Search Results

Search found 22623 results on 905 pages for 'base address'.

Page 140/905 | < Previous Page | 136 137 138 139 140 141 142 143 144 145 146 147  | Next Page >

  • (this == null) in C#!

    - by SLaks
    Due to a bug that was fixed in C# 4, the following program prints true. (Try it in LINQPad) void Main() { new Derived(); } class Base { public Base(Func<string> valueMaker) { Console.WriteLine(valueMaker()); } } class Derived : Base { string CheckNull() { return "Am I null? " + (this == null); } public Derived() : base(() => CheckNull()) { } } In VS2008 in Release mode, in throws an InvalidProgramException. (In Debug mode, it works fine) In VS2010 Beta 2, it doesn't compile (I didn't try Beta 1); I learned that the hard way Is there any other way to make this == null in pure C#?

    Read the article

  • Rails: url_for to be available in a isolated class that must be instanced

    - by Totty
    Rails: url_for to be available in a isolated class that must be instanced: class ProfilePresenter < ActionController::Base attr_reader :profile def initialize(profile) super @a = url_for(:controller => 'profiles', :action => 'view', :profile_url => 'dd') @a @profile = profile end end How to make the url_for work? i tried to extend the ActionController::Base and the ActionView::Base and i cant :s

    Read the article

  • Behavior of virtual function in C++

    - by Summer_More_More_Tea
    Hi everyone: I have a question, here are two class below: class Base{ public: virtual void toString(); // generic implementation } class Derive : public Base{ public: ( virtual ) void toString(); // specific implementation } The question is: If I wanna subclass of class Derive perform polymophism using a pointer of type Base, is keyword virtual in the bracket necessary? If the answer is no, what's the difference between member function toString of class Derive with and without virtual?

    Read the article

  • linq to xml enumerating over descendants

    - by gh9
    Hi trying to write a simple linq query from a tutorial I read. But i cannot seem to get it to work. I am trying to display both the address in the attached xml document, but can only display the first one. Can someone help me figure out why both aren't being printed. Thank you very much <?xml version="1.0" encoding="utf-8" ?> <Emails> <Email group="FooBar"> <Subject>Test subject</Subject> <Content>Test Content</Content> <EmailTo> <Address>[email protected]</Address> <Address>[email protected]</Address> </EmailTo> </Email> </Emails> Dim steve = (From email In emailList.Descendants("Email") _ Where (email.Attribute("group").Value.Equals("FooBar")) _ Select content = email.Element("EmailTo").Descendants("Address")).ToList() If Not steve Is Nothing Then For Each addr In steve Console.WriteLine(addr.Value) Next Console.ReadLine() End If

    Read the article

  • Whats wrong with the following code, its not compiling

    - by Ganesh Kundapur
    #include <iostream> #include <vector> using namespace std; class Base { public: void Display( void ) { cout<<"Base display"<<endl; } int Display( int a ) { cout<<"Base int display"<<endl; return 0; } }; class Derived : public Base { public: void Display( void ) { cout<<"Derived display"<<endl; } }; void main() { Derived obj; obj.Display(); obj.Display( 10 ); } $test1.cpp: In function ‘int main()’: test1.cpp:35: error: no matching function for call to ‘Derived::Display(int)’ test1.cpp:24: note: candidates are: void Derived::Display() On commenting obj.Display(10), it works.

    Read the article

  • How do I execute queries upon DB connection in Rails?

    - by sycobuny
    I have certain initializing functions that I use to set up audit logging on the DB server side (ie, not rails) in PostgreSQL. At least one has to be issued (setting the current user) before inserting data into or updating any of the audited tables, or else the whole query will fail spectacularly. I can easily call these every time before running any save operation in the code, but DRY makes me think I should have the code repeated in as few places as possible, particularly since this diverges greatly from the ideal of database agnosticism. Currently I'm attempting to override ActiveRecord::Base.establish_connection in an initializer to set it up so that the queries are run as soon as I connect automatically, but it doesn't behave as I expect it to. Here is the code in the initializer: class ActiveRecord::Base # extend the class methods, not the instance methods class << self alias :old_establish_connection :establish_connection # hide the default def establish_connection(*args) ret = old_establish_connection(*args) # call the default # set up necessary session variables for audit logging # call these after calling default, to make sure conn is established 1st db = self.class.connection db.execute("SELECT SV.set('current_user', 'test@localhost')") db.execute("SELECT SV.set('audit_notes', NULL)") # end "empty variable" err ret # return the default's original value end end end puts "Loaded custom establish_connection into ActiveRecord::Base" sycobuny:~/rails$ ruby script/server = Booting WEBrick = Rails 2.3.5 application starting on http://0.0.0.0:3000 Loaded custom establish_connection into ActiveRecord::Base This doesn't give me any errors, and unfortunately I can't check what the method looks like internally (I was using ActiveRecord::Base.method(:establish_connection), but apparently that creates a new Method object each time it's called, which is seemingly worthless cause I can't check object_id for any worthwhile information and I also can't reverse the compilation). However, the code never seems to get called, because any attempt to run a save or an update on a database object fails as I predicted earlier. If this isn't a proper way to execute code immediately on connection to the database, then what is?

    Read the article

  • Inheritance - initialization problem

    - by dumbquestion
    I have a c++ class derived from a base class in a framework. The derived class doesn't have any data members because I need it to be freely convertible into a base class and back - the framework is responsible for loading and saving the objects and I can't change it. My derived class just has functions for accessing the data. But there are a couple of places where I need to store some temporary local variables to speed up access to data in the base class. mydata* MyClass::getData() { if ( !m_mydata ) { // set to NULL in the constructor m_mydata = some_long_and complex_operation_to_get_the_data_in_the_base() } return m_mydata; } The problem is if I just access the object by casting the base class pointer returned from the framework to MyClass* the ctor for MyClass is never called and m_mydata is junk. Is there a way of only initializing the m_mydata pointer once?

    Read the article

  • make VIEW of SHOW TABLE query

    - by cneeds
    Is there a way to make a VIEW of this SHOW TABLE query? SHOW FULL TABLES FROM `db_name` WHERE `Table_type` = "Base table" When I save this as a view (using phpMyAdmin) I get #1064 - You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'SHOW FULL TABLES FROM `db_name` WHERE `Table_type` = "Base table"' at line 4 when phpMyAdmin tries to execute this CREATE ALGORITHM = UNDEFINED VIEW `Tables` AS SHOW FULL TABLES FROM `db_name` WHERE `Table_type` = "Base table"

    Read the article

  • Simple Fluent NHibernate Mapping Problem

    - by user500038
    I have the following tables I need to map: +-------------------------+ | Person | +-------------------------+ | PersonId | | FullName | +-------------------------+ +-------------------------+ | PersonAddress | +-------------------------+ | PersonId | | AddressId | | IsDefault | +-------------------------+ +-------------------------+ | Address | +-------------------------+ | AddressId | | State | +-------------------------+ And the following classes: public class Person { public virtual int Id { get; set; } public virtual string FullName { get; set; } } public class PersonAddress { public virtual Person Person { get; set; } public virtual Address Address { get; set; } public virtual bool IsDefault { get; set; } } public class Address { public virtual int Id { get; set; } public virtual string State { get; set; } } And finally the mappings: public class PersonMap : ClassMap<Person> { public PersonMap() { Id(x => x.Id, "PersonId"); } } public class PersonAddressMap : ClassMap<PersonAddress> { public PersonAddressMap() { CompositeId().KeyProperty(x => x.Person, "PersonID") .KeyProperty(x => x.Address, "AddressID"); } } public class AddressMap: ClassMap<Address> { public AddressMap() { Id(x => x.Id, "AddressId"); } } Assume I cannot alter the tables. If I take the mapping class (PersonAddress) out of the equation, everything works fine. If I put it back in I get: Could not determine type for: Person, Person, Version=1.0, Culture=neutral, PublicKeyToken=null, for columns: NHibernate.Mapping.Column(PersonId) What am I missing here? I'm sure this must be simple.

    Read the article

  • Getting a type for a template instantiation?

    - by ebo
    I have the following situation: I have a object of type MyClass, which has a method to cast itself to it's base class. The class includes a typedef for it's base class and a method to do the downcast. template <class T, class B> class BaseClass; template <class T> class NoAccess; template <class T> class MyClass : public BaseClass<T, NoAccess<T> > { private: typedef BaseClass<T, NoAccess<T> > base; public: base &to_base(); }; I need to pass the result of a base call to a functor Operator: template <class Y> class Operator { Operator(Y &x); }; Operator<???> op(myobject.to_base()); Is there a easy way to fill the ??? provided that I do not want to use NoAccess?

    Read the article

  • Why doesn't C++ allow you to request a pointer to the most derived class?

    - by Matthew Lowe
    (This question should probably be answered with a reference to Stroustrup.) It seems extremely useful to be able to request a pointer to the most derived class, as in the following: class Base { ... }; class DerivedA { ... }; class DerivedB { ... }; class Processor { public: void Do(Base* b) {...} void Do(DerivedA* d) {...} void Do(DerivedB* d) {...} }; list<Base*> things; Processor p; for(list<Base*>::iterator i=things.begin(), e=things.end(); i!=e; ++i) { p.Do(CAST_TO_MOST_DERIVED_CLASS(*i)); } But this mechanism isn't provided in c++. Why?

    Read the article

  • Figuring out what makes a C++ class abstract in VS2008

    - by suszterpatt
    I'm using VS2008 to build a plain old C++ program (not C++/CLI). I have an abstract base class and a non-abstract derived class, and building this: Base* obj; obj = new Derived(); fails with the error "'Derived': cannot instantiate abstract class". (It may be worth noting, however, that if I hover over Base with the cursor, VS will pop up a tooltip saying "class Base abstract", but hovering over Derived will only say "class Derived" (no "abstract")). The definitions of these classes are fairly large and I'd like to avoid manually checking if each method has been overridden. Can VS do this for me somehow? Any general tips on pinpointing the exact parts of the class' definition that make it abstract?

    Read the article

  • Rails 3 HABTM Strange Association: Project and Employee in a tree.

    - by Mauricio
    Hi guys I have to adapt an existing model to a new relation. I have this: A Project has many Employees. the Employees of a Project are organized in some kind of hierarchy (nothing fancy, I resolved this adding a parent_id for each employee to build the 'tree') class Employee < AR:Base belongs_to :project belongs_to :parent, :class_name => 'Employee' has_many :childs, :class_name => 'Employee', :foreign_column => 'parent_id' end class Project < AR:Base has_many :employees, end That worked like a charm, now the new requirement is: The Employees can belong to many Projects at the same time, and the hierarchy will be different according to the project. So I though I will need a new table to build the HABTM, and a new class to access the parent_id to build the tree. Something like class ProjectEmployee < AR:Base belongs_to :project belongs_to :employee belongs_to :parent, :class_name => 'Employee' # <--- ?????? end class Project < AR:Base has_many :project_employee has_many :employees, :through => :project_employee end class Employee < AR:Base has_many :project_employee has_many :projects, :through => :project_employee end How can I access the parent and the childs of an employee for a given project? I need to add and remove childs as wish from the employees of a project. Thank you!

    Read the article

  • multiple models in Rails with a shared interface

    - by dfondente
    I'm not sure of the best structure for a particular situation in Rails. We have several types of workshops. The administration of the workshops is the same regardless of workshop type, so the data for the workshops is in a single model. We collect feedback from participants about the workshops, and the questionnaire is different for each type of workshop. I want to access the feedback about the workshop from the workshop model, but the class of the associated model will depend on the type of workshop. If I was doing this in something other than Rails, I would set up an abstract class for WorkshopFeedback, and then have subclasses for each type of workshop: WorkshopFeedbackOne, WorkshopFeedbackTwo, WorkshopFeedbackThree. I'm unsure how to best handle this with Rails. I currently have: class Workshop < ActiveRecord::Base has_many :workshop_feedbacks end class Feedback < ActiveRecord::Base belongs_to :workshop has_many :feedback_ones has_many :feedback_twos has_many :feedback_threes end class FeedbackOne < ActiveRecord::Base belongs_to :feedback end class FeedbackTwo < ActiveRecord::Base belongs_to :feedback end class FeedbackThree < ActiveRecord::Base belongs_to :feedback end This doesn't seem like to the cleanest way to access the feedback from the workshop model, as accessing the correct feedback will require logic investigating the Workshop type and then choosing, for instance, @workshop.feedback.feedback_one. Is there a better way to handle this situation? Would it be better to use a polymorphic association for feedback? Or maybe using a Module or Mixin for the shared Feedback interface? Note: I am avoiding using Single Table Inheritance here because the FeedbackOne, FeedbackTwo, FeedbackThree models do not share much common data, so I would end up with a large sparsely populated table with STI.

    Read the article

  • How to implement a private virtual function within derived classes?

    - by Dane
    Hi, I know why I want to use private virtual functions, but how exactly can I implement them? For example: class Base{ [...] private: virtual void func() = 0; [...] } class Derived1: puplic Base{ void func() { //short implementation is ok here } } class Derived2: puplic Base{ void func(); //long implementation elsewhere (in cpp file) } [...] void Derived2::func() { //long implementation } The first version is ok but not always possible. Isn't the second version simply name hiding? How do you define the Base::func() of Derived2, if you cannot do it within the class declaration of Dereived2? Thanks

    Read the article

  • Retrieve value of one column in a table

    - by user327094
    Here is my problem: I have 2 tables Accounts and Transaction Logs. in Accounts table, it has column "Amount" which is a base amount of an account. and in Trans Logs table, it also has column "Amount" which is additional (add or minus to the base amount) amount of the account. and I don't know how to retrieve that base amount to edit it, then save it back to the table. That means I need to get a value of the right column by using Acc_No to find. I'm using DataSet, by the way. i think it should go like this: Dim Amount as Decimal Amount = *the code to retrieve the base amount* Amount = Amount + txtAmount.Text *the code to save the new amount back to Accounts table* Thank you!

    Read the article

  • how to avoid temporaries when copying weakly typed object

    - by Truncheon
    Hi. I'm writing a series classes that inherit from a base class using virtual. They are INT, FLOAT and STRING objects that I want to use in a scripting language. I'm trying to implement weak typing, but I don't want STRING objects to return copies of themselves when used in the following way (instead I would prefer to have a reference returned which can be used in copying): a = "hello "; b = "world"; c = a + b; I have written the following code as a mock example: #include <iostream> #include <string> #include <cstdio> #include <cstdlib> std::string dummy("<int object cannot return string reference>"); struct BaseImpl { virtual bool is_string() = 0; virtual int get_int() = 0; virtual std::string get_string_copy() = 0; virtual std::string const& get_string_ref() = 0; }; struct INT : BaseImpl { int value; INT(int i = 0) : value(i) { std::cout << "constructor called\n"; } INT(BaseImpl& that) : value(that.get_int()) { std::cout << "copy constructor called\n"; } bool is_string() { return false; } int get_int() { return value; } std::string get_string_copy() { char buf[33]; sprintf(buf, "%i", value); return buf; } std::string const& get_string_ref() { return dummy; } }; struct STRING : BaseImpl { std::string value; STRING(std::string s = "") : value(s) { std::cout << "constructor called\n"; } STRING(BaseImpl& that) { if (that.is_string()) value = that.get_string_ref(); else value = that.get_string_copy(); std::cout << "copy constructor called\n"; } bool is_string() { return true; } int get_int() { return atoi(value.c_str()); } std::string get_string_copy() { return value; } std::string const& get_string_ref() { return value; } }; struct Base { BaseImpl* impl; Base(BaseImpl* p = 0) : impl(p) {} ~Base() { delete impl; } }; int main() { Base b1(new INT(1)); Base b2(new STRING("Hello world")); Base b3(new INT(*b1.impl)); Base b4(new STRING(*b2.impl)); std::cout << "\n"; std::cout << b1.impl->get_int() << "\n"; std::cout << b2.impl->get_int() << "\n"; std::cout << b3.impl->get_int() << "\n"; std::cout << b4.impl->get_int() << "\n"; std::cout << "\n"; std::cout << b1.impl->get_string_ref() << "\n"; std::cout << b2.impl->get_string_ref() << "\n"; std::cout << b3.impl->get_string_ref() << "\n"; std::cout << b4.impl->get_string_ref() << "\n"; std::cout << "\n"; std::cout << b1.impl->get_string_copy() << "\n"; std::cout << b2.impl->get_string_copy() << "\n"; std::cout << b3.impl->get_string_copy() << "\n"; std::cout << b4.impl->get_string_copy() << "\n"; return 0; } It was necessary to add an if check in the STRING class to determine whether its safe to request a reference instead of a copy: Script code: a = "test"; b = a; c = 1; d = "" + c; /* not safe to request reference by standard */ C++ code: STRING(BaseImpl& that) { if (that.is_string()) value = that.get_string_ref(); else value = that.get_string_copy(); std::cout << "copy constructor called\n"; } If was hoping there's a way of moving that if check into compile time, rather than run time.

    Read the article

  • How do I change the class of an object to a subclass of its current class in C++?

    - by Jared P
    I have an array of pointers to a base class, so that I can make those pointers point to (different) subclasses of the base class, but still interact with them. (really only a couple of methods which I made virtual and overloaded) I'm wondering if I can avoid using the pointers, and instead just make an array of the base class, but have some way to set the class to the subclass of my choosing. I know there must be something there specifying the class, as it needs to use that to look up the function pointer for virtual methods. By the way, the subclasses all have the same ivars and layout. Note: the design is actually based on using a template argument instead of a variable, due to performance increases, so really the abstract base class is just the interface for the subclasses, which are all the same except for their compiled code. Thanks

    Read the article

  • Should I denormalize a has_many has_many?

    - by Cameron
    I have this: class User < ActiveRecord::Base has_many :serials has_many :sites, :through => :series end class Serial < ActiveRecord::Base belongs_to :user belongs_to :site has_many :episodes end class Site < ActiveRecord::Base has_many :serials has_many :users, :through => :serials end class Episode < ActiveRecord::Base belongs_to :serial end I would like to do some operations on User.serials.episodes but I know this would mean all sorts of clever tricks. I could in theory just put all the episode data into serial (denormalize) and then group_by Site when needed. If I have a lot of episodes that I need to query on would this be a bad idea? thanks

    Read the article

  • Java applet wont run

    - by Courtney
    I am trying to get a Java applet to run properly when linked to an HTML page in Dreamweaver CC. I'm new to all this so please bear with me here. First I saved this code to a .java file //Triangle.java import java.awt.*; import java.applet.Applet; public class Triangle extends Applet { public void paint (Graphics g){ int bottomX=80; int bottomY=200; int base=100; int height=100; g.drawLine(bottomX,bottomY,bottomX+base,bottomY); g.drawLine(bottomX+base,bottomY,bottomX+base/2,bottomY-height); g.drawLine(bottomX+base/2,bottomY-height, bottomX,bottomY); } } I then compiled it entering javac Triangle.java After that, I inserted it into a Dreamwever page using: <html> <applet code=Triangle.class width=400 height=400 > </applet> </html> Now when I try and open the page in Chrome I get an error reading: UnsupportedClassVersionError Triangle: Unsupported major.minor version 52.0 This, as I have read, is an issue with using two incompatible Java versions? In my Java Control Panel it says I am using version 1.8.0_20 and my JDK is jdk1.8.0_20. Does anyone see anything super obvious that I am doing wrong here?

    Read the article

  • Friendness and derived class

    - by ereOn
    Hi, Let's say I have the following class hierarchy: class Base { protected: virtual void foo() = 0; friend class Other; }; class Derived : public Base { protected: void foo() { /* Some implementation */ }; }; class Other { public: void bar() { Derived* a = new Derived(); a->foo(); // Compiler error: foo() is protected within this context }; }; I guess I could change it too a->Base::foo() but since foo() is pure virtual in the Base class, the call will result in calling Derived::foo() anyway. However, the compiler seems to refuse a->foo(). I guess it is logical, but I can't really understand why. Am I missing something ? Can't (shouldn't) it handle this special case ? Thank you.

    Read the article

  • OnShutdown() not working on XP

    - by Daro
    I have a service registered for shutdown events (.Net 3.5): public ServiceName() { InitializeComponent(); base.CanHandleSessionChangeEvent = true; base.CanHandlePowerEvent = true; base.CanShutdown = true; } protected override void OnShutdown() { try { if (Program.Debug2Eventlog == true) { WriteEventEntry( "Computer is shutting down.", EventLogEntryType.Information, 0, 3); } } catch {} base.OnShutdown(); } Windows 7 logs the event just fine, but XP doesn't. Am I missing something?

    Read the article

  • Magento - save quote_address on cart addAction using observer

    - by Byron
    I am writing a custom Magento module that gives rate quotes (based on an external API) on the product page. After I get the response on the product page, it adds some of the info from the response into the product view's form. The goal is to save the address (as well as some other things, but those can be in the session for now). The address needs to be saved to the quote, so that the checkout (onestepcheckout, free version) will automatically fill those values in (city, state, zip, country, shipping method [of which there are 3]) and load the rate quote via ajax (which it's already doing). I have gone about this by using an Observer, and watching for the cart events. I fill in the address and save it. When I end up on the cart page or checkout page ~4/5 times the data is lost, and the sql table shows that the quote_address is getting save with no address info, even though there is an explicit save. The observer method's I've used are: checkout_cart_update_item_complete checkout_cart_product_add_after The code saving is: (I've tried this with the address, quote and cart all not calling save() with the same results, as well as not calling setQuote() $quote->getShippingAddress() ->setCountryId($params['estimate_to_country']) ->setCity($params['estimate_to_city']) ->setPostcode($params['estimate_to_zip_code']) ->setRegionId($params['estimate_to_state_code']) ->setRegion($params['estimate_to_state']) ->setCollectShippingRates(true) ->setShippingMethod($params['carrier_method']) ->setQuote($quote) ->save(); $quote->getBillingAddress() ->setCountryId($params['estimate_to_country']) ->setCity($params['estimate_to_city']) ->setPostcode($params['estimate_to_zip_code']) ->setRegionId($params['estimate_to_state_code']) ->setRegion($params['estimate_to_state']) ->setCollectShippingRates(true) ->setShippingMethod($params['carrier_method']) ->setQuote($quote) ->save(); $quote->save(); $cart->save(); I imagine there's a good chance this is not the best place to save this info, but I am not quite sure. I was wondering if there is a good place to do this without overriding a whole controller to save the address on the add to cart action. Thanks so much, let me know if I need to clarify

    Read the article

< Previous Page | 136 137 138 139 140 141 142 143 144 145 146 147  | Next Page >