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  • Bad Design? Constructor of composition uses `this`

    - by tanascius
    Example: class MyClass { Composition m_Composition; void MyClass() { m_Composition = new Composition( this ); } } I am interested in using depenency-injection here. So I will have to refactor the constructor to something like: void MyClass( Composition composition ) { m_Composition = composition; } However I get a problem now, since the Composition-object relies on the object of type MyClass which is just created. Can a dependency container resolve this? Is it supposed to do so? Or is it just bad design from the beginning on?

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  • Getting up to speed on modern architecture

    - by Matt Thrower
    Hi, I don't have any formal qualifications in computer science, rather I taught myself classic ASP back in the days of the dotcom boom and managed to get myself a job and my career developed from there. I was a confident and, I think, pretty good programmer in ASP 3 but as others have observed one of the problems with classic ASP was that it did a very good job of hiding the nitty-gritty of http so you could become quite competent as a programmer on the basis of relatively poor understanding of the technology you were working with. When I changed on to .NET at first I treated it like classic ASP, developing stand-alone applications as individual websites simply because I didn't know any better at the time. I moved jobs at this point and spent the next several years working on a single site whose architecture relied heavily on custom objects: in other words I gained a lot of experience working with .NET as a middle-tier development tool using a quite old-fashioned approach to OO design along the lines of the classic "car" class example that's so often used to teach OO. Breaking down programs into blocks of functionality and basing your classes and methods around that. Although we worked under an Agile approach to manage the work the whole setup was classic client/server stuff. That suited me and I gradually got to grips with .NET and started using it far more in the manner that it should be, and I began to see the power inherent in the technology and precisely why it was so much better than good old ASP 3. In my latest job I have found myself suddenly dropped in at the deep end with two quite young, skilled and very cutting-edge programmers. They've built a site architecture which is modelling along a lot of stuff which is new to me and which, in truth I'm having a lot of trouble understanding. The application is built on a cloud computing model with multi-tenancy and the architecture is all loosely coupled using a lot of interfaces, factories and the like. They use nHibernate a lot too. Shortly after I joined, both these guys left and I'm now supposedly the senior developer on a system whose technology and architecture I don't really understand and I have no-one to ask questions of. Except you, the internet. Frankly I feel like I've been pitched in at the deep end and I'm sinking. I'm not sure if this is because I lack the educational background to understand this stuff, if I'm simply not mathematically minded enough for modern computing (my maths was never great - my approach to design is often to simply debug until it works, then refactor until it looks neat), or whether I've simply been presented with too much of too radical a nature at once. But the only way to find out which it is is to try and learn it. So can anyone suggest some good places to start? Good books, tutorials or blogs? I've found a lot of internet material simply presupposes a level of understanding that I just don't have. Your advice is much appreciated. Help a middle-aged, stuck in the mud developer get enthusastic again! Please!

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  • Which options do I have for Java process communication?

    - by Dmitriy Matveev
    We have a place in a code of such form: void processParam(Object param) { wrapperForComplexNativeObject result = jniCallWhichMayCrash(param); processResult(result); } processParam - method which is called with many different arguments. jniCallWhichMayCrash - a native method which is intended to do some complex processing of it's parameter and to create some complex object. It can crash in some cases. wrapperForComplexNativeObject - wrapper type generated by SWIG processResult - a method written in pure Java which processes it's parameter by creation of several kinds (by the kinds I'm not meaning classes, maybe some like hierarchies) of objects: 1 - Some non-unique objects which are referencing each other (from the same hierarchy), these objects can have duplicates created from the invocations of processParam() method with different parameter values. Since it's costly to keep all the duplicates it's necessary to cache them. 2 - Some unique objects which are referencing each other (from the same hierarchy) and some of the objects of 1st kind. After processParam is executed for each of the arguments from some set the data created in processResult will be processed together. The problem is in fact that jniCallWhichMayCrash method may crash the entire JVM and this will be very bad. The reason of crash may be such that it can happen for one argument value and not for the other. We've decided that it's better to ignore crashes inside of JVM and just skip some chunks of data when such crashes occur. In order to do this we should run processParam function inside of separate process and pass the result somehow (HOW? HOW?! This is a question) to the main process and in case of any crashes we will only lose some part of data (It's ok) without lose of everything else. So for now the main problem is implementation of transport between different processes. Which options do I have? I can think about serialization and transmitting of binary data by the streams, but serialization may be not very fast due to object complexity. Maybe I have some other options of implementing this?

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  • Technical non-terminating condition in a loop

    - by Snarfblam
    Most of us know that a loop should not have a non-terminating condition. For example, this C# loop has a non-terminating condition: any even value of i. This is an obvious logic error. void CountByTwosStartingAt(byte i) { // If i is even, it never exceeds 254 for(; i < 255; i += 2) { Console.WriteLine(i); } } Sometimes there are edge cases that are extremely unlikeley, but technically constitute non-exiting conditions (stack overflows and out-of-memory errors aside). Suppose you have a function that counts the number of sequential zeros in a stream: int CountZeros(Stream s) { int total = 0; while(s.ReadByte() == 0) total++; return total; } Now, suppose you feed it this thing: class InfiniteEmptyStream:Stream { // ... Other members ... public override int Read(byte[] buffer, int offset, int count) { Array.Clear(buffer, offset, count); // Output zeros return count; // Never returns -1 (end of stream) } } Or more realistically, maybe a stream that returns data from external hardware, which in certain cases might return lots of zeros (such as a game controller sitting on your desk). Either way we have an infinite loop. This particular non-terminating condition stands out, but sometimes they don't. A completely real-world example as in an app I'm writing. An endless stream of zeros will be deserialized into infinite "empty" objects (until the collection class or GC throws an exception because I've exceeded two billion items). But this would be a completely unexpected circumstance (considering my data source). How important is it to have absolutely no non-terminating conditions? How much does this affect "robustness?" Does it matter if they are only "theoretically" non-terminating (is it okay if an exception represents an implicit terminating condition)? Does it matter whether the app is commercial? If it is publicly distributed? Does it matter if the problematic code is in no way accessible through a public interface/API? Edit: One of the primary concerns I have is unforseen logic errors that can create the non-terminating condition. If, as a rule, you ensure there are no non-terminating conditions, you can identify or handle these logic errors more gracefully, but is it worth it? And when? This is a concern orthogonal to trust.

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  • C++ Headers/Source Files

    - by incrediman
    (Duplicate of C++ Code in Header Files) What is the standard way to split up C++ classes between header and source files? Am I supposed to put everything in the header file? Or should I declare the classes in the header file and define them in a .cpp file (source file)? Sorry if I'm shaky on the terminology here (declare, define, etc). So what's the standard?

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  • Name the pattern - Create, Set, Execute, Destroy?

    - by Seb Nilsson
    I somewhere heard that the .NET Framework was built around specific pattern, which they tried to uphold as much as possible. var rsa = new RSACryptoServiceProvider(); // Create rsa.ImportParameters(GetParameters()); // Set byte[] encrypted = rsa.Encrypt(data, true); // Execute // Destroyed by garbage-collector Are there any variants of this? What are the general pros and cons?

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  • Alternative to jQuery .data()?

    - by thebossman
    I'm a big fan of jQuery's .data() method, but I can't always use it. Often times I am rendering html templates that I pass via AJAX and I need to attach metadata to each of the elements in the template. For example: <ul> {% for item in itemlist %} <li metadata="{{ item.metadata }}">{{ item.name }}</li> {% endfor %} </ul> I know attaching attributes to store data is bad practice (and it might not even work in older versions of IE). What is the best practice? Is there a good alternative to this method?

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  • Use of properties vs backing-field inside owner class

    - by whatispunk
    I love auto-implemented properties in C# but lately there's been this elephant standing in my cubicle and I don't know what to do with him. If I use auto-implemented properties (hereafter "aip") then I no longer have a private backing field to use internally. This is fine because the aip has no side-effects. But what if later on I need to add some extra processing in the get or set? Now I need to create a backing-field so I can expand my getters and setters. This is fine for external code using the class, because they won't notice the difference. But now all of the internal references to the aip are going to invoke these side-effects when they access the property. Now all internal access to the once aip must be refactored to use the backing-field. So my question is, what do most of you do? Do you use auto-implemented properties or do you prefer to always use a backing-field? What do you think about properties with side-effects?

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  • Where do you put your unit test?

    - by soulmerge
    I have found several conventions to housekeeping unit tests in a project and I'm not sure which approach would be suitable for our next PHP project. I am trying to find the best convention to encourage easy development and accessibility of the tests when reviewing the source code. I would be very interested in your experience/opinion regarding each: One folder for productive code, another for unit tests: This separates unit tests from the logic files of the project. This separation of concerns is as much a nuisance as it is an advantage: Someone looking into the source code of the project will - so I suppose - either browse the implementation or the unit tests (or more commonly: the implementation only). The advantage of unit tests being another viewpoint to your classes is lost - those two viewpoints are just too far apart IMO. Annotated test methods: Any modern unit testing framework I know allows developers to create dedicated test methods, annotating them (@test) and embedding them in the project code. The big drawback I see here is that the project files get cluttered. Even if these methods are separated using a comment header (like UNIT TESTS below this line) it just bloats the class unnecessarily. Test files within the same folders as the implementation files: Our file naming convention dictates that PHP files containing classes (one class per file) should end with .class.php. I could imagine that putting unit tests regarding a class file into another one ending on .test.php would render the tests much more present to other developers without tainting the class. Although it bloats the project folders, instead of the implementation files, this is my favorite so far, but I have my doubts: I would think others have come up with this already, and discarded this option for some reason (i.e. I have not seen a java project with the files Foo.java and FooTest.java within the same folder.) Maybe it's because java developers make heavier use of IDEs that allow them easier access to the tests, whereas in PHP no big editors have emerged (like eclipse for java) - many devs I know use vim/emacs or similar editors with little support for PHP development per se. What is your experience with any of these unit test placements? Do you have another convention I haven't listed here? Or am I just overrating unit test accessibility to reviewers?

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  • Accessing the "super of this" in Java

    - by gerdemb
    This is what I'm doing now. Is there a better way to access the super class? public class SearchWidget { private void addWishlistButton() { final SearchWidget thisWidget = this; button.addClickHandler(new ClickHandler() { public void onClick(ClickEvent event) { // A better way to access the super class? // something like "this.super" ...? workWithWidget(thisWidget); } } } } I'm programming with Google Web Toolkit, but I think this is really a generic Java question.

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  • What types of objects should the ViewModel reference in the MVVM pattern?

    - by Blanthor
    I've seen quite a few examples of MVVM. I can see that the View should reference the ViewModel. I've seen recently an example of a ViewModel referencing a View, which seems wrong to me, as it would result in tighter coupling. Given that ViewModel is often described as an intermediary between the View and the Model, is there more to the ViewModel than a facade to domain objects? I hope I used the term "facade" correctly here.

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  • package private static member class vs. package private class

    - by Helper Method
    I was writing two implementations of a linked list for an assignment, a doubly linked list and a circular doubly linked list. Now as the class representing a Link within the linked list is the same in both implementations, I want to use it in both. Now I wonder which approach would be better: Implement the Link class as a package private static member class in the first implementation and then use this class in the second implementation or make the Link class a package private class.

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  • Do you ever make a code change and just test rather than trying to fully understand the change you'v

    - by Clay Nichols
    I'm working in a 12 year old code base which I have been the only developer on. There are times that I'll make a a very small change based on an intuition (or quantum leap in logic ;-). Usually I try to deconstruct that change and make sure I read thoroughly the code. However sometimes, (more and more these days) I just test and make sure it had the effect I wanted. (I'm a pretty thorough tester and would test even if I read the code). This works for me and we have surprisingly (compared to most software I see) few bugs escape into the wild. But what I'm wondering is whether this is just the "art" side of coding. Yes, in an ideal world you would exhaustively read every bit of code that your change modified, but I in practice, if you're confident that it only affects a small section of code, is this a common practice? I can obviously see where this would be a disastrous approach in the hands of a poor programmer. But then, I've seen programmers who ostensibly are reading the code and break stuff left and right (in their own code based which only they have been working on).

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  • MapReduce programming system in java-actionscript

    - by eco_bach
    Just finished reading ch23 in the excellent 'Beautiful Code' http://oreilly.com/catalog/9780596510046 on Distributed Programming with MapReduce. I understand that MapReduce is a programming system designed for large-scale data processing problems, but I have a hard time getting my head around the basic examples given and how I might apply them in real world situations. Can someone give a simple example of MapReduce implemented using either java, javascript or actionscript?

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  • Check if web form values has changed. Best practice

    - by Andrew Florko
    Hello everybody, I have multi-step form and user can navigate to any page to modify or add information. There is a menu that shows progress and steps user completed. This menu allows to navigate to any step user completed or going to complete. Inspite of big button "Save and Continue" some users click this menu to navigate further. I have to check - if values have changed in a form and ask: "Save changes? Yes/No". What is the best way (with minimum code) you suggest me to check if form values have changed. Thank you in advance!

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  • Am I using too much jQuery? When am I crossing the line?

    - by Andrea
    Lately I found myself using jQuery and JavaScript a lot, often to do the same things that I did before using CSS. For example, I alternate table rows color or create buttons and links hover effects using JavaScript/jQuery. Is this acceptable? Or should I keep using CSS for these kinds of things? So the real question is: When I'm using too much jQuery? How can I understand when I'm crossing the line?

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  • Where should my "filtering" logic reside with Linq-2-SQL and ASP.NET-MVC in View or Controller?

    - by Nate Bross
    I have a main Table, with several "child" tables. TableA and TableAChild1 and TableAChild2. I have a view which shows the information in TableA, and then has two columns of all items in TableAChild1 and TableAChild2 respectivly, they are rendered with Partial views. Both child tables have a bit field for VisibleToAll, and depending on user role, I'd like to either display all related rows, or related rows where VisibleToAll = true. This code, feels like it should be in the controller, but I'm not sure how it would look, because as it stands, the controller (limmited version) looks like this: return View("TableADetailView", repos.GetTableA(id)); Would something like this be even work, and would it be bad what if my DataContext gets submitted, would that delete all the rows that have VisibleToAll == false? var tblA = repos.GetTableA(id); tblA.TableAChild1 = tblA.TableAChild1.Where(tmp => tmp.VisibleToAll == true); tblA.TableAChild2 = tblA.TableAChild2.Where(tmp => tmp.VisibleToAll == true); return View("TableADetailView", tblA); It would also be simple to add that logic to the RendarPartial call from the main view: <% Html.RenderPartial("TableAChild1", Model.TableAChild1.Where(tmp => tmp.VisibleToAll == true); %>

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  • Finding databases for use in applications

    - by JonF
    Does anyone have some recommendations on how I can find databases for random things that I might want to use in my application. For example, a database of zip code locations, area code cities, car engines, IP address locations, or whatever. I'm just asking generally when you decide you need a bunch of data where are some good places to start looking other than google?

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  • using ref to view error

    - by Avram
    Hello. I working now on firm that using ref in every function. The reason, is to catch errors. There example : //return true if the read is success //otherwise writing to the error ,the problem bool ReadFile(ref string error) Question: How do you catching errors? Using ref,exceptions or other way?

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  • Design pattern to separate messages from actual process.

    - by Manish Gupta
    I am having a C# application to sync data between PC and palm devices. There are codes written like below: showMessage("synchronizing Table1"); Sync(destTable1,sourceTable1); Sync(destTable2,sourceTable2); showMessage("synchronizing Table2"); // more code How do I separate the actual process of synchronizing from displaying message? Which design pattern to follow? Thanks in advance...

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  • What is the reason not to use select * ?

    - by Chris Lively
    I've seen a number of people claim that you should specifically name each column you want in your select query. Assuming I'm going to use all of the columns anyway, why would I not use SELECT *? Even considering the question from 9/24, I don't think this is an exact duplicate as I'm approaching the issue from a slightly different perspective. One of our principles is to not optimize before it's time. With that in mind, it seems like using SELECT * should be the preferred method until it is proven to be a resource issue or the schema is pretty much set in stone. Which, as we know, won't occur until development is completely done. That said, is there an overriding issue to not use SELECT *?

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