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• How to add precedence to LALR parser like in YACC?

  - by greenoldman

  Please note, I am asking about writing LALR parser, not writing rules for LALR parser. What I need is... ...to mimic YACC precedence definitions. I don't know how it is implemented, and below I describe what I've done and read so far. For now I have basic LALR parser written. Next step -- adding precedence, so 2+3*4 could be parsed as 2+(3*4). I've read about precedence parsers, however I don't see how to fit such model into LALR. I don't understand two points: how to compute when insert parenthesis generator how to compute how many parenthesis the generator should create I insert generators when the symbols is taken from input and put at the stack, right? So let's say I have something like this (| denotes boundary between stack and input): ID = 5 | + ..., at this point I add open, so it gives ID = < 5 | + ..., then I read more input ID = < 5 + | 5 ... and more ID = < 5 + 5 | ; ... and more ID = < 5 + 5 ; | ... At this point I should have several reduce moves in normal LALR, but the open parenthesis does not match so I continue reading more input. Which does not make sense. So this was when problem. And about count, let's say I have such data < 2 + < 3 * 4 >. As human I can see that the last generator should create 2 parenthesis, but how to compute this? After all there could be two scenarios: ( 2 + ( 3 *4 )) -- parenthesis is used to show the outcome of generator or (2 + (( 3 * 4 ) ^ 5) because there was more input Please note that in both cases before 3 was open generator, and after 4 there was close generator. However in both cases, after reading 4 I have to reduce, so I have to know what generator "creates".

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• Floating point undesireable in highly critical code?

  - by Kirt Undercoffer

  Question 11 in the Software Quality section of "IEEE Computer Society Real-World Software Engineering Problems", Naveda, Seidman, lists fp computation as undesirable because "the accuracy of the computations cannot be guaranteed". This is in the context of computing acceleration for an emergency braking system for a high speed train. This thinking seems to be invoking possible errors in small differences between measurements of a moving object but small differences at slow speeds aren't a problem (or shouldn't be), small differences between two measurements at high speed are irrelevant - can there be a problem with small roundoff errors during deceleration for an emergency braking system? This problem has been observed with airplane braking systems resulting in hydroplaning but could this actually happen in the context of a high speed train? The concern about fp errors seems to not be well-founded in this context. Any insight? The fp is used for acceleration so perhaps the concern is inching over a speed limit? But fp should be just fine if they use a double in whatever implementation language. The actual problem in the text states: During the inspection of the code for the emergency braking system of a new high speed train (a highly critical, real-time application), the review team identifies several characteristics of the code. Which of these characteristics are generally viewed as undesirable? The code contains three recursive functions (well that one is obvious). The computation of acceleration uses floating point arithmetic. All other computations use integer arithmetic. The code contains one linked list that uses dynamic memory allocation (second obvious problem). All inputs are checked to determine that they are within expected bounds before they are used.

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• How should I structure my database to gain maximum efficiently in this scenario?

  - by Bob Jansen

  I'm developing a PHP script that analyzes the web traffic of my clients websites. By placing a link to a javascript on the clients website (think of Google Analyses), my script harvests information like: the visitors IP address, reference link, current page link, user agent, etc. Now my clients can view these statistics via a control panel that I have build. These clients can also adjust profile settings, set firewall rules, create support tickets and pay invoices. Currently all the the traffic is stored in one table. You can imagine that this tabel would become very large as some my clients receive thousands of pageviews per day. Furthermore, all the traffic data of each client would be stored in the same table, creating a mess. This is the same for the firewall rules currently, and the invoice and support system. I'm looking for way to structure my database in a more organized way to hold large amounts of data of multiple users. This is the first project that I'm developing that deals with so much data, and would like to hear suggestions and tips. I was thinking of using multiple databases to structure the data. The main database will store users data (email,pass,id,etc) admin/website settings. Than each client will have an unique database labeled prefix_userid, which carry tables holding their traffic, invoice, and support ticket data. Would this be a solution, and would it slow down or speed up overall performances (that is spreading the data over muliple databases). I have a solid VPS, but would like to safe and be as effient as possible.

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• Understanding and memorizing git rebase parameters

  - by Robert Dailey

  So far the most confusing portion of git is rebasing onto another branch. Specifically, it's the command line arguments that are confusing. Each time I want to rebase a small piece of one branch onto the tip of another, I have to review the git rebase documentation and it takes me about 5-10 minutes to understand what each of the 3 main arguments should be. git rebase <upstream> <branch> --onto <newbase> What is a good rule of thumb to help me memorize what each of these 3 parameters should be set to, given any kind of rebase onto another branch? Bear in mind I have gone over the git-rebase documentation again, and again, and again, and again (and again), but it's always difficult to understand (like a boring scientific white-paper or something). So at this point I feel I need to involve other people to help me grasp it. My goal is that I should never have to review the documentation for these basic parameters. I haven't been able to memorize them so far, and I've done a ton of rebases already. So it's a bit unusual that I've been able to memorize every other command and its parameters so far, but not rebase with --onto.

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• conflict with php zend libs and c++ libs(ctime) to build extension for php [migrated]

  - by user69800

  Im going to build an extension for PHP 5.3.x everything is OK when I build without vc++ lib. error C2039: 'clock_t' : is not a member of '`global namespace'' error C2873: 'clock_t' : symbol cannot be used in a using-declaration error C2039: 'asctime' : is not a member of '`global namespace'' error C2873: 'asctime' : symbol cannot be used in a using-declaration and... I include just and got this error. I know this problem is from my include header file in properties that required from PHP zend engine, But I do not know how solve this problem. thanks

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• Checking preconditions or not

  - by Robert Dailey

  I've been wanting to find a solid answer to the question of whether or not to have runtime checks to validate input for the purposes of ensuring a client has stuck to their end of the agreement in design by contract. For example, consider a simple class constructor: class Foo { public: Foo( BarHandle bar ) { FooHandle handle = GetFooHandle( bar ); if( handle == NULL ) { throw std::exception( "invalid FooHandle" ); } } }; I would argue in this case that a user should not attempt to construct a Foo without a valid BarHandle. It doesn't seem right to verify that bar is valid inside of Foo's constructor. If I simply document that Foo's constructor requires a valid BarHandle, isn't that enough? Is this a proper way to enforce my precondition in design by contract? So far, everything I've read has mixed opinions on this. It seems like 50% of people would say to verify that bar is valid, the other 50% would say that I shouldn't do it, for example consider a case where the user verifies their BarHandle is correct, but a second (and unnecessary) check is also being done inside of Foo's constructor.

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• Office arangement - comfort vs. teamwork?

  - by finrod

  Our team works in an open-space office. Luckily the cubicles are quite big (L shaped tables for everyone!), there is quite a lot of space so we are not sandwiched. Without going into further detail, there are comfortable spots (window), normal spots and stupid spots (near the corridor). Until recently, the development team of twelve engineers was seated so that all types of spots were occupied and we were all close together. In the old arrangement, verbal communication was very easy - half of the team was withing talking distance. The other half was like ten steps away. Often times I could ask, discuss, solve problems without leaving the cube. Most of the communication is work related, no bullshit or mental masturbation that would unnecessarily distract others. Now we have moved to another part of the building and have larger space to occupy. At this point, everyone could pick their spot. Naturally all stupid spots are left empty (for the poor newcomers to occupy bwehaha). In the new arrangement, the development team is stretched across the floor and some of the key engineers are seated 'far' from each other - definitely not within talking distance. I have yet to experience how this works out but am getting concerned that team work and communication may have been traded for personal comfort. Finally the questions... What do you think is better office arrangement? Such that allows for free verbal communication but trading for some developer's comfort, or such that potentially hinders verbal communication but makes developer's more comfortable in their spot? Or maybe it does not matter at all and we will evolve to be efficient in any arrangement? What is your personal experience? Note - yes I read books and posts how workplace is important in our job. However in this case - we are all still in open space and the difference between the different spots are not really groundbreaking. So I'm thinking the little comfort that few developers gain is not worth the loss of easy communication.

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• What is a good C or Obj-C framework for manipulating Git Repositories?

  - by Andrew Theken

  What Obj-C/C libraries have you used for manipulating git repos in your Mac apps? I am working on a Mac app that I would like to be able to clone and modify git repos. Using git directly is not an option as it is GPL and I'd like to sell my app commercially without opening the source. I've seen libgit2, which I could link, but I'm not sure how to do that properly, and it doesn't appear to implement any of the things necessary for pushing/pulling repos over the git protocol.

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• How to really master ASP.NET MVC?

  - by user1620696

  Some years ago I've worked with web development just using PHP without focus on object orientation and so on. When I knew a little bit about it, and the benefits it brings, I've started moving to ASP.NET MVC. First, I've studied C# in the book Visual C# Step by Step. I've found it a good book for a beginner, and I could learn a lot of this new language with it. Now, when I've came to study ASP.NET MVC, I hadn't so much luck. I've studied on some books that explained MVC well and so on, but then started just saying: "do that, and now that, and then that", and I feel I couldn't really master ASP.NET MVC. I feel this, because when I was reading, I knew how to do the things the book taught, like implementing DI with Ninject and so on, but some time later, without looking at it for some time, I couldn't do it by myself. What I'm trying to say, is that usually I don't know where to start, how to do things in this framework and so on. How can I really master ASP.NET MVC? There is some book, some tutorial series, anything, that can really help with that? I'm pretty happy with the .NET framework, my problem isn't it, my only problem is working with the MVC framework, and applying the techniques from object orientation there. I don't know if this question is on-topic here, but I'm really just looking for some good references, to become better with this framework.

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• Program instantly closing [migrated]

  - by Ben Clayton

  I made this program and when I compiled it there were no errors but the program just instantly closed, any answers would be appreciated. #include <iostream> //Main commands #include <string> // String commands #include <windows.h> // Sleep using namespace std; int main () { //Declaring variables float a; bool end; std::string input; end = false; // Making sure program doesn't end instantly cout << "Enter start then the number you want to count down from." << ".\n"; while (end = false){ cin >> input; cout << ".\n"; if (input.find("end") != std::string::npos) // Ends the program if user types end end = true; else if (input.find("start" || /* || is or operator*/ "restart") != std::string::npos) // Sets up the countdown timer if the user types start { cin >> a; cout << ".\n"; while (a>0){ Sleep(100); a = a - 0.1; cout << a << ".\n"; } cout << "Finished! Enter restart and then another number, or enter end to close the program" << ".\n"; } else // Tells user to start program cout << "Enter start"; } return 0; // Ends program when (end = true) }

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• What is a good strategy for binding view objects to model objects in C++?

  - by B.J.

  Imagine I have a rich data model that is represented by a hierarchy of objects. I also have a view hierarchy with views that can extract required data from model objects and display the data (and allow the user to manipulate the data). Actually, there could be multiple view hierarchies that can represent and manipulate the model (e.g. an overview-detail view and a direct manipulation view). My current approach for this is for the controller layer to store a reference to the underlying model object in the View object. The view object can then get the current data from the model for display, and can send the model object messages to update the data. View objects are effectively observers of the model objects and the model objects broadcast notifications when properties change. This approach allows all the views to update simultaneously when any view changes the model. Implemented carefully, this all works. However, it does require a lot of work to ensure that no view or model objects hold any stale references to model objects. The user can delete model objects or sub-hierarchies of the model at any time. Ensuring that all the view objects that hold references to the model objects that have been deleted is time-consuming and difficult. It feels like the approach I have been taking is not especially clean; while I don't want to have to have explicit code in the controller layer for mediating the communication between the views and the model, it seems like there must be a better (implicit) approach for establishing bindings between the view and the model and between related model objects. In particular, I am looking for an approach (in C++) that understands two key points: There is a many to one relationship between view and model objects If the underlying model object is destroyed, all the dependent view objects must be cleaned up so that no stale references exist While shared_ptr and weak_ptr can be used to manage the lifetimes of the underlying model objects and allows for weak references from the view to the model, they don't provide for notification of the destruction of the underlying object (they do in the sense that the use of a stale weak_ptr allows for notification), but I need an approach that notifies the dependent objects that their weak reference is going away. Can anyone suggest a good strategy to manage this?

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• Is there a canonical book on general abstractions and modeling?

  - by David The Man

  I've been trying to understand the fundamentals of general abstractions and modeling: there are quite a lot of books when you search for abstractions, but most of those seem to be about learning object-oriented programming in a given language. Is there a book out there that's the de-facto standard for describing best practices, design methodologies, and other helpful information about general abstractions and modeling? What about that book makes it special?

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• Requriing static class setter to be called before Constructor, bad design?

  - by roverred

  I have a class, say Foo, and every instance of Foo will need and contain the same List object, myList. Since every class instance will share the same List Object, I thought it would be good to make myList static and use a static function to set myList before the constructor is called. I was wondering if this was bad, because this requires the setter to be called before the constructor. If the person doesn't, the program will crash. Alternative way would be passing myList every time. Thanks.

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• Languages with similar features to JavaFX Script

  - by bunglestink

  I just completed a small project in JavaFX, only finding that it has been declared dead by Oracle. JavaFX Script actually seemed to be a pretty interesting language with some neat features for its domain, particularly with bind for data binding and on replace for triggered events. These features actually make the language very useful for small, quick, RIA type apps, which leads to my question: Are there any mainstream languages with features similar to bind and on replace? After working with JavaFX, I got some ideas for some small personal (academic) projects that could take advantage of these features, but I would prefer to not start anything new in a language considered extinct by its owners.

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• Software licensing template that gives room for restricting usage to certain industries/uses of software/source

  - by BSara

  *Why this question is not a duplicate of the questions specified as such: I did not ask if there was a license that restricted specific uses and I did not ask if I could rewrite every line of any open source project. I asked very specifically: "Does there exist X? If not, can I Y with Z?". As far as I can tell, the two questions that were specified as duplicates do not answer my specific question. Please remove the duplicate status placed on the question. I'm developing some software that I would like to be "semi" open source. I would like to allow for anyone to use my software/source unless they are using the software/source for certain purposes. For example, I don't want to allow usage of the software/source if it is being used to create, distribute, view or otherwise support pornography, illegal purposes, etc. I'm no lawyer and couldn't ever hope to write a license myself nor do I have to time to figure how to best do this. My question is this: Does there exist a freely available license or a template for a license that I can use to license my software under they conditions explained above just like one can use the Creative Commons licenses? If not, am I allowed to just alter one of Creative Commons licenses to meet my needs?

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• How to implement smart card authentication with a .NET Fat client?

  - by John Nevermore

  I know very little about smart card authentication in general so please point out or correct me if anything below doesn't make sense. Lets say i have: A Certificate Authority "X"-s smart card (non-exportable private key) Drivers for that smart card written in C A smart card reader CA-s authentication OCSP web service A requirement to implement user authentication in a .NET fat client application via a smart card, that was given out by the CA "X". I tried searching info on the web but no prevail. What would the steps be ? My first thought was: Set up a web service, that would allow saving of (for example) scores of a ping pong game for each user. Each time someone tries to submit a score via the client application, he can only do so by inserting the smart card into the reader. Then the public key is read from the smart card by native c calls through .NET and sent to my custom web service, which in return uses the CA-s authentication OCSP web service to prove the validity of the public key/public certificate (?). If the public key is okay and valid, encrypt a random sequence of bytes with the public key and send it to the client application. If the client application sends back the correctly decrypted random sequence of bytes along with the score of the ping pong game, then the score is saved in the database for the given user. My question is, is this the correct way to do it ? What else should i know about smart card authentication ?

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• What user-friendly term should I use for a view that lives under a tab in a tab bar app?

  - by Emile Cormier

  My app uses a tab bar controller. In the user documentation, I'm not sure what name to use for a view that lives under a tab. For example, the app has a Settings tab. In the user documentation, I have a sentence that goes something like this: This threshold can be adjusted in the Settings tab. "Settings tab" is not terribly user-friendly. What would be a better term than "tab"? I've looked though Apple's Human Interface Guideline, but I can't find what would be the official user-friendly term for "view that lives under a tab".

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• Algorithm for perfect non-binary graph layout

  - by mariki

  I have a complex non-binary graph model. Each tree node can have multiple children&parents (a node can also have a connection to it's "brother"). A node is represented as square on screen with lines to the connected nodes. For that I want to use Draw2D and GEF libraries. The problem I am facing is the graph layout. I need a nice algorithm that can reposition the square nodes and the connections with minimum intersections and also make it symmetric as possible.

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• Most effective way to do daily standup meeting when a few people are remote

  - by Burhan Ali

  I am a software developer in a small team of seven. We are not an Agile (with a big 'A') team but are experimenting with some aspects of agile. One of these is the daily "standup" meeting. The difficulty here is that for two days of the week we have at least one person working from home so the full team isn't available in the same room. What is the best way to carry out a daily standup in this situation? Some facts that may be relevant: We all work in a single open plan room. We use Skype in our company. We don't have any video conferencing capability. We all work the same hours so there are no timezone complexities involved. The development manager is one of the people who works from home one day a week. Things we have tried: Conference call using Skype: This is tricky for those in the office because you can hear people speak in the room and then a split second later through the headset. This can e very distracting. Conference phone: Awful experience. Hard to get them to work and poor quality audio. Text-based updates using Skype. This is not as engaging and is no different than just firing off a status email in the morning. I have seen other questions about remote collaboration but they are mainly about completely remote teams and/or teams that span multiple time zones. We are not affected by either of these problems. What can we do to make our standup meetings better in these circumstances?

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• Composing programs from small simple pieces: OOP vs Functional Programming

  - by Jay Godse

  I started programming when imperative programming languages such as C were virtually the only game in town for paid gigs. I'm not a computer scientist by training so I was only exposed to Assembler and Pascal in school, and not Lisp or Prolog. Over the 1990s, Object-Oriented Programming (OOP) became more popular because one of the marketing memes for OOP was that complex programs could be composed of loosely coupled but well-defined, well-tested, cohesive, and reusable classes and objects. And in many cases that is quite true. Once I learned object-oriented programming my C programs became better because I structured them more like classes and objects. In the last few years (2008-2014) I have programmed in Ruby, an OOP language. However, Ruby has many functional programming (FP) features such as lambdas and procs, which enable a different style of programming using recursion, currying, lazy evaluation and the like. (Through ignorance I am at a loss to explain why these techniques are so great). Very recently, I have written code to use methods from the Ruby Enumerable library, such as map(), reduce(), and select(). Apparently this is a functional style of programming. I have found that using these methods significantly reduce code volume, and make my code easier to debug. Upon reading more about FP, one of the marketing claims made by advocates is that FP enables developers to compose programs out of small well-defined, well-tested, and reusable functions, which leads to less buggy code, and low code volume. QUESTIONS: Is the composition of complex program by using FP techniques contradictory to or complementary to composition of a complex program by using OOP techniques? In which situations is OOP more effective, and when is FP more effective? Is it possible to use both techniques in the same complex program? Do the techniques overlap or contradict each other?

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• What is the philosophy/reasoning behind C#'s Pascal-casing method names?

  - by Nocturne

  I'm just starting to learn C#. Coming from a background in Java, C++ and Objective-C, I find C#'s Pascal-casing its method-names rather unique, and a tad difficult to get used to at first. What is the reasoning and philosophy behind this? I'm guessing it is because of C# properties. Unlike in Objective-C, where method names can be exactly the same as an instance variables, this is not the case with C#. I would guess one of the goals with properties (as it is with most of the languages that support it) is to make properties truly indistinguishable from variables and methods. So, one can have an "int x" in C#, and the corresponding property becomes X. To ensure that properties and methods are indistinguishable, all method names I'm guessing are also therefore expected to start with an uppercase letter. (This is just my hypothesis based on what I know of C# so far—I'm still learning). I'm very curious to know how this curious guideline came into being (given that it's not something one sees in most other languages where method names are expected to start with a lowercase letter) (EDIT: By Pascal-casing, I mean PascalCase (which is basically camelCase but starting with a capital letter). Method names typically start with a lowercase letter in most languages)

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• Will Apple abandon OpenCL?

  - by John

  I am developing OpenCL applications, amongst others for MacOS. The new Macbook pro 13 inch comes with an Intel HD Graphics 3000 card so it seams reasonable to assume all their mainstream computers like Macbook and Mac mini will also come out with this Intel graphics card soon. OpenCL is not available for Intel graphics cards. Intel having a terrible reputation in developing graphics drivers and Apple knowing this makes me wonder Apple is abandoning OpenCL already again. Especially considering OpenCL should run anywhere, not only on high end systems. Developing applications only for the high end Macs with dedicated graphics hardware or for previous generation hardware with the Geforce 320M would not be a feasible option for me. Does anybody have any thoughts on this?

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• Will software development be completely outsourced to Asia?

  - by gablin

  Lots of things are nowadays done in Asia which used to be done in the U.S. or Europe: car manufacturing, making of clothes and shoes, almost all computer components, etc. And it looks that part of software development is heading the same way. In fact, it is already underway. Where I previously worked as a functional tester for a 150+ developers-project, almost a third of the positions were outsourced to India. Will this process go further and further until all software development is done in Asia?

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• Headaches using distributed version control for traditional teams?

  - by J Cooper

  Though I use and like DVCS for my personal projects, and can totally see how it makes managing contributions to your project from others easier (e.g. your typical Github scenario), it seems like for a "traditional" team there could be some problems over the centralized approach employed by solutions like TFS, Perforce, etc. (By "traditional" I mean a team of developers in an office working on one project that no one person "owns", with potentially everyone touching the same code.) A couple of these problems I've foreseen on my own, but please chime in with other considerations. In a traditional system, when you try to check your change in to the server, if someone else has previously checked in a conflicting change then you are forced to merge before you can check yours in. In the DVCS model, each developer checks in their changes locally and at some point pushes to some other repo. That repo then has a branch of that file that 2 people changed. It seems that now someone must be put in charge of dealing with that situation. A designated person on the team might not have sufficient knowledge of the entire codebase to be able to handle merging all conflicts. So now an extra step has been added where someone has to approach one of those developers, tell him to pull and do the merge and then push again (or you have to build an infrastructure that automates that task). Furthermore, since DVCS tends to make working locally so convenient, it is probable that developers could accumulate a few changes in their local repos before pushing, making such conflicts more common and more complicated. Obviously if everyone on the team only works on different areas of the code, this isn't an issue. But I'm curious about the case where everyone is working on the same code. It seems like the centralized model forces conflicts to be dealt with quickly and frequently, minimizing the need to do large, painful merges or have anyone "police" the main repo. So for those of you who do use a DVCS with your team in your office, how do you handle such cases? Do you find your daily (or more likely, weekly) workflow affected negatively? Are there any other considerations I should be aware of before recommending a DVCS at my workplace?

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• Humor in Documentation

  - by Lex Fridman

  Is a small amount of lighthearted wording or humor acceptable in source code documentation? For example, I have an algorithm that has a message hop around a graph (network) until its path forms a cycle. When this happens it is removed from the queue of the node it last resided on which removes it from memory. I write that in a comment, and finish the comment with "Rest in peace, little guy". That serves very little documenting purpose, but it cheers me up a bit, and I imagine it might cheer up other people I'm working with as they read through the code. Is this an acceptable practice, or should my in-code documentation resemble as much as possible the speeches of 2004 presidential candidate John Kerry? ;-)

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