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  • How to implement the disposable pattern in a class that inherits from another disposable class?

    - by TheRHCP
    Hi, I often used the disposable pattern in simple classes that referenced small amount of resources, but I never had to implement this pattern on a class that inherits from another disposable class and I am starting to be a bit confused in how to free the whole resources. I start with a little sample code: public class Tracer : IDisposable { bool disposed; FileStream fileStream; public Tracer() { //Some fileStream initialization } public void Dispose() { this.Dispose(true); GC.SuppressFinalize(this); } protected virtual void Dispose(bool disposing) { if (!disposed) { if (disposing) { if (fileStream != null) { fileStream.Dispose(); } } disposed = true; } } } public class ServiceWrapper : Tracer { bool disposed; ServiceHost serviceHost; //Some properties public ServiceWrapper () { //Some serviceHost initialization } //protected override void Dispose(bool disposing) //{ // if (!disposed) // { // if (disposing) // { // if (serviceHost != null) // { // serviceHost.Close(); // } // } // disposed = true; // } //} } My real question is: how to implement the disposable pattern inside my ServiceWrapper class to be sure that when I will dispose an instance of it, it will dispose resources in both inherited and base class? Thanks.

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  • How to restrict user from modifying data in mysql data base?

    - by Paul
    We need to deploy application(developed by Java) WAR file in client place which make use of MySql 5.0. But we would like to restrict the user from modifying any data in the database. Is there any way to protect data. The client can make use of the application but they should not be able to change any value in database. How to do that?

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  • Problem understanding Inheritance

    - by dhruvbird
    I've been racking my brains over inheritance for a while now, but am still not completely able to get around it. For example, the other day I was thinking about relating an Infallible Human and a Fallible Human. Let's first define the two: Infallible Human: A human that can never make a mistake. It's do_task() method will never throw an exception Fallible Human: A human that will occasionally make a mistakes. It's do_task() method may occasionally throw a ErrorProcessingRequest Exception The question was: IS an infallible human A fallible human OR IS a fallible human AN infallible human? The very nice answer I received was in the form of a question (I love these since it gives me rules to answer future questions I may have). "Can you pass an infallible human where a fallible human is expected OR can you pass a fallible human where an infallible human is expected?" It seems apparent that you can pass an infallible human where a fallible human is expected, but not the other way around. I guess that answered my question. However, it still feels funny saying "An infallible human is a fallible human". Does anyone else feel queasy when they say it? It almost feels as if speaking out inheritance trees is like reading out statements from propositional calculus in plain English (the if/then implication connectives don't mean the same as that in spoken English). Does anyone else feel the same?

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  • Boost shared_ptr use_count function

    - by photo_tom
    My application problem is the following - I have a large structure foo. Because these are large and for memory management reasons, we do not wish to delete them when processing on the data is complete. We are storing them in std::vector<boost::shared_ptr<foo>>. My question is related to knowing when all processing is complete. First decision is that we do not want any of the other application code to mark a complete flag in the structure because there are multiple execution paths in the program and we cannot predict which one is the last. So in our implementation, once processing is complete, we delete all copies of boost::shared_ptr<foo>> except for the one in the vector. This will drop the reference counter in the shared_ptr to 1. Is it practical to use shared_ptr.use_count() to see if it is equal to 1 to know when all other parts of my app are done with the data. One additional reason I'm asking the question is that the boost documentation on the shared pointer shared_ptr recommends not using "use_count" for production code.

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  • Is it bad practice to use Reflection in Unit testing?

    - by Sebi
    During the last years I always thought that in Java, Reflection is widely used during Unit testing. Since some of the variables/methods which have to be checked are private, it is somehow necessary to read the values of them. I always thought that the Reflection API is also used for this purpose. Last week i had to test some packages and therefore write some JUnit tests. As always i used Reflection to access private fields and methods. But my supervisor who checked the code wasn't really happy with that and told me that the Reflection API wasn't meant to use for such "hacking". Instead he suggested to modifiy the visibility in the production code. Is it really bad practice to use Reflection? I can't really believe that

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  • Programming DataEntry&Forms: Population of Official Common Data Lists

    - by rlb.usa
    As a programmer of data-entry forms of all kinds, I often find myself making fields for things like Country and State. Consider: Perhaps a list the 50 United States names is an easy thing to find (does one include DC?) , but the countries are not. Nearly every site you find has a differing list with all of the political goings on over the years, and they become outdated quickly. What's the best practice regarding population of these kinds of lists? Is there an official list somewhere that one uses to populate these kinds of formal/official fields? Where do you get this data from, when it's not exactly specified in the specs?

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  • Sequential coupling in code

    - by dotnetdev
    Hi, Is sequential coupling (http://en.wikipedia.org/wiki/Sequential_coupling) really a bad thing in code? Although it's an anti-pattern, the only risk I see is calling methods in the wrong order but documentation of an API/class library with this anti-pattern should take care of that. What other problems are there from code which is sequential? Also, this pattern could easily be fixed by using a facade it seems. Thanks

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  • Implement abstract class as a local class? pros and cons

    - by sinec
    Hi, for some reason I'm thinking on implementing interface within a some function(method) as local class. Consider following: class A{ public: virtual void MethodToOverride() = 0; }; A * GetPtrToAImplementation(){ class B : public A { public: B(){} ~B(){} void MethodToOverride() { //do something } }; return static_cast<A *>(new B()); } int _tmain(int argc, _TCHAR* argv[]) { A * aInst = GetPtrToAImplementation(); aInst->MethodToOverride(); delete aInst; return 0; } the reason why I'm doing this are: I'm lazy to implement class (B) in separate files MethodToOverride just delegates call to other class Class B shouldn't be visible to other users no need to worry about deleting aInst since smart pointers are used in real implementation So my question is if I'm doing this right? Thanks in advance!

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  • Global State and Singletons Dependency injection

    - by Manu
    this is a problem i face lot of times when i am designing a new app i'll use a sample problem to explain this think i am writing simple game.so i want to hold a list of players. i have few options.. 1.use a static field in some class private static ArrayList<Player> players = new ArrayList<Integer>(); public Player getPlayer(int i){ return players.get(i); } but this a global state 2.or i can use a singleton class PlayerList{ private PlayerList instance; private PlayerList(){...} public PlayerList getInstance() { if(instance==null){ ... } return instance; } } but this is bad because it's a singleton 3.Dependency injection class Game { private PlayerList playerList; public Game(PlayerList list) { this.list = list; } public PlayerList getPlayerList() { return playerList; } } this seems good but it's not, if any object outside Game need to look at PlayerList (which is the usual case) i have to use one of the above methods to make the Game class available globally. so I just add another layer to the problem. didn't actually solve anything. what is the optimum solution ? (currently i use Singleton approach)

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  • Flexible array members in C - bad?

    - by Lionel
    I recently read that using flexible array members in C was poor software engineering practice. However, that statement was not backed by any argument. Is this an accepted fact? (Flexible array members are a C feature introduced in C99 whereby one can declare the last element to be an array of unspecified size. For example: ) struct header { size_t len; unsigned char data[]; };

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  • How to change the value of progressbar in C#?

    - by shekhar
    Hi, I want to add an progress bar into my C# based application. I would like to know what is the good way of updating its value at particular events? My problem is, I have single function in UI which does all the processing.This function in turn calls many more functions, creates objects, updates database, etc. (basically performs all the work) and returns values in an output file. I have access to that function only. So in this how to update the progressbar's value at the end of each step? What is the best practice for this kind of situation? What is the good way to keep UI logic and business logic seperate? I want to avoid writting progressbar related code in my library code. Please suggest some solution. Thanks and Regards,

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  • UI Design - design pattern for city/country drop down? (ASP.NET MVC)

    - by JK
    What is the best way to do a city/country dropdown pair in ASP.NET MVC? I see lots of places with country above city, but that's unnatural: in real life we write city/country. I've used city, then country, but the problem is that the user then has to go backwards after changing the country. The other problem is what do you do about cities/countries not in your list? If city/country are both drop downs, then the user cant type their own city if it is missing. But if you have a dropdown and a textbox, that makes it unwieldy (you end up with 4 controls to enter 2 pieces of data). Are there any examples websites where the city/country dropdown pair are done in a very useable and clear manner?

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  • Call a non member funcion on an instance before is constructed.

    - by Tom
    Hi everyone. I'm writing a class, and this doubt came up. Is this undef. behaviour? On the other hand, I'm not sure its recommended, or if its a good practice. Is it one if I ensure no exceptions to be thrown in the init function? //c.h class C{ float vx,vy; friend void init(C& c); public: C(); ~C(); }; //c.cpp C::C() { init(*this); } void init(C& c) //throws() to ensure no exceptions ? { c.vx = 0; c.vy = 0; } Thanks in advance

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  • When using Sessions is bad thing, and whats wrong with it?

    - by Amr ElGarhy
    I know that in community server which means that you can't use Sessions, and few years ago i remember i was working on a website where we were not allowed to use sessions. In my point of view sessions are a very helpful tool if we managed how to use the right way, but is using session variable in a website is something bad, when its bad and when its not?

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  • Best way to make an attribute always an array?

    - by Shadowfirebird
    I'm using my MOO project to teach myself Test Driven Design, and it's taking me interesting places. For example, I wrote a test that said an attribute on a particular object should always return an array, so -- t = Thing.new("test") p t.names #-> ["test"] t.names = nil p t.names #-> [] The code I have for this is okay, but it doesn't seem terribly ruby to me: class Thing def initialize(names) self.names = names end def names=(n) n = [] if n.nil? n = [n] unless n.instance_of?(Array) @names = n end attr_reader :names end Is there a more elegant, Ruby-ish way of doing this? (NB: if anyone wants to tell me why this is a dumb test to write, that would be interesting too...)

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  • Should I create a new extension for an xml file?

    - by macleojw
    I'm working with a data model stored in XML files. I want to create some metadata for the model and store it alongside, but would like to be able to distinguish between the two. The data model is imported into some software from time to time and we don't want it to try to import the meta data files. To get round this, I've been thinking of creating a new extension for the metadata xml files (say .mdml). Is this good practice?

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  • Is it bad practice to initialize a variable to a dummy value?

    - by froadie
    This question is a result of the answers to this question that I just asked. It was claimed that this code is "ugly" because it initializes a variable to a value that will never be read: String tempName = null; try{ tempName = buildFileName(); } catch(Exception e){ ... System.exit(1); } FILE_NAME = tempName; Is this indeed bad practice? Should one avoid initializing variables to dummy values that will never actually be used? (EDIT - And what about initializing a String variable to "" before a loop that will concatenate values to the String...? Or is this in a separate category? e.g. String whatever = ""; for(String str : someCollection){ whatever += str; } )

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