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  • Errors when using a Ruby On Rails scaffold with a data type of interger

    - by bublebboy
    I am learning Ruby On Rails. I am on a shared hosting with Ruby version 1.8.1 and Rails version 2.3.10. I am working my way through a tutorial at http://railstutorial.org/chapters/a-demo-app?version=2.3#top and at one point in the tutorial it has me run: script/generate scaffold Micropost content:string user_id:interger The tutorial is using the default database, SQLite3. The command works and I use rake db:migrate to create the database. I can view the page listing the microposts (which is empty), but when I try to add a micropost (microposts/new) I get an error undefined method `user_id' for #<Micropost:0x7f710e4988e8> After doing some testing on my own it seems I experience the problem by using the data type of interger. While I understand that using a scaffold is not the best way of building a ruby on rails, I'm just beginning and would still like to know why I am experiencing this problem to help me better understand how rails works.

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  • Memory management for "id<ProtocolName> variableName" type properties

    - by Malakim
    Hi, I'm having a problem with properties of the following type: id<ProtocolName> variableName; ..... ..... @property (nonatomic, retain) id<ProtocolName> variableName; I can access and use them just fine, but when I try to call [variableName release]; I get compiler warnings: '-release' not found in protocol(s) Do I need to define a release method in the interface, or how do I release the memory reserved for the variable? Thanks!

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  • Type hinting and optional attributes in PHP

    - by Álvaro G. Vicario
    I have a class method that deals with dates: public function setAvailability(DateTime $start, DateTime $end){ } Since item availability can have lower limit, upper limit, both or none, I'd like to make setAvailability() accept NULL values as well. However, the NULL constant violates the type hinting: $foo->setAvailability(NULL, $end); triggers: Catchable fatal error: Argument 1 passed to Foo::setAvailability() must be an instance of DateTime, null given And, as far as I know, I cannot have a DateTime instance with no value. (Can I?) For a reason I cannot grasp, this seems to work: public function setAvailability(DateTime $start=NULL, DateTime $end=NULL){ } ... $foo->setAvailability(NULL, $end); But it looks like a hack that works by pure chance. How would you deal with unset dates in PHP classes?

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  • SimpleInjector - Register a type for all it's interfaces

    - by Karl Cassar
    Is it possible to register a type for all it's implementing interfaces? E.g, I have a: public class Bow : IWeapon { #region IWeapon Members public string Attack() { return "Shooted with a bow"; } #endregion } public class HumanFighter { private readonly IWeapon weapon = null; public HumanFighter(IWeapon weapon) { this.weapon = weapon; } public string Fight() { return this.weapon.Attack(); } } [Test] public void Test2b() { Container container = new Container(); container.RegisterSingle<Bow>(); container.RegisterSingle<HumanFighter>(); // this would match the IWeapon to the Bow, as it // is implemented by Bow var humanFighter1 = container.GetInstance<HumanFighter>(); string s = humanFighter1.Fight(); }

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  • non-scalar type requested

    - by lego69
    can somebody please help me with an error conversion from `A' to non-scalar type `B' requested I have class A and derived from it B, but I have problems with these rows: A a(1); A *pb = new B(a); B b = *pb; //here I have an error thanks in advance for any help class A { protected: int player; public: A(int initPlayer = 0); A(const A&); A& operator=(const A&); virtual ~A(){}; virtual void foo(); void foo() const; operator int(); }; class B: public A { public: B(int initPlayer): A(initPlayer){}; ~B(){}; virtual void foo(); };

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  • Detect all changes to a <input type="text"> (immediately) using JQuery

    - by Dustin Boswell
    There are many ways the value of a <input type="text"> can change, including: keypresses copy/paste modified with JavaScript auto-completed by browser or a toolbar I want my JavaScript function to be called (with the current input value) any time it changes. And I want it to be called right away, not just when the input loses focus. I'm looking for the cleanest and most robust way to do this across all browsers (using jQuery preferably). Example use case: On the Twitter Signup page, the username field's value gets shown in the url "http://twitter/username" below it.

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  • HTML select form with option to enter custom value

    - by Ib33X
    I would like to have input field that users can enter custom text value or choose from drop down, normal select only offers drop down options. How can it accept custom value for instance ford? <select> <option value="volvo">Volvo</option> <option value="saab">Saab</option> <option value="mercedes">Mercedes</option> <option value="audi">Audi</option> </select> Edit: I used this http://bit.wisestamp.com/uncategorized/htmljquery-editable-combo-2/ solution. Also I tried jquery ui combobox and it is not working properly

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  • C++ Boost bind value type

    - by aaa
    hello. I look in documentation and source code but cannot figure out how to get return value type of boost bind functor. I am trying to accomplish following: 35 template<typename T,size_t N, class F> 36 boost::array<typename F::value_type, N> make_array(T (&input)[N], F unary) { 37 boost::array<typename F::value_type, N> array; 38 std::transform(input, input + N, array.begin(), unary); 39 return array; 40 } where F can be bind functor. the above does not work because functor does not have value_type. for that matter, is there standard interface for unary/binary functor as far as return value. Thanks

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  • super(type,subclass) in simple singleton implementation

    - by Tianchen Wu
    when I was implementing naive singleton in python, I came up with a problem with super key word. As usual the behavior of super is always tricky and buggy, hope someone can shed light on it. Thanks :) The problem is that: class Singleton(object): def __new__(cls,*args,**kw): if not hasattr(cls,'_instance'): #create a instance of type cls, origin=super(Singleton,Singleton).__new__(cls,*args,**kw) cls._instance=origin return cls._instance class B(Singleton): def __init__(self,b): self.b=b It actually works, but I am wondering Will it be better if I change line 5 to the below, like in most of the books? origin=super(Singleton,cls).__new__(cls,*args,**ks) what's the difference to make?

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  • Unable to type cast <AnonymousType#1> to <WindowsFormsApplication1.Attributes> [ C#3.0 ]

    - by Newbie
    I have List<Attributes> la = new List<Attributes>(); la = (from t in result let t1 = t.AttributeCollection from t2 in t1 where t2.AttributeCode.Equals(attributeType) let t3 = t2.TimeSeriesData from k in t3.ToList() where k.Key.Equals(startDate) && k.Key.Equals(endDate) select new { AttributeCode = attributeType, TimeSeriesData = fn(k.Key, k.Value.ToString()) }).ToList<Attributes>(); I am getting the error: 'System.Collections.Generic.IEnumerable<AnonymousType#1>' does not contain a definition for 'ToList' and the best extension method overload 'System.Linq.Enumerable.ToList<TSource>(System.Collections.Generic.IEnumerable<TSource>)' has some invalid arguments I understood tye error meaning but how to type cast it. I have used var and then iterating over it got the result. But without that any other way by which I can do it? Using C# 3.0 Thanks

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  • SQLite: does data type depend on the quotes?

    - by Septagram
    In SQLite, the datatype of a value is associated with the value itself, not with the column type. So suppose we have a table with an integer primary key "id" and an integer column "some_number". If I do a query like this: INSERT INTO mytable (id, some_number) VALUES (NULL, "1234") Will 123 be inserted as an integer or as string? What consequences it will have later for me, say, when I'm comparing it with other value like "234" (as a number 1234 234, as a string "1234" < "234", right?)?

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  • how to create property of type generic class?

    - by Anish
    public class SelectionList<T> : ObservableCollection<SelectionItem<T>> where T : IComparable<T> { // Code } public class SelectionItem<T> : INotifyPropertyChanged { // Code } I need to create a property which is of the type SelectionList...as follows: public SelectionList<string> Sports { get; set; }. But when I replace string with DataRowView, as public SelectionList<DataRowView> Sports { get; set; }. I am getting error. Please help

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  • How to use a Visual C++ .Net String type as argument in a function

    - by stefangachter
    Probably this is not a difficult question, but I am always a little bit confused on how to treat String type as an argument in Visual C++. I have the following to functions: void function_1(String ^str_1) { str_1 = gcnew String("Test"); } void function_2() { String ^str_2 = nullptr; function_1(str_2); } After calling function_1, str_2 is still equal to null, but what I want to achieve is that str_2 is equal to Test. So, how can I achieve that the content of str_1 is passed to function_2? Thanks for any advice.

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  • Difference between User Control and Custom Control Library

    - by Rod
    I'm working on creating a date/time user control in WPF using C# 2008. My first user control. I'm also using Matthew MacDonald's book, "Pro WPF in C# 2008". In that book he strongly recommended creating a user control using the WPF Custom Control Library project template; so I followed his suggestion. I've finished writing the code which would go into what I think of as the code-behind file. Now I'm ready to write the XAML. The only problem is, I just discovered there is no corresponding .xaml file? So, I don't get why using a WPF Custom Control Library project is better, or prefered, when writing a user control?

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  • Instantiating custom PropertySourcesPlaceholderConfigurer from spring context

    - by mmona
    I want to define a custom PropertySourcesPlaceholderConfigurer in spring context xml. I want to use there multiple PropertySources, so that I can load part of the configuration from several property files and provide other part dynamically by my custom PropertySource implementation. The advantage is that it should be then easy to adjust the order of loading these property sources just by making modifications to the xml spring configuration. And here I run into a problem: how to define an arbitrary list of PropertySources and inject it into PropertySourcesPlaceholderConfigurer, so that it uses the sources defined by me? Seems to be a basic thing that should be provided by spring, but since yesterday I cannot find a way to do it. Using namespace would enable me to load several property files, but I also need to define the id of the PropertySourcesPlaceholderConfigurer (as other projects refer to it), and also I want to use my custom implementation. That is why I am defining the bean explicitly and not using the namespace. The most intuitive way would be to inject a list of PropertySources into PropertySourcesPlaceholderConfigurer like this: <bean id="applicationPropertyPlaceholderConfigurer" class="org.springframework.context.support.PropertySourcesPlaceholderConfigurer"> <property name="ignoreUnresolvablePlaceholders" value="true" /> <property name="ignoreResourceNotFound" value="true" /> <property name="order" value="0"/> <property name="propertySources"> <list> <!-- my PropertySource objects --> </list> </property> </bean> but unfortunately propertySources is of type PropertySources and does not accept a list. The PropertySources interface has one and only implementor which is MutablePropertySources, which indeed stores list of PropertySource objects, but has no constructor nor setter through which I can inject this list. It only has add*(PropertySource) methods. The only workaround I see now is to implement my own PropertySources class, extending MutablePropertySources, which would accept list of PropertySource objects on creation and manually add it via using add*(PropertySource) method. But why so much workaround would be needed to provide something that I thought was supposed to be the main reason of introducing the PropertySources (having flexible configuration manageable from spring configuration level). Please clarify what am I getting wrong :)

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  • step attribute not working with HTML5 <input type="range"> on Safari

    - by Claudiu
    Are there known issues with range inputs not working fully on Safari? I have the following input element: <input type=?"range" min=?"0" max=?"360" step=?"0.0001" value=?"0">? On Chrome, the input goes according to the step variable. On Safari, it only goes by integer values. Even setting the step to 10 still makes it go by increments of 1. I'm confused because I thought Chrome and Safari both used WebKit.

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  • session variable not available in global before(:each, :type => :controller)

    - by Rob
    Hi, I'm refactoring some specs, in controller specs I have a before(:each) which sets up things required in the session my before filter is... config.before(:each, :type => :controller) do ... session[:current_user] = @user session[:instance] = @instance ... end @user and @instance are also set in the before(:each) i've just hidden them for readability here I get the following error when running the controller tests undefined method `session' for nil:NilClass I would expect the global before callbacks to have the same things as the ones in the individual tests but I guess maybe they are loaded before the rails environment has been initialised? Thanks

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  • Are there any good materials or examples on creating a custom Designer in the Delphi IDE

    - by Mark Elder
    I am working on creating a custom form designer in the Delphi IDE. I'm trying to use the RegisterCustomModule, TBaseCustomModule, and ICustomModule functions, classes, and interfaces. My first question on this pointed me to the Delphi Developer's Handbook and the idea that I could even create a custom form designer. However, that book seems to be all Delphi 3 information and things have really changed since then. I'm not finding any material in the Delphi Help file, and searches have not returned very much. I did find the Accidental Programmer's page on the Open Tools, but that looks like it was last up dated in 1998? It does at least have the correct unit names and uses the new interfaces. I'm willing to track down and buy an older book if that is the best reference.

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  • converting tag number to int

    - by Ehtesham Sajed
    i m using Visual C++2008. i've assigned tag value=2 of all buttons from button property(using drag n drop). now i want to make some math calculation with tag value. need to change it in int. what is the default data type tag? i used this code, //code sample if(((int)this-button1-Tag)((int)this-button2-Tag)((int)this-button3-Tag)==50) { ........ //i.e, if tag value of button1*tag value of button2*tag value of button 3==50 then... ........ } generated following run time error on a messegebox An unhandled exception of type 'System.InvalidCastException' occurred in learncpp1.exe Additional information: Specified cast is not valid.

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  • Adapting non-iterable containers to be iterated via custom templatized iterator

    - by DAldridge
    I have some classes, which for various reasons out of scope of this discussion, I cannot modify (irrelevant implementation details omitted): class Foo { /* ... irrelevant public interface ... */ }; class Bar { public: Foo& get_foo(size_t index) { /* whatever */ } size_t size_foo() { /* whatever */ } }; (There are many similar 'Foo' and 'Bar' classes I'm dealing with, and it's all generated code from elsewhere and stuff I don't want to subclass, etc.) [Edit: clarification - although there are many similar 'Foo' and 'Bar' classes, it is guaranteed that each "outer" class will have the getter and size methods. Only the getter method name and return type will differ for each "outer", based on whatever it's "inner" contained type is. So, if I have Baz which contains Quux instances, there will be Quux& Baz::get_quux(size_t index), and size_t Baz::size_quux().] Given the design of the Bar class, you cannot easily use it in STL algorithms (e.g. for_each, find_if, etc.), and must do imperative loops rather than taking a functional approach (reasons why I prefer the latter is also out of scope for this discussion): Bar b; size_t numFoo = b.size_foo(); for (int fooIdx = 0; fooIdx < numFoo; ++fooIdx) { Foo& f = b.get_foo(fooIdx); /* ... do stuff with 'f' ... */ } So... I've never created a custom iterator, and after reading various questions/answers on S.O. about iterator_traits and the like, I came up with this (currently half-baked) "solution": First, the custom iterator mechanism (NOTE: all uses of 'function' and 'bind' are from std::tr1 in MSVC9): // Iterator mechanism... template <typename TOuter, typename TInner> class ContainerIterator : public std::iterator<std::input_iterator_tag, TInner> { public: typedef function<TInner& (size_t)> func_type; ContainerIterator(const ContainerIterator& other) : mFunc(other.mFunc), mIndex(other.mIndex) {} ContainerIterator& operator++() { ++mIndex; return *this; } bool operator==(const ContainerIterator& other) { return ((mFunc.target<TOuter>() == other.mFunc.target<TOuter>()) && (mIndex == other.mIndex)); } bool operator!=(const ContainerIterator& other) { return !(*this == other); } TInner& operator*() { return mFunc(mIndex); } private: template<typename TOuter, typename TInner> friend class ContainerProxy; ContainerIterator(func_type func, size_t index = 0) : mFunc(func), mIndex(index) {} function<TInner& (size_t)> mFunc; size_t mIndex; }; Next, the mechanism by which I get valid iterators representing begin and end of the inner container: // Proxy(?) to the outer class instance, providing a way to get begin() and end() // iterators to the inner contained instances... template <typename TOuter, typename TInner> class ContainerProxy { public: typedef function<TInner& (size_t)> access_func_type; typedef function<size_t ()> size_func_type; typedef ContainerIterator<TOuter, TInner> iter_type; ContainerProxy(access_func_type accessFunc, size_func_type sizeFunc) : mAccessFunc(accessFunc), mSizeFunc(sizeFunc) {} iter_type begin() const { size_t numItems = mSizeFunc(); if (0 == numItems) return end(); else return ContainerIterator<TOuter, TInner>(mAccessFunc, 0); } iter_type end() const { size_t numItems = mSizeFunc(); return ContainerIterator<TOuter, TInner>(mAccessFunc, numItems); } private: access_func_type mAccessFunc; size_func_type mSizeFunc; }; I can use these classes in the following manner: // Sample function object for taking action on an LMX inner class instance yielded // by iteration... template <typename TInner> class SomeTInnerFunctor { public: void operator()(const TInner& inner) { /* ... whatever ... */ } }; // Example of iterating over an outer class instance's inner container... Bar b; /* assume populated which contained items ... */ ContainerProxy<Bar, Foo> bProxy( bind(&Bar::get_foo, b, _1), bind(&Bar::size_foo, b)); for_each(bProxy.begin(), bProxy.end(), SomeTInnerFunctor<Foo>()); Empirically, this solution functions correctly (minus any copy/paste or typos I may have introduced when editing the above for brevity). So, finally, the actual question: I don't like requiring the use of bind() and _1 placeholders, etcetera by the caller. All they really care about is: outer type, inner type, outer type's method to fetch inner instances, outer type's method to fetch count inner instances. Is there any way to "hide" the bind in the body of the template classes somehow? I've been unable to find a way to separately supply template parameters for the types and inner methods separately... Thanks! David

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  • Why is cakephp form input stored in $this->data and POST data stored in $this->params['form'] ?

    - by spudnik1979
    the cakephp rest tutorial says that post data should be in $this-data, but I am finding that it is not, but instead inside $this-params['form'] However, when using cakephp form helper in a view, the data is in $this-data. Am I correct to have to check both locations in my controller? It just seems a bit of a waste of extra code. Shouldnt the data appear in one place for whether it came from a rest rest requestor or Cakephp form post? ps im using cakephp 1.3

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  • Linking/Combining Type Classes in Haskell

    - by thegravian
    Say I have two type classes defined as follows that are identical in function but different in names: class Monad m where (>>=) :: m a -> (a -> m b) -> m b return :: a -> m a class PhantomMonad p where pbind :: p a -> (a -> p b) -> p b preturn :: a -> p b Is there a way to tie these two classes together so something that is an instance of PhantomMonad will automatically be an instance of Monad, or will instances for each class have to be explicitly written? Any insight would be most appreciated, thanks!

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