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  • c++ class member functions selected by traits

    - by Jive Dadson
    I am reluctant to say I can't figure this out, but I can't figure this out. I've googled and searched stackoverflow, and come up empty. The abstract, and possibly overly vague form of the question is, how can I use the traits-pattern to instantiate non-virtual member functions? The question came up while modernizing a set of multivariate function optimizers that I wrote more than 10 years ago. The optimizers all operate by selecting a straight-line path through the parameter space away from the current best point (the "update"), then finding a better point on that line (the "line search"), then testing for the "done" condition, and if not done, iterating. There are different methods for doing the update, the line-search, and conceivably for the done test, and other things. Mix and match. Different update formulae require different state-variable data. For example, the LMQN update requires a vector, and the BFGS update requires a matrix. If evaluating gradients is cheap, the line-search should do so. If not, it should use function evaluations only. Some methods require more accurate line-searches than others. Those are just some examples. The original version instatiates several of the combinations by means of virtual functions. Some traits are selected by setting mode bits. Yuck. It would be trivial to define the traits with #define's and the member functions with #ifdef's and macros. But that's so twenty years ago. It bugs me that I cannot figure out a whiz-bang modern way. If there were only one trait that varied, I could use the curiously recurring template pattern. But I see no way to extend that to arbitrary combinations of traits. I tried doing it using boost::enable_if, etc.. The specialized state info was easy. I managed to get the functions done, but only by resorting to non-friend external functions that have the this-pointer as a parameter. I never even figured out how to make the functions friends, much less member functions. Perhaps tag-dispatch is the key. I haven't gotten very deeply into that. Surely it's possible, right? If so, what is best practice?

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  • property not updating in object when page is posted

    - by Jared
    Hi I have set a property in a constructor like so function __construct() { $this->count = count(@$_SESSION['filearray']); //count how many files in array } and using it in condition statements if($this->count > 10) //then do something but it appears the count isn't being updated when I use another method of injecting values into this 'filearray' until I refresh the page. am I doing something wrong? I thought that my constructor would detect a change had been made in the session and whenever I call $this-count I would get the current count value but it seems to be 1 step behind until I refresh the page. If this is all vague I can include my form page that has all the method calls, but this is the jist of my question, why is my property not updating and how do I fix it :) TIA

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  • Django filter bool not iterable

    - by dana
    I want to filter all Relation Objects where (relation= following relation in a virtual community) the date one has initiated the following is in the past, related to the moment now. The following declaration seems to be wrong, as a bool object is not iterable. Is there another way to do that? d = Relations.objects.filter(date_follow < datetime.now())

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  • how to perform click to the output of ActionLink by jQuery or javascript?

    - by user324003
    <%= Ajax.ActionLink("Edit", "Update", "Home", new { id = item.mID }, new AjaxOptions { OnBegin = "function(){ $('#edit" + item.mID + "').show();}", HttpMethod = "get", UpdateTargetId = "edit" + item.mID })%> The above code generates the html source code. when user click the link, it works well. But there're so many links there, I must click them one by one. Is there any method to click once, all of them excutes? I tried the method: $("a.buttonID").click() and modified the above code: <%= Ajax.ActionLink("Edit", "Update", "Home", new { id = item.mID }, new AjaxOptions { OnBegin = "function(){ $('#edit" + item.mID + "').show();}", HttpMethod = "get", UpdateTargetId = "edit" + item.mID } new{@class="buttonID"})%> But it doesn't work. Because it only excutes the onclick event of a tag, the href attribute doesn't work.

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  • many-to-many query

    - by kofto4ka
    Hello, guys! I have a problem and I dont know what is better solution. Okay, I have 2 tables: posts(id, title), posts_tags(post_id, tag_id). I have next task: must select posts with tags ids for example 4, 10 and 11. Not exactly, post could have any other tags at the same time. So, how I could do it more optimized? Creating temporary table in each query? Or may be some kind of stored procedure? In the future, user could ask script to select posts with any count of tags (it could be 1 tag only or 10 at the same time) and I must be sure that method that I will choose would be the best method for my problem. Sorry for my english, thx for attention.

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  • Retrieving the type of a Collection

    - by nevets1219
    So I have something like the following in Java: private List<SomeType>variable; // ....variable is instantiated as so ... variable = new ArrayList<SomeType>(); // there's also a getter public List<SomeType> getVariable() { /* code */ } What I would like to be able to do is figure out that variable is a collection of SomeType programmatically. I read here that I can determine that from the method getVariable() but is there any way to tell directly from variable? I have been able to retrieve SomeType from the getter method based on the information in the link. I have also been successful in retrieving all the fields of the surrounding class via SurroundingClass.getClass().getDeclaredFields() but this doesn't tell me that it is List<SomeType>.

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  • C# Get Type of IEnumerable<TModel>

    - by Jimbo
    I have a method to which I pass an IEnumerable<TModel>. Then depending on the type of TModel, the method carries out a set of instructions as below: public void MyMethod<TModel>(IEnumerable<TModel> items) where TModel : class { int operationType; switch (typeof(TModel)) { case typeof(MyModelOne): operationType = 1; break; case typeof(MyModelTwo): operationType = 2; break; case typeof(MyModelThree): operationType = 3; break; default: throw new Exception("The collection model passed to MyMethod is not recognized"); } ... } This doesnt work, I get the error: There is no application variable or memeber 'TModel'

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  • WriteableBitmap in .NET 4

    - by Jamie
    Hi there, I have got a problem: I would like to use a method Render() for WriteableBitmap object. However, as I noticed, the method is not available without using a Silverlight assembly System.Windows.dll. I need to use RenderTargetBitmap in my project (PresentationCore assembly for standard .net). Here is the problem - there are definitions of some classes in both assemblies, thus they are in conflict. Basically, I need to add some stuff to Bgra32 bitmap. However, RenderTargetBitmap works only with Pbgra32 ones. I found that using WriteableBitmap to render would be nice. Maybe I am wrong? Do you have any ideas? Thank you in advance for the reply! Cheers

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  • R ggplot barplot; Fill based on two separate variables

    - by user1476968
    A picture says more than a thousand words. As you can see, my fill is based on the variable variable. Within each bar there is however multiple data entities (black borders) since the discrete variable complexity make them unique. What I am trying to find is something that makes each section of the bar more distinguishable than the current look. Preferable would be if it was something like shading. Here's an example (not the same dataset, since the original was imported): dat <- read.table(text = "Complexity Method Sens Spec MMC 1 L Alpha 50 20 10 2 M Alpha 40 30 80 3 H Alpha 10 10 5 4 L Beta 70 50 60 5 M Beta 49 10 80 6 H Beta 90 17 48 7 L Gamma 19 5 93 8 M Gamma 18 39 4 9 H Gamma 10 84 74", sep = "", header=T) library(ggplot2) library(reshape) short.m <- melt(dat) ggplot(short.m, aes(x=Method, y= value/100 , fill=variable)) + geom_bar(stat="identity",position="dodge", colour="black") + coord_flip()

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  • Searching Outlook Global Adress List

    - by MoominTroll
    I'm pulling up the Global Address List from Outlook like so... Microsoft.Office.Interop.Outlook.Application oApp = new Microsoft.Office.Interop.Outlook.Application(); AddressList gal = oApp.Session.GetGlobalAddressList(); ...with the aim of eventually being able to search through this in my own application to retrieve contact information which I can then supply to a method that squirrels off an email. Unfortunately given that my own GAL has about 20K entries in (the customers much more) using a foreach or something simply doesn't work in an acceptable timeframe. I want to pass a string like "Tom" to a method and have it return a list of possible contacts. Is this possible outside of actually opening up Outlook and creating the mail there? Note: There are a couple of other questions similar to this but most seem to have no good answer. I'm hoping I have more luck.

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  • Constructor versus setter injection

    - by Chris
    Hi, I'm currently designing an API where I wish to allow configuration via a variety of methods. One method is via an XML configuration schema and another method is through an API that I wish to play nicely with Spring. My XML schema parsing code was previously hidden and therefore the only concern was for it to work but now I wish to build a public API and I'm quite concerned about best-practice. It seems that many favor javabean type PoJo's with default zero parameter constructors and then setter injection. The problem I am trying to tackle is that some setter methods implementations are dependent on other setter methods being called before them in sequence. I could write anal setters that will tolerate themselves being called in many orders but that will not solve the problem of a user forgetting to set the appropriate setter and therefore the bean being in an incomplete state. The only solution I can think of is to forget about the objects being 'beans' and enforce the required parameters via constructor injection. An example of this is in the default setting of the id of a component based on the id of the parent components. My Interface public interface IMyIdentityInterface { public String getId(); /* A null value should create a unique meaningful default */ public void setId(String id); public IMyIdentityInterface getParent(); public void setParent(IMyIdentityInterface parent); } Base Implementation of interface: public abstract class MyIdentityBaseClass implements IMyIdentityInterface { private String _id; private IMyIdentityInterface _parent; public MyIdentityBaseClass () {} @Override public String getId() { return _id; } /** * If the id is null, then use the id of the parent component * appended with a lower-cased simple name of the current impl * class along with a counter suffix to enforce uniqueness */ @Override public void setId(String id) { if (id == null) { IMyIdentityInterface parent = getParent(); if (parent == null) { // this may be the top level component or it may be that // the user called setId() before setParent(..) } else { _id = Helpers.makeIdFromParent(parent,getClass()); } } else { _id = id; } } @Override public IMyIdentityInterface getParent() { return _parent; } @Override public void setParent(IMyIdentityInterface parent) { _parent = parent; } } Every component in the framework will have a parent except for the top level component. Using the setter type of injection, then the setters will have different behavior based on the order of the calling of the setters. In this case, would you agree, that a constructor taking a reference to the parent is better and dropping the parent setter method from the interface entirely? Is it considered bad practice if I wish to be able to configure these components using an IoC container? Chris

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  • Using an array in embedded x86 assembly??

    - by Mark V.
    Hey all I have a method (C++) that returns a character and takes an array of characters as its parameters. I'm messing with assembly for the first time and just trying to return the first character of the array in the dl register. Here's what I have so far: char returnFirstChar(char arrayOfLetters[]) { char max; __asm { push eax push ebx push ecx push edx mov dl, 0 mov eax, arrayOfLetters[0] xor edx, edx mov dl, al mov max, dl pop edx pop ecx pop ebx pop eax } return max; } For some reason this method returns a ? Any idea whats going on? Thanks

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  • Unique_ptr compiler errors

    - by Godric Seer
    I am designing and entity-component system for a project, and C++ memory management is giving me a few issues. I just want to make sure my design is legitimate. So to start I have an Entity class which stores a vector of Components: class Entity { private: std::vector<std::unique_ptr<Component> > components; public: Entity() { }; void AddComponent(Component* component) { this -> components.push_back(std::unique_ptr<Component>(component)); } ~Entity(); }; Which if I am not mistaken means that when the destructor is called (even the default, compiler created one), the destructor for the Entity, will call ~components, which will call ~std::unique_ptr for each element in the vector, and lead to the destruction of each Component, which is what I want. The component class has virtual methods, but the important part is its constructor: Component::Component(Entity parent) { parent.addComponent(this) // I am not sure if this would work like I expect // Other things here } As long as passing this to the method works, this also does what I want. My confusion is in the factory. What I want to do is something along the lines of: std::shared_ptr<Entity> createEntity() { std::shared_ptr<Entity> entityPtr(new Entity()); new Component(*parent); // Initialize more, and other types of Components return entityPtr; } Now, I believe that this setup will leave the ownership of the Component in the hands of its Parent Entity, which is what I want. First a small question, do I need to pass the entity into the Component constructor by reference or pointer or something? If I understand C++, it would pass by value, which means it gets copied, and the copied entity would die at the end of the constructor. The second, and main question is that code based on this sample will not compile. The complete error is too large to print here, however I think I know somewhat of what is going on. The compiler's error says I can't delete an incomplete type. My Component class has a purely virtual destructor with an implementation: inline Component::~Component() { }; at the end of the header. However since the whole point is that Component is actually an interface. I know from here that a complete type is required for unique_ptr destruction. The question is, how do I work around this? For reference I am using gcc 4.4.6.

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  • Using Session Bean provided data on JSF welcome page

    - by takachgeza
    I use JSF managed beans calling EJB methods that are provide data from database. I want to use some data already on the welcome page of the application. What is the best solution for it? EJBs are injected into JSF managed beans and it looks like the injection is done after executing the constructor. So I am not able to call EJB methods in the constructor. The normal place for EJB call is in the JSF action methods but how to call such a method prior to loding the first page of the application? A possible solution would be to call the EJB method conditionally in a getter that is used on the welcome page, for example: public List getProductList(){ if (this.productList == null) this.productList = myEJB.getProductList(); return this.productList; } Is there any better solution? For example, in some config file?

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  • How to add Transactions with a DataSet created using the Add Connection Wizard?

    - by RoguePlanetoid
    I have a DataSet that I have added to my project where I can Insert and Add records using the Add Query function in Visual Studio 2010, however I want to add transactions to this, I have found a few examples but cannot seem to find one that works with these. I know I need to use the SQLClient.SQLTransaction Class somehow. I used the Add New Data Source Wizard and added the Tables/View/Functions I need, I just need an example using this process such as How to get the DataConnection my DataSet has used. Assuming all options have been set in the wizard and I am only using the pre-defined adapters and options asked for in this wizard, how to I add the Transaction logic to my Database. For example I have a DataSet called ProductDataSet with the XSD created for this, I have then added my Stock table as a Datasource and Added an AddStock method with a wizard, this also if a new item calls an AddItem method, if either of these fails I want to rollback the AddItem and AddStock in this case.

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  • why is this rails association loading individually after an eager load?

    - by codeman73
    I'm trying to avoid the N+1 queries problem with eager loading, but it's not working. The associated models are still being loaded individually. Here are the relevant ActiveRecords and their relationships: class Player < ActiveRecord::Base has_one :tableau end Class Tableau < ActiveRecord::Base belongs_to :player has_many :tableau_cards has_many :deck_cards, :through => :tableau_cards end Class TableauCard < ActiveRecord::Base belongs_to :tableau belongs_to :deck_card, :include => :card end class DeckCard < ActiveRecord::Base belongs_to :card has_many :tableaus, :through => :tableau_cards end class Card < ActiveRecord::Base has_many :deck_cards end and the query I'm using is inside this method of Player: def tableau_contains(card_id) self.tableau.tableau_cards = TableauCard.find :all, :include => [ {:deck_card => (:card)}], :conditions => ['tableau_cards.tableau_id = ?', self.tableau.id] contains = false for tableau_card in self.tableau.tableau_cards # my logic here, looking at attributes of the Card model, with # tableau_card.deck_card.card; # individual loads of related Card models related to tableau_card are done here end return contains end Does it have to do with scope? This tableau_contains method is down a few method calls in a larger loop, where I originally tried doing the eager loading because there are several places where these same objects are looped through and examined. Then I eventually tried the code as it is above, with the load just before the loop, and I'm still seeing the individual SELECT queries for Card inside the tableau_cards loop in the log. I can see the eager-loading query with the IN clause just before the tableau_cards loop as well. EDIT: additional info below with the larger, outer loop Here's the larger loop. It is inside an observer on after_save def after_save(pa) @game = Game.find(turn.game_id, :include => :goals) @game.players = Player.find :all, :include => [ {:tableau => (:tableau_cards)}, :player_goals ], :conditions => ['players.game_id =?', @game.id] for player in @game.players player.tableau.tableau_cards = TableauCard.find :all, :include => [ {:deck_card => (:card)}], :conditions => ['tableau_cards.tableau_id = ?', player.tableau.id] if(player.tableau_contains(card)) ... end end end

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  • Setting a value into a object using reflection

    - by marionmaiden
    Hello I have an object that has a lot of attributes, each one with it's getter and setter. Each attribute has a non primitive type, that I don't know at runtime. For example, what I have is this: public class a{ private typeA attr1; private typeB attr2; public typeA getAttr1(){ return attr1; } public typeB getAttr2(){ return attr2; } public void setAttr1(typeA at){ attr1 = at; } public void setAttr2(typeB at){ attr2 = at; } } public class typeA{ public typeA(){ // doesn't matter } } public class typeB{ public typeB(){ // doesn't matter } } So, using reflection, I obtained the setter method for an attribute. Setting a value in the standard way is something like this: a test = new a(); a.setAttr1(new typeA()); But how can I do this using reflection? I already got the setAttr1() method using reflection, but I don't know how to create a new typeA object to be inserted in the setter.

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  • Smoothing Small Data Set With Second Order Quadratic Curve

    - by Rev316
    I'm doing some specific signal analysis, and I am in need of a method that would smooth out a given bell-shaped distribution curve. A running average approach isn't producing the results I desire. I want to keep the min/max, and general shape of my fitted curve intact, but resolve the inconsistencies in sampling. In short: if given a set of data that models a simple quadratic curve, what statistical smoothing method would you recommend? If possible, please reference an implementation, library, or framework. Thanks SO!

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  • Custom Providers & Design Patterns

    - by Code Sherpa
    Hi. I am using ASP.NET 2.0 and its various providers. I have overridden most of the methods I need and have the following custom providers: ProjectMembershipProvider ProjectProfileProvider ProjectRoleProvider In the design of my project, my intention was to wrap the custom providers in a facade - style design - mixing and matching profiling, membership, and roles in API methods to simplify things for developers. But, I am finding that a lot of the methods in my custom providers don't need to change, really. And, it seems silly to wrap a stand-alone method in another method that does exactly the same thing. So - is my approach wrong? Or, should I allow end - users to instantiate the custom providers when needed and the mix/match api when needed? This seems a bit redundant to me but I can't see another way. Advice appreciated. Thanks.

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  • Common views in viewControllers - Code re-usability

    - by Nitish
    I have few common views in most of my viewControllers. What I noticed is that I can reuse single code for all viewControllers which is absolutely wise. For this I decided to create a class Utils which has static methods like +(void)createCommonViews:(float)yAxis:(NSString*)text; In my case common views are three labels and two images. Problem : I am not able to add these views from Utils. I am wondering how can I send self as a parameter so that I may add the views from Utils. It may be wrong to add views outside the viewController. In that case what can be the solution? Taking all these views in a UIView, setting return type of Utils method as UIView and then adding UIView to viewController(after calling method from viewController) might solve my problem. But what I am looking for is some other solution. Thanks, Nitish

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  • Can PHP restart Apache?

    - by JohnA
    I have a local server which needs to make changes to a virtual hosts apache config file and then restart apache so the new config takes effect. Can PHP do this? I tried passthru and exec but they didn't work. Maybe the problem is that I'm trying to restart PHP's parent process? Thanks for any help!!

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  • Console-like control that allows full control over individual text formatting

    - by Rich.Carpenter
    I'm tinkering with writing a simple text-based role-playing game. I would like to use WinForms, and utilize WinForm controls for the UI and simple text for the output. The catch is, I would like to have complete control over the formatting of the individual text - some words being different colors, etc. A simple console control would suffice, as that would provide control over text colors, but it would be nice to also be able to change style, font and size. Less important: it would be nice to have complete control over where text appears in the control through a coordinate system, as with DOS windows of old. I'd appreciate suggestions on the best method of implementing this. Perhaps there is a better method I had not considered for rendering the output of a text-based game.

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  • Fast 4x4 matrix multiplication in Java with NIO float buffers

    - by kayahr
    I know there are LOT of questions like that but I can't find one specific to my situation. I have 4x4 matrices implemented as NIO float buffers (These matrices are used for OpenGL). Now I want to implement a multiply method which multiplies Matrix A with Matrix B and stores the result in Matrix C. So the code may look like this: class Matrix4f { private FloatBuffer buffer = FloatBuffer.allocate(16); public Matrix4f multiply(Matrix4f matrix2, Matrix4f result) { {{{result = this * matrix2}}} <-- I need this code return result; } } What is the fastest possible code to do this multiplication? Some OpenGL implementations (Like the OpenGL ES stuff in Android) provide native code for this but others doesn't. So I want to provide a generic multiplication method for these implementations.

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  • Is .NET a write once, run anywhere (WORA) platform like Java claims to be?

    - by Scott Saad
    I remember Sun's slogan so vividly... "Write Once, Run Anywhere". The idea being that since programs are compiled into standard byte codes, any device with a Java Virtual Machine could run it. Over the years, Java seems to have made it onto many platforms/devices. Is this the intention or was it ever the intention of .NET. If so, what kind of efforts are being put forth to make this a reality?

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