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Search found 50247 results on 2010 pages for 'base class'.

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  • Is correct name enough to make it happen?

    - by Knowing me knowing you
    Guys, I've just dipped in to limits.h by MS. I tried to check what's the return type for max() fnc and to my surprise I see something like this: // TEMPLATE CLASS numeric_limits template<class _Ty> class numeric_limits : public _Num_base { // numeric limits for arbitrary type _Ty (say little or nothing) public: static _Ty (__CRTDECL min)() _THROW0() { // return minimum value return (_Ty(0)); } static _Ty (__CRTDECL max)() _THROW0() { // return maximum value return (_Ty(0));//EXACTLY THE SAME WHAT IN min<<------------------ } //... other stuff }; so how is it possiple that in both min and max return does exactly the same? So does it mean if I would write makeSanwich() return (_Ty(0)) it would make a sandwich for me? How is it possible that having this same code just fnc names different we are getting different results?

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  • Where Should Using Statements Be Located [closed]

    - by Bobby Ortiz - DotNetBob
    Possible Duplicate: What is the difference between these two declarations? I recently started working on a project with using statement located inside the NameSpace block. namespace MyApp.Web { using System; using System.Web.Security; using System.Web; public class MyClass { I usually put my using statements above the namespace block. using System; using System.Web.Security; using System.Web; namespace MyApp.Web { public class MyClass { I don't think it matters, but I am currious if someone else had a recommendation and could they explain why one way is better than another. Note: I always have one class per file.

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  • Are `return` and `break` useless inside a Ruby block when used as a callback?

    - by Skilldrick
    In Rails, blocks can be used as callbacks, e.g.: class User < ActiveRecord::Base validates_presence_of :login, :email before_create {|user| user.name = user.login.capitalize if user.name.blank?} end When a block is used like this, is there any use for break and return? I'm asking because normally in a block, break will break out of the loop, and return will return from the enclosing method. But in a callback context, I can't get my head round what that means. The Ruby Programming Language suggests that return could cause a LocalJumpError but I haven't been able to reproduce this in a Rails callback. Edit: with the following code I'd expect a LocalJumpError, but all the return does is stop the rest of the callback executing. class User < ActiveRecord::Base validates_presence_of :login, :email before_create do |user| return user.name = user.login.capitalize end

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  • Programming to interfaces while mapping with Fluent NHibernate.

    - by Lucious
    Fluent Mapping I Have the following scenario public class CustomerMap : ClassMap { public CustomerMap() { Table("Customer"); Id(c = c.Id); Map(c = c.Name); HasMany(c = c.Orders); } } public class OrderMap : ClassMap<IOrder> { public OrderMap() { Table("Orders"); References(o => o.Customer).Access.; Id(o => o.Id); Map(o => o.DateCreated); } } Problems When schema exported the order table has two columns ICustomer_Id,Customer_Id. refers to an unmapped class Order exception Can you please help me out?

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  • Are static members inherited? (C++)

    - by Keand64
    When static members are inherited, are they static for the entire heirarchy, or just that class, ie: class SomeClass { public: SomeClass(){total++;} static int total; }; class SomeDerivedClass: public SomeClass { public: SomeDerivedClass(){total++;} }; int main() { SomeClass A; SomeClass B; SomeDerivedClass C; return 0; } would total be 3 in all three instances, or would it be 2 for SomeClass and 1 for SomeDerivedClass?

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  • does anyone see any issues with this thread pattern?

    - by prmatta
    Here is a simple thread pattern that I use when writing a class that needs just one thread, and needs to a specific task. The usual requirements for such a class are that it should be startable, stopable and restartable. Does anyone see any issues with this pattern that I use? public class MyThread implements Runnable { private boolean _exit = false; private Thread _thread = null; public void start () { if (_thread == null) { _thread = new Thread(this, "MyThread"); _thread.start(); } } public void run () { while (_exit) { //do something } } public void stop () { _exit = true; if (_thread != null) { _thread.interrupt(); _thread = null; } } } I am looking for comments around if I am missing something, or if there is a better way to write this.

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  • Cannot call struct properties from HAML file

    - by Lander
    I have the following code in my controller: @nav_items = ActiveSupport::OrderedHash.new @nav_items[:home] = Struct::NavItem.new("Home", nil, "/", "icon-home") @nav_items[:about] = Struct::NavItem.new("About", nil, "/about", "icon-heart") @nav_items[:contact] = Struct::NavItem.new("Contact", nil, "/contact", "icon-envelope") if (current_user != nil && current_user.admin?) @nav_items[:admin_divider] = Struct::NavItem.new(nil, "divider-vertical", nil, nil) @nav_items[:admin] = Struct::NavItem.new("Admin", nil, "/admin", "") end And the following in my view: - @nav_items.each do |nav_item| %li{ :class => nav_item[:class] } %a{ :href => nav_item[:link] }= nav_item[:text] And my struct definition: Struct.new("NavItem", :text, :class, :link, :icon_class) I'm relatively new to Ruby, Rails, and HAML, but in another project using ERB rendering, code like that worked fine. I've tried referencing properties by doing something like nav_item.link as well, but that still does not work. The error I get with my current code is: Symbol as array index By using code like nav_item.link: undefined method `link' for #< Array:0x126970ff0 As this is my first time using HAML, I'm not too sure what I'm doing wrong.

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  • 'Caching' a large table in ASP.NET

    - by TheNewGuy
    I understand that each page refresh, especially in 'AjaxLand', causes my back-end/code-behind class to be called from scratch... This is a problem because my class (which is a member object in System.Web.UI.Page) contains A LOT of data that it sources from a database. So now every page refresh in AjaxLand is causing me to making large backend DB calls, rather than just to reuse a class object from memory. Any fix for this? Is this where session variables come into play? Are session variables the only option I have to retain an object in memory that is linked to a single-user and a single-session instance?

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  • Objective C - Custom Getter with inheritance

    - by anhdat
    Recently I have worked with Core Data. When I want to set a default value for some fields, I came up with this problem: So I made a simple represent: We have 2 class Parent and Child, in which Child inherit from Parent. // Parent.h @interface Parent : NSObject @property (strong, nonatomic) NSString *lastName; // Child.h @interface Child : Parent In Parent class, I made a custom getter to set a default value when nothing is set: // Parent.h - (NSString *)lastName { if (_lastName) { return _lastName; } else { return @"Parent Default Name"; } } But I cannot make a custom default value for the field "name" which Child inherits from its Parent. // Child.h @implementation Child - (NSString *)lastname { if (super.lastName) { return super.lastName; } else { return @"Child Default Name"; } } Apparently, this method is never called. So my question here is: How can I set a custom getter for the field the Child class inherits from Parent without define an overriding property?

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  • Rails - using :include to find objects based on their child's attributes

    - by adam
    I have a sentence and correction model class Sentence < ActiveRecord::Base has_one :correction class Correction < ActiveRecord::Base belongs_to :sentence and I'm trying find all sentences which don't have a correction. To do this I'm simply looking for corrections which don't exist i.e. whose id = nil. But it is failing and i can't figure out why Sentence.find :all, :include => :correction, :conditions => {:correction => {:id => nil}} Perhaps its the syntax or maybe just the overall approach. Can anyone help?

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  • New records added to DataGridView aren't displayed

    - by Ross
    I have a custom Order class, groups of which are stored in List<Order> and a DataGridView. I think the problem is in my implementation so here's how I'm using it: In the form enclosing DataGridView (as OrdersDataGrid): public partial class MainForm : Form { public static List<Order> Orders; public MainForm() { // code to populate Orders with values, otherwise sets Orders to new List<Order>(); OrdersDataGrid.DataSource = Orders; } Then in another form that adds an Order: // Save event public void Save(object sender, EventArgs e) { Order order = BuildOrder(); // method that constructs an order object from form data MainForm.Orders.Add(order); } From what I can tell from the console this is added successfully. I thought the DataGrid would be updated automatically after this since Orders has changed - is there something I'm missing? The DataGrid accepts the class since it generates columns from the members.

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  • Passing User Data with SetTimer

    - by GJ
    I am calling SetTimer in a function of a Class. SetTimer(NULL, 0, 10000, (TIMERPROC) TimerCallBack); Where TimerCallBack is: static VOID CALLBACK TimerCallBack(HWND, UINT, UINT, DWORD) Now my need is to call one of the method of class which initiated timer, since TimerCallBack is static it has no access to the class object anymore. I cant find any way to pass object pointer along with the SetTimer so that I can receive it back on Callback function. Is there any other way to achieve this, if its not supported using SetTimer then which other way I can implement this.

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  • Why are Objective-C instance variables declared in an interface?

    - by Chase
    I'm just getting into Objective-C (Java is my primary OO language). Defining an object's instance variables in the interface instead of the class seems strange. I'm used to an interface being a public API definition with nothing besides method signatures (not counting constants here). Is there some reason that state is defined in an interface (even if it is private) and behaviour is defined in a class. It just seems odd that since objects are state+behavior that the definition would be split into two separate places. Is it a design benefit is some way? A pain in the rear issue that you are just forced to deal with in Objective-C? A non-issue, just different? Any background on why it's done this way? Or can you put object state in a class and I just haven't hit that part in my book yet?

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  • How to instantiate objects of classes that have dependencies injected?

    - by chester89
    Let's say I have some class with dependency injected: public class SomeBusinessCaller { ILogger logger; public SomeBusinessCaller(ILogger logger) { this.logger = logger; } } My question is, how do I instantiate an object of that class? Let's say I have an implementation for this, called AppLogger. After I say ObjectFactory.For<ILogger>().Use<AppLogger>(); how do I call constructor of SomeBusinessCaller? Am I calling SomeBusinessCaller caller = ObjectFactory.GetInstance<SomeBusinessCaller>(); or there is a different strategy for that?

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  • app engine's back referencing is too slow. How can I make it faster?

    - by Ray Yun
    Google app engine has smart feature named back references and I usually iterate them where the traditional SQL's computed column need to be used. Just imagine that need to accumulate specific force's total hp. class Force(db.Model): hp = db.IntegerProperty() class UnitGroup(db.Model): force = db.ReferenceProperty(reference_class=Force,collection_name="groups") hp = db.IntegerProperty() class Unit(db.Model): group = db.ReferenceProperty(reference_class=UnitGroup,collection_name="units") hp = db.IntegerProperty() When I code like following, it was horribly slow (almost 3s) with 20 forces with single group - single unit. (I guess back-referencing force reload sub entities. Am I right?) def get_hp(self): hp = 0 for group in self.groups: group_hp = 0 for unit in group.units: group_hp += unit.hp hp += group_hp return hp How can I optimize this code? Please consider that there are more properties should be computed for each force/unit-groups and I don't want to save these collective properties to each entities. :)

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  • Global Import/using Aliasing in .NET

    - by Josh Stodola
    Using import aliasing in a single class, we can reference class library namespaces by assigning our own custom alias like this: ' VB Imports Db = Company.Lib.Data.Objects // C# using Db = Company.Lib.Data.Objects; And then we are able to reference the classes inside of Company.Lib.Data.Objects by using the Db alias that we assigned. Is it possible to do this at the global level so that the alias is applied to the entire solution instead of the given file? Currently, we are working with web applications, so I was hoping we could add something to web.config, but I am also interested in whether or not this is possible with windows forms, console apps, and/or class libraries.

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  • Parsing data without HMLT tags

    - by user296507
    Hi, I need to extract the actual phone number form the html listed below, but I'm not really sure how to do it using Nokogiri CSS since there are no html tags around it. When an at_css(.phonetitle) it only parse Phone and not the number. <div class="detail"> <span class="address">Corner of Toorak Road and Chapel Street, South Yarra</span><br> <span class="phonetitle">Phone</span> 95435 34341 <br><br> </div>

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  • C++ enforce conditions on inherited classes

    - by user231536
    I would like to define an abstract base class X and enforce the following: a) every concrete class Y that inherits from X define a constructor Y(int x) b) it should be possible to test whether two Y objects are equal. For a, one not very good solution is to put a pure virtual fromInt method in X which concrete class will have to define. But I cannot enforce construction. For b), I cannot seem to use a pure virtual method in X bool operator == (const X& other) const =0; because in overridden classes this remains undefined. It is not enough to define bool operator == (const Y& other) const { //stuff} because the types don't match. How do I solve these problems?

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  • Another thread safe queue implementation

    - by jensph
    I have a class, Queue, that I tried to make thread safe. It has these three member variables: std::queue<T> m_queue; pthread_mutex_t m_mutex; pthread_cond_t m_condition; and a push and pop implemented as: template<class T> void Queue<T>::push(T value) { pthread_mutex_lock( &m_mutex ); m_queue.push(value); if( !m_queue.empty() ) { pthread_cond_signal( &m_condition ); } pthread_mutex_unlock( &m_mutex ); } template<class T> bool Queue<T>::pop(T& value, bool block) { bool rtn = false; pthread_mutex_lock( &m_mutex ); if( block ) { while( m_queue.empty() ) { pthread_cond_wait( &m_condition, &m_mutex ); } } if( !m_queue.empty() ) { value = m_queue.front(); m_queue.pop(); rtn = true; } pthread_mutex_unlock( &m_mutex ); return rtn; } Unfortunately there are occasional issues that may be the fault of this code. That is, there are two threads and sometimes thread 1 never comes out of push() and at other times thread 2 never comes out of pop() (the block parameter is true) though the queue isn't empty. I understand there are other implementations available, but I'd like to try to fix this code, if needed. Anyone see any issues? The constructor has the appropriate initializations: Queue() { pthread_mutex_init( &mMutex, NULL ); pthread_cond_init( &mCondition, NULL ); } and the destructor, the corresponding 'destroy' calls.

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  • SQLiteOpenHelper problem

    - by Harsha M V
    I have created SQLiteOpenHelper class to help me open write the database. but i am not able to invoke it from the main.java activity I have created an Class which extends the Database Helper which is stored at /Messaging/src/com/v3/messaging/DatabaseHelper.java Code: http://pastebin.com/Z5qp32xu now i have this class called Main.java which will be the first activity on the launch of the application. But how can i make the DatabaseHelper.java run just to create the database but still be at the Main.java file. The database should be created with the tables only when the db or the tables dont exist. Main.java code: http://pastebin.com/LVFVuhA0 Now when i run the program. the database is not being created :( I am trying to learn Android. So please excuse me if i forgot to tell something.

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  • Why can't I enforce derived classes to have parameterless constructors?

    - by FrisbeeBen
    I am trying to do the following: public class foo<T> where T : bar, new() { public foo() { _t = new T(); } private T _t; } public abstract class bar { public abstract void someMethod(); // Some implementation } public class baz : bar { public overide someMethod(){//Implementation} } And I am attempting to use it as follows: foo<baz> fooObject = new foo<baz>(); And I get an error explaining that 'T' must be a non-abstract type with a public parameterless constructor in order to use it as parameter 'T' in the generic type or method. I fully understand why this must be, and also understand that I could pass a pre-initialized object of type 'T' in as a constructor argument to avoid having to 'new' it, but is there any way around this? any way to enforce classes that derive from 'bar' to supply parameterless constructors?

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  • What is the definition of a Service object ?

    - by Maskime
    I've been working a lot with PHP. But recently i was sent on a work wich use Java. In PHP i used to do a lot of Singleton object but this pattern has not the same signification in Java that it has in PHP. So i wanted to go for an utility class (a class with static method) but my chief doesn't like this kind of classes and ask me to go for services object. So my guess was that a service object is just a class with a constructor that implement some public methods... Am i right ?

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  • Force result for empty() test on an object

    - by hsz
    Hello ! Simple class for example: class Foo { protected $_bar; public function setBar( $value ) { $this->_bar = $value; } } And here is the question: $obj = new Foo(); var_dump( empty( $obj ) ); // true $obj->setBar( 'foobar' ); var_dump( empty( $obj ) ); // false Is it possible to change class's behaviour with testing it with empty() function so it will returns true when object is not filled with data ? I know about magic function __isset( $name ) but it is called only when we test specific field like: empty( $obj->someField ); but not when test whole object.

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  • Filtering SQLAlchemy query on attribute_mapped_collection field of relationship

    - by bsa
    I have two classes, Tag and Hardware, defined with a simple parent-child relationship (see the full definition at the end). Now I want to filter a query on Tag using the version field in Hardware through an attribute_mapped_collection, eg: def get_tags(order_code=None, hardware_filters=None): session = Session() query = session.query(Tag) if order_code: query = query.filter(Tag.order_code == order_code) if hardware_filters: for k, v in hardware_filters.iteritems(): query = query.filter(getattr(Tag.hardware, k).version == v) return query.all() But I get: AttributeError: Neither 'InstrumentedAttribute' object nor 'Comparator' object associated with Tag.hardware has an attribute 'baseband The same thing happens if I strip it back by hard-coding the attribute, eg: query.filter(Tag.hardware.baseband.version == v) I can do it this way: query = query.filter(Tag.hardware.any(artefact=k, version=v)) But why can't I filter directly through the attribute? Class definitions class Tag(Base): __tablename__ = 'tag' tag_id = Column(Integer, primary_key=True) order_code = Column(String, nullable=False) version = Column(String, nullable=False) status = Column(String, nullable=False) comments = Column(String) hardware = relationship( "Hardware", backref="tag", collection_class=attribute_mapped_collection('artefact'), ) __table_args__ = ( UniqueConstraint('order_code', 'version'), ) class Hardware(Base): __tablename__ = 'hardware' hardware_id = Column(Integer, primary_key=True) tag_id = Column(String, ForeignKey('tag.tag_id')) product_id = Column(String, nullable=True) artefact = Column(String, nullable=False) version = Column(String, nullable=False)

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