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  • Unresolved External Symbol linker error (C++)

    - by Niranjan
    Hi, I am trying to develop abstract design pattern code for one of my project as below.. But, I am not able to compile the code ..giving some compile errors(like "unresolved external symbol "public: virtual void __thiscall Xsecs::draw_lines(double,double)" (?draw_lines@Xsecs@@UAEXNN@Z)" ).. Can any one please help me out in this... #include "stdafx.h" #include <iostream> #include <vector> #include "Xsecs.h" using namespace std; //Product class class Xsecs { public: virtual void draw_lines(double pt1, double pt2); virtual void draw_curves(double pt1, double rad); }; class polyline: public Xsecs { public: virtual void draw_lines(double pt1,double pt2) { cout<<"draw_line in polygon"<<endl; } virtual void draw_curves(double pt1, double rad) { cout<<"Draw_curve in circle"<<endl; } /*void create_polygons() { cout<<"create_polygon_thru_draw_lines"<<endl; }*/ }; class circle: public Xsecs { public: virtual void draw_lines(double pt1,double pt2) { cout<<"draw_line in polygon"<<endl; } virtual void draw_curves(double pt1, double rad) { cout<<"Draw_curve in circle"<<endl; } /*void create_circles() { cout<<"Create circle"<<endl; }*/ }; //Factory class class Factory { public: virtual polyline* create_polyline()=0; virtual circle* create_circle()=0; }; class Factory1: public Factory { public: polyline* create_polyline() { return new polyline(); } circle* create_circle() { return new circle(); } }; class Factory2: public Factory { public: circle* create_circle() { return new circle(); } polyline* create_polyline() { return new polyline(); } }; int _tmain(int argc, _TCHAR* argv[]) { Factory1 f1; Factory * fp=&f1; return 0; }

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  • Methods for making R plots look like Excel plots?

    - by brianjd
    I've been poking around with R graphical parameters trying to make my plots look a little more professional (e.g., las=1, bty="n" usually help). But not quite there. Started playing with tikzDevice. A huge improvement! Amazing how much better things look when the font sizes and styles in the figure match those of the surrounding document. Still, not quite there. What I'm ultimately looking for are those professional gradient shading, rounded corners, and shadow effects found in MS Excel plots. I know they're probably considered chart junk, but I like them. They're just nice looking. Q: How can I get these effects into my R plots? Do people usually just export to Inkscape and doodle over there? It would be nice if there were a literate programming approach. Is there an R package that handles these effects outright?

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  • Is it possible to use AutoMapper to wrap methods?

    - by Woj
    I have two classes: public class TestClass1 { public int TestInt { get; set; } public void TestMethod() { // Do something } } public class TestClass2 { public int TestInt { get; set; } public void TestMethod() { // Do something } } I want to create interface that I can use for both classes. The easiest solution is to implement the interface on TestClass1 and TestClass2 but I don;t have access to the implementation of these classes (external dll). I was wondering if I can create new interface and use AutoMapper to map TestClass1 and TestClass2 to ITestInterface: public interface ITestInterface { int TestInt { get; set; } void TestMethod(); }

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  • What is a good practice to access class attributes in class methods?

    - by Clem
    I always wonder about the best way to access a class attribute from a class method in Java. Could you quickly convince me about which one of the 3 solutions below (or a totally different one :P) is a good practice? public class Test { String a; public String getA(){ return this.a; } public setA(String a){ this.a = a; } // Using Getter public void display(){ // Solution 1 System.out.println(this.a); // Solution 2 System.out.println(getA()); // Solution 3 System.out.println(this.getA()); } // Using Setter public void myMethod(String b, String c){ // Solution 1 this.a = b + c; // Solution 2 setA(b + c); // Solution 3 this.setA(b + c); } }

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  • Dynamic domain methods missing from grails service when injected into java service in grails app.

    - by Gordon C
    I had the idea that I would write my GroovyDao as a grails service. Next I would write a MyJavaService in java and locate it in the java sources dir in my grails app. MyJavaService contains a instance reference to groovyDao for spring injection. I would wire up in resources.groovy the MyJavaService with a groovyDao = ref("GroovyDao"). Everything starts up fine. However if I make call to MyJavaService any Domain method like Domain.list() returns a Method not found error. Any help is appreciated.

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  • MySQL & PHP: auto connect to DB or to properly way to pass host/db to MySQL methods

    - by SODA
    Hi, does anyone know of a known method in PHP to auto connect to MySQL db/table in case an app is using multiple databases on multiple hosts? Question 1: are there scripts around that allow to auto connect to necessary host/DB based on query? Question 2: if above is not possible, is there a known approach to properly passing host/DB info to make sure app is properly connected before executing the query?

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  • Binding an Ilist to datagridview containing another object in a field

    - by JaSk
    I have pretty much the same problem as this question http://stackoverflow.com/questions/970741 but in windows forms, can anyone help me solve it? this is my code, so you don't have to check the other question: public class Material { public virtual int id { get; private set; } public virtual string nombre { get; set; } public virtual string unidad { get; set; } public virtual Categorias Categoria { get; set; } public virtual IList Materiales { get; set; } public Material() { Materiales = new List<Materiales>(); } public virtual void AddMateriales(Materiales materiales) { materiales.Material = this; this.Materiales.Add(materiales); } } as you can see I have an object within the IList so when I use the List as the data source for a datagridview I get a object.categoria where I want to get the Categoria.Name property, can anyone help me?. Thanks

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  • How to override inner class methods if the inner class is defined as a property of the top class

    - by Maddy
    I have a code snippet like this class A(object): class b: def print_hello(self): print "Hello world" b = property(b) And I want to override the inner class b (please dont worry about the lowercase name) behaviour. Say, I want to add a new method or I want to change an existing method, like: class C(A): class b(A.b): def print_hello(self): print "Inner Class: Hello world" b = property(b) Now if I create C's object as c = C(), and call c.b I get TypeError: 'property' object is not callable error. How would I get pass this and call print_hello of the extended inner class? Disclaimer: I dont want to change the code for A class.

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  • Can I detect unused extra parameters passed to javascript methods?

    - by Pablojim
    In Javascript I can call any method with more than the necessary amount of parameters and the extra parameters are silently ignored. e.g. letters = ['a','b','c'] //correct letters.indexOf('a') //This also works without error or warning letters.indexOf('a', "blah", "ignore me", 38) Are there ways to detect cases where this occurs? My motivation is that in my experience cases where this occurs are usually bugs. Identification of these by code analysis or at runtime would help track these errors down. These cases are especially prevalent where people are expecting alterations to base types which may not have occurred. Logging a warning where this happens e.g. Date.parse('02--12--2012', 'dd--MM--YYYY') Notes: To be clear I would like a solution that doesn't involve me sprinkling checks all over my code and other peoples' code.

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  • Can someone explain the declaration of these java generic methods?

    - by Tony Giaccone
    I'm reading "Generics in the Java Programming Language" by Gilad Bracha and I'm confused about a style of declaration. The following code is found on page 8: interface Collection<E> { public boolean containsAll(Collection<?> c); public boolean addAll(Collection<? extends E> c); } interface Collection<E> { public <T> boolean containsAll(Collection<T> c); public <T extends E> boolean addAll(Collection<T> c); // hey, type variables can have bounds too! } My point of confusion comes from the second declaration. It's not clear to me what the purpose the <T> declaration serves in the following line: public <T> boolean containsAll(Collection<T> c); The method already has a type (boolean) associated with it. Why would you use the <T> and what does it tell the complier? I think my question needs to be a bit more specific. Why would you write: public <T> boolean containsAll(Collection<T> c); vs public boolean containsAll(Collection<T> c); It's not clear to me, what the purpose of <T> is, in the first declaration of containsAll.

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  • Python:How to override inner class methods if the inner class is defined as a property of the top cl

    - by Maddy
    I have a code snippet like this class A(object): class b: def print_hello(self): print "Hello world" b = property(b) And I want to override the inner class 'b'(please dont worry about the lowercase name) behaviour. Say, I want to add a new method or I want to change an existing method, like: class C(A): class b(A.b): def print_hello(self): print "Inner Class: Hello world" b = property(b) Now if I create C's object as c = C(), and call c.b I get TypeError: 'property' object is not callable error. How would I get pass this and call print_hello of the extended inner class? Disclaimer: I dont want to change the code for A class.

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  • Style question: Writing "this." before instance variable and methods: good or bad idea?

    - by Uri
    One of my nasty (?) programming habits in C++ and Java is to always precede calls or accesses to members with a this. For example: this.process(this.event). A few of my students commented on this, and I'm wondering if I am teaching bad habits. My rationale is: 1) Makes code more readable — Easier to distinguish fields from local variables. 2) Makes it easier to distinguish standard calls from static calls (especially in Java) 3) Makes me remember that this call (unless the target is final) could end up on a different target, for example in an overriding version in a subclass. Obviously, this has zero impact on the compiled program, it's just readability. So am I making it more or less readable? Related Question Note: I turned it into a CW since there really isn't a correct answer.

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  • Is arithmetic overflow/underflow generally checked in .Net framework methods?

    - by YWE
    For example, let's use the Add method of the ArrayList class. If I am using the default compiler settings in Visual Studio C# project in which arithmetic overflow is not checked, would ArrayList.Add() throw an OverflowException if I added too many items? Would surrounding the method call with checked or unchecked make any difference? BTW, I would write a test program to determine the answer to this question if I had Visual Studio available to me right now.

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  • FluentNHibernate - AutoMappings producing incorrect one-to-many column key

    - by Alberto
    Hi I'm new to NHibernate and FNH and am trying to map these simple classes by using FluentNHibernate AutoMappings feature: public class TVShow : Entity { public virtual string Title { get; set;} public virtual ICollection<Season> Seasons { get; protected set; } public TVShow() { Seasons = new HashedSet<Season>(); } public virtual void AddSeason(Season season) { season.TVShow = this; Seasons.Add(season); } public virtual void RemoveSeason(Season season) { if (!Seasons.Contains(season)) { throw new InvalidOperationException("This TV Show does not contain the given season"); } season.TVShow = null; Seasons.Remove(season); } } public class Season : Entity { public virtual TVShow TVShow { get; set; } public virtual int Number { get; set; } public virtual IList<Episode> Episodes { get; set; } public Season() { Episodes = new List<Episode>(); } public virtual void AddEpisode(Episode episode) { episode.Season = this; Episodes.Add(episode); } public virtual void RemoveEpisode(Episode episode) { if (!Episodes.Contains(episode)) { throw new InvalidOperationException("Episode not found on this season"); } episode.Season = null; Episodes.Remove(episode); } } I'm also using a couple of conventions: public class MyForeignKeyConvention : IReferenceConvention { #region IConvention<IManyToOneInspector,IManyToOneInstance> Members public void Apply(FluentNHibernate.Conventions.Instances.IManyToOneInstance instance) { instance.Column("fk_" + instance.Property.Name); } #endregion } The problem is that FNH is generating the section below for the Seasons property mapping: <bag name="Seasons"> <key> <column name="TVShow_Id" /> </key> <one-to-many class="TVShowsManager.Domain.Season, TVShowsManager.Domain, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null" /> </bag> The column name above should be fk_TVShow rather than TVShow_Id. If amend the hbm files produced by FNH then the code works. Does anyone know what it's wrong? Thanks in advance.

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  • Are there .NET Framework methods to parse an email (MIME)?

    - by Neil C. Obremski
    Is there a class or set of functions built into the .NET Framework (3.5+) to parse raw emails (MIME documents)? I am not looking for anything fancy or a separate library, it needs to be built-in. I'm going to be using this in some unit tests and need only grab the main headers of interest (To, From, Subject) along with the body (which in this case will always be text and therefore no MIME trees or boundaries). I've written several MIME parsers in the past and if there isn't anything readily available, I'll just put together something from regular expressions. It would be great to be able to do something like: MailMessage msg = MailMessage.Parse(text); Thoughts?

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  • Javascript / Flash : When exactly are flash external callback methods triggered ?

    - by felace
    I have a flash application using callbacks to javascript functions (eg. when it receives some data over a socket, it'll call a js script which would change the content of a div according to that given data). Afaik, there is no actual mutual exclusion in javascript so I'm not sure if I can/need to simulate something like : callbackFunc() { lock(mutex1) foo unlock(mutex1) } ... someOtherFunc() { lock(mutex1) bar unlock(mutex1) } So, the question is, when are those callbacks called ? Are they simply queued to be executed right after the browser finishes its task or are they triggered randomly ?

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  • how do i write action methods for partial views?

    - by ZX12R
    I rendering a view partially like this. <%= render(:partial => "index" ,:controller=>"controller_name") %> so this will partially render controller_name/_index.html.erb here is my doubt. can i write an action method for this _index. something like this? class ControllerNameController < ApplicationController def _index end end thanks.

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  • 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.

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  • [C#] Three System.Drawing methods manifest slow drawing or flickery: Solutions? or Other Options?

    - by Luke Mcneice
    Hi all, I am doing a little graphing via the System.Drawing and im having a few problems. I'm holding data in a Queue and i'm drawing(graphing) out that data onto three picture boxes this method fills the picture box then scrolls the graph across. so not to draw on top of the previous drawings (and graduly looking messier) i found 2 solutions to draw the graph. Call plot.Clear(BACKGOUNDCOLOR) before the draw loop [block commented] although this causes a flicker to appear from the time it takes to do the actual drawing loop. call plot.DrawLine(channelPen[5], j, 140, j, 0); just before each drawline [commented] although this causes the drawing to start ok then slow down very quickly to a crawl as if a wait command had been placed before the draw command. Here is the Code for reference: /*plotx.Clear(BACKGOUNDCOLOR) ploty.Clear(BACKGOUNDCOLOR) plotz.Clear(BACKGOUNDCOLOR)*/ for (int j = 1; j < 599; j++) { if (j > RealTimeBuffer.Count - 1) break; QueueEntity past = RealTimeBuffer.ElementAt(j - 1); QueueEntity current = RealTimeBuffer.ElementAt(j); if (j == 1) { //plotx.DrawLine(channelPen[5], 0, 140, 0, 0); //ploty.DrawLine(channelPen[5], 0, 140, 0, 0); //plotz.DrawLine(channelPen[5], 0, 140, 0, 0); } //plotx.DrawLine(channelPen[5], j, 140, j, 0); plotx.DrawLine(channelPen[0], j - 1, (((past.accdata.X - 0x7FFF) / 256) + 64), j, (((current.accdata.X - 0x7FFF) / 256) + 64)); //ploty.DrawLine(channelPen[5], j, 140, j, 0); ploty.DrawLine(channelPen[1], j - 1, (((past.accdata.Y - 0x7FFF) / 256) + 64), j, (((current.accdata.Y - 0x7FFF) / 256) + 64)); //plotz.DrawLine(markerPen, j, 140, j, 0); plotz.DrawLine(channelPen[2], j - 1, (((past.accdata.Z - 0x7FFF) / 256) + 94), j, (((current.accdata.Z - 0x7FFF) / 256) + 94)); } Is there any tricks to avoid these overheads? If not would there be any other/better solutions?

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  • [C#] Two System.Drawing methods manifest slow drawing or flickery: Solutions? or Other Options?

    - by Luke Mcneice
    Hi all, I am doing a little graphing via the System.Drawing and im having a few problems. I'm holding data in a Queue and i'm drawing(graphing) out that data onto three picture boxes this method fills the picture box then scrolls the graph across. so not to draw on top of the previous drawings (and graduly looking messier) i found 2 solutions to draw the graph. Call plot.Clear(BACKGOUNDCOLOR) before the draw loop [block commented] although this causes a flicker to appear from the time it takes to do the actual drawing loop. call plot.DrawLine(channelPen[5], j, 140, j, 0); just before each drawline [commented] although this causes the drawing to start ok then slow down very quickly to a crawl as if a wait command had been placed before the draw command. Here is the Code for reference: /*plotx.Clear(BACKGOUNDCOLOR) ploty.Clear(BACKGOUNDCOLOR) plotz.Clear(BACKGOUNDCOLOR)*/ for (int j = 1; j < 599; j++) { if (j > RealTimeBuffer.Count - 1) break; QueueEntity past = RealTimeBuffer.ElementAt(j - 1); QueueEntity current = RealTimeBuffer.ElementAt(j); if (j == 1) { //plotx.DrawLine(channelPen[5], 0, 140, 0, 0); //ploty.DrawLine(channelPen[5], 0, 140, 0, 0); //plotz.DrawLine(channelPen[5], 0, 140, 0, 0); } //plotx.DrawLine(channelPen[5], j, 140, j, 0); plotx.DrawLine(channelPen[0], j - 1, (((past.accdata.X - 0x7FFF) / 256) + 64), j, (((current.accdata.X - 0x7FFF) / 256) + 64)); //ploty.DrawLine(channelPen[5], j, 140, j, 0); ploty.DrawLine(channelPen[1], j - 1, (((past.accdata.Y - 0x7FFF) / 256) + 64), j, (((current.accdata.Y - 0x7FFF) / 256) + 64)); //plotz.DrawLine(markerPen, j, 140, j, 0); plotz.DrawLine(channelPen[2], j - 1, (((past.accdata.Z - 0x7FFF) / 256) + 94), j, (((current.accdata.Z - 0x7FFF) / 256) + 94)); } Is there any tricks to avoid these overheads? If not would there be any other/better solutions?

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  • What's the preferred way to use helper methods in Ruby?

    - by DR
    Disclaimer: Although I'm asking in context of a Rails application, I'm not talking about Rails helpers (i.e. view helpers) Let's say I have a helper method/function: def dispatch_job(job = {}) #Do something end Now I want to use this from several places (mostly controllers, but also a few BackgrounDRb workers) What's the preferred way to do this? I can think of two possibilities: 1. Use a class and make the helper a static method: class MyHelper def self.dispatch_job(job = {}) end end class MyWorker def run MyHelper.dispatch_job(...) end end 2. Use a module and include the method into whatever class I need this functionality module MyHelper def self.dispatch_job(job = {}) end end class MyWorker include MyHelper def run dispatch_job(...) end end 3. Other possibilities I don't know yet ... The first one is more Java-like, but I'm not sure if the second one is really an appropriate use of Ruby's modules.

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