for a single scenario, but what happens when I need multiple "include strategies"? For instance, one situation might call for including the Fees collection and NOT the LineItems collection. Is there any way with RIA Services to control what's included at runtime without redefining your model and/or creating dtos with the attributes statically placed for each use-case?

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• Can't get Javac to work on Mac OS X

  - by elguapo-85

  I am trying to compile with javac on Snow Leopard through the command line. I have Xcode installed. I am just using a simple Hello World file, it works in Eclipse but I can't get it to work using javac. javac -version returns javac 1.6.0_17 HelloWorld.java public class HelloWorld { public static void main(String[] args) { String message = "Welcome to Java!"; System.out.println(message); } } I type: javac HelloWorld.java and get the following error. HelloWorld.java:1: class, interface, or enum expected public class HelloWorld ^ 1 error and... javac -cp . HelloWorld.java returns the same. echo $CLASSPATH just returns blank. Thanks for the help.

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• C++ overloading virtual = operator

  - by taz

  Hello, here is the code for my question: class ICommon { public: virtual ICommon& operator=(const ICommon & p)const=0; }; class CSpecial : public ICommon { public: CSpecial& operator=(const CSpecial & cs) { //custom operations return *this; } }; CSpecial obj; Basically: I want the interface ICommon to force it's descendants to implement = operator but don't want to have any typecasts in the implementation. The compiler says "can't instantiate an abstract class. Any help/advice will be appreciated.

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• Hibernate/JPA - annotating bean methods vs fields

  - by Benju

  I have a simple question about usage of Hibernate. I keep seeing people using JPA annotations in one of two ways by annotating the fields of a class and also by annotating the get method on the corresponding beans. My question is as follows: Is there a difference between annotating fields and bean methods with JPA annoations such as @Id. example: @Entity public class User { **@ID** private int id; public int getId(){ return this.id; } public void setId(int id){ this.id=id; } } -----------OR----------- @Entity public class User { private int id; **@ID** public int getId(){ return this.id; } public void setId(int id){ this.id=id; } }

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• Java interface design

  - by Nayn

  Hi, I had an interface initially as below. public interface testMe { public Set<String> doSomething(); } public class A implements testMe { public Set<String> doSomething() { return // Set<String> } } I had similar classes implementing testMe. Now I have to add one more class which returns Set<Some Object> public class X implements testMe() { public Set<Some OBject> doSomething() { } } How could i add this mehtod in the interface without breaking existing classes? Thanks Nayn

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• Preprocessor Conditionals

  - by Mike

  I was wondering if it would be possible to have a define which changes values at some point in the code be used in a conditional. Basically something like this: //////////////////////////////////////////// SomeFile.cpp #define SHUTDOWN false while(window->isOpen()) { if(SHUTDOWN) window->close(); // Rest of the main loop } //////////////////////////////////////////// SomeOtherFile.cpp if(Escape.isPressed()) { #undef SHUTDOWN #define SHUTDOWN true } Thus causing the app to close. If it's not, would having a function like RenderWindow* getWindow() { return window; } and then calling if(Escape.isPressed()) getWindow()->close(); The best way to do it? I'd rather not go that route because the classes that are calling the key event are members of the class controlling the main loop and the window, so I'd have to set pointers to the containing class in the smaller classes to call getWindow() and it just seems like a more complicated method. But if I can't do it with preprocessor directives I'll just have to use pointers to the parent class.

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• SMBfs mounting OK, listing OK, Read KO, smbclient OK

  - by Kwaio

  I've tried to make the title the most meaningfull I could but it still looks ugly. The premises. We are using RHEL3-U8 as OS on most servers here, don't ask me why or suggest to upgrade, it's not on today's schedule. That means kernel used is 2.4.21 I have no access to the remote server, but I know it is a netApp NAS rack. $> smbclient --version Version 3.0.9-1.3E.9 Here is the /etc/fstab line : //NASHOSTNAME/share /mnt/mydir smbfs ro,uid=123,gid=123,workgroup=XXXX,credentials=/somefile 0 0 Here is the following mount output line //NASHOSTNAME/share on /mnt/mydir type smbfs (0) The symptoms. I can list the share without problems, even cd in there. The issue appears if I try to read any file : $> cat /mnt/mydir/fileX.txt cat: /mnt/mydir/fileX.txt: Input/output error In the system logs (/var/log/kernel for example) the following errors appear. Jul 30 15:40:02 hostname kernel: smb_errno: class ERRHRD, code 31 from command 0x2 Jul 30 15:40:02 hostname kernel: smb_errno: class ERRHRD, code 31 from command 0x2 Jul 30 15:40:02 hostname kernel: smb_open: fileX.txt open failed, result=-5 Jul 30 15:40:02 hostname kernel: smb_errno: class ERRHRD, code 31 from command 0x2 Jul 30 15:40:02 hostname kernel: smb_errno: class ERRHRD, code 31 from command 0x2 Jul 30 15:40:02 hostname kernel: smb_open: fileX.txt open failed, result=-5 Jul 30 15:40:02 hostname kernel: smb_readpage_sync: fileX.txt open failed, error=-5 The ERRHRD code 0x001F error is "General hardware failure" although it seems samba sometimes uses it for a different purpose, see http://www.ubiqx.org/cifs/SMB.html [Strange behaviour Alert] Additionnal informations : There is another SMB mountpoint on the system pointing to a (linux) host using samba and this one works. What I have tried. I have tried adding debug=4 to the mounting options and remounting the share and the logs still look the same. I have tried to mount the share with smbclient and I am able to fetch files with the get command. Both targets are in the same subnet, so network problem should be out, even if the LAN goes through a VPN with optimizers, MTU has already been decreased to 1450. I can also mount the share through NFS but then the files are all root.root 700 and I need to read them with another user...

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• Rails ActiveRecord- has_many through and belongs_to a related model

  - by Nick

  I have 3 models sites, user_favorites and users. Relevant relationships: class Site < ActiveRecord::Base has_many :users, :through => :user_favorites class UserFavorite < ActiveRecord::Base belongs_to :user, :counter_cache => true belongs_to :site end class User < ActiveRecord:Base has_many :user_favorites has_many :sites, :through => :user_favorites All of that works just fine. I'd like to add a new attribute to the Site model to indicate which user created it. I don't believe this constitutes a has_and_belongs_to_many scenario. A site has many users through user_favorites but I want it to belong to a single user reflecting the owner/creator. I'm wondering what the ORM best practice is for this. SQL wise I'd just use different joins depending on what I was trying to query with a created_by FK in Site. Sorry if I'm missing something basic here. Thanks

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