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  • Manipulating the address of a variable to store a smaller type?

    - by Sidnicious
    This is what I get for pampering myself with high-level programming languages. I have a function which writes a 32-bit value to a buffer, and a uint64_t on the stack. Is the following code a sane way to store it? uint64_t size = 0; // ... getBytes((uint32_t*)&size+0x1); I'm assuming that this would be the canonical, safe style: uint64_t size = 0; // ... uint32_t smallSize; getBytes(&smallSize); size = smallSize;

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  • Building a minimal plugin architecture in Python.

    - by dF
    I have an application, written in Python, which is used by a fairly technical audience (scientists). I'm looking for a good way to make the application extensible by the users, i.e. a scripting/plugin architecture. I am looking for something extremely lightweight. Most scripts, or plugins, are not going to be developed and distributed by a third-party and installed, but are going to be something whipped up by a user in a few minutes to automate a repeating task, add support for a file format, etc. So plugins should have the absolute minimum boilerplate code, and require no 'installation' other than copying to a folder (so something like setuptools entry points, or the Zope plugin architecture seems like too much.) Are there any systems like this already out there, or any projects that implement a similar scheme that I should look at for ideas / inspiration?

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  • What are Code Smells? What is the best way to correct them?

    - by Rob Cooper
    OK, so I know what a code smell is, and the Wikipedia Article is pretty clear in its definition: In computer programming, code smell is any symptom in the source code of a computer program that indicates something may be wrong. It generally indicates that the code should be refactored or the overall design should be reexamined. The term appears to have been coined by Kent Beck on WardsWiki. Usage of the term increased after it was featured in Refactoring. Improving the Design of Existing Code. I know it also provides a list of common code smells. But I thought it would be great if we could get clear list of not only what code smells there are, but also how to correct them. Some Rules Now, this is going to be a little subjective in that there are differences to languages, programming style etc. So lets lay down some ground rules: ** ONE SMELL PER ANSWER PLEASE! & ADVISE ON HOW TO CORRECT! ** See this answer for a good display of what this thread should be! DO NOT downmod if a smell doesn't apply to your language or development methodology We are all different. DO NOT just quickly smash in as many as you can think of Think about the smells you want to list and get a good idea down on how to work around. DO downmod answers that just look rushed For example "dupe code - remove dupe code". Let's makes it useful (e.g. Duplicate Code - Refactor into separate methods or even classes, use these links for help on these common.. etc. etc.). DO upmod answers that you would add yourself If you wish to expand, then answer with your thoughts linking to the original answer (if it's detailed) or comment if its a minor point. DO format your answers! Help others to be able to read it, use code snippets, headings and markup to make key points stand out!

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  • What ways are there for cleaning an R environment from objects?

    - by Tal Galili
    I know I can use ls() and rm() to see and remove objects that exist in my environment. However, when dealing with "old" .RData file, one needs to sometimes pick an environment a part to find what to keep and what to leave out. What I would like to do, is to have a GUI like interface to allow me to see the objects, sort them (for example, by there size), and remove the ones I don't need (for example, by a check-box interface). Since I imagine such a system is not currently implemented in R, what ways do exist? What do you use for cleaning old .RData files? Thanks, Tal

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  • Service Layer Patter - Could we avoid the service layer on a specific case?

    - by lidermin
    Hi, we are trying to implement an application using the Service Layer Pattern cause our application needs to connect to other multiple applications too, and googling on the web, we found this link of a demostrative graphic for the "right" way of apply the pattern: martinfowler.com - Service Layer Pattern But now we have a question: what if our system needs to implement some business logic, only for our application (like some maintenance data for the system itself) that we don't need to share with other systems. Based on this graphic: As it seems, it will be unnecesary to implement a service layer just for that; it will be more practical to avoid the service layer, and just go from User Interface to the Business Layer (for example). What should be the right way in this case to implement the Service Layer Pattern? What do you suggest us for a scenario like the one I told you? Thanks in advance.

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  • Service Layer Patter - Could we avoid the service layer on a specific case?

    - by lidermin
    Hi, we are trying to implement an application using the Service Layer Pattern cause our application needs to connect to other multiple applications too, and googling on the web, we found this link of a demostrative graphic for the "right" way of apply the pattern: martinfowler.com - Service Layer Pattern But now we have a question: what if our system needs to implement some business logic, only for our application (like some maintenance data for the system itself) that we don't need to share with other systems. Based on this graphic: As it seems, it will be unnecesary to implement a service layer just for that; it will be more practical to avoid the service layer, and just go from User Interface to the Business Layer (for example). What should be the right way in this case to implement the Service Layer Pattern? What do you suggest us for a scenario like the one I told you? Thanks in advance.

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  • Working with multiple input and output files in Python

    - by Morlock
    I need to open multiple files (2 input and 2 output files), do complex manipulations on the lines from input files and then append results at the end of 2 output files. I am currently using the following approach: in_1 = open(input_1) in_2 = open(input_2) out_1 = open(output_1, "w") out_2 = open(output_2, "w") # Read one line from each 'in_' file # Do many operations on the DNA sequences included in the input files # Append one line to each 'out_' file in_1.close() in_2.close() out_1.close() out_2.close() The files are huge (each potentially approaching 1Go, that is why I am reading through these input files one at a time. I am guessing that this is not a very Pythonic way to do things. :) Would using the following form good? with open("file1") as f1: with open("file2") as f2: # etc. If yes, could I do it while avoiding the highly indented code that would result? Thanks for the insights!

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  • What problems do you find with this view on domain-driven design?

    - by Bozho
    I just wrote a long (and messy) blogpost about my view on domain-driven design at present day, with frameworks like spring and hibernate massively in use. I'd ask you to spot any problems with my views on the matter - why this won't work, why it isn't giving the benefits of DDD, why it is not a good idea in general. The blogpost is here (I don't think I need to copy-paste it on SO - if you think I should, tell me). I know the question is subjective, but it is aimed at gathering the most predominant opinions. (I'm tagging Java, since the frameworks discussed are Java frameworks)

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  • Guidelines for good webcrawler 'Etiquette'

    - by Harry
    I'm building a search engine (for fun) and it has just struck me that potentially my little project might wreak havok by clicking on ads and all sorts of problems. So what are the guidelines for good webcrawler 'Etiquette'? Things that spring to mind: Observe Robot.txt instructions Limit the number of simultaneous requests to the same domain Don't follow ad links? Stopping the crawler from clicking on ads - This one is particularly on my mind at the moment... how do i stop my bot from 'clicking' on ads? if it is going straight to the url in the ad is it counted as a click?

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  • Overriding properties of child view controller vs setting them via parent view controller

    - by robinjam
    If you want to modify the default behaviour of a View Controller by changing the value of one of its properties, is it considered better form to instantiate the class and set its property directly, or subclass it and override the property? With the former it would become the parent View Controller's responsibility to configure its children, whereas with the latter the children would effectively configure themselves. EDIT: Some more information: The class I am referring to is FetchedTableViewController, a subclass of UITableViewController that I made to display the results of a Core Data fetch operation. There are two places I want to display the results of a fetch, and they each have different fetch requests. I'm trying to decide whether it's better to create a subclass for each one, and override the fetchRequest property, or make it the responsibility of the parent controller to set the fetchRequest property for its children.

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  • Should java try blocks be scoped as tightly as possible?

    - by isme
    I've been told that there is some overhead in using the Java try-catch mechanism. So, while it is necessary to put methods that throw checked exception within a try block to handle the possible exception, it is good practice performance-wise to limit the size of the try block to contain only those operations that could throw exceptions. I'm not so sure that this is a sensible conclusion. Consider the two implementations below of a function that processes a specified text file. Even if it is true that the first one incurs some unnecessary overhead, I find it much easier to follow. It is less clear where exactly the exceptions come from just from looking at statements, but the comments clearly show which statements are responsible. The second one is much longer and complicated than the first. In particular, the nice line-reading idiom of the first has to be mangled to fit the readLine call into a try block. What is the best practice for handling exceptions in a funcion where multiple exceptions could be thrown in its definition? This one contains all the processing code within the try block: void processFile(File f) { try { // construction of FileReader can throw FileNotFoundException BufferedReader in = new BufferedReader(new FileReader(f)); // call of readLine can throw IOException String line; while ((line = in.readLine()) != null) { process(line); } } catch (FileNotFoundException ex) { handle(ex); } catch (IOException ex) { handle(ex); } } This one contains only the methods that throw exceptions within try blocks: void processFile(File f) { FileReader reader; try { reader = new FileReader(f); } catch (FileNotFoundException ex) { handle(ex); return; } BufferedReader in = new BufferedReader(reader); String line; while (true) { try { line = in.readLine(); } catch (IOException ex) { handle(ex); break; } if (line == null) { break; } process(line); } }

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  • Should non-English member names be changed to English?

    - by M.A. Hanin
    Situation: Automatically generated memebers, such as MenuStrip items, have their (automatically generated) names based on the text entered when the item was created. My most common situation is creating a menu-strip and adding menu-items by entering their text (using the graphical designer). Since my GUI is in Hebrew, all these members have a name which contains a Hebrew string. Something like "(hebrew-text)ToolStripItem". When I create event handlers, the event handlers "inherit" the hebrew text: "(hebrew-text)ToolStripMenuItem_Click". This actually works well, IntelliSense has no problem with Hebrew text, and so does the compiler. The question is: should I change these names (or prevent them from being created in the first place)? What are the possible consequences of keeping those names?

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  • What is the most EVIL code you have ever seen in a production enterprise environment?

    - by Registered User
    What is the most evil or dangerous code fragment you have ever seen in a production environment at a company? I've never encountered production code that I would consider to be deliberately malicious and evil, so I'm quite curious to see what others have found. The most dangerous code I have ever seen was a stored procedure two linked-servers away from our core production database server. The stored procedure accepted any NVARCHAR(8000) parameter and executed the parameter on the target production server via an double-jump sp_executeSQL command. That is to say, the sp_executeSQL command executed another sp_executeSQL command in order to jump two linked servers. Oh, and the linked server account had sysadmin rights on the target production server.

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  • What design pattern shall I use in this question?

    - by iyad al aqel
    To be frank, this is a homework question, so I'll tell you my opinion. Can you let me know my mistakes rather than giving me the solution? This is the question : Assume a restaurant that only offers the following two types of meals: (a) a full meal and (b)an economic meal. The full meal consists of the following food items and is served in the following order: 1. Appetizer 2. Drink 3. Main dish 4. Dessert Meanwhile the economic meal consists of the following food items and is served in the following order: 1. Drink 2. Main dish Identify the most appropriate design pattern that can be used to allow a customer to only order using one of the two types of meals provided and that the meal components must be served in the given order. I'm confused between the Factory and the Iterator and using them both together. Using the factory Pattern we can create the two meals full and economic and provide the user with with a base object class that will decide upon. But how can we enforce the ordering of the elements, I thought of using the iterator along that will iterate through the the composite of the two created factories sort of speak. What do you think?

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  • Dependency Injection: I don't get where to start!

    - by Andy
    I have several articles about Dependency Injection, and I can see the benefits, especially when it comes to unit testing. The units can me loosely coupled, and mocking of dependencies can be made. The trouble is - I just don't get where to start. Consider this snippet below of (much edited for the purpose of this post) code that I have. I am instantiating a Plc object from the main form, and passing in a communications mode via the Connect method. In it's present form it becomes hard to test, because I can't isolate the Plc from the CommsChannel to unit test it. (Can I?) The class depends on using a CommsChannel object, but I am only passing in a mode that is used to create this channel within the Plc itself. To use dependancy injection, I should really pass in an already created CommsChannel (via an 'ICommsChannel' interface perhaps) to the Connect method, or maybe via the Plc constructor. Is that right? But then that would mean creating the CommsChannel in my main form first, and this doesn't seem right either, because it feels like everything will come back to the base layer of the main form, where everything begins. Somehow it feels like I am missing a crucial piece of the puzzle. Where do you start? You have to create an instance of something somewhere, but I'm struggling to understand where that should be. public class Plc() { public bool Connect(CommsMode commsMode) { bool success = false; // Create new comms channel. this._commsChannel = this.GetCommsChannel(commsMode); // Attempt connection success = this._commsChannel.Connect(); return this._connected; } private CommsChannel GetCommsChannel(CommsMode mode) { CommsChannel channel; switch (mode) { case CommsMode.RS232: channel = new SerialCommsChannel( SerialCommsSettings.Default.ComPort, SerialCommsSettings.Default.BaudRate, SerialCommsSettings.Default.DataBits, SerialCommsSettings.Default.Parity, SerialCommsSettings.Default.StopBits); break; case CommsMode.Tcp: channel = new TcpCommsChannel( TCPCommsSettings.Default.IP_Address, TCPCommsSettings.Default.Port); break; default: // Throw unknown comms channel exception. } return channel; } }

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  • Choosing between instance methods and separate functions?

    - by StackedCrooked
    Adding functionality to a class can be done by adding a method or by defining a function that takes an object as its first parameter. Most programmers that I know would choose for the solution of adding a instance method. However, I sometimes prefer to create a separate function. For example, in the example code below Area and Diagonal are defined as separate functions instead of methods. I find it better this way because I think these functions provide enhancements rather than core functionality. Is this considered a good/bad practice? If the answer is "it depends", then what are the rules for deciding between adding method or defining a separate function? class Rect { public: Rect(int x, int y, int w, int h) : mX(x), mY(y), mWidth(w), mHeight(h) { } int x() const { return mX; } int y() const { return mY; } int width() const { return mWidth; } int height() const { return mHeight; } private: int mX, mY, mWidth, mHeight; }; int Area(const Rect & inRect) { return inRect.width() * inRect.height(); } float Diagonal(const Rect & inRect) { return std::sqrt(std::pow(static_cast<float>(inRect.width()), 2) + std::pow(static_cast<float>(inRect.height()), 2)); }

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  • DRYing up Rails Views with Nested Resources

    - by viatropos
    What is your solution to the problem if you have a model that is both not-nested and nested, such as products: a "Product" can belong_to say an "Event", and a Product can also just be independent. This means I can have routes like this: map.resources :products # /products map.resources :events do |event| event.resources :products # /events/1/products end How do you handle that in your views properly? Note: this is for an admin panel. I want to be able to have a "Create Event" page, with a side panel for creating tickets (Product), forms, and checking who's rsvp'd. So you'd click on the "Event Tickets" side panel button, and it'd take you to /events/my-new-event/tickets. But there's also a root "Products" tab for the admin panel, which could list tickets and other random products. The 'tickets' and 'products' views look 90% the same, but the tickets will have some info about the event it belongs to. It seems like I'd have to have views like this: products/index.haml products/show.haml events/products/index.haml events/products/show.haml But that doesn't seem DRY. Or I could have conditionals checking to see if the product had an Event (@product.event.nil?), but then the views would be hard to understand. How do you deal with these situations? Thanks so much.

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  • IEnumerable and IEnumerator in the same class, bad idea?

    - by David Rutten
    Is this a bad idea? Private Class GH_DataStructureEnumerator(Of Q As Types.IGH_Goo) Implements IEnumerable(Of Q) Implements IEnumerator(Of Q) .... .... 'Current, MoveNext, Reset etc.' .... .... Public Function GetEnumerator_Generic() As IEnumerator(Of Q) _ Implements IEnumerable(Of Q).GetEnumerator Return Me End Function End Class This class is only visible as an IEnumerable(Of T) readonly property, and it saves me an additional class that wraps IEnumerator(Of T). But somehow it just seems wrong. Is there a better way?

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  • Problem implementing Interceptor pattern

    - by ph0enix
    I'm attempting to develop an Interceptor framework (in C#) where I can simply implement some interfaces, and through the use of some static initialization, register all my Interceptors with a common Dispatcher to be invoked at a later time. The problem lies in the fact that my Interceptor implementations are never actually referenced by my application so the static constructors never get called, and as a result, the Interceptors are never registered. If possible, I would like to keep all references to my Interceptor libraries out of my application, as this is my way of (hopefully) enforcing loose coupling across different modules. Hopefully this makes some sense. Let me know if there's anything I can clarify... Does anyone have any ideas, or perhaps a better way to go about implementing my Interceptor pattern? Update: I came across Spring.NET. I've heard of it before, but never really looked into it. It sounds like it has a lot of great features that would be very useful for what I'm trying to do. Does anyone have any experience with Spring.NET? TIA, Jeremy

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  • How to allow for modular development while still running in same JVM?

    - by Marcus
    Our current app runs in a single JVM. We are now splitting up the app into separate logical services where each service runs in its own JVM. The split is being done to allow a single service to be modified and deployed without impacting the entire system. This reduces the need to QA the entire system - just need to QA the interaction with the service being changed. For interservice communication we use a combination of REST, an MQ system bus, and database views. What I don't like about this: REST means we have to marshal data to/from XML DB views couple the systems together which defeats the whole concept of separate services MQ / system bus is added complexity There is inevitably some code duplication between services You have set up n JBoss server configurations, we have to do n number of deployments, n number of set up scripts, etc, etc. Is there a better way to structure an internal application to allow modular development and deployment while allowing the app to run in a single JVM (and achieving the associated benefits)?

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