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• How does URL Rewriting affect SEO?

  - by Costa

  The following paragraph is from SEO Google Guide Google is good at crawling all types of URL structures, even if they're quite complex, but spending the time to make your URLs as simple as possible for both users and search engines can help. Some webmasters try to achieve this by rewriting their dynamic URLs to static ones; while Google is fine with this, we'd like to note that this is an advanced procedure and if done incorrectly, could cause crawling issues with your site. What makes URL re-writing implementation incorrect for GoogleBot? I am using Asp.net 3.5 framework.

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• What options are there for splitting UI layout from code logic using a markup language?

  - by Daenyth

  What tools similar to GWT's UIBinder exist in other languages? By this I mean a system where you can define your UI layout in a markup language (preferably html+css) and attach the functionality to the layout using the code. I'm most interested in anything for python, but answers in other languages would interest me as well. I'm interested because the benefits of having a non-programmer work directly on the layout without needing to touch the code and adjust a bunch of UI toolkit method calls is very productive. I'm aware of Flex for flash, but is there anything else out there? What search terms might I use to find such frameworks? I've looked around but I haven't found anything concrete.

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• returning null vs returning zero, which would be better?

  - by Dark Star1

  I inherited a project that I am managing and having to maintain pending the redevelopment of the code base. At the moment I am being tasked with adding little feature all over the place and have gotten into the habit of returning null instead of zero in parts of the code where I am working on. The problem is we have a client that is using this code and parts of code that require data from my implemented features recieve a null and dump the stack trace in UI. I would like to avoid this entirely from my input but without the nullPointer exceptions there's the potential that errors would be introduced into the client's data which may go un-noticed. Usually I would have come up with my own error notification system but I have never inherited a project before. so I am unsure whether to continue down this path. I still believe that the stack dump is preferable to un-noticed data corruption/inaccuracies.

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• IoC containers and service locator pattern

  - by TheSilverBullet

  I am trying to get an understanding of Inversion of Control and the dos and donts of this. Of all the articles I read, there is one by Mark Seemann (which is widely linked to in SO) which strongly asks folks not to use the service locator pattern. Then somewhere along the way, I came across this article by Ken where he helps us build our own IoC. I noticed that is is nothing but an implementation of service locator pattern. Questions: Is my observation correct that this implementation is the service locator pattern? If the answer to 1. is yes, then Do all IoC containers (like Autofac) use the service locator pattern? If the answer to 1. is no, then why is this differen? Is there any other pattern (other than DI) for inversion of control?

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• Finding the displacment of a robot [closed]

  - by Jordan Brown

  I'm building a quadruped (4 legs 3 DOF) for my major work in electronics at high school. I need to know the displacement of the robot and I can't use an encoding wheel. I've done my research and I found a system where I use an accelerometer, gyroscope and a magnetometer to determine the displacement but I'm not sure how to code it. I'm using Arduino and will use compatible sensors. I would like to be able to implement something similar to this video which demonstrates the principles evaluated in this paper. I don't need to map the data on a screen, just be able to read its displacement from its last recorded position. EG. (Read Position) --- (Do "stuff") --- (Read Position) --- (Calculate displacement caused by "stuff")

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• Anemic Domain Model, Business Logic and DataMapper (PHP)

  - by sunwukung

  I've implemented a rudimentary ORM layer based on DataMapper (I don't want to use a full blown ORM like Propel/Doctrine - for anything beyond simple fetch/save ops I prefer to access the data directly layer using a SQL abstraction layer). Following the DataMapper pattern, I've endeavoured to keep all persistence operations in the Mapper - including the location of related entities. My Entities have access to their Mapper, although I try not to call Mapper logic from the Entity interface (although this would be simple enough). The result is: // get a mapper and produce an entity $ProductMapper = $di->get('product_mapper'); $Product = $ProductMapper->find('[email protected]','email'); //.. mutaute some values.. save $ProductMapper->save($Product) // uses __get to trigger relation acquisition $Manufacturer = $Product->manufacturer; I've read some articles regarding the concept of an Anemic Domain model, i.e. a Model that does not contain any "business logic". When demonstrating the sort of business logic ideally suited to a Domain Model, however, acquiring related data items is a common example. Therefore I wanted to ask this question: Is persistence logic appropriate in Domain Model objects?

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• Why is x=x++ undefined?

  - by ugoren

  It's undefined because the it modifies x twice between sequence points. The standard says it's undefined, therefore it's undefined. That much I know. But why? My understanding is that forbidding this allows compilers to optimize better. This could have made sense when C was invented, but now seems like a weak argument. If we were to reinvent C today, would we do it this way, or can it be done better? Or maybe there's a deeper problem, that makes it hard to define consistent rules for such expressions, so it's best to forbid them? So suppose we were to reinvent C today. I'd like to suggest simple rules for expressions such as x=x++, which seem to me to work better than the existing rules. I'd like to get your opinion on the suggested rules compared to the existing ones, or other suggestions. Suggested Rules: Between sequence points, order of evaluation is unspecified. Side effects take place immediately. There's no undefined behavior involved. Expressions evaluate to this value or that, but surely won't format your hard disk (strangely, I've never seen an implementation where x=x++ formats the hard disk). Example Expressions x=x++ - Well defined, doesn't change x. First, x is incremented (immediately when x++ is evaluated), then it's old value is stored in x. x++ + ++x - Increments x twice, evaluates to 2*x+2. Though either side may be evaluated first, the result is either x + (x+2) (left side first) or (x+1) + (x+1) (right side first). x = x + (x=3) - Unspecified, x set to either x+3 or 6. If the right side is evaluated first, it's x+3. It's also possible that x=3 is evaluated first, so it's 3+3. In either case, the x=3 assignment happens immediately when x=3 is evaluated, so the value stored is overwritten by the other assignment. x+=(x=3) - Well defined, sets x to 6. You could argue that this is just shorthand for the expression above. But I'd say that += must be executed after x=3, and not in two parts (read x, evaluate x=3, add and store new value). What's the Advantage? Some comments raised this good point. It's not that I'm after the pleasure of using x=x++ in my code. It's a strange and misleading expression. What I want is to be able to understand complicated expressions. Normally, a complicated expression is no more than the sum of its parts. If you understand the parts and the operators combining them, you can understand the whole. C's current behavior seems to deviate from this principle. One assignment plus another assignment suddenly doesn't make two assignments. Today, when I look at x=x++, I can't say what it does. With my suggested rules, I can, by simply examining its components and their relations.

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• Avoiding null in a controller

  - by Kevin Burke

  I'm trying to work through how to write this code. def get(params): """ Fetch a user's details, or 404 """ user = User.fetch_by_id(params['id']) if not user: abort(404) # Render some template for the user... What's the best way to handle the case where the lookup fails? One principle says you should avoid returning null values from functions. These lead to mistakes and AttributeErrors etc. later on in the file. Another idea is to have fetch_by_id raise a ValueError or similar if no user exists with that id. However there's a general principle that you shouldn't use exceptions for control flow, either, which doesn't help much. What could be done better in this case?

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• How do you plan your asynchronous code?

  - by NullOrEmpty

  I created a library that is a invoker for a web service somewhere else. The library exposes asynchronous methods, since web service calls are a good candidate for that matter. At the beginning everything was just fine, I had methods with easy to understand operations in a CRUD fashion, since the library is a kind of repository. But then business logic started to become complex, and some of the procedures involves the chaining of many of these asynchronous operations, sometimes with different paths depending on the result value, etc.. etc.. Suddenly, everything is very messy, to stop the execution in a break point it is not very helpful, to find out what is going on or where in the process timeline have you stopped become a pain... Development becomes less quick, less agile, and to catch those bugs that happens once in a 1000 times becomes a hell. From the technical point, a repository that exposes asynchronous methods looked like a good idea, because some persistence layers could have delays, and you can use the async approach to do the most of your hardware. But from the functional point of view, things became very complex, and considering those procedures where a dozen of different calls were needed... I don't know the real value of the improvement. After read about TPL for a while, it looked like a good idea for managing tasks, but in the moment you have to combine them and start to reuse existing functionality, things become very messy. I have had a good experience using it for very concrete scenarios, but bad experience using them broadly. How do you work asynchronously? Do you use it always? Or just for long running processes? Thanks.

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• Should one use a separate database for application data and user data?

  - by trycatch

  I’ve been working on a project for a little while and I’m unsure which is the better architecture. I’m interested in the consensus. The answer to me seems fairly obvious but something about it is digging at me and I can't pick out what. The TL;DR is: how do you handle a program with application data and user data in the same DB which needs to be able to receive updates to the application data periodically? One database for user data and one for application, or both in one? The detailed version is.. if an application has a database which needs to maintain application data AND user data, and the user data all references application data, it feels more natural to me to store them in the same database. But if there exists a need to be able to update the application data within this database periodically, should this be stripped into two databases so that one can simply download the updated application data database file as an update and replace the old one? Or should they remain as one database, and the application data be updated via a script which inserts the new data into the existing database? The second sounds clearly preferable to me... but for some reason just doesn’t feel right, and I can't pick out quite why.

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• How can I cleanly and elegantly handle data and dependancies between classes

  - by Neophyte

  I'm working on 2d topdown game in SFML 2, and need to find an elegant way in which everything will work and fit together. Allow me to explain. I have a number of classes that inherit from an abstract base that provides a draw method and an update method to all the classes. In the game loop, I call update and then draw on each class, I imagine this is a pretty common approach. I have classes for tiles, collisions, the player and a resource manager that contains all the tiles/images/textures. Due to the way input works in SFML I decided to have each class handle input (if required) in its update call. Up until now I have been passing in dependencies as needed, for example, in the player class when a movement key is pressed, I call a method on the collision class to check if the position the player wants to move to will be a collision, and only move the player if there is no collision. This works fine for the most part, but I believe it can be done better, I'm just not sure how. I now have more complex things I need to implement, eg: a player is able to walk up to an object on the ground, press a key to pick it up/loot it and it will then show up in inventory. This means that a few things need to happen: Check if the player is in range of a lootable item on keypress, else do not proceed. Find the item. Update the sprite texture on the item from its default texture to a "looted" texture. Update the collision for the item: it might have changed shape or been removed completely. Inventory needs to be updated with the added item. How do I make everything communicate? With my current system I will end up with my classes going out of scope, and method calls to each other all over the place. I could tie up all the classes in one big manager and give each one a reference to the parent manager class, but this seems only slightly better. Any help/advice would be greatly appreciated! If anything is unclear, I'm happy to expand on things.

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• Is the Entity Component System architecture object oriented by definition?

  - by tieTYT

  Is the Entity Component System architecture object oriented, by definition? It seems more procedural or functional to me. My opinion is that it doesn't prevent you from implementing it in an OO language, but it would not be idiomatic to do so in a staunchly OO way. It seems like ECS separates data (E & C) from behavior (S). As evidence: The idea is to have no game methods embedded in the entity. And: The component consists of a minimal set of data needed for a specific purpose Systems are single purpose functions that take a set of entities which have a specific component I think this is not object oriented because a big part of being object oriented is combining your data and behavior together. As evidence: In contrast, the object-oriented approach encourages the programmer to place data where it is not directly accessible by the rest of the program. Instead, the data is accessed by calling specially written functions, commonly called methods, which are bundled in with the data. ECS, on the other hand, seems to be all about separating your data from your behavior.

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• Preferred way for dealing with customer-defined data in enterprise application

  - by Axarydax

  Let's say that we have a small enterprise web (intranet) application for managing data for car dealers. It has screens for managing customers, inventory, orders, warranties and workshops. This application is installed at 10 customer sites for different car dealers. First version of this application was created without any way to provide for customer-specific data. For example, if dealer A wanted to be able to attach a photo to a customer, dealer B wanted to add e-mail contact to each workshop, and dealer C wanted to attach multiple PDF reports to a warranty, each and every feature like this was added to the application, so all of the customers received everything on new update. However, this will inevitably lead to conflicts as the number of customers grow as their usage patterns are unique, and if, for instance, a specific dealer requested to have an ability to attach (for some reason) a color of inventory item (and be able to search by this color) as a required item, others really wouldn't need this feature, and definitely will not want it to be a required item. Or, one dealer would like to manage e-mail contacts for their employees on a separate screen of the application. I imagine that a solution for this is to use a kind of plugin system, where we would have a core of the application that provides for standard features like customers, inventory, etc, and all of the customer's installed plugins. There would be different kinds of plugins - standalone screens like e-mail contacts for employees, with their own logic, and customer plugin which would extend or decorate inventory items (like photo or color). Inventory (customer,order,...) plugins would require to have installation procedure, hooks for plugging into the item editor, item displayer, item filtering for searching, backup hook and such. Is this the right way to solve this problem?

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• What are the advantages of storing xml in a relational database?

  - by Chris

  I was poking around the AdventureWorks database today and I noticed that a number of tables (HumanResources.JobCandidate and Sales.Individual for example) have a column which is storing xml data. What I would to know is, what is the advantage of storing basically a database table row's worth of data in another table's column? Doesn't this make it difficult to query off of this information? Or is the assumption that the data won't need to be queried and just needs to be stored?

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• Designing a user-defined list to be stored in a relational database - Should I include user index?

  - by Zaemz

  By index, I mean, as the user creates the list, each item receives an integer index for its place in that particular list. Since there will be a table of ListItems, I'd prefer to avoid using the name "Index" for the field. Then I was thinking - should I even include the list index in the database? I figured I would because the list would be created in the same fashion every time, then. Or I could order the list for the user based on its actual primary key, since the list items are created in succession anyway... What should I do?

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• Checking timeouts made more readable

  - by Markus

  I have several situations where I need to control timeouts in a technical application. Either in a loop or as a simple check. Of course – handling this is really easy, but none of these is looking cute. To clarify, here is some C# (Pseudo) code: private DateTime girlWentIntoBathroom; girlWentIntoBathroom = DateTime.Now; do { // do something } while (girlWentIntoBathroom.AddSeconds(10) > DateTime.Now); or if (girlWentIntoBathroom.AddSeconds(10) > DateTime.Now) MessageBox.Show("Wait a little longer"); else MessageBox.Show("Knock louder"); Now I was inspired by something a saw in Ruby on StackOverflow: Now I’m wondering if this construct can be made more readable using extension methods. My goal is something that can be read like “If girlWentIntoBathroom is more than 10 seconds ago” 1st attempt if (girlWentIntoBathroom > (10).Seconds().Ago()) MessageBox.Show("Wait a little longer"); else MessageBox.Show("Knock louder"); So I wrote an extension for integer that converts the integer into a TimeSpan public static TimeSpan Seconds(this int amount) { return new TimeSpan(0, 0, amount); } After that, I wrote an extension for TimeSpan like this: public static DateTime Ago(this TimeSpan diff) { return DateTime.Now.Add(-diff); } This works fine so far, but has a great disadvantage. The logic is inverted! Since girlWentIntoBathroom is a timestamp in the past, the right side of the equation needs to count backwards: impossible. Just inverting the equation is no solution, because it will invert the read sentence as well. 2nd attempt So I tried something new: if (girlWentIntoBathroom.IsMoreThan(10).SecondsAgo()) MessageBox.Show("Knock louder"); else MessageBox.Show("Wait a little longer"); IsMoreThan() needs to transport the past timestamp as well as the span for the extension SecondsAgo(). It could be: public static DateWithIntegerSpan IsMoreThan(this DateTime baseTime, int span) { return new DateWithIntegerSpan() { Date = baseTime, Span = span }; } Where DateWithIntegerSpan is simply: public class DateWithIntegerSpan { public DateTime Date {get; set;} public int Span { get; set; } } And SecondsAgo() is public static bool SecondsAgo(this DateWithIntegerSpan dateAndSpan) { return dateAndSpan.Date.Add(new TimeSpan(0, 0, dateAndSpan.Span)) < DateTime.Now; } Using this approach, the English sentence matches the expected behavior. But the disadvantage is, that I need a helping class (DateWithIntegerSpan). Has anyone an idea to make checking timeouts look more cute and closer to a readable sentence? Am I a little too insane thinking about something minor like this?

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• Isn't class scope purely for organization?

  - by Di-0xide

  Isn't scope just a way to organize classes, preventing outside code from accessing certain things you don't want accessed? More specifically, is there any functional gain to having public, protected, or private-scoped methods? Is there any advantage to classifying method/property scope rather than to, say, just public-ize everything? My presumption says no simply because, in binary code, there is no sense of scope (other than r/w/e, which isn't really scope at all, but rather global permissions for a block of memory). Is this correct? What about in languages like Java and C#[.NET]?

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• Dynamic Query Generation : suggestion for better approaches

  - by Gaurav Parmar

  I am currently designing a functionality in my Web Application where the verified user of the application can execute queries which he wishes to from the predefined set of queries with where clause varying as per user's choice. For example,Table ABC contains the following Template query called SecretReport "Select def as FOO, ghi as BAR from MNO where " SecretReport can have parameters XYZ, ILP. Again XYZ can have values as 1,2 and ILP can have 3,4 so if the user chooses ILP=3, he will get the result of the following query on his screen "Select def as FOO, ghi as BAR from MNO where ILP=3" Again the user is allowed permutations of XYZ / ILP My initial thought is that User will be shown a list of Report names and each report will have parameters and corresponding values. But this approach although technically simple does not appear intuitive. I would like to extend this functionality to a more generic level. Such that the user can choose a table and query based on his requirements. Of course we do not want the end user to take complete control of DB. But only tables and fields that are relevant to him. At present we are defining what is relevant in the code. But I want the Admin to take over this functionality such that he can decide what is relevant and expose the same to the user. On user's side it should be intuitive what is available to him and what queries he can form. Please share your thoughts what is the most user friendly way to provide this feature to the end user.

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• How do you prevent inflation in a virtual economy?

  - by Tetrad

  With your typical MMORPG, players can usually farm the world for raw materials essentially forever. Monsters/mineral veins/etc are usually on some sort of respawn timer, so other than time there really isn't a good way to limit the amount of new currency entering the system. That really only leaves money sinks to try to take money out of the system. What are some strategies to prevent inflation of the in-game currency?

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• How should UI layer pass user input to BL layer?

  - by BornToCode

  I'm building an n-tier application, I have UI, BL, DAL & Entities (built from POCO) projects. (All projects have a reference to the Entities). My question is - how should I pass user input from the UI to the BL, as a bunch of strings passed to the BL method and the BL will build the object from the parameters, or should I build the objects inside the UI submit_function and send objects as parameters? EDIT: I wrote n-tier application, but what I actually meant was just layers.

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• How to control messages to the same port from different emitters?

  - by Alex In Paris

  Scene: A company has many factories X, each emits a message to the same receive port in a Biztalk server Y; if all messages are processed without much delay, each will trigger an outgoing message to another system Z. Problem: Sometimes a factory loses its connection for a half-day or more and, when the connection is reestablished, thousands of messages get emitted. Now, the messages still get processed well by Y (Biztalk can easily handle the load) but system Z can't handle the flood and may lock up and severely delay the processing of all other messages from the other X. What is the solution? Creating multiple receive locations that permits us to pause one X or another would lose us information if the factory isn't smart enough to know whether the message was received or not. What is the basic pattern to apply in Biztalk for this problem? Would some throttling parameters help to limit the flow from any one X? Or are their techniques on the end part of Y which I should use instead ? I would prefer this last one since I can be confident that the message box will remember any failures, which could then be resumed.

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• Advice on reconciling discordant data

  - by Justin

  Let me support my question with a quick scenario. We're writing an app for family meal planning. We'll produce daily plans with a target calorie goal and meals to achieve it for our nuclear family. Our calorie goal will be calculated for each person from their attributes (gender, age, weight, activity level). The weight attribute is the simplest example here. When Dad (the fascist nerd who is inflicting this on his family) first uses the application he throws approximate values into it for Daughter. He thinks she is 5'2" (157 cm) and 125 lbs (56kg). The next day Mom sits down to generate the menu and looks back over what the bumbling Dad did, quietly fumes that he can never recall anything about the family, and says the value is really 118 lbs! This is the first introduction of the discord. It seems, in this scenario, Mom is probably more correct that Dad. Though both are only an approximation of the actual value. The next day the dear Daughter decides to use the program and sees her weight listed. With the vanity only a teenager could muster she changes the weight to 110 lbs. Later that day the Mom returns home from a doctor's visit the Daughter needed and decides that it would be a good idea to update her Daughter's weight in the program. Hooray, another value, this time 117 lbs. Now how do you reconcile these data points? Measurement error, confidence in parties, bias, and more all confound the data. In some idealized world we'd have a weight authority of some nature providing the one and only truth. How about in our world though? And the icing on the cake is that this single data point changes over time. How have you guys solved or managed this conflict?

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• Should I force users to update an application?

  - by Brian Green

  I'm writing an application for a medium sized company that will be used by about 90% of our employees and our clients. In planning for the future we decided to add functionality that will verify that the version of the program that is running is a version that we still support. Currently the application will forcequit if the version is not among our supported versions. Here is my concern. Hypothetically, in version 2.0.0.1 method "A" crashes and burns in glorious fashion and method "B" works just fine. We release 2.0.0.2 to fix method A and deprecate version 0.1. Now if someone is running 0.1 to use method B they will be forced to update to fix something that isn't an issue for them right now. My question is, will the time saved not troubleshooting old, unsupported versions outweigh the cost in usability?

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• Logic or Algorithm to solve this problem [closed]

  - by jade

  I have two lists. List1 {a,b,c,d,e} and List2 {f,g,h,i,j} The relation between the two list is as follows a->g,a->h,h->c,h->d,d->i,d->j Now I have these two lists displayed. Based on the relation above on selecting element a from List1, List2 shows g,h. On selecting h from List2, in List1 c,d are shown in List1. On selecting d from List1 it shows i,j in List2. How to trace back to initial state by deselecting the elements in reverse order in which they have been selected?

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• Summary of usage policies for website integration of various social media networks?

  - by Dallas

  To cut to the chase... I look at Twitter's usage policy and see limitations on what can and can't be done with their logo. I also see examples of websites that use icons that have been integrated with the look and feel of their own site. Given Twitter's policy, for example, it would appear that legal conversations/agreements would need to take place to do this, especially on a commercial site. I believe it is perfectly acceptable to have a plain text button that simply has the word "Tweet" on it, that has the same functionality. My question is if anyone can provide online (or other) references that attempt to summarize what can and can't be done when integrating various social networks into your own work? The answer I will mark as the correct one will be the one which provides the best resource(s) giving the best summaries of what can and can't be done with specific logos/icons, with a secondary factor being that a variety of social networking sites are addressed in your answer. Before people point to specific questions, I am looking for a well-rounded approach that considers a breadth of networks and considerations. Background: I would like to incorporate social media icons and functionality, but would like to consider what type of modifications can be done without needing to involve lawyers. For example, can I bring in a standard Facebook logo, but incorporate my site color into the logo? Would the answer differ if I maintained their color, but add in a few pixels of another color to transition? I am not saying I want to do this, but rather using it as an example.

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