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  • Is case after case in a switch efficient?

    - by RandomGuy
    Just a random question regarding switch case efficiency in case after case; is the following code (assume pseudo code): function bool isValid(String myString){ switch(myString){ case "stringA": case "stringB": case "stringC": return true; default: return false; } more efficient than this: function bool isValid(String myString){ switch(myString){ case "stringA": return true; case "stringB": return true; case "stringC": return true; default: return false; } Or is the performance equal? I'm not thinking in a specific language but if needed let's assume it's Java or C (for this case would be needed to use chars instead of strings).

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  • Clean way to use mutable implementation of Immutable interfaces for encapsulation

    - by dsollen
    My code is working on some compost relationship which creates a tree structure, class A has many children of type B, which has many children of type C etc. The lowest level class, call it bar, also points to a connected bar class. This effectively makes nearly every object in my domain inter-connected. Immutable objects would be problematic due to the expense of rebuilding almost all of my domain to make a single change to one class. I chose to go with an interface approach. Every object has an Immutable interface which only publishes the getter methods. I have controller objects which constructs the domain objects and thus has reference to the full objects, thus capable of calling the setter methods; but only ever publishes the immutable interface. Any change requested will go through the controller. So something like this: public interface ImmutableFoo{ public Bar getBar(); public Location getLocation(); } public class Foo implements ImmutableFoo{ private Bar bar; private Location location; @Override public Bar getBar(){ return Bar; } public void setBar(Bar bar){ this.bar=bar; } @Override public Location getLocation(){ return Location; } } public class Controller{ Private Map<Location, Foo> fooMap; public ImmutableFoo addBar(Bar bar){ Foo foo=fooMap.get(bar.getLocation()); if(foo!=null) foo.addBar(bar); return foo; } } I felt the basic approach seems sensible, however, when I speak to others they always seem to have trouble envisioning what I'm describing, which leaves me concerned that I may have a larger design issue then I'm aware of. Is it problematic to have domain objects so tightly coupled, or to use the quasi-mutable approach to modifying them? Assuming that the design approach itself isn't inherently flawed the particular discussion which left me wondering about my approach had to do with the presence of business logic in the domain objects. Currently I have my setter methods in the mutable objects do error checking and all other logic required to verify and make a change to the object. It was suggested that this should be pulled out into a service class, which applies all the business logic, to simplify my domain objects. I understand the advantage in mocking/testing and general separation of logic into two classes. However, with a service method/object It seems I loose some of the advantage of polymorphism, I can't override a base class to add in new error checking or business logic. It seems, if my polymorphic classes were complicated enough, I would end up with a service method that has to check a dozen flags to decide what error checking and business logic applies. So, for example, if I wanted to have a childFoo which also had a size field which should be compared to bar before adding par my current approach would look something like this. public class Foo implements ImmutableFoo{ public void addBar(Bar bar){ if(!getLocation().equals(bar.getLocation()) throw new LocationException(); this.bar=bar; } } public interface ImmutableChildFoo extends ImmutableFoo{ public int getSize(); } public ChildFoo extends Foo implements ImmutableChildFoo{ private int size; @Override public int getSize(){ return size; } @Override public void addBar(Bar bar){ if(getSize()<bar.getSize()){ throw new LocationException(); super.addBar(bar); } My colleague was suggesting instead having a service object that looks something like this (over simplified, the 'service' object would likely be more complex). public interface ImmutableFoo{ ///original interface, presumably used in other methods public Location getLocation(); public boolean isChildFoo(); } public interface ImmutableSizedFoo implements ImmutableFoo{ public int getSize(); } public class Foo implements ImmutableSizedFoo{ public Bar bar; @Override public void addBar(Bar bar){ this.bar=bar; } @Override public int getSize(){ //default size if no size is known return 0; } @Override public boolean isChildFoo return false; } } public ChildFoo extends Foo{ private int size; @Override public int getSize(){ return size; } @Override public boolean isChildFoo(); return true; } } public class Controller{ Private Map<Location, Foo> fooMap; public ImmutableSizedFoo addBar(Bar bar){ Foo foo=fooMap.get(bar.getLocation()); service.addBarToFoo(foo, bar); returned foo; } public class Service{ public static void addBarToFoo(Foo foo, Bar bar){ if(foo==null) return; if(!foo.getLocation().equals(bar.getLocation())) throw new LocationException(); if(foo.isChildFoo() && foo.getSize()<bar.getSize()) throw new LocationException(); foo.setBar(bar); } } } Is the recommended approach of using services and inversion of control inherently superior, or superior in certain cases, to overriding methods directly? If so is there a good way to go with the service approach while not loosing the power of polymorphism to override some of the behavior?

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  • Colleague unwilling to use unit tests "as it's more to code"

    - by m.edmondson
    A colleague is unwilling to use unit tests and instead opting for a quick test, pass it to the users, and if all is well it is published live. Needless to say some bugs do get through. I mentioned we should think about using unit tests - but she was all against it once it was realised more code would have to be written. This leaves me in the position of modifying something and not being sure the output is the same, especially as her code is spaghetti and I try to refactor it when I get a chance. So whats the best way forward for me?

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  • Modular enterprise architecture using MVC and Orchard CMS

    - by MrJD
    I'm making a large scale MVC application using Orchard. And I'm going to be separating my logic into modules. I'm also trying to heavily decouple the application for maximum extensibility and testability. I have a rudimentary understanding of IoC, Repository Pattern, Unit of Work pattern and Service Layer pattern. I've made myself a diagram. I'm wondering if it is correct and if there is anything I have missed regarding an extensible application. Note that each module is a separate project. Update So I have many UI modules that use the db module, that's why they've been split up. There are other services the UI modules will use. The UI modules have been split up because they will be made over time, independent of each other.

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  • Is LINQ to objects a collection of combinators?

    - by Jimmy Hoffa
    I was just trying to explain the usefulness of combinators to a colleague and I told him LINQ to objects are like combinators as they exhibit the same value, the ability to combine small pieces to create a single large piece. Though I don't know that I can call LINQ to objects combinators. I've seen 2 levels of definition for combinator that I generalize as such: A combinator is a function which only uses things passed to it A combinator is a function which only uses things passed to it and other standard atomic functions but not state The first is very rigid and can be seen in the combinatory calculus systems and in haskell things like $ and . and various similar functions meet this rule. The second is less rigid and would allow something like sum as it uses the + function which was not passed in but is standard and not stateful. Though the LINQ extensions in C# use state in their iteration models, so I feel I can't say they're combinators. Can someone who understands the definition of a combinator more thoroughly and with more experience in these realms give a distinct ruling on this? Are my definitions of 'combinator' wrong to begin with?

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  • How do I mashup Google Maps with geolocated photos from one or more social networks?

    - by PureCognition
    I'm working on a proof of concept for a project, and I need to pin random photos to a Google Map. These photos can come from another social network, but need to be non-porn. I've done some research so far, Google's Image Search API is deprecated. So, one has to use the Custom Search API. A lot of the images aren't photos, and I'm not sure how well it handles geolocation yet. Twitter seems a little more well suited, except for the fact that people can post pictures of pretty much anything. I was also going to look into the API's for other networks such as Flickr, Picasa, Pinterest and Instagram. I know there are some aggregate services out there that might have done some of this mash-up work for me as well. If there is anyone out there that has a handle on social APIs and where I should look for this type of solution, I would really appreciate the help. Also, in cases where server-side implementation matters, I'm a .NET developer by experience.

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  • What should be a fair amount of time in an interview before rejecting a candidate?

    - by Danish
    As a panelist for technical interviews, you often come across candidates who have all the requried educational qualifications, skill sets and experience level on resumes, but struggle to answer even the most basic questions. Ideally, technical interviews should try to check different aspects of a candidate and test them on various skills. So, if the candidate falters on one aspect, one should test the other ones before coming to a conclusion. But often, if a candidates falters on the first few questions, the red flag rises up pretty quickly. What in your opinion should be the bare minimum time spent with a candidate before making a fair accessment of his/her skills and suitability for the job?

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  • Architecture/pattern resources for small applications and tools

    - by s73v3r
    I was wondering if anyone had any resources or advice related to using architecture patterns like MVVM/MVC/MVP/etc on small applications and tools, as opposed to large, enterprisy ones. EDIT: Most of the information I see on application architecture is directed at large, enterprise applications. I'm just writing small programs and tools. As far as using these architecture patterns, is it generally worthwhile to go through the overhead of using an MVC/MVVM framework? Or would I be better off keeping it simple?

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  • Error Copying Source File in Audio Spectrum Visualizer [closed]

    - by David Dimalanta
    I'm testing this code using LibGDX, Java, and Eclipse to test the music player that detects the frequency. I saw this one on this website plus the link on GitHub: http://gtomee.com/2012/07/28/audio-spectrum-visualizer-with-libgdx/ It works when running on desktop project folder but not on Android project folder and the result is this: 10-10 13:57:45.320: E/AndroidRuntime(9421): FATAL EXCEPTION: GLThread 16845 10-10 13:57:45.320: E/AndroidRuntime(9421): com.badlogic.gdx.utils.GdxRuntimeException: Error copying source file: soundtrack 1 bioman.mp3 (Internal) 10-10 13:57:45.320: E/AndroidRuntime(9421): To destination: tmp/audio-spectrum.mp3 (External) 10-10 13:57:45.320: E/AndroidRuntime(9421): at com.badlogic.gdx.files.FileHandle.copyFile(FileHandle.java:625) 10-10 13:57:45.320: E/AndroidRuntime(9421): at com.badlogic.gdx.files.FileHandle.copyTo(FileHandle.java:534) 10-10 13:57:45.320: E/AndroidRuntime(9421): at com.bodapps.rhythm.Drop.create(Drop.java:393) 10-10 13:57:45.320: E/AndroidRuntime(9421): at com.badlogic.gdx.backends.android.AndroidGraphics.onSurfaceChanged(AndroidGraphics.java:292) 10-10 13:57:45.320: E/AndroidRuntime(9421): at android.opengl.GLSurfaceView$GLThread.guardedRun(GLSurfaceView.java:1505) 10-10 13:57:45.320: E/AndroidRuntime(9421): at android.opengl.GLSurfaceView$GLThread.run(GLSurfaceView.java:1240) 10-10 13:57:45.320: E/AndroidRuntime(9421): Caused by: com.badlogic.gdx.utils.GdxRuntimeException: Error stream writing to file: tmp/audio-spectrum.mp3 (External) 10-10 13:57:45.320: E/AndroidRuntime(9421): at com.badlogic.gdx.files.FileHandle.write(FileHandle.java:313) 10-10 13:57:45.320: E/AndroidRuntime(9421): at com.badlogic.gdx.files.FileHandle.copyFile(FileHandle.java:623) 10-10 13:57:45.320: E/AndroidRuntime(9421): ... 5 more 10-10 13:57:45.320: E/AndroidRuntime(9421): Caused by: com.badlogic.gdx.utils.GdxRuntimeException: Error writing file: tmp/audio-spectrum.mp3 (External) 10-10 13:57:45.320: E/AndroidRuntime(9421): at com.badlogic.gdx.files.FileHandle.write(FileHandle.java:293) 10-10 13:57:45.320: E/AndroidRuntime(9421): at com.badlogic.gdx.files.FileHandle.write(FileHandle.java:305) 10-10 13:57:45.320: E/AndroidRuntime(9421): ... 6 more 10-10 13:57:45.320: E/AndroidRuntime(9421): Caused by: java.io.FileNotFoundException: /storage/sdcard0/tmp/audio-spectrum.mp3: open failed: EACCES (Permission denied) 10-10 13:57:45.320: E/AndroidRuntime(9421): at libcore.io.IoBridge.open(IoBridge.java:416) 10-10 13:57:45.320: E/AndroidRuntime(9421): at java.io.FileOutputStream.<init>(FileOutputStream.java:88) 10-10 13:57:45.320: E/AndroidRuntime(9421): at com.badlogic.gdx.files.FileHandle.write(FileHandle.java:289) 10-10 13:57:45.320: E/AndroidRuntime(9421): ... 7 more 10-10 13:57:45.320: E/AndroidRuntime(9421): Caused by: libcore.io.ErrnoException: open failed: EACCES (Permission denied) 10-10 13:57:45.320: E/AndroidRuntime(9421): at libcore.io.Posix.open(Native Method) 10-10 13:57:45.320: E/AndroidRuntime(9421): at libcore.io.BlockGuardOs.open(BlockGuardOs.java:110) 10-10 13:57:45.320: E/AndroidRuntime(9421): at libcore.io.IoBridge.open(IoBridge.java:400) 10-10 13:57:45.320: E/AndroidRuntime(9421): ... 9 more I'm not sure if I come this to the right place for help and suggestions.

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  • Why no more macro languages?

    - by Muhammad Alkarouri
    In this answer to a previous question of mine about scripting languages suitability as shells, DigitalRoss identifies the difference between the macro languages and the "parsed typed" languages in terms of string treatment as the main reason that scripting languages are not suitable for shell purposes. Macro languages include nroff and m4 for example. What are the design decisions (or compromises) needed to create a macro programming language? And why are most of the mainstream languages parsed rather than macro? This very similar question (and the accepted answer) covers fairly well why the parsed typed languages, take C for example, suffer from the use of macros. I believe my question here covers different grounds: Macro languages or those working on a textual level are not wholly failures. Arguably, they include bash, Tcl and other shell languages. And they work in a specific niche such as shells as explained in my links above. Even m4 had a fairly long time of success, and some of the web template languages can be regarded as macro languages. It is quite possible that macros and parsed typing do not go well together and that is why macros "break" common languages. In the answer to the linked question, a macro like #define TWO 1+1 would have been covered by the common rules of the language rather than conflicting with those of the host language. And issues like "macros are not typed" and "code doesn't compile" are not relevant in the context of a language designed as untyped and interpreted with little concern for efficiency. The question about the design decisions needed to create a macro language pertain to a hobby project which I am currently working on on designing a new shell. Taking the previous question in context would clarify the difference between adding macros to a parsed language and my objective. I hope the clarification shows that the question linked doesn't cover this question, which is two parts: If I want to create a macro language (for a shell or a web template, for example), what limitations and compromises (and guidelines, if exist) need to be done? (Probably answerable by a link or reference) Why have no macro languages succeed in becoming mainstream except in particular niches? What makes typed languages successful in large programming, while "stringly-typed" languages succeed in shells and one-liner like environments?

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  • How do you develop web applications? [closed]

    - by ck3g
    How do you and/or your team develop your web applications? Language, framework or platform doesn't matter. I would like to know about the structure of your environment. For example: Using IDE on workstation and project files on remote host accessing via sftp. Files are saved instantly on remote host; All files are local and are uploaded on remote host during saving; Files are local, web server is running on local computer and is tested at local host. etc. You could write down also about the benefits of your approach, this will be useful for me. Thanks upd: Here must be a question and here it is: which is the best approach by your opinion?

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  • How do you dive into large code bases?

    - by miku
    What tools and techniques do you use for exploring and learning an unknown code base? I am thinking of tools like grep, ctags, unit-tests, functional test, class-diagram generators, call graphs, code metrics like sloccount and so on. I'd be interested in your experiences, the helpers you used or wrote yourself and the size of the codebase, with which you worked with. I realize, that this is also a process (happening over time) and that learning can mean "can give a ten minute intro" to "can refactor and shrink this to 30% of the size". Let's leave that open for now.

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  • Organizing code for iOS app development

    - by KronoS
    I've been developing an app for the iOS platform, and as I've been going along, I've noticed that I've done a terrible job of keeping my files (.h, .m, .mm) organized. Is there any industry standards or best practices when it comes to organizing files for an iOS project? My files include custom classes (beside the view controllers), customized View Controllers, third-party content, code that works only on iOS 5.0+ and code that works on previous versions. What I'm looking for is a solution to keep things organized in a manner that others (or myself in years to come) can look at this and understand the basic structure of the application and not get lost in the multiple files found therein.

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  • Should I break contract early?

    - by cbang
    About 7 months ago I made the switch from a 5 year permie role (as a support developer in C#) to a contract role. I did this because I was stagnating in my old role. The extra cash contracting is really helping too. Unfortunately my team leader has taken a dislike to me from day 1. He regularly tells me I went out contracting too early, and frequently remarks that people in their 20's have no idea what they are talking about (I am 29). I was recently given the task of configuring our reports via our in house reporting library. It works off of a database driven criteria base, with controls being loaded as needed. The configs can get fairly complex, with controls having various levels of dependency on each other. I had a short time frame to get 50 reports working, and I was told to just get the basic configuration done, after which they will be handed over to the reporting team for fine tuning, then the test team. Our updated system was deployed 2 weeks ago, and it turned out that about 15 reports had issues causing incorrect data to be returned. Upon investigation I discovered that the reporting team hadn't even looked at them, and the test team hadn't bothered to test the reports. In spite of this, my team leader has told me that it is 100% my fault. As a result, our help desk got hit hard. I worked back until 2am that night to fix the highest priority issues (on my wedding anniversary!). The next day I arrive at work at 7:45 am to continue with the fixes. I got no thanks, but keep getting repeatedly told by my manager that "I fucked up" and "this is all my fault". I told my team leader I would spend part of my weekend working to fix the remaining issues. His response was "so you fucking should! you fucked it all up!" in front of the rest of the team. I responded "No worries." and left. I spent a decent chunk of my weekend working on it. Within 2 business days of finding out about the issues, I had all the medium and high priority issues fixed. The only comments my team leader has made to me in the last 2 weeks is to tell me how I have caused a big mess, and to tell me it was all my fault. I get this multiple times a day. If I make any jokes to anyone else in the team, I get told not to be a smartass... even though the rest of the team jokes throughout the day. Apart from that, all I get is angry looks any time I am anywhere near the guy. I don't give any response other than "alright" or silence when he starts giving me a hard time. Today we found out that the pilot release for the next stage has been pushed back. My team leader has said this was caused by me (but the higher ups said no such thing). He also said I have "no understanding of the ramifications of my actions". My question is, should I break contract (I am contracted until June 30) and find another role? No one else in my team will speak up in my favour, as they are contractors too and have no interest in rocking the boat. I could complain to my team leaders boss, but I can't see that helping, as I will still be stuck in the same team. As this is my first contract, I imagine getting the next one will be hard without a reference. I can't figure out if this guy is trying to get me fired up to provoke a confrontation (the guy loves conflict), or if he is just venting anger, or what. Copping this blame day after day is really wearing me down and making me depressed... especially since I have a wife and kid to support).

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  • Changing frontend cache

    - by Utsav
    Our architecture consists of a front-end cache that most read only users obtain their data from directly. The front-end cache sits in front of a farm of webservers that serve pages written in PHP. We need to be able to detect certain conditions at the front-end cache level and pass those values through to the back-end via HTTP headers. For example we would like to manually tag the carrier network based on the IP address. So, for incoming traffic if the user is say coming from an IP address in the range of "41.202.192.0"/19 we would tag them as being a Orange Cameroon user by setting the appropriate HTTP request header, e.g., X-Carrier = "Orange Cameroon". Based on the setting of this header we would like to vary the cache and serve a different banner to the end user. How would you go about doing this? Keep in mind that we don't want to pollute the cache and we also don't want to create too many small cache segments. Assumptions: You can assume that the X-Carrier has already been detected in our cache. So, for the purposes of your test you can just set this value manually in your example script.

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  • How to Implement Complex Form Data?

    - by SoulBeaver
    I'm supposed to implement a relatively complex form that looks like follows, but has at least four more pages requiring the user to fill in all necessary information for the tracks: This data will need to be sent to the server, which is implemented using Dropwizard. I'm looking for best practices on how to upload and send such a complex form with potentially dozens of songs to the server. The simplest available solution I have seen is a simple multipart/form-data request with the following form schema (Source): Client <html> <body> <h1>File Upload with Jersey</h1> <form action="rest/file/upload" method="post" enctype="multipart/form-data"> <p> Select a file : <input type="file" name="file" size="45" /> </p> <input type="submit" value="Upload It" /> </form> </body> </html> Server @POST @Path("/upload") @Consumes(MediaType.MULTIPART_FORM_DATA) public Response uploadTrack(final FormDataMultiPart multiPart) { List<FormDataBodyPart> artists = multiPart.getFields("artist"); StringBuffer output = new StringBuffer(); for (FormDataBodyPart artist : artists) output.append(artist.getValueAs(String.class)); List<FormDataBodyPart> tracks = multiPart.getFields("track"); for (FormDataBodyPart track : tracks) writeToFile(track.getValueAs(InputStream.class), "Foo"); return Response.status(200).entity(output.toString()).build(); } Then I have also read about file uploads via Ajax or Formdata (Mozilla HttpRequest) which allows for Posts in the formats application/x-www-form-urlencoded, multipart/form-data, or text/plain. I don't know which approach, if any, is best. An ideal solution would be to utilize Jackson to convert a json string into my data objects, but I don't get the impression that this is possible with binary data.

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  • Looking for tips on managing complexity with SCM repositories

    - by Philip Regan
    I am a solo developer in my department and I have a lot of individual projects, all created and managed by me. I started using SVN at ProjectLocker via Versions on the Mac a couple years ago when the variety of projects started getting unwieldy. Scenario 1: Now I have a process that is of reasonable complexity it can be broken up into multiple smaller applications and they all share files. In one phase, there is a single shared file—a constants file—that is shared between a Cocoa app and an iPhone app framework. In the second phase, the iPhone app framework will be used to create individual apps of the same ilk—controller classes and what not will all be the same—but with different content in each. The problem that I am running across is that the file in the first phase is in one repository with the application that started it, and the app framework is in a second, separate repository. Scenario 2: I have another application framework that partially relies on code from an open source project. This is all internal, non-commerical work, but again, the application framework is going to be used to create a variety of unique products and processes. So, now I have an internally managed repository and an externally managed one out of my control. I make little changes to the open source code to meet the needs of my framework when there is an update I download, but I never commit back into the external repository (though, now that I think about it, I don't think I'm committing it to mine either. Oops). The Problem I have all of this set up on my production Mac quite nicely, but duplicating and subsequently maintaining that environment on my laptop has been challenging. For Scenario 1, I've thought of merging these two projects together into the same repository because they are, for all intents and purposes inextricably linked. But, Scenario 2, I think I'm stuck just managing files as best I can. The Question I'm wondering if anyone has any tips on how to manage either of these situations, as well as other complex SCM scenarios when it comes to linking various files from various repositories together. My familiarity with SVN only comes from my work with Versions. It's been great, but I'm a little out of my depth here.

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  • git, maven and jenkins - versioning, dev and release builds workflow

    - by varesa
    What is the preferred way to do the following with git, maven and jenkins: I am developping an application, which I would like to maintain "dev" and "release" branches. I would like jenkins to build both. It could be so that the release-artifacts would have versions like 1.5.2 and the dev-builds would just be 0.0.1-SNAPSHOTs. I would like to not have to have 2 different pom.xml files. I looked into profiles, but they don't seem to be able to change artifact versions. One way I looked at could be adding a 'qualifier' to the test-builds. Of course I could just rename the file, because the real artifact-information on this is not important, because the app is a standalone one. What would be the preferred way to doing this? Or how would you do this?

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  • Unit test SHA256 wrapper queries

    - by Sam Leach
    I am just beginning to write unit tests. So please bear with me. I have the following SHA256 wrapper. public static string SHA256(string plainText) { StringBuilder sb = new StringBuilder(); SHA256CryptoServiceProvider provider = new SHA256CryptoServiceProvider(); var hashedBytes = provider.ComputeHash(Encoding.UTF8.GetBytes(plainText)); for (int i = 0; i < hashedBytes.Length; i++) { sb.Append(hashedBytes[i].ToString("x2").ToLower()); } return sb.ToString(); } Do I want to be testing it? If so, what do you recommend? My thought process is as follows: What logic is there here. The answer is my for loop and ToString("x2") so from my understanding I want to be testing this part? I can assume Encoding.UTF8.GetBytes(plainText) works. Correct assumption? I can assume SHA256CryptoServiceProvider.ComputeHash() works. Correct assumption? I want to be only testing my logic. In this case is limited to the printing of hex encoded hash. Correct? Thanks.

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  • How to make creating viewmodels at runtime less painful

    - by Mr Happy
    I apologize for the long question, it reads a bit as a rant, but I promise it's not! I've summarized my question(s) below In the MVC world, things are straightforward. The Model has state, the View shows the Model, and the Controller does stuff to/with the Model (basically), a controller has no state. To do stuff the Controller has some dependencies on web services, repository, the lot. When you instantiate a controller you care about supplying those dependencies, nothing else. When you execute an action (method on Controller), you use those dependencies to retrieve or update the Model or calling some other domain service. If there's any context, say like some user wants to see the details of a particular item, you pass the Id of that item as parameter to the Action. Nowhere in the Controller is there any reference to any state. So far so good. Enter MVVM. I love WPF, I love data binding. I love frameworks that make data binding to ViewModels even easier (using Caliburn Micro a.t.m.). I feel things are less straightforward in this world though. Let's do the exercise again: the Model has state, the View shows the ViewModel, and the ViewModel does stuff to/with the Model (basically), a ViewModel does have state! (to clarify; maybe it delegates all the properties to one or more Models, but that means it must have a reference to the model one way or another, which is state in itself) To do stuff the ViewModel has some dependencies on web services, repository, the lot. When you instantiate a ViewModel you care about supplying those dependencies, but also the state. And this, ladies and gentlemen, annoys me to no end. Whenever you need to instantiate a ProductDetailsViewModel from the ProductSearchViewModel (from which you called the ProductSearchWebService which in turn returned IEnumerable<ProductDTO>, everybody still with me?), you can do one of these things: call new ProductDetailsViewModel(productDTO, _shoppingCartWebService /* dependcy */);, this is bad, imagine 3 more dependencies, this means the ProductSearchViewModel needs to take on those dependencies as well. Also changing the constructor is painful. call _myInjectedProductDetailsViewModelFactory.Create().Initialize(productDTO);, the factory is just a Func, they are easily generated by most IoC frameworks. I think this is bad because Init methods are a leaky abstraction. You also can't use the readonly keyword for fields that are set in the Init method. I'm sure there are a few more reasons. call _myInjectedProductDetailsViewModelAbstractFactory.Create(productDTO); So... this is the pattern (abstract factory) that is usually recommended for this type of problem. I though it was genius since it satisfies my craving for static typing, until I actually started using it. The amount of boilerplate code is I think too much (you know, apart from the ridiculous variable names I get use). For each ViewModel that needs runtime parameters you'll get two extra files (factory interface and implementation), and you need to type the non-runtime dependencies like 4 extra times. And each time the dependencies change, you get to change it in the factory as well. It feels like I don't even use a DI container anymore. (I think Castle Windsor has some kind of solution for this [with it's own drawbacks, correct me if I'm wrong]). do something with anonymous types or dictionary. I like my static typing. So, yeah. Mixing state and behavior in this way creates a problem which don't exist at all in MVC. And I feel like there currently isn't a really adequate solution for this problem. Now I'd like to observe some things: People actually use MVVM. So they either don't care about all of the above, or they have some brilliant other solution. I haven't found an in-depth example of MVVM with WPF. For example, the NDDD-sample project immensely helped me understand some DDD concepts. I'd really like it if someone could point me in the direction of something similar for MVVM/WPF. Maybe I'm doing MVVM all wrong and I should turn my design upside down. Maybe I shouldn't have this problem at all. Well I know other people have asked the same question so I think I'm not the only one. To summarize Am I correct to conclude that having the ViewModel being an integration point for both state and behavior is the reason for some difficulties with the MVVM pattern as a whole? Is using the abstract factory pattern the only/best way to instantiate a ViewModel in a statically typed way? Is there something like an in depth reference implementation available? Is having a lot of ViewModels with both state/behavior a design smell?

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  • How to get multiple open-source projects to use a standard way of doing something.

    - by Marco
    Problem In the last couple weeks, I've used 3 different "repository" tools (listed in alphabetical order): gradle ivy maven I'm calling them "repository" tools because I've also used sbt -- which fortunately uses ivy to manage it's cache or local repository. Each of these tools will create it's own repository. The defaults are: ~/.m2/repository for maven ~/.gradle/cache ~/.ivy2/cache Why can't they all use the same cache? Goal I'd like to change the world so that all three build tools could use the same cache. I'm looking for advice about issues I'm likely to run into and smart ways to get around them. By "use the same cache", I do not mean "retrieve from another build tool's cache". I mean "retrieve from and store in another build tool's cache". While I could go ahead and submit issues to the three projects, I know from experience (as a developer on an open source project), that if you want something done, you're best off getting it done yourself. Also, it seems like I need to get all 3 communities on board to some degree. What is the recommended approach for getting this kind of thing done? How do I approach the different communities? Do I work on patches for the 3 different projects, or would it be better off to create my own "interface" project that deals with these issues and have the 3 tools interface with that? Is this a standards question that I need to address on that front? Lastly, if I'm missing something and this is possible (in an globally configurable fashion), then please let me know.

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  • C library build system dependencies

    - by Ninefingers
    Hello all, This debate has cropped up on a mailing list for a project I'm involved in. Unfortunately we're quite a small bunch at the moment, so I want to ask a wider audience. We're writing a C library (for arbitrary precision arithmetic) and are investigating build systems. Currently we have a bash script in desperate need of work. I believe we can't use autotools etc due to licensing (bsd vs gpl). So I suggested we use a modern scripting language like python or perl. The question is: is having something like perl or python around at build time an unrealistic dependency on Unix-like platforms these days?

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  • What characteristic of a software determines its operational scope?

    - by Dark Star1
    How can I classify whether a software is a medium with the ability to grow into an enterprise level software or whether it is already there? And how should I use the information to choose the appropriate language/tool to create the software? At first I was asking whether Java or PHP is the best tool to design enterprise level software, however I've suddenly realized that I am unable to put the software I'm tasked with redesigning into the proper scope so I'm lost. Edit: I guess I'm looking for tell tale signs in software that may tip the favour towards enterprise level type software in the sense of functional and operational characteristics; functional: what it does (multi-functional), Architectural characteristics such as highly modular. operational: multi-sourced and multi-homed, databases, e.t.c. To be honest the reason I ask is because I'm skeptical about the use of PhP to design a piece of employee and partial accounting software. I'm more tipping towards the use of JSP and an hmvc framework such as JSF, wickets, e.t.c. where as the other guy wants to go the PhP way although I'm not experienced with PhP, as far as I know it's not an OO oriented language hence my skepticsm towards it.

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  • Win32 and Win64 programming in C sources?

    - by Nick Rosencrantz
    I'm learning OpenGL with C and that makes me include the windows.h file in my project. I'd like to look at some more specific windows functions and I wonder if you can cite some good sources for learning the basics of Win32 and Win64 programming in C (or C++). I use MS Visual C++ and I prefer to stick with C even though much of the Windows API seems to be C++. I'd like my program to be portable and using some platform-indepedent graphics library like OpenGL I could make my program portable with some slight changes for window management. Could you direct me with some pointers to books or www links where I can find more info? I've already studied the OpenGL red book and the C programming language, what I'm looking for is the platform-dependent stuff and how to handle that since I run both Linux and Windows where I find the development environment Visual Studio is pretty good but the debugger gdb is not available on windows so it's a trade off which environment i'll choose in the end - Linux with gcc or Windows with MSVC. Here is the program that draws a graphics primitive with some use of windows.h This program is also runnable on Linux without changing the code that actually draws the graphics primitive: #include <windows.h> #include <gl/gl.h> LRESULT CALLBACK WindowProc(HWND, UINT, WPARAM, LPARAM); void EnableOpenGL(HWND hwnd, HDC*, HGLRC*); void DisableOpenGL(HWND, HDC, HGLRC); int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, LPSTR lpCmdLine, int nCmdShow) { WNDCLASSEX wcex; HWND hwnd; HDC hDC; HGLRC hRC; MSG msg; BOOL bQuit = FALSE; float theta = 0.0f; /* register window class */ wcex.cbSize = sizeof(WNDCLASSEX); wcex.style = CS_OWNDC; wcex.lpfnWndProc = WindowProc; wcex.cbClsExtra = 0; wcex.cbWndExtra = 0; wcex.hInstance = hInstance; wcex.hIcon = LoadIcon(NULL, IDI_APPLICATION); wcex.hCursor = LoadCursor(NULL, IDC_ARROW); wcex.hbrBackground = (HBRUSH)GetStockObject(BLACK_BRUSH); wcex.lpszMenuName = NULL; wcex.lpszClassName = "GLSample"; wcex.hIconSm = LoadIcon(NULL, IDI_APPLICATION);; if (!RegisterClassEx(&wcex)) return 0; /* create main window */ hwnd = CreateWindowEx(0, "GLSample", "OpenGL Sample", WS_OVERLAPPEDWINDOW, CW_USEDEFAULT, CW_USEDEFAULT, 256, 256, NULL, NULL, hInstance, NULL); ShowWindow(hwnd, nCmdShow); /* enable OpenGL for the window */ EnableOpenGL(hwnd, &hDC, &hRC); /* program main loop */ while (!bQuit) { /* check for messages */ if (PeekMessage(&msg, NULL, 0, 0, PM_REMOVE)) { /* handle or dispatch messages */ if (msg.message == WM_QUIT) { bQuit = TRUE; } else { TranslateMessage(&msg); DispatchMessage(&msg); } } else { /* OpenGL animation code goes here */ glClearColor(0.0f, 0.0f, 0.0f, 0.0f); glClear(GL_COLOR_BUFFER_BIT); glPushMatrix(); glRotatef(theta, 0.0f, 0.0f, 1.0f); glBegin(GL_TRIANGLES); glColor3f(1.0f, 0.0f, 0.0f); glVertex2f(0.0f, 1.0f); glColor3f(0.0f, 1.0f, 0.0f); glVertex2f(0.87f, -0.5f); glColor3f(0.0f, 0.0f, 1.0f); glVertex2f(-0.87f, -0.5f); glEnd(); glPopMatrix(); SwapBuffers(hDC); theta += 1.0f; Sleep (1); } } /* shutdown OpenGL */ DisableOpenGL(hwnd, hDC, hRC); /* destroy the window explicitly */ DestroyWindow(hwnd); return msg.wParam; } LRESULT CALLBACK WindowProc(HWND hwnd, UINT uMsg, WPARAM wParam, LPARAM lParam) { switch (uMsg) { case WM_CLOSE: PostQuitMessage(0); break; case WM_DESTROY: return 0; case WM_KEYDOWN: { switch (wParam) { case VK_ESCAPE: PostQuitMessage(0); break; } } break; default: return DefWindowProc(hwnd, uMsg, wParam, lParam); } return 0; } void EnableOpenGL(HWND hwnd, HDC* hDC, HGLRC* hRC) { PIXELFORMATDESCRIPTOR pfd; int iFormat; /* get the device context (DC) */ *hDC = GetDC(hwnd); /* set the pixel format for the DC */ ZeroMemory(&pfd, sizeof(pfd)); pfd.nSize = sizeof(pfd); pfd.nVersion = 1; pfd.dwFlags = PFD_DRAW_TO_WINDOW | PFD_SUPPORT_OPENGL | PFD_DOUBLEBUFFER; pfd.iPixelType = PFD_TYPE_RGBA; pfd.cColorBits = 24; pfd.cDepthBits = 16; pfd.iLayerType = PFD_MAIN_PLANE; iFormat = ChoosePixelFormat(*hDC, &pfd); SetPixelFormat(*hDC, iFormat, &pfd); /* create and enable the render context (RC) */ *hRC = wglCreateContext(*hDC); wglMakeCurrent(*hDC, *hRC); } void DisableOpenGL (HWND hwnd, HDC hDC, HGLRC hRC) { wglMakeCurrent(NULL, NULL); wglDeleteContext(hRC); ReleaseDC(hwnd, hDC); }

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  • With which class to start Test Driven Development of card game application? And what would be the next 5 to 7 tests?

    - by Maxis
    I have started to write card game applications. Some model classes: CardSuit, CardValue, Card Deck, IDeckCreator, RegularDeckCreator, DoubleDeckCreator Board Hand and some game classes: Turn, TurnHandler IPlayer, ComputerPlayer, HumanPlayer IAttackStrategy, SimpleAttachStrategy, IDefenceStrategy, SimpleDefenceStrategy GameData, Game are already written. My idea is to create engine, where two computer players could play game and then later I could add UI part. Already for some time I'm reading about Test Driven Development (TDD) and I have idea to start writing application from scratch, as currently I have tendency to write not needed code, which seems usable in future. Also code doesn't have any tests and it is hard to add them now. Seems that TDD could improve all these issue - minimum of needed code, good test coverage and also could help to come to right application design. But I have one issue - I can't decide from where to start TDD? Should I start from bottom - Card related classes or somewhere on top - Game, TurnHandler, ... ? With which class you would start? And what would be the next 5 to 7 tests? (use the card game you know the best) I would like to start TDD with your help and then continue on my own!

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