Search Results

Search found 10536 results on 422 pages for 'dan course'.

Page 286/422 | < Previous Page | 282 283 284 285 286 287 288 289 290 291 292 293  | Next Page >

• Writing or extending existing emacs packages: is it worth or should I move to Netbeans/Eclipse?

  - by Andrea

  I'm finishing my master degree course in CS and I've almost become addicted to Emacs. I've used it to write in C, Latex, Java, JSP,XML, CommonLisp, Ada and other languages no other editor supported, like AMPL. I'd like to improve the packages I've been using the most or create new ones, but, in practice, I find that the implementation of Emacs leaves a lot to be desired. There are a lot of poorly-featured/poorly-maintained packages with either overlapping functionalities or obscure incompatibilities, and Elisp just seems to foster the situation by lacking the common features modern lisps have. In contrast Eclipse and Netbeans are actively improved and it does seem they can be effective for non-mainstream languages. I tried Hibachi for Ada in Eclipse and it worked well, there's CUPS for Lisp in Eclipse and LambdaBeans built using NetBeans components. On the other hand those plugins seem to be less active than their Emacs' counterparts, for example Hibachi was archived last year. What's your opinion on this? Which editor should I write extension for? EDIT: To answer Larry Coleman (see comment below): I like Emacs as a user because it is efficient both for me and the computer I'm using. It's fast and the textual interface (i.e. minibuffer) allows for quick interaction. It's solid and packages are usually small and easy to manage. If I need to correct or remove something I usually just have to change a row in my .emacs or an elisp file, or delete a directory. Eclipse plugins rely on a more complicated process that screwed my Eclipse configuration a couple of times, forcing me to do a clean reinstall. Emacs works as long as I use the basic packages. If I need something more complicated the situation gets pretty hairy. As a "power user" I think that the best I can hope for is to write a severely crippled version of the extensions I'd actually like to have; in other words, that it's not worth the trouble. I'd like to write extensions for the things I'd like to have automated in Emacs, for example project support with automated tag-table update on file writing. There are a few projects on this that lack integration, documentation, extensibility and so forth. The best one is probably CEDET, for which I believe the Greenspun's 10th rule can be applied. EDIT: To comment Larry Coleman's answer I'm pretty sure I can pick elisp programming but the extensions I have in mind don't exist yet despite their relative simplicity and the effort more knowledgeable people poured into related projects.This makes me wonder whether it is so because of the way emacs is developed, i.e. people tend to write their own little extensions without coordination, or its implementation, its extension language not being able to keep up with the growing complexity.

  Read the article

• What Counts for a DBA: Passion

  - by drsql

  One of my first questions, when interviewing for a DBA/Programmer position, is always: “Why do you want this job?” The answers I receive range from cheesy hyperbole (“I want to enhance your services with my vast knowledge”) to deadpan realism (“I have N kids who all have a hole in the front of their face where food goes"). Both answers are fine in their own way, at least displaying some self-confidence, humour and honesty, but once in a while, I'll hear the answer that is music to me ears... “I LOVE DATABASES!” Whenever I hear it, my nerves tingle in hopeful anticipation; have I found someone for whom working with database isn't just a job, but a passion? Inevitably, I'm often disappointed. What initially seemed like passion turns out to be rather shallow enthusiasm; the person is enthusiastic about working with databases in the same way he or she might be about eating a bag of Cajun spiced kettle chips; enjoyable, but not something to think about too deeply or take too seriously. Enthusiasm comes, and enthusiasm goes. I've seen countless technical forum users burst onto the scene in a blaze of frantic question-answering, only to fade away within days, never to be heard from again. Passion, however, is more of a longstanding commitment. The biographies of the great technologists and authors of the recent past are full of the sort of passion and engrossment that lead a person to write a novel non-stop for a fortnight with no sleep and only dog food to eat (Philip K. Dick), or refuse to leave the works of the first tunnel under the Thames, even though it was flooded (Brunel). In a similar (though more modest) way, my passion for working with databases has led me to acts that might cause someone for whom it was "just a job" to roll their eyes in disbelief. Most evenings you're more likely to find me reading a database book than watching TV. I've spent hundreds of hours of my spare time writing blogs and articles (some of which are only read by tens of people); I've spent hundreds of dollars travelling to conferences, paying my own flight and hotel expenses, so that I can share a little of what I know, and mix with some like-minded people. And I know I'm far from alone in this, in the SQL Server community. Passion isn't everything, of course, and it isn't always accompanied by any great skill, but in almost every case, that skill can be cultivated over time. If you are doing what you are passionate about, work turns into more than just a way to feed your kids; it becomes your hobby, entertainment, and preoccupation. And it is this passion that gives a DBA the obsessive stubbornness, the refusal to be beaten by even the most difficult problem, which is often so crucial. A final word of warning though: passion without limits can turn weird. Never let it get in the way of your wife, kids, bills, or personal hygiene.

  Read the article

• Data structures for a 2D multi-layered and multi-region map?

  - by DevilWithin

  I am working on a 2D world editor and a world format subsequently. If I were to handle the game "world" being created just as a layered set of structures, either in top or side views, it would be considerably simple to do most things. But, since this editor is meant for 3rd parties, I have no clue how big worlds one will want to make and I need to keep in mind that eventually it will become simply too much to check, handling and comparing stuff that are happening completely away from the player position. I know the solution for this is to subdivide my world into sub regions and stream them on the fly, loading and unloading resources and other data. This way I know a virtually infinite game area is achievable. But, while I know theoretically what to do, I really have a few questions I'd hoped to get answered for some hints about the topic. The logic way to handle the regions is some kind of grid, would you pick evenly distributed blocks with equal sizes or would you let the user subdivide areas by taste with irregular sized rectangles? In case of even grids, would you use some kind of block/chunk neighbouring system to check when the player transposes the limit or just put all those in a simple array? Being a region a different data structure than its owner "game world", when streaming a region, would you deliver the objects to the parent structures and track them for unloading later, or retain the objects in each region for a more "hard-limit" approach? Introducing the subdivision approach to the project, and already having a multi layered scene graph structure on place, how would i make it support the new concept? Would you have the parent node have the layers as children, and replicate in each layer node, a node per region? Or the opposite, parent node owns all the regions possible, and each region has multiple layers as children? Or would you just put the region logic outside the graph completely(compatible with the first suggestion in Q.3) When I say virtually infinite worlds, I mean it of course under the contraints of the variable sizes and so on. Using float positions, a HUGE world can already be made. Do you think its sane to think beyond that? Because I think its ok to stick to this limit since it will never be reached so easily.. As for when to stream a region, I'm implementing it as a collection of watcher cameras, which the streaming system works with to know what to load/unload. The problem here is, i will be needing some kind of warps/teleports built in for my game, and there is a chance i will be teleporting a player to a unloaded region far away. How would you approach something like this? Is it sane to load any region to memory which can be teleported to by a warp within a radius from the player? Sorry for the huge question, any answers are helpful!

  Read the article

• How to force a clock update using ntp?

  - by ysap

  I am running Ubuntu on an ARM based embedded system that lacks a battery backed RTC. The wake-up time is somewhere during 1970. Thus, I use the NTP service to update the time to the current time. I added the following line to /etc/rc.local file: sudo ntpdate -s time.nist.gov However, after startup, it still takes a couple of minutes until the time is updated, during which period I cannot work effectively with tar and make. How can I force a clock update at any given time? UPDATE 1: The following (thanks to Eric and Stephan) works fine from command line, but fails to update the clock when put in /etc/rc.local: $ date ; sudo service ntp stop ; sudo ntpdate -s time.nist.gov ; sudo service ntp start ; date Thu Jan 1 00:00:58 UTC 1970 * Stopping NTP server ntpd [ OK ] * Starting NTP server [ OK ] Thu Feb 14 18:52:21 UTC 2013 What am I doing wrong? UPDATE 2: I tried following the few suggestions that came in response to the 1st update, but nothing seems to actually do the job as required. Here's what I tried: Replace the server to us.pool.ntp.org Use explicit paths to the programs Remove the ntp service altogether and leave just sudo ntpdate ... in rc.local Remove the sudo from the above command in rc.local Using the above, the machine still starts at 1970. However, when doing this from command line once logged in (via ssh), the clock gets updated as soon as I invoke ntpdate. Last thing I did was to remove that from rc.local and place a call to ntpdate in my .bashrc file. This does update the clock as expected, and I get the true current time once the command prompt is available. However, this means that if the machine is turned on and no user is logged in, then the time never gets updates. I can, of course, reinstall the ntp service so at least the clock is updated within a few minutes from startup, but then we're back at square 1. So, is there a reason why placing the ntpdate command in rc.local does not perform the required task, while doing so in .bashrc works fine?

  Read the article

• Real-Time Multi-User Gaming Platform

  - by Victor Engel

  I asked this question at Stack Overflow but was told it's more appropriate here, so I'm posting it again here. I'm considering developing a real-time multi-user game, and I want to gather some information about possibilities before I do some real development. I've thought about how best to ask the question, and for simplicity, the best way that occurred to me was to make an analogy to the field (or playground) game darebase. In the field game of darebase, there are two or more bases. To start, there is one team on each base. The game is a fancy game of tag. When two people meet out in the field, the person who left his base most recently timewise captures the other person. They then return to that person's base. Play continues until everyone is part of the same team. So, analogizing this to an online computer game, let's suppose there are an indefinite number of bases. When a person starts up the game, he has a team that is located at, for example, his current GPS coordinates. It could be a virtual world, but for sake of argument, let's suppose the virtual world corresponds to the player's actual GPS coordinates. The game software then consults the database to see where the closest other base is that is online, and the two teams play their game of virtual tag. Note that the user of the other base could have a different base than the one run by the current user as the closest base to him, in which case, he would be in two simultaneous battles, one with each base. When they go offline, the state of their players is saved on a server somewhere. Game logic calls for the players to have some automaton-logic of some sort, so they can fend for themselves in a limited way using basic rules, until their user goes online again. The user doesn't control the players' movements directly, but issues general directives that influence the players' movement logic. I think this analogy is good enough to frame my question. What sort of platforms are available to develop this sort of game? I've been looking at smartfoxserver, but I'm not convinced yet that it is the best option or even that it will work at all. One possibility, of course, would be to roll out my own web server, but I'd rather not do that if there is an existing service out there already that I could tap into. I will be developing for iOS devices at first. So any suggestions would be greatly appreciated. I think I need to establish the architecture first before proceeding with this project. Note that darbase is not the game I intend to implement, but, upon reflection, that might not be a bad idea either.

  Read the article

• Should a server "be lenient" in what it accepts and "discard faulty input silently"?

  - by romkyns

  I was under the impression that by now everyone agrees this maxim was a mistake. But I recently saw this answer which has a "be lenient" comment upvoted 137 times (as of today). In my opinion, the leniency in what browsers accept was the direct cause of the utter mess that HTML and some other web standards were a few years ago, and have only recently begun to properly crystallize out of that mess. The way I see it, being lenient in what you accept will lead to this. The second part of the maxim is "discard faulty input silently, without returning an error message unless this is required by the specification", and this feels borderline offensive. Any programmer who has banged their head on the wall when something fails silently will know what I mean. So, am I completely wrong about this? Should my program be lenient in what it accepts and swallow errors silently? Or am I mis-interpreting what this is supposed to mean? The original question said "program", and I take everyone's point about that. It can make sense for programs to be lenient. What I really meant, however, is APIs: interfaces exposed to other programs, rather than people. HTTP is an example. The protocol is an interface that only other programs use. People never directly provide the dates that go into headers like "If-Modified-Since". So, the question is: should the server implementing a standard be lenient and allow dates in several other formats, in addition to the one that's actually required by the standard? I believe the "be lenient" is supposed to apply to this situation, rather than human interfaces. If the server is lenient, it might seem like an overall improvement, but I think in practice it only leads to client implementations that end up relying on the leniency and thus failing to work with another server that's lenient in slightly different ways. So, should a server exposing some API be lenient or is that a very bad idea? Now onto lenient handling of user input. Consider YouTrack (a bug tracking software). It uses a language for text entry that is reminiscent of Markdown. Except that it's "lenient". For example, writing - foo - bar - baz is not a documented way of creating a bulleted list, and yet it worked. Consequently, it ended up being used a lot throughout our internal bugtracker. Next version comes out, and this lenient feature starts working slightly differently, breaking a bunch of lists that (mis)used this (non)feature. The documented way to create bulleted lists still works, of course. So, should my software be lenient in what user inputs it accepts?

  Read the article

• Updating an Entity through a Service

  - by GeorgeK

  I'm separating my software into three main layers (maybe tiers would be a better term): Presentation ('Views') Business logic ('Services' and 'Repositories') Data access ('Entities' (e.g. ActiveRecords)) What do I have now? In Presentation, I use read-only access to Entities, returned from Repositories or Services, to display data. $banks = $banksRegistryService->getBanksRepository()->getBanksByCity( $city ); $banksViewModel = new PaginatedList( $banks ); // some way to display banks; // example, not real code I find this approach quite efficient in terms of performance and code maintanability and still safe as long as all write operations (create, update, delete) are preformed through a Service: namespace Service\BankRegistry; use Service\AbstractDatabaseService; use Service\IBankRegistryService; use Model\BankRegistry\Bank; class Service extends AbstractDatabaseService implements IBankRegistryService { /** * Registers a new Bank * * @param string $name Bank's name * @param string $bik Bank's Identification Code * @param string $correspondent_account Bank's correspondent account * * @return Bank */ public function registerBank( $name, $bik, $correspondent_account ) { $bank = new Bank(); $bank -> setName( $name ) -> setBik( $bik ) -> setCorrespondentAccount( $correspondent_account ); if( null === $this->getBanksRepository()->getDefaultBank() ) $this->setDefaultBank( $bank ); $this->getEntityManager()->persist( $bank ); return $bank; } /** * Makes the $bank system's default bank * * @param Bank $bank * @return IBankRegistryService */ public function setDefaultBank( Bank $bank ) { $default_bank = $this->getBanksRepository()->getDefaultBank(); if( null !== $default_bank ) $default_bank->setDefault( false ); $bank->setDefault( true ); return $this; } } Where am I stuck? I'm struggling about how to update certain fields in Bank Entity. Bad solution #1: Making a series of setters in Service for each setter in Bank; - seems to be quite reduntant, increases Service interface complexity and proportionally decreases it's simplicity - something to avoid if you care about code maitainability. I try to follow KISS and DRY principles. Bad solution #2: Modifying Bank directly through it's native setters; - really bad. If you'll ever need to move modification into the Service, it will be pain. Business logic should remain in Business logic layer. Plus, there are plans on logging all of the actions and maybe even involve user permissions (perhaps, through decorators) in future, so all modifications should be made only through the Service. Possible good solution: Creating an updateBank( Bank $bank, $array_of_fields_to_update) method; - makes the interface as simple as possible, but there is a problem: one should not try to manually set isDefault flag on a Bank, this operation should be performed through setDefaultBank method. It gets even worse when you have relations that you don't want to be directly modified. Of course, you can just limit the fields that can be modified by this method, but how do you tell method's user what they can and cannot modify? Exceptions?

  Read the article

• Several New Hints

  - by Ondrej Brejla

  Hi all! Today we would like to introduce you some of our new experimental hints for NetBeans 7.2. They are called: Unused Use Statement and Immutable Variables. Unused Use Statement This hint is quite simple. It highlights (underlines) your use statements, which are not used. Typical use case is after some refactoring, when you forgot to remove some obsolete use statements. This hint warns you on them and allows you to remove them easily. Just click on the hint bulb in the gutter and select Remove Unused Use Statement. And of course, it works in multiple use statements combined too. Immutable Variables The next one is the hint which checks too many assignments into a variable. And why? That's simple. Mostly you should use just one assignment into one variable. But sometimes you are lazy and you do something like: But it's quite wrong, because what you really do is: And that's exactly the case, when our new hint warns you, that Too many assignments (2) into variable $foo occured. Nothing more. Yes, we know that there are some cases, where could be more assignments and no warning should occur, e.g.: Because maybe one likes longer increment syntax more than the short one. So we tried to handle these cases to don't bother you if it's not a need. Note: We are almost sure that this hint doesn't cover all your use cases, because there are a lot of them. So if you find something strange, write it into our bugzilla so we can handle it better for you. Thanks for your patience! And the last thing is, that you can set the number of allowed assignments in Tools -> Options -> Editor -> Hints -> PHP: Immutable Variables. Note: This hint works just for a common variables, not for fields. We have an enhancement request for that and it should be implemented in next version of NetBeans (probably 7.3). And that's all for today and as usual, please test it and if you find something strange, don't hesitate to file a new issue (product php, component Editor). Thanks.

  Read the article

• Lookup Viewer

  - by Geertjan

  The Maven integrated view that I showed yesterday I was able to create because I happened to know that an implementation of SubprojectProvider and LogicalViewProvider are in the Lookup of Maven projects. With that knowledge, I was able to use and even delegate to those implementations. But what if you don't know that those implementations are in the Lookup of the Project object? In the case of the Maven Project implementation, you could look in the source code of the Maven Project implementation, at the "getLookup" method. However, any other module could be putting its own objects into that Lookup, dynamically, i.e., at runtime. So there's no way of knowing what's in the Lookup of any Project object or any other object with a Lookup. But now imagine that you have a Lookup Viewer, as a tool during development, which you would exclude when distributing the application. Whenever new objects are found in the Lookup, the viewer displays them. You could install the Lookup Viewer into NetBeans IDE, or any other NetBeans Platform application, and then get a quick impression of what's actually in the Lookup when you select a different item in the application during development. Here it is (though I vaguely remember someone else writing something similar): Above, a Maven Project is selected. The Lookup Window shows that, among many other classes, an implementation of SubprojectProvider and LogicalViewProvider are found in the Lookup when the Maven Project is selected. If an item in the Lookup Window has its own Lookup, the content of that Lookup is displayed as child nodes of the Lookup, etc, i.e., you can explore all the way down the Lookup of each item found within objects found within the current selection. (What's especially fun is seeing the SaveCookieImpl being added and removed from the Lookup Window when you make/save a change in a document.) Another example is below, showing the Lookup Window installed in a custom application created during a course at MIT in Boston: A small trick I had to apply is that I always show the previous Lookup, since the current Lookup, when you select one of the Nodes in the Lookup Window, would be the Lookup of the Lookup Window itself! If anyone is interested in this, I can publish the NetBeans module providing the above window to the NetBeans update center. 

  Read the article

• Was I wrong about JavaScript?

  - by jboyer

  Yes, I was. Recently, I’ve taken a good hard look at JavaScript. I’ve used it before but mostly in the capacity of web design. Using JQuery to make your web page do cool stuff is different than really creating a JavaScript application using all of the language constructs. What I’m finding as I use it more is that I may have been wrong about my assumptions about it. Let me explain.   I enjoyed doing cool stuff with JQuery but the limited experience with JavaScript as a language coupled with the bad things that I heard about it led me to not have any real interest in it. However, JavaScript is ubiquitous on the web and if I want to do any web development, which I do, I need to learn it. So here I am, diving deep into the language with the help of the JavaScript Fundamentals training course at Pluralsight (great training for a low price) and the JavaScript: The Good Parts book by Douglas Crockford.   Now, there are certainly parts of JavaScript that are bad. I think these are well known by any developer that uses it. The parts that I feel are especially egregious are the following: The global object null vs. undefined truthy and falsy limited (nearly nonexistent) scoping ‘==’ and ‘===’ (I just don’t get the reason for coercion)   However, what I am finding hiding under the covers of the bad things is a good language. I am finding that I am legitimately enjoying JavaScript. This I was not expecting. I’m not going to go into a huge dissertation on what I like about it, but some things include: Object literal notation dynamic typing functional style (JavaScript: The Good Parts describes it as LISP in C clothing) JSON (better than XML) There are parts of JavaScript that seem strange to OOP developers like myself. However, just because it is different or seems strange does not mean it is bad. Some differences are quite interesting and useful.   I feel that it is important for developers to challenge their assumptions and also to be able to admit when they are wrong on a topic. Many different situations can arise that lead to this, such as choosing the wrong technology for a problem’s solution, misunderstanding the requirements, etc. I decided to challenge my assumptions about JavaScript instead of moving straight into CoffeeScript or Dart. After exploring it, I find that I am beginning to enjoy it the more I use it. As long as there are those like Crockford to help guide me in the right way to code in JavaScript, I can create elegant and efficient solutions to problems and add another ‘arrow’ to the ‘quiver’, so to speak. I do still intend to learn CoffeeScript to see what the hub-bub is about, but now I no longer have to be afraid of JavaScript as a legitimate programming language.   Has something similar ever happened to you? Tell me about it in the comments below.

  Read the article

• Styling Windows Phone Silverlight Applications

  - by Tim Murphy

  If you have not developed with styles in Silverlight/XAML then it can be challenging and resources can be sparse depending on how deep you get.  One thing that you need to understand is what level you can apply styles and how much they can cascade.  What I am finding is that this doesn’t go to the level that we are used to in HTML and CSS. While styles can be defined at a page level if you want to share styles throughout your application they should be defined in the App.xaml file.  This is of course analogous to placing a style in your HTML file versus an external CSS file.  This is the type of style I will concentrate on in this post. The first thing to look it how styles associate to elements.  TargetType defines the object type that your style will apply to.  In the example below the style is targeting the TextBlock object type. <Style x:Key="TextBlockSmallGray" TargetType="TextBlock"> Next we use a Setter which allows you to apply values for specific attributes of the target object type.  The setters can be a simple value or complex.  The first example here is simply applying a color to the background property of the target. <Setter Property="Background" Value="White"/> The second setter example here is for the same property, but we are applying a the definition of a LinearGradientBrush. <Setter Property="Background"> <Setter.Value> <LinearGradientBrush> <GradientStop Offset="0" Color="Black"/> <GradientStop Offset="1" Color="White"/> </LinearGradientBrush> </Setter.Value> </Setter> The last thing I want to cover here is that you can leverage the system styles and then override or extend them.  The BasedOn attribute of the Style tag allows this sort of inheritance.  In the example below I am going to start with the PhoneTextTitleStyle and then override properties as needed. <Style x:Key="TextBlockTitle" BasedOn="{StaticResource PhoneTextTitle1Style}" TargetType="TextBlock"> So now that we have our styles defined applying it is fairly straight forward.  Add the style name as a static resource to the style property of the element in your page and off you go. <Grid x:Name="LayoutRoot" Style="{StaticResource PageGridStyle}"> So this is one step in creating consistency in your application’s look.  In future posts I will dig a little deeper. del.icio.us Tags: windows phone 7,mobile development,windows phone 7 development,.NET,software development,design,UX

  Read the article

• How to Remove Extensions From, and Force the Trailing Slash at the End of URLs?

  - by Kronbernkzion

  Example of current file structure: example.com/foo.php example.com/bar.html example.com/directory/ example.com/directory/foo.php example.com/directory/bar.html example.com/cgi-bin/directory/foo.cgi I would like to remove HTML, PHP and CGI extensions from, and then force the trailing slash at the end of URLs. So, it could look like this: example.com/foo/ example.com/bar/ example.com/directory/ example.com/directory/foo/ example.com/directory/bar/ example.com/cgi-bin/directory/foo/ I am very frustrated because I've searched for 17 hours straight for solution and visited more than a few hundred pages on various blogs and forums. I'm not joking. So I think I've done my research. Here is the code that sits in my .htaccess file right now: RewriteCond %{REQUEST_FILENAME} !-d RewriteCond %{REQUEST_FILENAME}\.html -f RewriteRule ^(([^/]+/)*[^./]+)/$ $1.html RewriteCond %{REQUEST_FILENAME} !-f RewriteCond %{REQUEST_FILENAME} !-d RewriteCond %{REQUEST_URI} !(\.[a-zA-Z0-9]|/)$ RewriteRule (.*)$ /$1/ [R=301,L] As you can see, this code only removes .html (and I'm not very happy with it because I think it could be done a lot simpler). I can remove the extension from PHP files when I rename them to .html through .htaccess, but that's not what I want. I want to remove it straight. This is the first thing I don't know how to do. The second thing is actually very annoying. My .htaccess file with code above, adds .html/ to every string entered after example.com/directory/foo/. So if I enter example.com/directory/foo/bar (obviously /bar doesn't exist since foo is a file), instead of just displaying message that page is not found, it converts it to example.com/directory/foo/bar.html/, then searches for a file for a few seconds and then displays the not found message. This, of course, is bad behavior. So, once again, I need the code in .htaccess to do the following things: Remove .html extension Remove .php extension Remove .cgi extension Force the trailing slash at the end of URLs Requests should behave correctly (no adding trailing slashes or extensions to strings if file or directory doesn't exist on server) Code should be as simple as possible I would very much appreciate any help. And to first person that gives me the solution, I'll send two $50 iTunes Store gift cards for US store. If this offends anyone, I am truly sorry and I apologize. Thanks in advance.

  Read the article

• What are the differences between abstract classes, interfaces, and when to use them

  - by user66662

  Recently I have started to wrap my head around OOP, and I am now to the point where the more I read about the differences between Abstract classes and Interfaces the more confused I become. So far, neither can be instantiated. Interfaces are more or less structural blueprints that determine the skeleton and abstracts are different by being able to partially develop code. I would like to learn more about these through my specific situation. Here is a link to my first question if you would like a little more background information: What is a good design model for my new class? Here are two classes I created: class Ad { $title; $description $price; function get_data($website){ } function validate_price(){ } } class calendar_event { $title; $description $start_date; function get_data($website){ //guts } function validate_dates(){ //guts } } So, as you can see these classes are almost identical. Not shown here, but there are other functions, like get_zip(), save_to_database() that are common across my classes. I have also added other classes Cars and Pets which have all the common methods and of course properties specific to those objects (mileage, weight, for example). Now I have violated the DRY principle and I am managing and changing the same code across multiple files. I intend on having more classes like boats, horses, or whatever. So is this where I would use an interface or abstract class? From what I understand about abstract classes I would use a super class as a template with all of the common elements built into the abstract class, and then add only the items specifically needed in future classes. For example: abstract class content { $title; $description function get_data($website){ } function common_function2() { } function common_function3() { } } class calendar_event extends content { $start_date; function validate_dates(){ } } Or would I use an interface and, because these are so similar, create a structure that each of the subclasses are forced to use for integrity reasons, and leave it up to the end developer who fleshes out that class to be responsible for each of the details of even the common functions. my thinking there is that some 'common' functions may need to be tweaked in the future for the needs of their specific class. Despite all that above, if you believe I am misunderstanding the what and why of abstracts and interfaces altogether, by all means let a valid answer to be stop thinking in this direction and suggest the proper way to move forward! Thanks!

  Read the article

• Training v. Teaching

  - by Chris Gardner

  Originally posted on: http://geekswithblogs.net/freestylecoding/archive/2014/05/28/training-v.-teaching.aspxAs some of you may know, I recently accepted a position to teach an undergraduate course at my alma mater. Yesterday, I had my first day in an academic classroom. I immediately noticed a difference with the interactions between the students. They don't act like students in a professional training or conference talk. I wanted to use this opportunity to enumerate some of those differences. The immediate thing I noticed was the lack of open environment. This is not to say the class was hostile towards me. I am used to entering the room, bantering with audience, loosening everyone a bit, and flowing into the discussion. A purely academic audience does not banter. At least, they do not banter on day one. I think I can attribute this to two factors. This first is a greater perception of authority. In a training or conference environment, I am an equal with the audience. This is true even if I am being a subject matter expert. We're all professionals. We're all there to learn from each other, share our stories, and enjoy the journey. In the academic classroom, there was a distinct class difference. I had forgotten about this distinction; I had the professional familiarity with the staff by the time I completed my masters. This leads to the other distinction. These was an expectation of performance. At conference and professional training, there is generally no (immediate) grading. This may be a preparation for a certification exam, but I'm not the one responsible for delivering the exam. This was not the case in the academic classroom. These students are battling for points, and I am the sole arbiter. These students are less likely to let the material wash over them, applying the material to their past experiences. They were down taking notes. I don't want to leave the impression that there was no interact in the classroom. I spent a good deal of time doing problems with the class on the whiteboard. I tried to get the class to help me work out the steps. This opened up a few of them. After every conference or training class, I always get a few people that will email me afterward to continue the conversation. I am very curious to see if anybody comes to my office hours tomorrow. However, that is a curiosity that will have to wait until tomorrow.

  Read the article

• How to interview a natural scientist for a dev position?

  - by Silas

  I already did some interviews for my company, mostly computer scientists for dev positions but also some testers and project managers. Now I have to fill a vacancy in our research group within the R&D department (side note: “research” means that we try to solve problems in our professional domain/market niche using software in research projects together with universities, other companies, research centres and end user organisations. It’s not computer science research; we’re not going to solve the P=NP problem). Now we invited a guy holding an MSc in chemistry (with a lot of physics in his CV, too), who never had any computer science lesson. I already talked with him about half an hour at a local university’s career days and there’s no doubt the guy is smart. Also his marks are excellent and he graduated with distinction. For his BSc he needed to teach himself programming in Mathematica and told me believably that he liked programming a lot. Also he solved some physical chemistry problem that I probably don’t understand using his own software, implemented in Mathematica, for his MSc thesis. It includes a GUI and a notable size of 8,000 LoC. He seems to be very attracted by what we’re doing in our research group and to be honest it’s quite difficult for an SME like us to get good people. I also am very interested in hiring him since he could assist me in writing project proposals, reports, doing presentations and so on. He would probably fit to our team, too. The only question left is: How can I check if he will get the programming skills he needs to do software implementation in our projects since this will be a significant part of the job? Of course I will ask him what it is, that is fascinating him about programming. I’ll also ask how he proceeded to write his natural science software and how he structured it. I’ll ask about how he managed to obtain the skills and information about software development he needed. But is there something more I could ask? Something more concrete perhaps? Should I ask him to explain his Mathematica solution? To be clear: I’m not looking for knowledge in a particular language or technology stack. We’re a .NET shop in product development but I want to have a free choice for our research projects. So I’m interested in the meta-competence being able to learn whatever is actually needed. I hope this question is answerable and not open-ended since I really like to know if there is a default way to check for the ability to get further programming skills on the job. If something is not clear to you please give me some comments and let me improve my question.

  Read the article

• Focusing on Mobile @ Oracle OpenWorld

  - by Carlos Chang

  Plenty of exciting trends in the industry today: Cloud, Big Data, Mobile, etc. The first two are amazing of course, but for me, it's mobile, mobile and... MOBILE.   Why? Think back to the mozilla browser (Marc Andreessen's mozilla, not today's mozilla.org), Netscape and the nascent beginnings of the World Wide Web. Amazing times. Companies were just starting to set up their home pages, basic HTML, hyperlinks, images, ooooh, aaaah.  Yahoo! was *the* search engine back then. :-\   Anywhoo, I would pose that mobile today, we are in a similar junction. Sure, there's millions of apps on Apple's App Store and Google Play, but within the enterprise, it's just getting started. I'm talking about going beyond the simple, tactical apps such as calendaring, contacts or directory service lookup. And while mobile first a common mantra, I'm referring to mobile plus which includes and looks upon the whole enterprise holistically and adds new parameters, such as your GPS location, perhaps even your vital signs. (Apple's health kit?)  Everything is going mobile. Everything connected. But with the enterprise - scalability, security, integration, app management, user management, etc. Amazing times ahead. Ok, got that off my mind. Oracle OpenWorld 2014 - Going Mobile!  If you're coming to the big dance, I've highlighted some key mobile sessions below. And if you see me around, and there's a bar within reach, high five me for a beer. I mean, if you read this far, and didn't already jump to the list below, I think you deserve one.   Cheers!  Monday, 9/29/14 at 10:15 AM - General Session: Time for You to Rethink Mobile? Oracle Mobile Strategy and Roadmap Tuesday, 9/30/14 @ 12:00 PM; MW3020 - Develop and Deploy Mobile Applications with Oracle’s Mobile Wednesday, 10/1/2014 @10:15 AM; MW 3022 Introduction to Oracle Mobile Application Framework Wednesday, 10/1/2014 @11:30 AM Accelerate Enterprise Mobility with Oracle Mobile Cloud Service Click here to view the complete Focus on Mobile sessions at this years Oracle OpenWorld 2014, and don't forget to follow @OracleMobile on Twitter. 

  Read the article

• It's possible to fulfill the social necessity of a human being through a social game in 3D like IMVU?

  - by Totty

  (I'm not advertising nor promoting this game, as it's just an example of my experience and I would like to have your opinion about the matter if possible) I've been started researching "things" about games and I've decided to begin to play IMVU as a friend of mine said it's cool. At first it seemed just another 3d social game, not so cool.. But I've "tried to like" and after 1 day I can say I'm addicted to it! Yes; I will explain better: About the game: You can go in chat-rooms, move to positions. Some positions are like sitting in a sofa, floor, dancing alone or with a partner, kissing and more in this way. In the free version of the game there is no nudity. You can even listen to music, view youtube... The 3d graphics are quite low end, so it's not as real as the paid PC games of today. About my experience: At first I was going with my friend in chat-rooms, they seemed very nice. There were people talking about general stuff, quite like in a real life. Well, I begin to know some girls (yes, virtual girls commanded by a real girl, I hope!). Things happened: Some girls are just crazy, not like in real life, they make out in before even talking; Other girls you can speak a little bit, then they add you to their friend-list. Sometimes they invite to their virtual places. Some girls have really IMVU boyfriends only (but not in reality) and most of them don't even make up in the game, so it's really a level of commitment involved here! But from what my friend told they last for him, at least, about 3 days... Some others have real and IMVU boyfriends that are the same. Until now I haven't find a girl with different boyfriend in the IMVU and reality. Nor multiple boyfriends. There are rooms where the same people find each selves every day and speak about general stuff, relationships and so on... They are nice with you, they "feel" you and show careness. This is what amazes me, they treat you like a real human being and as being their friend in the real world. (of course it's not always like this) There are jealous girls too and competitiveness between females lol, I know you loled! This is kind of social. So today I closed my door in my room and I've played it all day long and guess what, I didn't feel a need to stay with a real person at all. Normally, If I would stay a full day alone I would get quite crazy... So the question is: It's just me that seemed to be able to fulfill my social needs or there is something more? thanks for your precious time for reading my full question,

  Read the article

• Creating a shared library that might be used with desktop applications and web projects

  - by dreza

  I have been involved in a number of MVC.NET and c# desktop projects in our company over the last year or so while also managing to kept my nose poked into other projects (in a read-only learning capacity of course). From this I've noticed that across the various projects and teams there is a-lot of functionality that has been well designed against good interfaces and abstractions. Because we tend to like our own work at times, I noticed a couple of projects had the exact same class, method copied into it as it had obviously worked on one and so was easily moved to a new project (probably by the same developer who originally wrote it) I mentioned this fact in one of our programmer meetings we have occasionally and suggested we pull some of this functionality into a core company library that we can build up over time and use across multiple projects. Everyone agreed and I started looking into this possibility. However, I've come across a stumbling block pretty early on. Our team primarily focuses on MVC at the moment and we have projects mainly in 2.0 but are starting to branch to 3.0. We also have a number of desktop applications that might benefit from some shared classes and basic helper methods. Initially when creating this DLL I included some shared classes that could be used across any project type (Web, Client etc) but then I started looking at adding some shared modules that would be useful in our MVC applications only. However this meant I had to include a reference to some Microsoft Web DLL's in order to leverage some of the classes I was creating (at this stage MVC 2.0). Now my issue is that we have a shared DLL that has references to web specific libraries that could also possibly be used in a client application. Not only that, our DLL referenced initially MVC 2.0 and we will eventually move onto MVC 3.0 for all projects. But alot of the classes in this library I expect to still be relevant to MVC 3 etc Our code within this DLL is separated into it's own namespaces such as: CompanyDLL.Primitives CompanyDLL.Web.Mvc CompanyDLL.Helpers etc etc So, my questions are: Is it OK to do a shared library like this, or if we have web specific features in it should we create a separate web DLL only targeted at a specific framework or MVC version? If it's OK, what kind of issues might we face when using the library that references MVC 2 in a MVC 3 project for example. I would be thinking that we might run into some sort of compatibility issue, or even issues where the developers using the library doesn't realize they need MVC 2.0 libraries. They might only want to use some of the generic classes etc The concept seemed like a good idea at the time, but I'm starting to think maybe it's not really a practical solution. But the number of times I've seen copied classes and methods across projects because they are proven tested code is a bit unnerving to be perfectly honest!

  Read the article

• Interesting Topics in Comp. Sci. for New Students?

  - by SoulBeaver

  I hope this is the right forum to ask this question. Last friday I was in a discussion with my professors about the students' lack of motivation and interest in the field of Computer Science. All of the students are enrolled, but through questionnaires and other questions that my professor posed it was revealed that over 90% of all enrolled students are just in it for the reward of getting a job sometime in the future (since it's a growing field with high job potential) I asked my professor for the permission to take over the first couple of lectures and try and motivate, interest and inspire students for the field of Computer Science and programming in particular (this is the Intro to Programming course). This request was granted and I now have a week to come up with a lecture topic for my professor's five groups. My main goal isn't to teach, I just want to get students to be as interested in the field as I am. I want to show them what's possible, what awesome magical things have been done in the field, the future we are heading towards using programming and Comp. Sci. Therefore, I would like to pose this question: I have a few topics, materials and sample projects that I would like to talk about: -- Grace Hopper (It is my hope to interest the female programmers in the class. There are never more than two or three per group and they, more than males, are prone to jumping ship and abandoning Comp. Sci.) -- The Singularity Institute -- Alan Turing -- Robotics -- Programming not as a chore or a must, but the idea that we are, at our core, the nexus to which anything anybody does in the digital world is connected to. We are the problem solvers; we assemble all the parts together and we are the ones that, essentially, make the vision a reality. -- Give them an idea for a programming project which, through the help of the professor, could be significant to every student (I want students to not only feel interested in the topic, but they should feel important, that what they do here makes a difference) Do you have interesting topics worthy of discussion, something I can tell the students which they can get interested about? How would you approach the lecture? If you had 90 minutes worth of time to try and get students interested in the project, what would you do?

  Read the article

• Lenovo Thinkpad X1 Carbon support

  - by Robottinosino

  I am considering selling my Mac to get money towards a Lenovo Thinkpad X1 because what I really want to do is to be running an Ubuntu system all the time. Is this machine completely supported in Ubuntu, with no tiny little feature missing just because I am "going Linux"? Optional user story section, skip to the question below if you don't have time: I have a friend who bought a "works on Ubuntu" system a year ago and has hated the fact ever since: battery lasts less than if he boots in Windows (which he despises) and he ascribes that to "no good OS/harware integration and support for advanced chipset power management features", odd behaviour on suspend/resume/hibernate (says: "when it works 90% of the time and the other 10% it makes you lose your work is as good as broken - 90% is the same as 0% he says), some occasional graphics card glitches he can perfectly well live with and has almost grown affectionate to, and finally, and that is what would make him undo his choice if he could, bad "input device drivers". He says: trackpoint and trackpad just "feel different", "so much better" on Windows and that was impossible to know from the website brochure. That story makes me very doubtful... but I want to abandon this "walled garden" of prison that is my Mac and go Ubuntu all the way, no doubt about that! My dilemma at this time is just: "I don't want to live with those eternal frustrations for sure"! Here's a directly answerable phrasing of my question: Is the Lenovo Thinkpad X1 supported on Ubuntu? Yes/no, which version? Which hardware features are not supported? Provide a list Optionally: sort the list in descending order of frustration from your experience Optionally: mention if there are acceptable workarounds to the "out-of-the-box" condition described in the earlier points and whether this ameliorates frustration at least to "tolerable" levels Comment: the Ubuntu hardware certification page is so not-for-end-users it's unreal. Whoa. What would make it end-user friendly is: Link to "buy here and you'll be just fine, this is the right configuration for you, it'll work as long as you press BUY on that page and don't browse further" Remove mentions of may and might not work. Just tell it straight: press buy here and you will get a working system with the exception of A, B, C (so that I can decide whether the philosophical "freedom pleasure" I get from escaping an Apple world is enough to off-balance the loss, for instance, of Bluetooth capabilities (something that I of course use on my Mac) but "could" lose to use free (as in freedom) software The certification page fails to dispel doubts in me as an end-user. I don't feel "eased into Ubuntu", I feel "partially informed".

  Read the article

• How can I get my ATI / AMD drivers to work with any kernel above 3.2.0.x?

  - by TorakTu

  How can I get my ATI / AMD drivers to work with any kernel above 3.2.0.x ? WHAT DID WORK Installed original AMD64 version of Ubuntu 12.04 ISO image. Burned DVD and installed which shown kernel 3.2.0-23 to begin with. Got 5.1 surround sound working. Got ATI ( Now its AMD ) video drivers installed for my Radeon HD R6870 Video card from AMD's website. fglrxinfo came up and reported as normal. THE PROBLEM Kernel 3.2.0.x kept locking up so I tried higher kernel versions. But ATI / AMD Drivers do not install on any kernel Above 3.2.0.x WHAT I HAVE TRIED I have gone over this tutorial many times ( https://help.ubuntu.com/community/BinaryDriverHowto/ATI ) and it doesn't work on ANY kernel except 3.2.0.x. The problems I am having here are that the ATI / AMD drivers working for the 12.04 Precise with kernel 3.2.0-23 and 24, But the computer kept locking up. Although all my games would work, the lock ups were random and were constant. So I looked all over the web for 3 days trying to find an answer and the lock up issue was said to just update the kernel. So I did. Have tried many kernels. All of them .. no lock ups. BUT the Restricted AMD drivers from the AMD website will not install. And none of the OpenSource AMD drivers have EVER installed no matter what Kernel or version I tried. EXAMPLE OUTPUT OF 3D TYPE OF ERRORS Javax.media.opengl.GLException: glXGetConfig failed: error code GLX_NO_EXTENSION at com.sun.opengl.impl.x11.X11GLDrawableFactory.glXGetConfig(X11GLDrawableFactory.java:651) at com.sun.opengl.impl.x11.X11GLDrawableFactory.xvi2GLCapabilities(X11GLDrawableFactory.java:350) at com.sun.opengl.impl.x11.X11GLDrawableFactory.chooseGraphicsConfiguration(X11GLDrawableFactory.java:174) at javax.media.opengl.GLCanvas.chooseGraphicsConfiguration(GLCanvas.java:520) at javax.media.opengl.GLCanvas.<init>(GLCanvas.java:131) at haven.HavenPanel.<init>(HavenPanel.java:68) at haven.HavenPanel.<init>(HavenPanel.java:78) at haven.MainFrame.<init>(MainFrame.java:182) at haven.MainFrame.main2(MainFrame.java:306) at haven.MainFrame.access$100(MainFrame.java:34) at haven.MainFrame$7.run(MainFrame.java:360) at java.lang.Thread.run(Thread.java:722) And of course this is what fglrxinfo shows : X Error of failed request: BadRequest (invalid request code or no such operation) Major opcode of failed request: 139 (ATIFGLEXTENSION) Minor opcode of failed request: 66 () Serial number of failed request: 13 Current serial number in output stream: 13 EDIT : I forgot to mention that I DID look at this post over the last few days and it did not help.

  Read the article

• Partner BI Applications 4-Day Hands-on Training Workshop

  - by Mike.Hallett(at)Oracle-BI&EPM

  Normal 0 false false false EN-GB X-NONE X-NONE MicrosoftInternetExplorer4 /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0cm 5.4pt 0cm 5.4pt; mso-para-margin-top:0cm; mso-para-margin-right:0cm; mso-para-margin-bottom:10.0pt; mso-para-margin-left:0cm; line-height:115%; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi; mso-fareast-language:EN-US;} 12th - 15th February 2012, Oracle Reading (UK) - REGISTER NOW This training will provide attendees with an in-depth working understanding of the architecture, the technical and the functional content of the Oracle Business Intelligence Applications, whilst also providing an understanding of their installation, configuration and extension. The course will cover the following topics: Overview of Oracle Business Intelligence Applications Oracle BI Applications Fundamentals and Features Configuring BI Applications for Oracle E-Business Suite Understanding BI Applications Architecture Fundamentals of BI Applications Security Prerequisites - This training is only for OPN member Partners. Good understanding of basic data warehousing concepts Hands on experience in Oracle Business Intelligence Enterprise Edition Hands on experience in Informatica Good understanding of any of the following Oracle EBS modules: General Ledger, Accounts Receivables, Accounts Payables Some understanding of  Oracle BI Applications is required (See Sales & Technical Tutorials for OBI, BI-Apps and Hyperion EPM)  Please note that attendees are required to bring a laptop. Laptop 4GB RAM-Recognized by Windows 64 bits 80GB free space in Hard drive or External Device CPU Core 2 Duo or Higher Operating System Requirements Windows 7, Windows XP, Windows 2003 NOT ALLOWED with Windows Vista An Administrator User

  Read the article

• Keep Learning After Your Oracle Training Class is Over - Save 50%!

  - by KJones

  Written by Amit Kumar, Senior Director Oracle University Digital Training        Every training class you take about the latest Oracle application or technology moves you closer to developing the skills you need to succeed. But after class is over, how do you keep up with today’s accelerating pace of innovation? To   To keep with the very latest technological advances, you need an ongoing and flexible training solution.       One that lets you learn during your own downtime.       Knowledge that’s easy to access.       Interactive lessons where you connect with experts.       A simple way to increase your knowledge, on your own time and at your own pace. The new Oracle Learning Streams is the flexible training solution you're looking for. Continuously Learn with Oracle Learning Streams Over time, Oracle Learning Streams help you develop the depth and breadth of knowledge that will give you the tools to become an expert in your field. By taking advantage of comprehensive and frequently updated information, you can keep learning continuously, at your own pace, when it's convenient for you. Sign up today and get 12 months of unlimited access to: •    Hundreds of videos delivered by Oracle experts for fresh and continuous product learning•    Live connections with Oracle's top instructors•    Robust video search capability to find exactly what you’re looking for•    Features that allow you to build your own custom learning queue and request new content Oracle Learning Streams are now available for Oracle Database and Oracle Middleware. Take a moment to preview the content now.  For a Limited Time - Save 50% For a limited time, save 50% when you order Oracle Learning Streams with any other Oracle Classroom, Live Virtual Class or Training On Demand course. Now there is no reason for learning to stop when class is over!

  Read the article

• How to refactor my design, if it seems to require multiple inheritance?

  - by Omega

  Recently I made a question about Java classes implementing methods from two sources (kinda like multiple inheritance). However, it was pointed out that this sort of need may be a sign of a design flaw. Hence, it is probably better to address my current design rather than trying to simulate multiple inheritance. Before tackling the actual problem, some background info about a particular mechanic in this framework: It is a simple game development framework. Several components allocate some memory (like pixel data), and it is necessary to get rid of it as soon as you don't need it. Sprites are an example of this. Anyway, I decided to implement something ala Manual-Reference-Counting from Objective-C. Certain classes, like Sprites, contain an internal counter, which is increased when you call retain(), and decreased on release(). Thus the Resource abstract class was created. Any subclass of this will obtain the retain() and release() implementations for free. When its count hits 0 (nobody is using this class), it will call the destroy() method. The subclass needs only to implement destroy(). This is because I don't want to rely on the Garbage Collector to get rid of unused pixel data. Game objects are all subclasses of the Node class - which is the main construction block, as it provides info such as position, size, rotation, etc. See, two classes are used often in my game. Sprites and Labels. Ah... but wait. Sprites contain pixel data, remember? And as such, they need to extend Resource. But this, of course, can't be done. Sprites ARE nodes, hence they must subclass Node. But heck, they are resources too. Why not making Resource an interface? Because I'd have to re-implement retain() and release(). I am avoiding this in virtue of not writing the same code over and over (remember that there are multiple classes that need this memory-management system). Why not composition? Because I'd still have to implement methods in Sprite (and similar classes) that essentially call the methods of Resource. I'd still be writing the same code over and over! What is your advice in this situation, then?

  Read the article

• Caching items in Orchard

  - by Bertrand Le Roy

  Orchard has its own caching API that while built on top of ASP.NET's caching feature adds a couple of interesting twists. In addition to its usual work, the Orchard cache API must transparently separate the cache entries by tenant but beyond that, it does offer a more modern API. Here's for example how I'm using the API in the new version of my Favicon module: _cacheManager.Get( "Vandelay.Favicon.Url", ctx => { ctx.Monitor(_signals.When("Vandelay.Favicon.Changed")); var faviconSettings = ...; return faviconSettings.FaviconUrl; }); .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } There is no need for any code to test for the existence of the cache entry or to later fill that entry. Seriously, how many times have you written code like this: var faviconUrl = (string)cache["Vandelay.Favicon.Url"]; if (faviconUrl == null) { faviconUrl = ...; cache.Add("Vandelay.Favicon.Url", faviconUrl, ...); } Orchard's cache API takes that control flow and internalizes it into the API so that you never have to write it again. Notice how even casting the object from the cache is no longer necessary as the type can be inferred from the return type of the Lambda. The Lambda itself is of course only hit when the cache entry is not found. In addition to fetching the object we're looking for, it also sets up the dependencies to monitor. You can monitor anything that implements IVolatileToken. Here, we are monitoring a specific signal ("Vandelay.Favicon.Changed") that can be triggered by other parts of the application like so: _signals.Trigger("Vandelay.Favicon.Changed"); In other words, you don't explicitly expire the cache entry. Instead, something happens that triggers the expiration. Other implementations of IVolatileToken include absolute expiration or monitoring of the files under a virtual path, but you can also come up with your own.

  Read the article

< Previous Page | 282 283 284 285 286 287 288 289 290 291 292 293  | Next Page >