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  • Does a C++ destructor always or only sometimes call data member destructors?

    - by Magnus
    I'm trying to validate my understanding of C++ destructors. I've read many times that C++ supplies a default destructor if I don't write one myself. But does this mean that if I DO write a destructor that the compiler WON'T still provide the default cleanup of stack-allocated class fields? My hunch is that the only sane behavior would be that all class fields are destroyed no matter what, whether I provide my own destructor or not. In which case the statement I've read so many times is actually a little misleading and could be better stated as: "Whether or not you write your own destructor, the C++ compiler always writes a default destructor-like sequence to deallocate the member variables of your class. You may then specify additional deallocations or other tasks as needed by defining your own destructor" Is this correct?

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  • Do I need to enable DRS to use Dynacache in Websphere Application Server Cluster

    - by rabs
    We are running a websphere commerce application with several websphere application servers configured in a cluster. We are using dynacache, so each server in the cluster will have its own cached objects in its own JVM. We are using CACHEIVL with database triggers for all cache invalidations. I was reading http://www.ibm.com/developerworks/websphere/library/techarticles/0603_crick/0603_crick.html and found an interesting sentence: "Furthermore, cache replication is necessary to ensure that invalidation messages are shared between the servers in a cluster." After thinking about this it would make sense that for the invalidation to work it would need to be triggered on all the servers in the cluster, but I couldn't find confirmation of this in the mountains of IBM doco. Does anyone know if you can use trigger based cache invalidation (through CACHEIVL) when you have several application servers clustered each with their own cache without DRS turned on? or do I need to use DRS for this to work?

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  • Making Wix uninstall an old plug-in when performing an upgrade

    - by IanM
    I have a main product which is installed using Wix and has its own UpgradeCode In between releases of the main product we sometimes release plug-ins which add or patch some functionality. The plug-ins are packaged in their own Wix generated .msi files with their own UpgradeCodes and generally install addition files is a separate folder from the main product. I want to create a new version of the main product which includes the functionality which was previously available in a plug-in. A user upgrading to the new version will no longer need the plug-in so it would be nice to uninstall it as part of the upgrade. Is there a way of making Wix uninstall a product with UpgradeCode2 when it is upgrading product with UpgradeCode1?

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  • Treating a fat webservice in .net 3.5 c#

    - by Chris M
    I'm dealing with an obese 3rd party webservice that returns about 3mb of data for a simple search results, about 50% of the data in that response is junk. Would it make sense then to remap this data to my own result object and ditch the response so I'm storing 1-2 mb in memory for filtering and sorting rather than using the web-responses own object and using 2-4 or am I missing a point? So far I've been accessing the webservice from a separate project and using a new class to provide the interaction and to handle the persistence so my project looks like this |- Web (mvc2 proj) |- DAL (database/storage fluent-nhibernate) |- SVCGateway (interaction layer + webservice related models) |- Services -------------- |- Tests |- Specs I'm trying to make the application behave fast and I also need to store the result set temporarily in case a customer goes to view the product and wants to go back to the results. (Service returns only 500 of possible 14K results). So basically I'm looking for confirmation that I'm doing the right thing in pushing the results into my own objects or if I'm breaking some rule or even if there's a better way of handling it. Thanks

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  • How to build Linux system from kernel to UI layer

    - by mohit
    Hi, I have been looking into MeeGo, maemo, Android architecture. They all have Linux Kernel, build some libraries on it, then build middle layer libraries [e.g telephony, media etc...]. Suppose i wana build my own system, say Linux Kernel, with some binariers like glibc, Dbus,.... UI toolkit like GTK+ and its binaries. I want to compile every project from source to customize my own linux system for desktop, netbook and handheld devices. [starting from netbook first :)] How can i build my own customize system from kernel to UI.

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  • Simple RIA backend

    - by Jeremy
    I'm creating a prototype for a java web application. Frontend is a Swing-based java applet. Backend should be a type of web-service, that is called by applet. Backend should run inside a servlet container and should have its own security (username/password) database. I know, that Tomcat has its own user database (realm), but the app should have own. Web-services, in turn, carrying out app logic and database access (via Hibernate). I'm a newbie for a web development and I'm getting lost in a huge amount of the java web frameworks. Even just reading 'introduction' and 'getting started' documents takes a lot of time. So I need an advice which framework(s) are suitable for the task and not very complex for a quick start. Thank you

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  • iOS Question. Is There a Framework for Build Time Based Apps.

    - by dugla
    I have the need for some time based effects in the iPad app I am building. The UIView class animation capability beginAnimatins/commitAnimations is exactly the sort of thing I am looking for but it is restricted to specific properties of UIView deemed animatable. Ideally, I am looking for a solution that lets me drive an a time-based function that can perhaps send messages to a class of my own choosing at the rate I specify in the animation. Specifically, I have a function - my implementation of the RenderMan function "smoothstep" which is essentially an ease-in ease-out curve common in animation. It takes [0 - 1] as input and outputs [0 - 1] as the curve is evaluated. I want to drive this function for a duration of my own choosing at rate of my own choosing. Thanks in advance. -Doug

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  • Torrents: Can I protect my software by sending wrong bytes?

    - by Martijn Courteaux
    Hi, It's a topic that everyone interests. How can I protect my software against stealing, hacking, reverse engineering? I was thinking: Do my best to protect the program for reverse engineering. Then people will crack it and seed it with torrents. Then I download my own cracked software with a torrent with my own torrent-software. My own torrent-software has then to seed incorrect data (bytes). Of course it has to seed critical bytes. So people who want to steal my software download my wrong bytes. Just that bytes that are important to startup, saving and loading data, etc... So if the stealer download from me (and seed it later) can't do anything with it, because it is broken. Is this idea relevant? Maybe, good torrent-clients check hashes from more peers to check if the packages (containing my broken bytes) I want to seed are correct or not? Thanks

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  • Under what circumstances would a Ruby $LOAD_PATH be acquired from a parent process?

    - by Dr Nic
    In my cucumber scenarios, if I call rake db:schema:load within a target Rails app folder, I get the cucumber process's $LOAD_PATH and not the Rails app's own Gemfile/load path. I think this is very weird. The consequence is that I get the following error: no such file to load -- rails/all I can't reproduce it outside of my cucumber scenario. ruby -rubygems -e "system 'rake -T'" works normally - the 'rake -T' has the application's own Gemfile-based $LOAD_PATH; and doesn't generate the error above. Can anyone think why a child process (rake -T or rake db:schema:load or rails runner...; invoked by either system, exec, %x[...] or backtick; would start with the parent processes' $LOAD_PATH (from the cucumber scenario's Gemfile) instead of its own $LOAD_PATH (from the Rails app's Gemfile)?

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  • allocator with no template

    - by Merni
    Every stl container take an allocator as a second object, template < class T, class Allocator = allocator<T> > class vector; If you write your own class It is possible to use your own allocator. But is it possible to write your own allocator without using templates? For example, writing this function is not easy if you are not allowed to use templates pointer allocate(size_type n, const_pointer = 0) { void* p = std::malloc(n * sizeof(T)); if (!p) throw std::bad_alloc(); return static_cast<pointer>(p); } Because how could you know the size of T?

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  • Multitrack sound recording - Downloadable control?

    - by Kenny Bones
    Hi, I was just wondering if anyone knows of any free Open Source software wich demonstrates multitrack recording support? I was thinking of something in the lines of this: http://www.soft411.com/company/NCH-Software/MixPad-Audio-Mixer%5Fscreenshot.html I want to include multitrack support in my own software, for personal use and I don't even know where to start to be able to do that. So preferrably a control or something would have been great. I could also be able to pay for something like this, as long as I'd be able to include it in my own VB.NET solution. Any replies are much appreciated! :) Edit: What's with the vote down? I was just wondering if there are any components I can buy and download to use in my own project..

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  • how to convert legacy query to ActiveRecord Rails way

    - by josh
    I have a query in my code as below @sqladdpayment = "INSERT INTO payments (orderid, ttlprodcost, paytype, paystatus,created_at,updated_at,userid,storeid) VALUES ('" + session[:ordersid] + "', '" + session[:totalcost] + "', '" + "1"+ "', '" + "complete" +"',current_date, current_date, '"+"1"+"','"+ "1"+"')" Here the table payments and primary key is orderid. Now, I know if I convert this to the ActiveRecord way then I will not have to put update_date, current_date because it will put that on it's own. It will also put orderid on it's own also (auto_increment). I am looking for a way to convert the above query to ActiveRecord Rails way but still be able to put orderid on my own (session[:ordersid]). I do not want to rely on auto_increment because then I will have to refactor lot of the other code. This might be a quick and dirty fix but I want to know whether this type of flexibility is offered in rails? I have wondered about this question many times. Why won't rails allow me to have that flexibility?

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  • How do I get stdout into mstest output when running in new app domain?

    - by btlog
    I have been working on test framework, which creates a new app domain to run the tests in. The primary reason being the dll's that we are testing has some horrible code that relies on the dll being located in the app domain path. (No I can't change this code.) The problem that I am having is that my test team is writing a bunch of functional tests in mstest and one of the loggers, that writes to Console.Out, does not have any of the log information captured in the trx output. When running the code through a console app all of the log information is output fine. So do the other loggers that have been implemented. My thought is that mstest is setting its own TextWriter to Console.Out, but the new app doamin has it's own TextWriter for Console.Out as the new app domain has it's own set of statics. I appreciate your ideas.

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  • Github without merging

    - by tfmoraes
    I have the following situation: A software hosted at github. 4 developers, each have her own fork in github. Each developer creates and develops using branches in her own fork. Given that we use branches to develop, we want to merge our branches (in our forks) to the upstream repo. How do I merge in github without using pull request? Is it possible to merge to upstream from my own fork? Thanks in advance.

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  • Automatically Host User Domains in Rails/Apache

    - by Steve F
    Hi, I'm currently developing a user facing web application that gives each new user their own subdomain on the site, which is fine (using subdomain_fu), but is there a way to let a user map their own domain to this subdomain? I know how to do this manually through SSH-ing into the server and editing the Apache Vhosts file by hand, but is there a way to do this automatically so that a user simply enters their domain into a box on the site (obviously they'd have to change their own DNS elsewhere)? I'm using Ruby 1.8 and Rails 2.3.3 on top of Apache. Essentially letting; http://user.application.com/article-1 be accessed from http://userdomain.com/article-1 Thanks for any help!

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  • Python change the working directory for an exe opened with startfile

    - by Saulpila
    In python i'm using the os.startfile command to start a windows executable that does especific stuff in its own folder, the python code is running from another folder, so when I start the file, it starts in the python script's working directory, but it has to start in its own directory. I've tried to use os.chdir(path) to change the working directory, but it fails, the file still not runs in it's own folder. I thought maybe there is a command like shortcut's "Start in" line. I've searched everywere, but not success. The only solution comes to my mind is to create a shortcut and add the "start in" line, then launch the shortcut, but that is very impractical.

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  • Qt Should I derive from QDataStream?

    - by ShaChris23
    I'm currently using QDataStream to serialize my classes. I have quite a few number of my own classes that I serialize often. Should I derive QDataStream to create my own DataStream class? Or is there a better pattern than this? Note that these custom classes are used by many of our projects, so maybe doing so will make coding easier. Another way to phrase this question is: when a framework provides you with a serialization class, how do you handle serializing your own custom-type classes such that you don't have to remember how to serialize them everytime.

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  • Clean Code: A Handbook of Agile Software Craftsmanship – book review

    - by DigiMortal
       Writing code that is easy read and test is not something that is easy to achieve. Unfortunately there are still way too much programming students who write awful spaghetti after graduating. But there is one really good book that helps you raise your code to new level – your code will be also communication tool for you and your fellow programmers. “Clean Code: A Handbook of Agile Software Craftsmanship” by Robert C. Martin is excellent book that helps you start writing the easily readable code. Of course, you are the one who has to learn and practice but using this book you have very good guide that keeps you going to right direction. You can start writing better code while you read this book and you can do it right in your current projects – you don’t have to create new guestbook or some other simple application to start practicing. Take the project you are working on and start making it better! My special thanks to Robert C. Martin I want to say my special thanks to Robert C. Martin for this book. There are many books that teach you different stuff and usually you have markable learning curve to go before you start getting results. There are many books that show you the direction to go and then leave you alone figuring out how to achieve all that stuff you just read about. Clean Code gives you a lot more – the mental tools to use so you can go your way to clean code being sure you will be soon there. I am reading books as much as I have time for it. Clean Code is top-level book for developers who have to write working code. Before anything else take Clean Code and read it. You will never regret your decision. I promise. Fragment of editorial review “Even bad code can function. But if code isn’t clean, it can bring a development organization to its knees. Every year, countless hours and significant resources are lost because of poorly written code. But it doesn’t have to be that way. What kind of work will you be doing? You’ll be reading code—lots of code. And you will be challenged to think about what’s right about that code, and what’s wrong with it. More importantly, you will be challenged to reassess your professional values and your commitment to your craft. Readers will come away from this book understanding How to tell the difference between good and bad code How to write good code and how to transform bad code into good code How to create good names, good functions, good objects, and good classes How to format code for maximum readability How to implement complete error handling without obscuring code logic How to unit test and practice test-driven development This book is a must for any developer, software engineer, project manager, team lead, or systems analyst with an interest in producing better code.” Table of contents Clean code Meaningful names Functions Comments Formatting Objects and data structures Error handling Boundaries Unit tests Classes Systems Emergence Concurrency Successive refinement JUnit internals Refactoring SerialDate Smells and heuristics A Concurrency II org.jfree.date.SerialDate Cross references of heuristics Epilogue Index

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  • Low level programming - what's in it for me?

    - by back2dos
    For years I have considered digging into what I consider "low level" languages. For me this means C and assembly. However I had no time for this yet, nor has it EVER been neccessary. Now because I don't see any neccessity arising, I feel like I should either just schedule some point in time when I will study the subject or drop the plan forever. My Position For the past 4 years I have focused on "web technologies", which may change, and I am an application developer, which is unlikely to change. In application development, I think usability is the most important thing. You write applications to be "consumed" by users. The more usable those applications are, the more value you have produced. In order to achieve good usability, I believe the following things are viable Good design: Well-thought-out features accessible through a well-thought-out user interface. Correctness: The best design isn't worth anything, if not implemented correctly. Flexibility: An application A should constantly evolve, so that its users need not switch to a different application B, that has new features, that A could implement. Applications addressing the same problem should not differ in features but in philosophy. Performance: Performance contributes to a good user experience. An application is ideally always responsive and performs its tasks reasonably fast (based on their frequency). The value of performance optimization beyond the point where it is noticeable by the user is questionable. I think low level programming is not going to help me with that, except for performance. But writing a whole app in a low level language for the sake of performance is premature optimization to me. My Question What could low level programming teach me, what other languages wouldn't teach me? Am I missing something, or is it just a skill, that is of very little use for application development? Please understand, that I am not questioning the value of C and assembly. It's just that in my everyday life, I am quite happy that all the intricacies of that world are abstracted away and managed for me (mostly by layers written in C/C++ and assembly themselves). I just don't see any concepts, that could be new to me, only details I would have to stuff my head with. So what's in it for me? My Conclusion Thanks to everyone for their answers. I must say, nobody really surprised me, but at least now I am quite sure I will drop this area of interest until any need for it arises. To my understanding, writing assembly these days for processors as they are in use in today's CPUs is not only unneccesarily complicated, but risks to result in poorer runtime performance than a C counterpart. Optimizing by hand is nearly impossible due to OOE, while you do not get all kinds of optimizations a compiler can do automatically. Also, the code is either portable, because it uses a small subset of available commands, or it is optimized, but then it probably works on one architecture only. Writing C is not nearly as neccessary anymore, as it was in the past. If I were to write an application in C, I would just as much use tested and established libraries and frameworks, that would spare me implementing string copy routines, sorting algorithms and other kind of stuff serving as exercise at university. My own code would execute faster at the cost of type safety. I am neither keen on reeinventing the wheel in the course of normal app development, nor trying to debug by looking at core dumps :D I am currently experimenting with languages and interpreters, so if there is anything I would like to publish, I suppose I'd port a working concept to C, although C++ might just as well do the trick. Again, thanks to everyone for your answers and your insight.

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  • Use Case Actors - Primary versus Secondary

    - by Dave Burke
    The Unified Modeling Language (UML1) defines an Actor (from UseCases) as: An actor specifies a role played by a user or any other system that interacts with the subject. In Alistair Cockburn’s book “Writing Effective Use Cases” (2) Actors are further defined as follows: Primary Actor: The primary actor of a use case is the stakeholder that calls on the system to deliver one of its services. It has a goal with respect to the system – one that can be satisfied by its operation. The primary actor is often, but not always, the actor who triggers the use case. Supporting Actors: A supporting actor in a use case in an external actor that provides a service to the system under design. It might be a high-speed printer, a web service, or humans that have to do some research and get back to us. In a 2006 article (3) Cockburn refined the definitions slightly to read: Primary Actors: The Actor(s) using the system to achieve a goal. The Use Case documents the interactions between the system and the actors to achieve the goal of the primary actor. Secondary Actors: Actors that the system needs assistance from to achieve the primary actor’s goal. Finally, the Oracle Unified Method (OUM) concurs with the UML definition of Actors, along with Cockburn’s refinement, but OUM also includes the following: Secondary actors may or may not have goals that they expect to be satisfied by the use case, the primary actor always has a goal, and the use case exists to satisfy the primary actor. Now that we are on the same “page”, let’s consider two examples: A bank loan officer wants to review a loan application from a customer, and part of the process involves a real-time credit rating check. Use Case Name: Review Loan Application Primary Actor: Loan Officer Secondary Actors: Credit Rating System A Human Resources manager wants to change the job code of an employee, and as part of the process, automatically notify several other departments within the company of the change. Use Case Name: Maintain Job Code Primary Actor: Human Resources Manager Secondary Actors: None The first example is quite straight forward; we need to define the Secondary Actor because without the “Credit Rating System” we cannot successfully complete the Use Case. In other words, the goal of the Primary Actor is to successfully complete the Loan Application, but they need the explicit “help” of the Secondary Actor (Credit Rating System) to achieve this goal. The second example is where people sometimes get confused. Within OUM we would not include the “other departments” as Secondary Actors and therefore not include them on the Use Case diagram for the following reasons: The other departments are not required for the successful completion of the Use Case We are not expecting any response from the other departments (at least within the bounds of the Use Case under discussion) Having said that, within the detail of the Use Case Specification Main Success Scenario, we would include something like: “The system sends a notification to the related department heads (ref. Business Rule BR101)” Now let’s consider one final example. A Procurement Manager wants to place a “bid” for some goods using an On-Line Trading Community (B2B version of eBay) Use Case Name: Create Bid Primary Actor: Procurement Manager Secondary Actors: On-Line Trading Community You might wonder why the Trading Community is listed as a Secondary Actor, i.e. if all we are going to do is place a bid for a specific quantity of goods at a given price and send that off to the Trading Community, then why would the Trading Community need to “assist” in that Use Case? Well, once again, it comes back to the “User Experience” and how we want to optimize that when we think about our Use Case, and ultimately, when the developer comes to assembling some code. In this final example, the Procurement Manager cannot successfully complete the “Create Bid” Use Case until they receive an affirmative confirmation back from the Trading Community that the Bid has been accepted. Therefore, the Trading Community must become a Secondary Actor and be referenced both on the Use Case diagram and Use Case Specification. Any astute readers who are wondering about the “single sitting” rule will have to wait for a follow-up Blog entry to find out how that consideration can be factored in!!! Happy Use Case writing! (1) OMG Unified Modeling LanguageTM (OMG UML), Superstructure Version 2.4.1 (2) Cockburn, A, 2000, Writing Effective Use Case, Addison-Wesley Professional; Edition 1 (3) Cockburn, A, 2006 “Use Case fundamentals” viewed 20th March 2012, http://alistair.cockburn.us/Use+case+fundamentals

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  • Planning development when academic research is involved

    - by Another Anonymous User
    Dear fellow programmers, how do you do "software planning" when academic research is involved? And, on a side note, how do you convince your boss that writing software is not like building a house and it's more like writing a novel? The gory details are below. I am in charge of a small dev team working in a research lab. We started developing a software with the purpose of going public one day (i.e. sell and make money off that). Such software depends on, amongst other things, at least two independent research lines: that is, there are at least two Ph.D. candidates that will, hopefully, one day come out with a working implementation of what we need. The main software depends also on other, more concrete resources that we as developers can take care of: graphics rendering, soft bodies deformation, etc. My boss asked me to write the specifications, requirements AND a bloody GANTT chart of the entire project. Faced with the fact that I don't have a clue about the research part, and that such research is fundamental for the software, he said "make assumptions." For the clarity of the argument, he is a professor whose Ph.D. students should come up with the research we need. And he comes from a strictly engineering background: plan everything first, write down specifications and only then write down code that "it's the last part". What I am doing now: I broke down the product in features; each 'feature' is, de facto, a separate product; Each feature is built on top of the previous one; Once a feature (A) has a working prototype the team can start working on the next feature (B), while QA for is being done for A (if money allows, more people can be brought in, etc.); Features that depend on research will come last: by then, hopefully, the research part will be completed (when is still a big question) ; Also, I set the team to use SCRUM for the development of 'version 1.0', due in a few months. This deadline could be set based on reasonable assumptions: we listed all required features, we counted our availability, and we gave a reasonable estimate. So my questions, again, are: How do I make my boss happy while at the same time get something out the door? How do I write specifications for something we -the developers- have no clue whether it's possible to do or not? (We still haven't decided which libraries to use for some tasks; we'll do so when we'll need to) How do I get the requirements for that, given that there are yet no clients nor investors, just lots of interests and promises? How do I get peace in the world? I am sure at least one of my questions will be answered :) ps: I am writing this anonymously since a potential investor might backfire if this is discovered. Hope you'll understand. However I must say I do not like this mentality of 'hiding the truth': this program will likely benefit many, and not being able to talk openly about this (with my name and my reputation attached) feels like censorship. But alas, I care more about your suggestions now.

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  • SQL Authority News – Secret Tool Box of Successful Bloggers: 52 Tips to Build a High Traffic Top Ranking Blog

    - by Pinal Dave
    When I started this blog, it was meant as a bookmark for myself for helpful tips and tricks.  Gradually, it grew into a blog that others were reading and commenting on.  While SQL and databases are my first love and the reason I started this blog, the side effect was that I discovered I loved writing.  I discovered a secret goal I didn’t even know I wanted – I wanted to become an author.  For a long time, writing this blog satisfied that urge.  Gradually, though, I wanted to see my name in print. 12th Book Over the past few years I have authored and co-authored a number of books – they are all based on my knowledge of SQL Server, and were meant to spread my years of experience into the world, to share what I have learned with my community.  I currently have elevan of these “manuals” available for sale.  As exciting as it was to see my name in print, I still felt that there was more I could do as an author. That is when I realized that I am more than just a SQL expert.  I have been writing this blog now for more than 10 years, and it grew from a personal bookmark to a thriving website with over 2 million views per month.  I thought to myself “I could write a book about how to create a successful blog!”  And that is exactly what I did.  I am extremely excited to share with all of you my new book – “Secret Toolbox of Successful Bloggers.” A Labor of Love This project has been a labor of love for me.  It started out as a series for this blog – I would post one article a week until I felt the topic had been covered.  I found that as I wrote, new topics kept popping up in my mind, and eventually this small blog series grew into a full book.  The blog series was large enough to last a whole year, so I definitely thought that it could be a full book.  Ideas on how to become a successful blogger were so frequent that, I will admit, I feel like there is so much I left out of this book.  I had a lot more to say than I originally thought! I am so excited to be sharing this book with all of you.  I am so passionate about this topic, and I feel like there are so many people who can benefit from this book.  I know that when I started this blog, I did not know what I was doing, and I would have loved a “helping hand” to tell what to do and what not to do.  If this book can act that way to any of my readers, I feel it is a success. Rules of Thumb If you are interested in the topic of becoming a blogger, as you read this book, keep in mind that it is suggestions only.  Blogging is so new to the world that while there are “rules of thumb” about what to do and what not to do, a map of steps (“first, do x, then do y”) is not going to work for every single blogger.  This book is meant to encourage new bloggers to put their content out there in the world, to be brave and create a community like the one I have here at SQL Authority.  I have gained so much from this community, I wanted to give something back, and this book is just one small part. I hope that everyone who reads this books finds at least one helpful tip, and that everyone can experience the joy of blogging.  That is the whole reason I wrote this book, and what I hope everyone takes away from it. Where Can You Get It? You can get the book from following URL: Kindle eBook | Print Book Reference: Pinal Dave (http://blog.SQLAuthority.com)Filed under: About Me, PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, SQLAuthority Author Visit, T SQL

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  • Planning development when academic research is involved

    - by Another Anonymous User
    Dear fellow programmers, how do you do "software planning" when academic research is involved? And, on a side note, how do you convince your boss that writing software is not like building a house and it's more like writing a novel? The gory details are below. I am in charge of a small dev team working in a research lab. We started developing a software with the purpose of going public one day (i.e. sell and make money off that). Such software depends on, amongst other things, at least two independent research lines: that is, there are at least two Ph.D. candidates that will, hopefully, one day come out with a working implementation of what we need. The main software depends also on other, more concrete resources that we as developers can take care of: graphics rendering, soft bodies deformation, etc. My boss asked me to write the specifications, requirements AND a bloody GANTT chart of the entire project. Faced with the fact that I don't have a clue about the research part, and that such research is fundamental for the software, he said "make assumptions." For the clarity of the argument, he is a professor whose Ph.D. students should come up with the research we need. And he comes from a strictly engineering background: plan everything first, write down specifications and only then write down code that "it's the last part". What I am doing now: I broke down the product in features; each 'feature' is, de facto, a separate product; Each feature is built on top of the previous one; Once a feature (A) has a working prototype the team can start working on the next feature (B), while QA for is being done for A (if money allows, more people can be brought in, etc.); Features that depend on research will come last: by then, hopefully, the research part will be completed (when is still a big question) ; Also, I set the team to use SCRUM for the development of 'version 1.0', due in a few months. This deadline could be set based on reasonable assumptions: we listed all required features, we counted our availability, and we gave a reasonable estimate. So my questions, again, are: How do I make my boss happy while at the same time get something out the door? How do I write specifications for something we -the developers- have no clue whether it's possible to do or not? (We still haven't decided which libraries to use for some tasks; we'll do so when we'll need to) How do I get the requirements for that, given that there are yet no clients nor investors, just lots of interests and promises? How do I get peace in the world? I am sure at least one of my questions will be answered :) ps: I am writing this anonymously since a potential investor might backfire if this is discovered. Hope you'll understand. However I must say I do not like this mentality of 'hiding the truth': this program will likely benefit many, and not being able to talk openly about this (with my name and my reputation attached) feels like censorship. But alas, I care more about your suggestions now.

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  • The long road to bug-free software

    - by Tony Davis
    The past decade has seen a burgeoning interest in functional programming languages such as Haskell or, in the Microsoft world, F#. Though still on the periphery of mainstream programming, functional programming concepts are gradually seeping into the imperative C# language (for example, Lambda expressions have their root in functional programming). One of the more interesting concepts from functional programming languages is the use of formal methods, the lofty ideal behind which is bug-free software. The idea is that we write a specification that describes exactly how our function (say) should behave. We then prove that our function conforms to it, and in doing so have proved beyond any doubt that it is free from bugs. All programmers already use one form of specification, specifically their programming language's type system. If a value has a specific type then, in a type-safe language, the compiler guarantees that value cannot be an instance of a different type. Many extensions to existing type systems, such as generics in Java and .NET, extend the range of programs that can be type-checked. Unfortunately, type systems can only prevent some bugs. To take a classic problem of retrieving an index value from an array, since the type system doesn't specify the length of the array, the compiler has no way of knowing that a request for the "value of index 4" from an array of only two elements is "unsafe". We restore safety via exception handling, but the ideal type system will prevent us from doing anything that is unsafe in the first place and this is where we start to borrow ideas from a language such as Haskell, with its concept of "dependent types". If the type of an array includes its length, we can ensure that any index accesses into the array are valid. The problem is that we now need to carry around the length of arrays and the values of indices throughout our code so that it can be type-checked. In general, writing the specification to prove a positive property, even for a problem very amenable to specification, such as a simple sorting algorithm, turns out to be very hard and the specification will be different for every program. Extend this to writing a specification for, say, Microsoft Word and we can see that the specification would end up being no simpler, and therefore no less buggy, than the implementation. Fortunately, it is easier to write a specification that proves that a program doesn't have certain, specific and undesirable properties, such as infinite loops or accesses to the wrong bit of memory. If we can write the specifications to prove that a program is immune to such problems, we could reuse them in many places. The problem is the lack of specification "provers" that can do this without a lot of manual intervention (i.e. hints from the programmer). All this might feel a very long way off, but computing power and our understanding of the theory of "provers" advances quickly, and Microsoft is doing some of it already. Via their Terminator research project they have started to prove that their device drivers will always terminate, and in so doing have suddenly eliminated a vast range of possible bugs. This is a huge step forward from saying, "we've tested it lots and it seems fine". What do you think? What might be good targets for specification and verification? SQL could be one: the cost of a bug in SQL Server is quite high given how many important systems rely on it, so there's a good incentive to eliminate bugs, even at high initial cost. [Many thanks to Mike Williamson for guidance and useful conversations during the writing of this piece] Cheers, Tony.

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  • Does *every* project benefit from written specifications?

    - by nikie
    I know this is holy war territory, so please read the question to the end before answering. There are many cases where written specifications make a lot of sense. For example, if you're a contractor and you want to get paid, you need written specs. If you're working in a team with 20 persons, you need written specs. If you're writing a programming language compiler or interpreter (and it's not perl), you'll usually write a formal specification. I don't doubt that there are many more cases where written specifications are a really good idea. I just think that there are cases where there's so little benefit in written specs, that it doesn't outweigh the costs of writing and maintaining them. EDIT: The close votes say that "it is difficult to say what is asked here", so let me clarify: The usefulness of written, detailed specifications is often claimed like a dogma. (If you want examples, look at the comments.) But I don't see the use of them for the kind of development I'm doing. So what is asked here is: How would written specifications help me? Background information: I work for a small company that's developing vertical market software. If our product is easier to use and has better performance than the competition, it sells. If it's harder to use, even if it behaves 100% as the specification says, it doesn't sell. So there are no "external forces" for having written specs. The advantage would have to be somewhere in the development process. Now, I can see how frozen specifications would make a developer's life easier. But we'll never have frozen specs. If we see in the middle of development that feature X is not intuitive to use the way it's specified, then we can only choose between changing the specification or developing a product that won't sell. You'll probably ask by now: How do you know when you're done? Well, we're continually improving our product. The competition does the same. So (hopefully) we're never done. We keep improving the software, and when we reach a point when the benefits of the improvements we've added since the last release outweigh the costs of an update, we create a new release that is then tested, localized, documented and deployed. This also means that there's rarely any schedule pressure. Nobody has to do overtime to make a deadline. If the feature isn't done by the time we want to release the next version, it'll simply go into the next version. The next question might be: How do your developers know what they're supposed to implement? The answer is: They have a lot of domain knowledge. They know the customers business well enough, so a high-level description of the feature (or even just the problem that the customer needs solved) is enough to implement it. If it's not clear, the developer creates a few fake screens to get feedback from marketing/management or customers, but this is nowhere near the level of detail of actual specifications. This might be inefficient for larger teams, but for a small team with low turnover it works quite well. It has the additional benefit that the developer in question often comes up with a better solution than the person writing the specs might have. This question is already getting very long, but let me address one last point: Testing. Like I said in the beginning, if our software behaves 100% like the spec says, it still can be crap. In fact, if it's so unintuitive that you need a spec to know how to test it, it probably is crap. It makes sense to have fixed, written tests for some core functionality and for regression bugs, but again, this is nowhere near a full written spec of how the software should behave when. The main test is: hand the software to a user who doesn't know it yet and tell him to use the new feature X. If she can figure out how to use it and it works, it works.

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