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  • Class members allocation on heap/stack? C++

    - by simplebutperfect
    If a class is declared as follows: class MyClass { char * MyMember; MyClass() { MyMember = new char[250]; } ~MyClass() { delete[] MyMember; } }; And it could be done like this: class MyClass { char MyMember[250]; }; How does a class gets allocated on heap, like if i do MyClass * Mine = new MyClass(); Does the allocated memory also allocates the 250 bytes in the second example along with the class instantiation? And will the member be valid for the whole lifetime of MyClass object? As for the first example, is it practical to allocate class members on heap?

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  • Is there anything wrong with my Factory class?

    - by Alex
    class PieceFactory { @SuppressWarnings("rawtypes") public Piece createPiece(String pieceType) throws Throwable{ Class pieceClass = Class.forName(pieceType); Piece piece = (Piece) pieceClass.newInstance(); return piece; } } I'm not all used to handling exceptions yet therefore I'm just throwing them, but everywhere I use a method that uses this factory it tells me I have to throw exceptions like throwable. For example, in one of my classes I have a method that instantiates a lot of objects using the method that uses the factory. I can use the method in that class by just throwing the exception, however it won't work if I try to pass a reference to that class to another class and then use the method from there. Then it forces me to try catch the exception. I probably don't need a factory but it seemed interesting and I'd like to try to use patterns. The reason I created the factory was that I have 6 subclasses of Piece and I wan't to use a method to instantiate them by passing the type of subclass I want as an argument to the method.

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  • Using C++, how to call a base class method from a derived class method and apply this to an object passed as an argument?

    - by Chris
    I can't figure out how to call a base class method from a derived class method but concurrently applying this method call at an object passed as argument. What I mean is this: class Animal { virtual void eat(Animal& to_be_eaten) = 0; }; class Carnivores: public Animal { virtual void eat(Animal& to_be_eaten) { /*implementation here*/} }; class Wolf : public Carnivores { virtual void eat(Animal& to_be_eaten) { /*call eat method(of Base class) of Base to_be_eaten here*/ } } I thought of something like this dynamic_cast<Carnivores&>(to_be_eaten).eat(*this) //and got a segmentation fault Is there any way for this to be done? Thank you! New edit:: Updated the code

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  • API Class with intensive network requests

    - by Marco Acierno
    I'm working an API which works as "intermediary" between a REST API and the developer. In this way, when the programmer do something like this: User user = client.getUser(nickname); it will execute a network request to download from the service the data about the user and then the programmer can use the data by doing things like user.getLocation(); user.getDisplayName(); and so on. Now there are some methods like getFollowers() which execute another network request and i could do it in two ways: Download all the data in the getUser method (and not only the most important) but in this way the request time could be very long since it should execute the request to various urls Download the data when the user calls the method, it looks like the best way and to improve it i could cache the result so the next call to getFollowers returns immediately with the data already download instead of execute again the request. What is the best way? And i should let methods like getUser and getFollowers stop the code execution until the data is ready or i should implement a callback so when the data is ready the callback gets fired? (this looks like Javascript)

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  • menu with: hover, click, class change and ajax

    - by abdullah kahraman
    Hello! I have made a menu that adds class "active" on hover to each li, and removes the class when hovered out, except on li s that has a class "active" already. So far, this is done. However I have another .click() on every li that loads a content to somewhere with ajax. The problem starts here, when I click, I want to add class "active" to clicked element and remove class from all of them. I add the class, but the li that had class "active" before the click doesn't get "active" when hovered, I think the "active" class is not removed from it? Can anyone help? <div id="menu"> <ul> <li><a href="index.php" id="homeLink">home</a></li> <li><a href="#">news</a></li> <li><a id="test" href="#" class="active">blog</a></li> <li><a href="#">gallery</a></li> <li><a href="#">about</a></li> <li><a href="contact.php" id="contactLink">contact</a></li> <li id="ajaxP" style="display:none"><img alt="loading" style="border:none;" src="images/ajax-loader.gif"/></li> </ul> </div> Here is the jquery: $("#menu").find("a").not(".active").each(function(){ $(this).hover(function(){ alert($(this)); $(this).addClass("active"); },function(){ $(this).not(".clicking").removeClass("active"); }); }); $("#homeLink").click(function(){ var myThis=$(this); $("#ajaxP").fadeIn("slow"); $("#normalcontent").hide("slow").load("index.php #normalcontent").slideDown("slow"); $("#primarycontainer").hide("slow").load("index.php #primarycontainer").slideDown("slow"); $("#ajaxP").fadeOut("normal"); $("#menu").find("a").each(function(){ $(this).unbind('mouseover').unbind("mouseout"); $(this).removeClass("active clicking"); }); myThis.addClass("active clicking"); return false; });

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  • MCP 1.7.10 Java class navigation

    - by Elias Benevedes
    So, I'm new to the Minecraft modding community and trying to understand where to start. I've attempted to do it before, but dropped it to the complexity of starting and the lack of a site like this to help (Mind that I'm also semi-new to Java, but have worked extensively in Javascript and Python. I understand how Java is different from the two). I have downloaded MCP 9.08 (Decompiles 1.7.10), and decompiled Minecraft. I'm looking to mod client, so I didn't supply it with a server jar. Everything seemed to work fine in decompile (Only error was it couldn't find the server jar). I can find my files in /mcp908/src/minecraft/net/minecraft. However, if I open up one of the classes in, say, block, I see a bunch of variables starting with p_ and ending with _. Is there any way to make these variables more decipherable, to understand what's going on so I can learn by example? Thank you.

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  • Abstract classes in shared library

    - by JTom
    Hi, I have an ordinary abstract class that has couple of pure virtual methods. The class itself is a part of the shared library. The compilation of the shared library itself is OK. But when the library is linked to another program that has another class deriving from the abstract one in the shared library and defining the pure virtual methods, I get the following linker error: I compile like this..: g++ -I../path/to/the/library main.cpp derived.cpp -L../path/to/the/library -lsomename -o shared ...and the linker error is: libsomename.so: undefined reference to `AbstractClass::method()' It's like the abstract class cannot access its pure virtual methods but I do not try to make any instance of the abstract class anywhere in the library. What could be the problem?

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  • use jQuery to get 'true size' of image without removing the class

    - by jon3laze
    I am using Jcrop on an image that is resized with css for uniformity. JS <script type="text/javascript"> $(window).load(function() { //invoke Jcrop API and set options var api = $.Jcrop('#image', { onSelect: storeCoords, trueSize: [w, h] }); api.disable(); //disable until ready to use //enable the Jcrop on crop button click $('#crop').click(function() { api.enable(); }); }); function storeCoords(c) { $('#X').val(c.x); $('#Y').val(c.y); $('#W').val(c.w); $('#H').val(c.h); }; </script> HTML <body> <img src="/path/to/image.jpg" id="image" class="img_class" alt="" /> <br /> <span id="crop" class="button">Crop Photo</span> <span id="#X" class="hidden"></span> <span id="#Y" class="hidden"></span> <span id="#W" class="hidden"></span> <span id="#H" class="hidden"></span> </body> CSS body { font-size: 13px; width: 500px; height: 500px; } .image { width: 200px; height: 300px; } .hidden { display: none; } I need to set the h and w variables to the size of the actual image. I tried using the .clone() manipulator to make a copy of the image and then remove the class from the clone to get the sizing but it sets the variables to zeros. var pic = $('#image').clone(); pic.removeClass('image'); var h = pic.height(); var w = pic.width(); It works if I append the image to an element in the page, but these are larger images and I would prefer not to be loading them as hidden images if there is a better way to do this. Also removing the class, setting the variables, and then re-adding the class was producing sporadic results. I was hoping for something along the lines of: $('#image').removeClass('image', function() { h = $(this).height(); w = $(this).width(); }).addClass('image'); But the removeClass function doesn't work like that :P

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  • Instantiate proper class based on some input

    - by Adam Backstrom
    I'm attempting to understand how "switch as a code smell" applies when the proper code path is determined by some observable piece of data. My Webapp object sets an internal "host" object based on the hostname of the current request. Each Host subclass corresponds to one possible hostname and application configuration: WwwHost, ApiHost, etc. What is an OOP way for a host subclass to accept responsibility for a specific hostname, and for Webapp to get an instance of the appropriate subclass? Currently, the hostname check and Host instantiation exists within the Webapp object. I could move the test into a static method within the Host subclasses, but I would still need to explicitly list those subclasses in Webapp unless I restructure further. It seems like any solution will require new subclasses to be added to some centralized list.

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  • How do we provide valid time estimates during Sprint Planning without doing "too much" design?

    - by Michael Edenfield
    My team is getting up to speed with Scrum, but most of us are more familiar with non-agile or "pseudo-"agile methodologies. The part that is the biggest hurdle for us is running an efficient Sprint Planning meeting where we break our backlog items into tasks, and estimate hours. (I'm using the terminology from the VS2010 Scrum Template; apologies if I use the wrong word somewhere.) When we try to figure out how long a task is going to take, we often fall into the trap of designing the feature at the code level -- table layout, interfaces, etc -- in order to figure out how long that's going to take. I'm pretty sure this is not the appropriate place to be doing that kind of design. We should be scheduling tasks for these design meetings during the sprint. However, we are having trouble figuring out how else to come up with meaningful estimates for the tasks. Are there any practical habits/techniques/etc. for making a judgement call about how long a feature is going to take, without knowing how you plan to implement it? If our time estimates are going to change significantly once the design has been completed, how can we properly budget our Sprint backlog ahead of time? EDIT: Just to clarify, since some of the comments/answers are very valid but I think addressing the wrong question. We know that what we're doing is not right, and that we should be building time into the sprint for this design. Conceptually all of the developers understand that. We also also bringing in a team member with Scrum experience to keep us on track if we start going off into the weeds. The problem is that, without going through this design process, we are finding it difficult to provide concrete time estimates for anything. We are constantly saying things like "well if we design it this way it might take 8 hours but if we end up having to do this other way instead that will take about 32 but it might not be as bad once we start trying to write it...". I also assume that this process will get better once we have some historical velocity to work from, but many of the technologies and architectural patterns we are using are new to us. But if potentially-wildly-wrong estimates are just a natural part of adapting this process then we will just need to recondition ourselves to accept that :)

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  • Google I/O 2012 - So You've Read the Design Guide; Now What?

    Google I/O 2012 - So You've Read the Design Guide; Now What? Daniel Lehmann, Tor Norbye, Richard Ngo The Android Design Guide describes how to design beautiful Android apps, but not how to build them. In this talk we'll give practical tips for how to apply fit & finish as you are implementing your design, we'll show you how to avoid some common pitfalls, we'll describe some useful patterns, and show you how tools can help. For all I/O 2012 sessions, go to developers.google.com From: GoogleDevelopers Views: 38 1 ratings Time: 56:31 More in Science & Technology

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  • propertyplaceholderconfigurer class name substitution problem

    - by Alex
    The following example works for "class name substitution using the PropertyPlaceHolderConfigurer": http://forum.springsource.org/showpost.php?p=228136&postcount=2 HOWEVER, when porting this code over (messages.properties, com.spring.ioc.TestClass, and spring-config.xml) to a web application, the class name substitution now fails! 1) I am running on the webapp on Tomcat through the Eclipse plugin. 2) In the web.xml I have the following: <context-param> <param-name>contextConfigLocation</param-name> <param-value>/WEB-INF/spring-config.xml</param-value> </context-param> <listener> <listener-class>org.springframework.web.context.ContextLoaderListener</listener-class> </listener> 3) The following is output in the log: 282 [main] DEBUG org.springframework.beans.factory.support.DefaultListableBeanFactory - Ignoring bean class loading failure for bean 'test' org.springframework.beans.factory.CannotLoadBeanClassException: Cannot find class [${test.class}] for bean with name 'test' defined in ServletContext resource [/WEB-INF/spring-config.xml]; nested exception is java.lang.ClassNotFoundException: ${test.class} at org.springframework.beans.factory.support.AbstractBeanFactory.resolveBeanClass(AbstractBeanFactory.java:1141) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.predictBeanType(AbstractAutowireCapableBeanFactory.java:524) at org.springframework.beans.factory.support.AbstractBeanFactory.isFactoryBean(AbstractBeanFactory.java:1177) at org.springframework.beans.factory.support.DefaultListableBeanFactory.getBeanNamesForType(DefaultListableBeanFactory.java:222) at org.springframework.context.support.AbstractApplicationContext.invokeBeanFactoryPostProcessors(AbstractApplicationContext.java:505) at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:362) at org.springframework.web.context.ContextLoader.createWebApplicationContext(ContextLoader.java:255) at org.springframework.web.context.ContextLoader.initWebApplicationContext(ContextLoader.java:199) at org.springframework.web.context.ContextLoaderListener.contextInitialized(ContextLoaderListener.java:45) at org.apache.catalina.core.StandardContext.listenerStart(StandardContext.java:3795) at org.apache.catalina.core.StandardContext.start(StandardContext.java:4252) at org.apache.catalina.core.ContainerBase.start(ContainerBase.java:1014) at org.apache.catalina.core.StandardHost.start(StandardHost.java:736) at org.apache.catalina.core.ContainerBase.start(ContainerBase.java:1014) at org.apache.catalina.core.StandardEngine.start(StandardEngine.java:443) at org.apache.catalina.core.StandardService.start(StandardService.java:448) at org.apache.catalina.core.StandardServer.start(StandardServer.java:700) at org.apache.catalina.startup.Catalina.start(Catalina.java:552) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25) at java.lang.reflect.Method.invoke(Method.java:597) at org.apache.catalina.startup.Bootstrap.start(Bootstrap.java:295) at org.apache.catalina.startup.Bootstrap.main(Bootstrap.java:433) Caused by: java.lang.ClassNotFoundException: ${test.class} at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1438) at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1284) at org.springframework.util.ClassUtils.forName(ClassUtils.java:211) at org.springframework.beans.factory.support.AbstractBeanDefinition.resolveBeanClass(AbstractBeanDefinition.java:385) at org.springframework.beans.factory.support.AbstractBeanFactory.resolveBeanClass(AbstractBeanFactory.java:1138) ... 23 more Note: I haven't included it, but the PropertyPlaceHolderConfigurer is successfully locating the messages.properties file, but this seems to happen AFTER the above error is output?! DOES ANYBODY KNOW WHY THIS IS THE CASE AND HOW I CAN OVERCOME THIS PROBLEM?

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  • How to access the backing field of an inherited class using fluent nhibernate

    - by Akk
    How do i set the Access Strategy in the mapping class to point to the inherited _photos field? public class Content { private IList<Photo> _photos; public Content() { _photos = new List<Photo>(); } public virtual IEnumerable<Photo> Photos { get { return _photos; } } public virtual void AddPhoto() {...} } public class Article : Content { public string Body {get; set;} } I am currently using thw following to try and locate the backing field but an exception is thrown as it cannot be found. public class ArticleMap : ClassMap<Article> { HasManyToMany(x => x.Photos) .Access.CamelCaseField(Prefix.Underscore) //_photos //... } i tried moving the backing field _photos directly into the class and the access works. So how can i access the backing field of an inherited class?

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  • abstract class in C++

    - by Alexander
    I have a derived derived class from an abstract class. The code is below. I have a FishTank class which is derived from an Aquarium and Aquarium is derived from item. My question is that should I put the definition of virtual int minWidth() const = 0; in aquarium again or is the code below sufficient? class Item{ public: virtual int minWidth() const = 0; }; class Aquarium{ public: virtual int calWidth() = 0; // Pure virtual function. }; class FishTank : public Aquarium{ public: FishTank(int base1, int base2, int height); ~FishTank(); int calWidth(); int minWidth(); };

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  • Objective-c class initializer executes multiple times

    - by apisip
    Unless I misunderstood it, this LINK from Apple's documentation clearly states that the class initializer, "+ (void)initialize)", only executes once per class. Here is the excerpt: Special Considerations initialize it is invoked only once per class. If you want to perform independent initialization for the class and for categories of the class, you should implement load methods. However, I'm getting a weird behavior on my project and the initializer is being executed twice. So I have to check if _classContext is null. I only got one class that has this method. What are the possible reasons why this is happening? I'm using XCode 4.5.2 and OS X 10.8.2. I got multiple iOS simulators, iPhone 5.1 and 6.0. + (void) initialize { num++; NSLog([NSString stringWithFormat:@"Times: %i", num]); if(_classContext == nil) _classContext = [[myClass alloc] init]; }

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  • implement string class with custom behavior

    - by truman
    In one of our class sir said that template allows one to customize behavior of class, and then he gave example of string class, that with few lines of code we can customize string class from STL, as in, we can make it to treat 'a' and 'z' same, 'b' and 'y' same, 'c' and 'x' same and so on. Similary 'A' and 'Z' same etc. "abc" == "zyx" is true; "Abc" == "zyx" is false; "Abc == "Zyx" is true; etc I was thinking of implementing such string class, but I am not able to do so. How can we implement such string class using templates?

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  • How should I declare default values for instance variables in Python?

    - by int3
    Should I give my class members default values like this: class Foo: num = 1 or like this? class Foo: def __init__(self): self.num = 1 In this question I discovered that in both cases, bar = Foo() bar.num += 1 is a well-defined operation. I understand that the first method will give me a class variable while the second one will not. However, if I do not require a class variable, but only need to set a default value for my instance variables, are both methods equally good? Or one of them more 'pythonic' than the other? One thing I've noticed is that in the Django tutorial, they use the second method to declare Models. Personally I think the second method is more elegant, but I'd like to know what the 'standard' way is.

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  • Is it feasible and useful to auto-generate some code of unit tests?

    - by skiwi
    Earlier today I have come up with an idea, based upon a particular real use case, which I would want to have checked for feasability and usefulness. This question will feature a fair chunk of Java code, but can be applied to all languages running inside a VM, and maybe even outside. While there is real code, it uses nothing language-specific, so please read it mostly as pseudo code. The idea Make unit testing less cumbersome by adding in some ways to autogenerate code based on human interaction with the codebase. I understand this goes against the principle of TDD, but I don't think anyone ever proved that doing TDD is better over first creating code and then immediatly therafter the tests. This may even be adapted to be fit into TDD, but that is not my current goal. To show how it is intended to be used, I'll copy one of my classes here, for which I need to make unit tests. public class PutMonsterOnFieldAction implements PlayerAction { private final int handCardIndex; private final int fieldMonsterIndex; public PutMonsterOnFieldAction(final int handCardIndex, final int fieldMonsterIndex) { this.handCardIndex = Arguments.requirePositiveOrZero(handCardIndex, "handCardIndex"); this.fieldMonsterIndex = Arguments.requirePositiveOrZero(fieldMonsterIndex, "fieldCardIndex"); } @Override public boolean isActionAllowed(final Player player) { Objects.requireNonNull(player, "player"); Hand hand = player.getHand(); Field field = player.getField(); if (handCardIndex >= hand.getCapacity()) { return false; } if (fieldMonsterIndex >= field.getMonsterCapacity()) { return false; } if (field.hasMonster(fieldMonsterIndex)) { return false; } if (!(hand.get(handCardIndex) instanceof MonsterCard)) { return false; } return true; } @Override public void performAction(final Player player) { Objects.requireNonNull(player); if (!isActionAllowed(player)) { throw new PlayerActionNotAllowedException(); } Hand hand = player.getHand(); Field field = player.getField(); field.setMonster(fieldMonsterIndex, (MonsterCard)hand.play(handCardIndex)); } } We can observe the need for the following tests: Constructor test with valid input Constructor test with invalid inputs isActionAllowed test with valid input isActionAllowed test with invalid inputs performAction test with valid input performAction test with invalid inputs My idea mainly focuses on the isActionAllowed test with invalid inputs. Writing these tests is not fun, you need to ensure a number of conditions and you check whether it really returns false, this can be extended to performAction, where an exception needs to be thrown in that case. The goal of my idea is to generate those tests, by indicating (through GUI of IDE hopefully) that you want to generate tests based on a specific branch. The implementation by example User clicks on "Generate code for branch if (handCardIndex >= hand.getCapacity())". Now the tool needs to find a case where that holds. (I haven't added the relevant code as that may clutter the post ultimately) To invalidate the branch, the tool needs to find a handCardIndex and hand.getCapacity() such that the condition >= holds. It needs to construct a Player with a Hand that has a capacity of at least 1. It notices that the capacity private int of Hand needs to be at least 1. It searches for ways to set it to 1. Fortunately it finds a constructor that takes the capacity as an argument. It uses 1 for this. Some more work needs to be done to succesfully construct a Player instance, involving the creation of objects that have constraints that can be seen by inspecting the source code. It has found the hand with the least capacity possible and is able to construct it. Now to invalidate the test it will need to set handCardIndex = 1. It constructs the test and asserts it to be false (the returned value of the branch) What does the tool need to work? In order to function properly, it will need the ability to scan through all source code (including JDK code) to figure out all constraints. Optionally this could be done through the javadoc, but that is not always used to indicate all constraints. It could also do some trial and error, but it pretty much stops if you cannot attach source code to compiled classes. Then it needs some basic knowledge of what the primitive types are, including arrays. And it needs to be able to construct some form of "modification trees". The tool knows that it needs to change a certain variable to a different value in order to get the correct testcase. Hence it will need to list all possible ways to change it, without using reflection obviously. What this tool will not replace is the need to create tailored unit tests that tests all kinds of conditions when a certain method actually works. It is purely to be used to test methods when they invalidate constraints. My questions: Is creating such a tool feasible? Would it ever work, or are there some obvious problems? Would such a tool be useful? Is it even useful to automatically generate these testcases at all? Could it be extended to do even more useful things? Does, by chance, such a project already exist and would I be reinventing the wheel? If not proven useful, but still possible to make such thing, I will still consider it for fun. If it's considered useful, then I might make an open source project for it depending on the time. For people searching more background information about the used Player and Hand classes in my example, please refer to this repository. At the time of writing the PutMonsterOnFieldAction has not been uploaded to the repo yet, but this will be done once I'm done with the unit tests.

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  • boost::enable_if class template method

    - by aaa
    I got class with template methods that looks at this: struct undefined {}; template<typename T> struct is_undefined : mpl::false_ {}; template<> struct is_undefined<undefined> : mpl::true_ {}; template<class C> struct foo { template<class F, class V> typename boost::disable_if<is_undefined<C> >::type apply(const F &f, const V &variables) { } template<class F, class V> typename boost::enable_if<is_undefined<C> >::type apply(const F &f, const V &variables) { } }; apparently, both templates are instantiated, resulting in compile time error. is instantiation of template methods different from instantiation of free functions? I have fixed this differently, but I would like to know what is up. Thank you

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  • How access PhysicalMaterial from Actor Class?

    - by EmAdpres
    I use Projectile for my weapon system and UDKProjectile has two main function to handle Hit of projectiles(=bullet of my weapon): simulated function ProcessTouch(Actor Other, Vector HitLocation, Vector HitNormal) // For Actors simulated event HitWall(vector HitNormal, actor Wall, PrimitiveComponent WallComp) // Everything except Actors ( I guess) the first method, the function just give me the actor which I hit and my question is How I can get that actor's physical material by first parameter ( Other ), in order to make a proper react about it ( for example a proper Sound of collide ) ... A tricky (but hateful ) way which I knew works is, make a Trace from a little back of that actor to that actor, and use HitInfo parameter which include physical Material ! But there should be a more standard way !

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  • Application Design in Interface Builder Challenge

    - by Sheehan Alam
    I want to design an app that launches other sub-apps. Main View will contain 4 buttons. Clicking on each button respectively will launch the other sub-apps. Each sub-app will have a UITabBarController which has its own different views. At any point I want the user to be able to go back to the Main View from any of the sub-apps. I am not sure how to design this in IB.

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