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  • The way I think about Diagnostic tools

    - by Daniel Moth
    Every software has issues, or as we like to call them "bugs". That is not a discussion point, just a mere fact. It follows that an important skill for developers is to be able to diagnose issues in their code. Of course we need to advance our tools and techniques so we can prevent bugs getting into the code (e.g. unit testing), but beyond designing great software, diagnosing bugs is an equally important skill. To diagnose issues, the most important assets are good techniques, skill, experience, and maybe talent. What also helps is having good diagnostic tools and what helps further is knowing all the features that they offer and how to use them. The following classification is how I like to think of diagnostics. Note that like with any attempt to bucketize anything, you run into overlapping areas and blurry lines. Nevertheless, I will continue sharing my generalizations ;-) It is important to identify at the outset if you are dealing with a performance or a correctness issue. If you have a performance issue, use a profiler. I hear people saying "I am using the debugger to debug a performance issue", and that is fine, but do know that a dedicated profiler is the tool for that job. Just because you don't need them all the time and typically they cost more plus you are not as familiar with them as you are with the debugger, doesn't mean you shouldn't invest in one and instead try to exclusively use the wrong tool for the job. Visual Studio has a profiler and a concurrency visualizer (for profiling multi-threaded apps). If you have a correctness issue, then you have several options - that's next :-) This is how I think of identifying a correctness issue Do you want a tool to find the issue for you at design time? The compiler is such a tool - it gives you an exact list of errors. Compilers now also offer warnings, which is their way of saying "this may be an error, but I am not smart enough to know for sure". There are also static analysis tools, which go a step further than the compiler in identifying issues in your code, sometimes with the aid of code annotations and other times just by pointing them at your raw source. An example is FxCop and much more in Visual Studio 11 Code Analysis. Do you want a tool to find the issue for you with code execution? Just like static tools, there are also dynamic analysis tools that instead of statically analyzing your code, they analyze what your code does dynamically at runtime. Whether you have to setup some unit tests to invoke your code at runtime, or have to manually run your app (and interact with it) under the tool, or have to use a script to execute your binary under the tool… that varies. The result is still a list of issues for you to address after the analysis is complete or a pause of the execution when the first issue is encountered. If a code path was not taken, no analysis for it will exist, obviously. An example is the GPU Race detection tool that I'll be talking about on the C++ AMP team blog. Another example is the MSR concurrency CHESS tool. Do you want you to find the issue at design time using a tool? Perform a code walkthrough on your own or with colleagues. There are code review tools that go beyond just diffing sources, and they help you with that aspect too. For example, there is a new one in Visual Studio 11 and searching with my favorite search engine yielded this article based on the Developer Preview. Do you want you to find the issue with code execution? Use a debugger - let’s break this down further next. This is how I think of debugging: There is post mortem debugging. That means your code has executed and you did something in order to examine what happened during its execution. This can vary from manual printf and other tracing statements to trace events (e.g. ETW) to taking dumps. In all cases, you are left with some artifact that you examine after the fact (after code execution) to discern what took place hoping it will help you find the bug. Learn how to debug dump files in Visual Studio. There is live debugging. I will elaborate on this in a separate post, but this is where you inspect the state of your program during its execution, and try to find what the problem is. More from me in a separate post on live debugging. There is a hybrid of live plus post-mortem debugging. This is for example what tools like IntelliTrace offer. If you are a tools vendor interested in the diagnostics space, it helps to understand where in the above classification your tool excels, where its primary strength is, so you can market it as such. Then it helps to see which of the other areas above your tool touches on, and how you can make it even better there. Finally, see what areas your tool doesn't help at all with, and evaluate whether it should or continue to stay clear. Even though the classification helps us think about this space, the reality is that the best tools are either extremely excellent in only one of this areas, or more often very good across a number of them. Another approach is to offer a toolset covering all areas, with appropriate integration and hand off points from one to the other. Anyway, with that brain dump out of the way, in follow-up posts I will dive into live debugging, and specifically live debugging in Visual Studio - stay tuned if that interests you. Comments about this post by Daniel Moth welcome at the original blog.

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  • Becoming A Great Developer

    - by Lee Brandt
    Image via Wikipedia I’ve been doing the whole programming thing for awhile and reading and watching some of the best in the business. I have come to notice that the really great developers do a few things that (I think) makes them great. Now don’t get me wrong, I am not saying that I am one of these few. I still struggle with doing some of the things that makes one great at development. Coincidently, many of these things also make you a better person period. Believe That Guidance Is Better Than Answers This is one I have no problem with. I prefer guidance any time I am learning from another developer. Answers may get you going, but guidance will leave you stranded. At some point, you will come across a problem that can only be solved by thinking for yourself and this is where that guidance will really come in handy. You can use that guidance and extrapolate whatever technology to salve that problem (if it’s the right tool for solving that problem). The problem is, lots of developers simply want someone to tell them, “Do this, then this, then set that, and write this.” Favor thinking and learn the guidance of doing X and don’t ask someone to show you how to do X, if that makes sense. Read, Read and Read If you don’t like reading, you’re probably NOT going to make it into the Great Developer group. Great developers read books, they read magazines and they read code. Open source playgrounds like SourceForge, CodePlex and GitHub, have made it extremely easy to download code from developers you admire and see how they do stuff. Chances are, if you read their blog too, they’ll even explain WHY they did what they did (see “Guidance” above). MSDN and Code Magazine have not only code samples, but explanations of how to use certain technologies and sometimes even when NOT to use that same technology. Books are also out on just about every topic. I still favor the less technology centric books. For instance, I generally don’t buy books like, “Getting Started with Jiminy Jappets”. I look for titles like, “How To Write More Effective Code” (again, see guidance). The Addison-Wesley Signature Series is a great example of these types of books. They teach technology-agnostic concepts. Head First Design Patterns is another great guidance book. It teaches the "Gang Of Four" Design Patterns in a very easy-to-understand, picture-heavy way (I LIKE pictures). Hang Your Balls Out There Even though the advice came from a 3rd-shift Kinko’s attendant, doesn’t mean it’s not sound advice. Write some code and put it out for others to read, criticize and castigate you for. Understand that there are some real jerks out there who are absolute geniuses. Don’t be afraid to get some great advice wrapped in some really nasty language. Try to take what’s good about it and leave what’s not. I have a tough time with this myself. I don’t really have any code out there that is available for review (other than my demo code). It takes some guts to do, but in the end, there is no substitute for getting a community of developers to critique your code and give you ways to improve. Get Involved Speaking of community, the local and online user groups and discussion forums are a great place to hear about technologies and techniques you might never come across otherwise. Mostly because you might not know to look. But, once you sit down with a bunch of other developers and start discussing what you’re interested in, you may open up a whole new perspective on it. Don’t just go to the UG meetings and watch the presentations either, get out there and talk, socialize. I realize geeks weren’t meant to necessarily be social creatures, but if you’re amongst other geeks, it’s much easier. I’ve learned more in the last 3-4 years that I have been involved in the community that I did in my previous 8 years of coding without it. Socializing works, even if socialism doesn’t. Continuous Improvement Lean proponents might call this “Kaizen”, but I call it progress. We all know, especially in the technology realm, if you’re not moving ahead, you’re falling behind. It may seem like drinking from a fire hose, but step back and pick out the technologies that speak to you. The ones that may you’re little heart go pitter-patter. Concentrate on those. If you’re still overloaded, pick the best of the best. Just know that if you’re not looking at the code you wrote last week or at least last year with some embarrassment, you’re probably stagnating. That’s about all I can say about that, cause I am all out of clichés to throw at it. :0) Write Code Great painters paint, great writers write, and great developers write code. The most sure-fire way to improve your coding ability is to continue writing code. Don’t just write code that your work throws on you, pick that technology you love or are curious to know more about and walk through some blog demo examples. Take the language you use everyday and try to get it to do something crazy. Who knows, you might create the next Google search algorithm! All in all, being a great developer is about finding yourself in all this code. If it is just a job to you, you will probably never be one of the “Great Developers”, but you’re probably okay with that. If, on the other hand, you do aspire to greatness, get out there and GET it. No one’s going hand it to you.

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  • When is my View too smart?

    - by Kyle Burns
    In this posting, I will discuss the motivation behind keeping View code as thin as possible when using patterns such as MVC, MVVM, and MVP.  Once the motivation is identified, I will examine some ways to determine whether a View contains logic that belongs in another part of the application.  While the concepts that I will discuss are applicable to most any pattern which favors a thin View, any concrete examples that I present will center on ASP.NET MVC. Design patterns that include a Model, a View, and other components such as a Controller, ViewModel, or Presenter are not new to application development.  These patterns have, in fact, been around since the early days of building applications with graphical interfaces.  The reason that these patterns emerged is simple – the code running closest to the user tends to be littered with logic and library calls that center around implementation details of showing and manipulating user interface widgets and when this type of code is interspersed with application domain logic it becomes difficult to understand and much more difficult to adequately test.  By removing domain logic from the View, we ensure that the View has a single responsibility of drawing the screen which, in turn, makes our application easier to understand and maintain. I was recently asked to take a look at an ASP.NET MVC View because the developer reviewing it thought that it possibly had too much going on in the view.  I looked at the .CSHTML file and the first thing that occurred to me was that it began with 40 lines of code declaring member variables and performing the necessary calculations to populate these variables, which were later either output directly to the page or used to control some conditional rendering action (such as adding a class name to an HTML element or not rendering another element at all).  This exhibited both of what I consider the primary heuristics (or code smells) indicating that the View is too smart: Member variables – in general, variables in View code are an indication that the Model to which the View is being bound is not sufficient for the needs of the View and that the View has had to augment that Model.  Notable exceptions to this guideline include variables used to hold information specifically related to rendering (such as a dynamically determined CSS class name or the depth within a recursive structure for indentation purposes) and variables which are used to facilitate looping through collections while binding. Arithmetic – as with member variables, the presence of arithmetic operators within View code are an indication that the Model servicing the View is insufficient for its needs.  For example, if the Model represents a line item in a sales order, it might seem perfectly natural to “normalize” the Model by storing the quantity and unit price in the Model and multiply these within the View to show the line total.  While this does seem natural, it introduces a business rule to the View code and makes it impossible to test that the rounding of the result meets the requirement of the business without executing the View.  Within View code, arithmetic should only be used for activities such as incrementing loop counters and calculating element widths. In addition to the two characteristics of a “Smart View” that I’ve discussed already, this View also exhibited another heuristic that commonly indicates to me the need to refactor a View and make it a bit less smart.  That characteristic is the existence of Boolean logic that either does not work directly with properties of the Model or works with too many properties of the Model.  Consider the following code and consider how logic that does not work directly with properties of the Model is just another form of the “member variable” heuristic covered earlier: @if(DateTime.Now.Hour < 12) {     <div>Good Morning!</div> } else {     <div>Greetings</div> } This code performs business logic to determine whether it is morning.  A possible refactoring would be to add an IsMorning property to the Model, but in this particular case there is enough similarity between the branches that the entire branching structure could be collapsed by adding a Greeting property to the Model and using it similarly to the following: <div>@Model.Greeting</div> Now let’s look at some complex logic around multiple Model properties: @if (ModelPageNumber + Model.NumbersToDisplay == Model.PageCount         || (Model.PageCount != Model.CurrentPage             && !Model.DisplayValues.Contains(Model.PageCount))) {     <div>There's more to see!</div> } In this scenario, not only is the View code difficult to read (you shouldn’t have to play “human compiler” to determine the purpose of the code), but it also complex enough to be at risk for logical errors that cannot be detected without executing the View.  Conditional logic that requires more than a single logical operator should be looked at more closely to determine whether the condition should be evaluated elsewhere and exposed as a single property of the Model.  Moving the logic above outside of the View and exposing a new Model property would simplify the View code to: @if(Model.HasMoreToSee) {     <div>There’s more to see!</div> } In this posting I have briefly discussed some of the more prominent heuristics that indicate a need to push code from the View into other pieces of the application.  You should now be able to recognize these symptoms when building or maintaining Views (or the Models that support them) in your applications.

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  • Vista install works on one computer, but bluescreens another (on which Vista is known to work)

    - by Ken
    I hope my explanations make some sense -- please ask for clarification if they don't. I had a computer running Windows Vista (Ultimate, 64-bit). All was well! Then one day there was a nasty power surge at the office, and it died. (We didn't have surge protectors at the office, unfortunately. I assumed our lines were conditioned elsewhere, or was not an issue here. Oops.) After some testing, it was determined that the PSU, motherboard, and RAM were bad. While waiting for new hardware to arrive, I put my hard disk in a spare PC which had identical parts (mobo/CPU/RAM/PSU/video). Everything worked perfectly. The only way I could even tell it wasn't my computer is because Vista asked to re-activate itself with the new hardware, which worked fine, too. So the hard disk seems OK. Then the new parts arrived. The old motherboard model is no longer manufactured, so it's a new one with the same CPU/RAM/videocard/etc. slots. The PSU is also new, while the RAM I'm using is from the spare PC mentioned above. When I put it together and tried booting with my old hard disk, it starts to boot Windows, and then (fairly early in the process) gives a bluescreen and immediately reboots (so I can't see whatever the bluescreen is trying to tell me). I tried "safe mode", which also bluescreened. I tried booting the Vista DVD and running the repair utility, which found a Vista install, confirmed that it would not boot, and, eventually, declared that it was unable to repair it. I installed Vista fresh on a new hard disk, with the new mobo/etc., and it works perfectly. (That's what I'm running now.) I've also booted a Linux CD here, which ran great, and I've run Memtest86+ for a while, which found no errors. So all the hardware apart from the old hard disk seems OK, too. I don't think the problem is with my old Vista hard disk, since I used that with another mobo/CPU just fine. I don't think it's any other part of the new hardware, since I'm able to use it (and test it) with no trouble. It's just the combination of my old Vista install plus the new PC hardware that's not happy. I can get my data off my old hard disk and onto my new hard disk, and reinstall my apps, but it would be nice if I could fix things so I could continue to use my old hard disk as before. The latest hypothesis I've heard is that Vista had trouble with the new hardware (i.e., motherboard), but we have no idea what to do about that (except Safe Mode, which didn't work). Suggestions? Hypotheses for what's not right about this combination of Vista install and motherboard? Thanks!

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  • Where can I get source code for apps on the andorid emulator?

    - by Kaustubh
    Hello, greetings. I have 2 question to put forward: I was very interested, even intrigued by the Maps application on the android emulator. Where can I get the source code for it? There is a Maps Editor on the Android Market, it cannot be downloaded to the emualtor. but again, where can I find the source code to that? Thank You, Kaustubh.

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  • I am trying to use VBA code to save inkpicture contents, can only use vb.net or C#

    - by zaphod23
    I found this code that is missing the funtion call in thelast line, any ideas on what the save to file command would be?, I'll just kludge it in. 'CODE to SAVE InkPicture to FILE Dim objInk As MSINKAUTLib.InkPicture Dim bytArr() As Byte Dim File1 As String File1 = "C:\" & TrainerSig & ".gif" Set objInk = Me.InkPicture2.Object If objInk.Ink.Strokes.Count > 0 Then bytArr = objInk.Ink.Save(2) fSaveFile bytArr, File1 End If

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  • How can I create a graph of Nginx responses by HTTP status code?

    - by rmh
    I'm looking to create a graph somewhat similar to this: But instead of graphing requests, graph responses, with a line for each HTTP response code (200 OK, 404 Not Found, 500 Server Error, etc). Creating the graph isn't the issue (use RRDtool, Server Density or something similar), but how can I best retrieve this information from Nginx? Unfortunately, this data isn't available on the page generated by NginxHttpStubStatusModule. If it was, this would be pretty easy.

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  • C++ (And other languages) - Learning from source code examples.

    - by Gabe
    I found that the most effective way for me to learn html and css was to simply find a site, right click, view the source code, and see how it worked. I'm in the process of learning c++ and I think examples/source code to look through would help me a good deal. So, how can I do this? Are there online sites that serve this purpose? Any other recommendations on learning would be great, too.

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  • How to style a code block to make all the colours look pretty like my IDE and here in stackoverflow?

    - by BritishDeveloper
    When putting code samples in my blog I would like the code to have all the appropriate colours. How can I do that? Basically if I write: foreach (ListItem item in items) { item.Text = "something"; } I want it to appear in the correct colours like it does in my Visual Studio or here at stack*overflow*. I'm bored of styling the colours of each key word manually. Is there a pre-existing javascript library I can use?

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  • Stack Trace in error in Webpage in ASP not in my code?

    - by MarceloRamires
    I'm new to web-development in ASP, and I'm experiencing a problem where I try to access a certain page through a link and I get an error, the first part says it's an exception, then tips on debugging and then the stacktrace. What happens is that this code isn't on my application, I've had errors like this before, and the peace of code that appeared usually helped me a lot.

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  • changing .emacs to use IronPython.exe and using code completion for IronPython modules ?

    - by KaluSingh Gabbar
    I configured my Emacs for code completion and other help using this link (from another question here on SO). I am a complete newbie to emacs. Can anyone tell me what should I change so it (rope, ropemacs, pymacs, yasnippet etc) picks up symbols of IronPython modules for code completion and snippets. Also I want to map: C-x RET - to invoke IronPython.exe and not Python.exe (any clue on how to do that) PS I am using Emacs with Cygwin on XP machine

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  • how do i download source code using svn on OS X?

    - by Moshe
    How can I get source code off the internet using SVN? I'm trying to download Oolong game engine for iPhone OS. I am on Mac OS X 10.6 with XCode 3.2.2. svn checkout http://oolongengine.googlecode.com/svn/trunk/ oolongengine-read-only is the command I got from the Oolong Google Code page.

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  • How can I inject Javascript (including Prototype.js) in other sites without cluttering the global na

    - by Daniel Magliola
    I'm currently on a project that is a big site that uses the Prototype library, and there is already a humongous amount of Javascript code. We're now working on a piece of code that will get "injected" into other people's sites (picture people adding a <script> tag in their sites) which will then run our code and add a bunch of DOM elements and functionality to their site. This will have new pieces of code, and will also reuse a lot of the code that we use on our main site. The problem I have is that it's of course not cool to just add a <script> that will include Prototype in people's pages. If we do that in a page that's already using ANY framework, we're guaranteed to screw everything up. jQuery gives us the option to "rename" the $ object, so it could handle this situation decently, except obviously for the fact that we're not using jQuery, so we'd have to migrate everything. Right now i'm contemplating a number of ugly choices, and I'm not sure what's best... Rewrite everything to use jQuery, with a renamed $ object everywhere. Creating a "new" Prototype library with only the subset we'd be using in "injected" code, and renaming $ to something else. Then again I'd have to adapt the parts of my code that would be shared somehow. Not using a library at all in injected code, to keep it as clean as possible, and rewriting the shared code to use no library at all. This would obviously degenerate into us creating our own frankenstein of a library, which is probably the worst case scenario ever. I'm wondering what you guys think I could do, and also whether there's some magic option that would solve all my problems... For example, do you think I could use something like Caja / Cajita to sandbox my own code and isolate it from the rest of the site, and have Prototype inside of there? Or am I completely missing the point with that? I also read once about a technique for bookmarklets, were you add your code like this: (function() { /* your code */ })(); And then your code is all inside your anonymous function and you haven't touched the global namespace at all. Do you think I could make one file containing: (function() { /* Full Code of the Prototype file here */ /* All my code that will run in the "other" site */ InitializeStuff_CreateDOMElements_AttachEventHandlers(); })(); Would that work? Would it accomplish the objective of not cluttering the global namespace, and not killing the functionality on a site that uses jQuery, for example? Or is Prototype too complex somehow to isolate it like that? (NOTE: I think I know that that would create closures everywhere and that's slower, but I don't care too much about performance, my code is not doing anything that complex)

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  • How to tell if two exe's are the same code-wise?

    - by yumcious
    Is there a way to detect whether two EXE's (compiled from VS.Net 2008 for C++/MFC) do not have any code-level changes between them i.e. for purposes of knowing that there have been no statement changes. This is for compliance purposes when my vendor ships me an exe, ostensibly with no changes made to the code since the last time we tested it. Is there a tool to check that this is so? Cheers

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  • Python/Biophysics- Trying to code a simple stochastic simulation!

    - by user359597
    Hey guys- I'm trying to figure out what to make of the following code- this is not the clear, intuitive python I've been learning. Was it written in C or something then wrapped in a python fxn? The code I wrote (not shown) is using the same math, but I couldn't figure out how to write a conditional loop. If anyone could explain/decipher/clean this up, I'd be really appreciative. I mean- is this 'good' python- or does it look funky? I'm brand new to this- but it's like the order of the fxns is messed up? I understand Gillespie's- I've successfully coded several simpler simulations. So in a nutshell- good code-(pythonic)? order? c? improvements? am i being an idiot? The code shown is the 'answer,' to the following question from a biophysics text (petri-net not shown and honestly not necessary to understand problem): "In a programming language of your choice, implement Gillespie’s First Reaction Algorithm to study the temporal behaviour of the reaction A---B in which the transition from A to B can only take place if another compound, C, is present, and where C dynamically interconverts with D, as modelled in the Petri-net below. Assume that there are 100 molecules of A, 1 of C, and no B or D present at the start of the reaction. Set kAB to 0.1 s-1 and both kCD and kDC to 1.0 s-1. Simulate the behaviour of the system over 100 s." def sim(): # Set the rate constants for all transitions kAB = 0.1 kCD = 1.0 kDC = 1.0 # Set up the initial state A = 100 B = 0 C = 1 D = 0 # Set the start and end times t = 0.0 tEnd = 100.0 print "Time\t", "Transition\t", "A\t", "B\t", "C\t", "D" # Compute the first interval transition, interval = transitionData(A, B, C, D, kAB, kCD, kDC) # Loop until the end time is exceded or no transition can fire any more while t <= tEnd and transition >= 0: print t, '\t', transition, '\t', A, '\t', B, '\t', C, '\t', D t += interval if transition == 0: A -= 1 B += 1 if transition == 1: C -= 1 D += 1 if transition == 2: C += 1 D -= 1 transition, interval = transitionData(A, B, C, D, kAB, kCD, kDC) def transitionData(A, B, C, D, kAB, kCD, kDC): """ Returns nTransition, the number of the firing transition (0: A->B, 1: C->D, 2: D->C), and interval, the interval between the time of the previous transition and that of the current one. """ RAB = kAB * A * C RCD = kCD * C RDC = kDC * D dt = [-1.0, -1.0, -1.0] if RAB > 0.0: dt[0] = -math.log(1.0 - random.random())/RAB if RCD > 0.0: dt[1] = -math.log(1.0 - random.random())/RCD if RDC > 0.0: dt[2] = -math.log(1.0 - random.random())/RDC interval = 1e36 transition = -1 for n in range(len(dt)): if dt[n] > 0.0 and dt[n] < interval: interval = dt[n] transition = n return transition, interval if __name__ == '__main__': sim()

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