Search Results

Search found 4593 results on 184 pages for 'constructor injection'.

Page 54/184 | < Previous Page | 50 51 52 53 54 55 56 57 58 59 60 61  | Next Page >

  • Reduce Repetitive Initialization Code in C++ Applications by Using Delegating Constructors

    You're often required to repeat identical pieces of initialization code in every constructor of a class that declares multiple constructors. That's because unlike a few other programming languages, The C++ programming language doesn't allow a constructor to call another constructor of the same class. Luckily, this problem is about to disappear with the recent approval of a new C++0x feature called delegating constructors which are explained in this C++ tutorial.

    Read the article

  • I am using a constructor for my array but why is it saying i need a return type?

    - by JB
    using System; using System.IO; using System.Data; using System.Text; using System.Drawing; using System.Data.OleDb; using System.Collections; using System.ComponentModel; using System.Windows.Forms; using System.Drawing.Printing; using System.Collections.Generic; namespace Eagle_Eye_Class_Finder { public class GetSchedule { public class IDnumber { public string Name { get; set; } public string ID { get; set; } public string year { get; set; } public string class1 { get; set; } public string class2 { get; set; } public string class3 { get; set; } public string class4 { get; set; } IDnumber[] IDnumbers = new IDnumber[3]; public GetSchedule() //here i get an error saying method must have a return type??? { IDnumbers[0] = new IDnumber() { Name = "Joshua Banks",ID = "900456317", year = "Senior", class1 = "TEET 4090", class2 = "TEET 3020", class3 = "TEET 3090", class4 = "TEET 4290" }; IDnumbers[1] = new IDnumber() { Name = "Sean Ward", ID = "900456318", year = "Junior", class1 = "ENGNR 4090", class2 = "ENGNR 3020", class3 = "ENGNR 3090", class4 = "ENGNR 4290" }; IDnumbers[2] = new IDnumber() { Name = "Terrell Johnson",ID = "900456319",year = "Sophomore", class1 = "BUS 4090", class2 = "BUS 3020", class3 = "BUS 3090", class4 = "BUS 4290" }; } static void ProcessNumber(IDnumber myNum) { StringBuilder myData = new StringBuilder(); myData.AppendLine(IDnumber.Name); myData.AppendLine(": "); myData.AppendLine(IDnumber.ID); myData.AppendLine(IDnumber.year); myData.AppendLine(IDnumber.class1); myData.AppendLine(IDnumber.class2); myData.AppendLine(IDnumber.class3); myData.AppendLine(IDnumber.class4); MessageBox.Show(myData); } public string GetDataFromNumber(string ID) { foreach (IDnumber idCandidateMatch in IDnumbers) { if (IDCandidateMatch.ID == ID) { StringBuilder myData = new StringBuilder(); myData.AppendLine(IDnumber.Name); myData.AppendLine(": "); myData.AppendLine(IDnumber.ID); myData.AppendLine(IDnumber.year); myData.AppendLine(IDnumber.class1); myData.AppendLine(IDnumber.class2); myData.AppendLine(IDnumber.class3); myData.AppendLine(IDnumber.class4); return myData; } } return ""; } } } }

    Read the article

  • How to setup the c++ rule of three in a virtual base class

    - by Minion91
    I am trying to create a pure virtual base class (or simulated pure virtual) my goal: User can't create instances of BaseClass. Derived classes have to implement default constructor, copy constructor, copy assignment operator and destructor. My attempt: class Base { public: virtual ~Base() {}; /* some pure virtual functions */ private: Base() = default; Base(const Base& base) = default; Base& operator=(const Base& base) = default; } This gives some errors complaining that (for one) the copy constructor is private. But i don't want this mimicked constructor to be called. Can anyone give me the correct construction to do this if this is at all possible?

    Read the article

  • Examples of bad variable names and reasons [on hold]

    - by user470184
    I'll start with a class in the jdk package : public final class Sdp { should be : public final class SocketsDirectProtocol { Sdp is class name, this is ambigious, should be : Class<?> cl = Class.forName("java.net.SdpSocketImpl", true, null); should be : Class<?> clazz = Class.forName("java.net.SdpSocketImpl", true, null); cl is ambiguous private static void setAccessible(final AccessibleObject o) { should be : private static void setAccessible(final AccessibleObject accessibleObject) { There are various other examples in this class, do you have similar and/or differing examples of variables that were named badly ? package com.oracle.net; public final class Sdp { private Sdp() { } /** * The package-privage ServerSocket(SocketImpl) constructor */ private static final Constructor<ServerSocket> serverSocketCtor; static { try { serverSocketCtor = (Constructor<ServerSocket>) ServerSocket.class.getDeclaredConstructor(SocketImpl.class); setAccessible(serverSocketCtor); } catch (NoSuchMethodException e) { throw new AssertionError(e); } } /** * The package-private SdpSocketImpl() constructor */ private static final Constructor<SocketImpl> socketImplCtor; static { try { Class<?> cl = Class.forName("java.net.SdpSocketImpl", true, null); socketImplCtor = (Constructor<SocketImpl>)cl.getDeclaredConstructor(); setAccessible(socketImplCtor); } catch (ClassNotFoundException e) { throw new AssertionError(e); } catch (NoSuchMethodException e) { throw new AssertionError(e); } } private static void setAccessible(final AccessibleObject o) { AccessController.doPrivileged(new PrivilegedAction<Void>() { public Void run() { o.setAccessible(true); return null; } }); } /** * SDP enabled Socket. */ private static class SdpSocket extends Socket { SdpSocket(SocketImpl impl) throws SocketException { super(impl); } } /** * Creates a SDP enabled SocketImpl */ private static SocketImpl createSocketImpl() { try { return socketImplCtor.newInstance(); } catch (InstantiationException x) { throw new AssertionError(x); } catch (IllegalAccessException x) { throw new AssertionError(x); } catch (InvocationTargetException x) { throw new AssertionError(x); } } /** * Creates an unconnected and unbound SDP socket. The {@code Socket} is * associated with a {@link java.net.SocketImpl} of the system-default type. * * @return a new Socket * * @throws UnsupportedOperationException * If SDP is not supported * @throws IOException * If an I/O error occurs */ public static Socket openSocket() throws IOException { SocketImpl impl = createSocketImpl(); return new SdpSocket(impl); } /** * Creates an unbound SDP server socket. The {@code ServerSocket} is * associated with a {@link java.net.SocketImpl} of the system-default type. * * @return a new ServerSocket * * @throws UnsupportedOperationException * If SDP is not supported * @throws IOException * If an I/O error occurs */ public static ServerSocket openServerSocket() throws IOException { // create ServerSocket via package-private constructor SocketImpl impl = createSocketImpl(); try { return serverSocketCtor.newInstance(impl); } catch (IllegalAccessException x) { throw new AssertionError(x); } catch (InstantiationException x) { throw new AssertionError(x); } catch (InvocationTargetException x) { Throwable cause = x.getCause(); if (cause instanceof IOException) throw (IOException)cause; if (cause instanceof RuntimeException) throw (RuntimeException)cause; throw new RuntimeException(x); } } /** * Opens a socket channel to a SDP socket. * * <p> The channel will be associated with the system-wide default * {@link java.nio.channels.spi.SelectorProvider SelectorProvider}. * * @return a new SocketChannel * * @throws UnsupportedOperationException * If SDP is not supported or not supported by the default selector * provider * @throws IOException * If an I/O error occurs. */ public static SocketChannel openSocketChannel() throws IOException { FileDescriptor fd = SdpSupport.createSocket(); return sun.nio.ch.Secrets.newSocketChannel(fd); } /** * Opens a socket channel to a SDP socket. * * <p> The channel will be associated with the system-wide default * {@link java.nio.channels.spi.SelectorProvider SelectorProvider}. * * @return a new ServerSocketChannel * * @throws UnsupportedOperationException * If SDP is not supported or not supported by the default selector * provider * @throws IOException * If an I/O error occurs */ public static ServerSocketChannel openServerSocketChannel() throws IOException { FileDescriptor fd = SdpSupport.createSocket(); return sun.nio.ch.Secrets.newServerSocketChannel(fd); } }

    Read the article

  • C++ - what does the colon after a constructor mean?

    - by waitinforatrain
    I'd happily Google this but don't know what to call it to Google it. I have a piece of code here: class demo { private: unsigned char len, *dat; public: demo(unsigned char le = 5, unsigned char default) : len(le) { dat = new char[len]; for (int i = 0; i <= le; i++) dat[i] = default; } void ~demo(void) { delete [] *dat; } }; class newdemo : public demo { private: int *dat1; public: newdemo(void) : demo(0, 0) { *dat1 = 0; return 0; } }; (It's from a past exam paper and the question is to correct errors in the code so ignore errors!) My question is, what are the ": len(le) " and " : demo(0, 0)" called? Something to do with inheritance?

    Read the article

  • Inherit all methods of object (including "constructor"), but modify some of them.

    - by Kirzilla
    Hello, Let's imagine that we have object Animal $.Animal = function(options) { this.defaults = { name : null } this.options = $.extend(this.defaults, options); } $.Animal.prototype.saySomething = function() { alert("I'm animal!"); } Now I'd like to create Cat object. It is absolutely similar to $.Annimal, but method saySomething() will look like this one... $.Cat.prototype.saySomething = function() { alert("I'm cat!"); } How can I inherit from Animal to create new object Cat and redefine saySomething() method? Thank you.

    Read the article

  • How to call constructor of the current class and parent class at the same time?

    - by Siegfried
    public class A{ public A(int a, int b) {...} } public class B : A{ List a; List b; public B(){...} //constructor1 public B(int a, int b) : base(a,b){...} //constructor2 } My question is I need to initialize both list a and b in class B. If I put them in the constructor1, how can I call constructor1 in constructor2? I don't want to rewrite the initialization statements in constructor2 again. Thanks!

    Read the article

  • C# Virtual method call in constructor - how to refactor?

    - by Cristi Diaconescu
    I have an abstract class for database-agnostic cursor actions. Derived from that, there are classes that implement the abstract methods for handling database-specific stuff. The problem is, the base class ctor needs to call an abstract method - when the ctor is called, it needs to initialize the database-specific cursor. I know why this shouldn't be done, I don't need that explanation! This is my first implementation, that obviously doesn't work - it's the textbook "wrong way" of doing it. The overridden method accesses a field from the derived class, which is not yet instantiated: public abstract class CursorReader { private readonly int m_rowCount; protected CursorReader() { m_rowCount = CreateCursor(sqlCmd); //virtual call ! } protected abstract int CreateCursor(string sqlCmd); } public class SqlCursorReader : CursorReader { private SqlConnection m_sqlConnection; public SqlCursorReader(string sqlCmd, SqlConnection sqlConnection) { m_sqlConnection = sqlConnection; //field initialized here } protected override int CreateCursor(string sqlCmd) { //uses not-yet-initialized member *m_sqlConnection* //so this throws a NullReferenceException var cursor = new CustomCursor(sqlCmd, m_sqlConnection); return cursor.Count(); } } I will follow up with an answer on my attempts to fix this...

    Read the article

  • What happens if a bean attempts to load the Spring application context in its constructor?

    - by Derek Mahar
    Given the following Spring application context and class A, what happens when you run class A? applicationContext.xml (in classpath): <?xml version="1.0" encoding="UTF-8"?> <beans xmlns="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-2.5.xsd"> <bean name="a" class="A"/> </beans> A.java: class A { private ApplicationContext applicationContext = new ClassPathXmlApplicationContext("applicationContext.xml"); public static void main(String[] args) { A a = new A(); } }

    Read the article

  • How to expose a constructor variable(sic!) as read-only?

    - by Malax
    Hi StackOverflow! I have this rather simple question about Scala. Given that i have to following class definition: class Foo(var bar: Int) The code which is able to construct an instance of Foo must be able to pass the initial value for bar. But if I define bar as var the User is also able to change its value at runtime which is not what I want. The User should only be able to read bar. bar itself is modified internally so a val is not an option. I think I might be getting an answer very soon as this question is so simple. :-) Cheers, Malax

    Read the article

  • Is is possible to intercept a constructor on a class you do not own?

    - by code poet
    Referring to my possible answer to this question: http://stackoverflow.com/questions/2907535/how-would-you-audit-asp-net-membership-tables-while-recording-what-user-made-the/2911616#2911616 Is it possible to intercept a call, coming from code you do not own, to a ctor on a sealed internal class that you do not own with the intention of manipulating the object before returning? Concrete example: SqlMembershipProvider, for all of it's data access, instantiates a connection helper class, System.Web.DataAccess.SqlConnectionHolder. The desired result is to intercept this instantiation and perform an operation on the public connection that is opened in the ctor of System.Web.DataAccess.SqlConnectionHolder before letting execution continue. Is this possible. If so, an brief example would be appreciated.

    Read the article

  • How to ensure that a member variable is initialized before calling a class method

    - by Omkar Ekbote
    There's a class with a parametrized constructor that initializes a member variable. All public methods of the class then use this member variable to do something. I want to ensure that the caller always creates an object using the parametrized constructor (there is also a setter for this member variable) and then call that object's methods. In essence, it should be impossible for the caller to call any method without setting a value to the member variable (either by using the parametrized constructor or the setter). Currently, a caller can simply make an object using the default constructor and then call that object's method - I want to avoid checking whether or not the member variable is set in each and every one of the 20-odd methods of the class (and throw an exception if it is not). Though a runtime solution is acceptable (better than the one I mentioned above); a compile-time solution is preferable so that any developer will not be allowed to make that mistake and then waste hours debuggging it!

    Read the article

  • Problem with number/type of arguments passed to an overloaded c++ constructor wrapped with swig.

    - by MiKo
    I am trying to wrap a c++ class (let's call it "Spam") written by someone else with swig to expose it to Python. After solving several problems, I am able to import the module in python, but when I try to create an object of such class I obtain the following error: foo = Spam.Spam('abc',3) Traceback (most recent call last): File "<stdin>", line 1, in <module> File "Spam.py", line 96, in __init__ this = _Spam.new_Spam(*args) NotImplementedError: Wrong number of arguments for overloaded function 'new_Spam'. Possible C/C++ prototypes are: Spam(unsigned char *,unsigned long,bool,unsigned int,SSTree::io_action,char const *) Spam(unsigned char *,unsigned long,bool,unsigned int,SSTree::io_action) Spam(unsigned char *,unsigned long,bool,unsigned int) Spam(unsigned char *,unsigned long,bool) Spam(unsigned char *,unsigned long) Googling around, I realized that the error is probably caused by the type of the arguments and not by the number (which is quite confusing), but I still cannot identify. I suspect the problem lies in passing a string as the first argument, but have no idea on how to fix it (keep in mind that I know almost no c/c++).

    Read the article

  • How can one enforce calling a base class function after derived class constructor?

    - by Mike Elkins
    I'm looking for a clean C++ idiom for the following situation: class SomeLibraryClass { public: SomeLibraryClass() { /* start initialization */ } void addFoo() { /* we are a collection of foos */ } void funcToCallAfterAllAddFoos() { /* Making sure this is called is the issue */ } }; class SomeUserClass : public SomeLibraryClass { public: SomeUserClass() { addFoo(); addFoo(); addFoo(); // SomeUserClass has three foos. } }; class SomeUserDerrivedClass : public SomeUserClass { public: SomeUserDerrivedClass() { addFoo(); // This one has four foos. } }; So, what I really want is for SomeLibraryClass to enforce the calling of funcToCallAfterAllAddFoos at the end of the construction process. The user can't put it at the end of SomeUserClass::SomeUserClass(), that would mess up SomeUserDerrivedClass. If he puts it at the end of SomeUserDerrivedClass, then it never gets called for SomeUserClass. To further clarify what I need, imagine that /* start initialization */ acquires a lock, and funcToCallAfterAllAddFoos() releases a lock. The compiler knows when all the initializations for an object are done, but can I get at that information by some nice trick?

    Read the article

  • How to overwrite a convenience constructor the proper way?

    - by mystify
    For example I want to overwrite from UIButton: + (id)buttonWithType:(UIButtonType)buttonType So I would do: + (id)buttonWithType:(UIButtonType)buttonType { UIButton *button = [UIButton buttonWithType:buttonType]; if (button != nil) { // do own config stuff ... } return button; } is that the right way? Or did I miss something? (yeah, I have been overwriting thousands of instance methods, but never class methods ;) )

    Read the article

  • C++ Pass a hidden arg to a class constructor?

    - by JP
    I would like to define a class that accept the pointer to it's parent class as an Argument, but would it be possible to somehow pass it without needing to pass it directly such as: class Child { public: Child(Parent* hiddenArg); }; class Parent { public: Child myChild; }; I know this is weird, but I am making my own Signal/Slot implementation and Child would be a signal defined, but I would like to get the parent so I can use it's Event Dispatcher...

    Read the article

  • Why "constructor-way" of declaring variable in "for-loop" allowed but in "if-statement" not allowed?

    - by PiotrNycz
    Consider this simple example: /*1*/ int main() { /*2*/ for (int i(7); i;){break;} /*3*/ if (int i(7)) {} /*4*/ } Why line-2 compiles just fine, whilst line-3 gives the error? This is little strange to me why if-statement is in this aspect treated worse than for-loop? If this is compiler specific - I tested with gcc-4.5.1: prog.cpp: In function 'int main()': prog.cpp:3:7: error: expected primary-expression before 'int' prog.cpp:3:7: error: expected ')' before 'int' I was inspired by this question [UPDATE] I know this compiles just fine: /*1*/ int main() { /*2*/ for (int i = 7; i;){break;} /*3*/ if (int i = 7) {} /*4*/ }

    Read the article

  • Spring security custom ldap authentication provider

    - by wuntee
    I currently have my ldap authentication context set up like this: <ldap-server url="ldap://host/dn" manager-dn="cn=someuser" manager-password="somepass" /> <authentication-manager> <ldap-authentication-provider user-search-filter="(samaccountname={0})"/> </authentication-manager> Now, I need to be able to set up a custom authorities mapper (it uses a different ldap server) - so I am assuming I need to set up my ldap-server similar to (http://static.springsource.org/spring-security/site/docs/2.0.x/reference/ldap.html): <bean id="ldapAuthProvider" class="org.springframework.security.providers.ldap.LdapAuthenticationProvider"> <constructor-arg> <bean class="org.springframework.security.providers.ldap.authenticator.BindAuthenticator"> <constructor-arg ref="contextSource"/> <property name="userDnPatterns"> <list><value>uid={0},ou=people</value></list> </property> </bean> </constructor-arg> <constructor-arg> <bean class="org.springframework.security.ldap.populator.DefaultLdapAuthoritiesPopulator"> <constructor-arg ref="contextSource"/> <constructor-arg value="ou=groups"/> <property name="groupRoleAttribute" value="ou"/> </bean> </constructor-arg> </bean> But, how do I reference that 'ldapAuthProvider' to the ldap-server in the security context? I am also using spring-security 3, so '' does not exist...

    Read the article

  • Can an interface define the signature of a c#-class

    - by happyclicker
    I have a .net-app that provides a mechanism to extend the app with plugins. Each plugin must implement a plugin-interface and must provide furthermore a constructor that receives one parameter (a resource context). During the instantiation of the plugin-class I look via reflection, if the needed constructor exists and if yes, I instantiate the class (via Reflection). If the constructor does not exists, I throw an exception that says that the plugin not could be created, because the desired constructor is not available. My question is, if there is a way to declare the signature of a constructor in the plugin-interface so that everyone that implements the plugin-interface must also provide a constructor with the desired signature. This would ease the creation of plugins. I don’t think that such a possibility exists because I think such a feature falls not in the main purpose for what interfaces were designed for but perhaps someone knows a statement that does this, something like: public interface IPlugin { ctor(IResourceContext resourceContext); int AnotherPluginFunction(); } I want to add that I don't want to change the constructor to be parameterless and then set the resource-context through a property, because this will make the creation of plugins much more complicated. The persons that write plugins are not persons with deep programming experience. The plugins are used to calculate statistical data that will be visualized by the app.

    Read the article

< Previous Page | 50 51 52 53 54 55 56 57 58 59 60 61  | Next Page >