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  • Standard term for a thread I/O reorder buffer?

    - by Crashworks
    I have a case where many threads all concurrently generate data that is ultimately written to one long, serial file. I need to somehow serialize these writes so that the file gets written in the right order. ie, I have an input queue of 2048 jobs j0..jn, each of which produces a chunk of data oi. The jobs run in parallel on, say, eight threads, but the output blocks have to appear in the file in the same order as the corresponding input blocks — the output file has to be in the order o0o1o2... The solution to this is pretty self evident: I need some kind of buffer that accumulates and writes the output blocks in the correct order, similar to a CPU reorder buffer in Tomasulo's algorithm, or to the way that TCP reassembles out-of-order packets before passing them to the application layer. Before I go code it, I'd like to do a quick literature search to see if there are any papers that have solved this problem in a particularly clever or efficient way, since I have severe realtime and memory constraints. I can't seem to find any papers describing this though; a Scholar search on every permutation of [threads, concurrent, reorder buffer, reassembly, io, serialize] hasn't yielded anything useful. I feel like I must just not be searching the right terms. Is there a common academic name or keyword for this kind of pattern that I can search on?

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  • What to call factory-like (java) methods used with immutable objects

    - by StaxMan
    When creating classes for "immutable objects" immutable meaning that state of instances can not be changed; all fields assigned in constructor) in Java (and similar languages), it is sometimes useful to still allow creation of modified instances. That is, using an instance as base, and creating a new instance that differs by just one property value; other values coming from the base instance. To give a simple example, one could have class like: public class Circle { final double x, y; // location final double radius; public Circle(double x, double y, double r) { this.x = x; this.y = y; this.r = r; } // method for creating a new instance, moved in x-axis by specified amount public Circle withOffset(double deltaX) { return new Circle(x+deltaX, y, radius); } } So: what should method "withOffset" be called? (note: NOT what its name ought to be -- but what is this class of methods called). Technically it is kind of a factory method, but somehow that does not seem quite right to me, since often factories are just given basic properties (and are either static methods, or are not members of the result type but factory type). So I am guessing there should be a better term for such methods. Since these methods can be used to implement "fluent interface", maybe they could be "fluent factory methods"? Better suggestions? EDIT: as suggested by one of answers, java.math.BigDecimal is a good example with its 'add', 'subtract' (etc) methods. Also: I noticed that there's this question (by Jon Skeet no less) that is sort of related (although it asks about specific name for method)

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  • Imlpementations of an Interface with Different Types?

    - by b3njamin
    Searched as best I could but unfortunately I've learned nothing relevant; basically I'm trying to work around the following problem in C#... For example, I have three possible references (refA, refB, refC) and I need to load the correct one depending on a configuration option. So far however I can't see a way of doing it that doesn't require me to use the name of said referenced object all through the code (the referenced objects are provided, I can't change them). Hope the following code makes more sense: public ??? LoadedClass; public Init() { /* load the object, according to which version we need... */ if (Config.Version == "refA") { Namespace.refA LoadedClass = new refA(); } else if (Config.Version == "refB") { Namespace.refB LoadedClass = new refB(); } else if (Config.Version == "refC") { Namespace.refC LoadedClass = new refC(); } Run(); } private void Run(){ { LoadedClass.SomeProperty... LoadedClass.SomeMethod(){ etc... } } As you can see, I need the Loaded class to be public, so in my limited way I'm trying to change the type 'dynamically' as I load in which real class I want. Each of refA, refB and refC will implement the same properties and methods but with different names. Again, this is what I'm working with, not by my design. All that said, I tried to get my head around Interfaces (which sound like they're what I'm after) but I'm looking at them and seeing strict types - which makes sense to me, even if it's not useful to me. Any and all ideas and opinions are welcome and I'll clarify anything if necessary. Excuse any silly mistakes I've made in the terminology, I'm learning all this for the first time. I'm really enjoying working with an OOP language so far though - coming from PHP this stuff is blowing my mind :-)

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  • Where can I find my iPhone app's Core Data persistent store?

    - by Dr Dork
    I'm diving into iPhone development, so I apologize in advance if this is a ridiculous question, but in a new iPad app project using the Core Data framework, here's the generated code for creating the persistentStoreCoordinator... - (NSPersistentStoreCoordinator *)persistentStoreCoordinator { if (persistentStoreCoordinator != nil) { return persistentStoreCoordinator; } NSURL *storeUrl = [NSURL fileURLWithPath: [[self applicationDocumentsDirectory] stringByAppendingPathComponent: @"ApplicationName.sqlite"]]; NSError *error = nil; persistentStoreCoordinator = [[NSPersistentStoreCoordinator alloc] initWithManagedObjectModel:[self managedObjectModel]]; if (![persistentStoreCoordinator addPersistentStoreWithType:NSSQLiteStoreType configuration:nil URL:storeUrl options:nil error:&error]) { /* Replace this implementation with code to handle the error appropriately. abort() causes the application to generate a crash log and terminate. You should not use this function in a shipping application, although it may be useful during development. If it is not possible to recover from the error, display an alert panel that instructs the user to quit the application by pressing the Home button. Typical reasons for an error here include: * The persistent store is not accessible * The schema for the persistent store is incompatible with current managed object model Check the error message to determine what the actual problem was. */ NSLog(@"Unresolved error %@, %@", error, [error userInfo]); abort(); } return persistentStoreCoordinator; } My questions are... The first time I run the app, is the ApplicationName.sqllite database created automatically if it doesn't exist? If not, when is it created? When data is added to it programmatically? Once the DB does exist, where can I locate the file? I'd like to open it with a different program so I can manually manipulate the data. Thanks so much in advance for your help! I'm going to continue researching these questions right now.

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  • Commenting out portions of code in Scala

    - by akauppi
    I am looking for a C(++) #if 0 -like way of being able to comment out whole pieces of Scala source code, for keeping around experimental or expired code for a while. I tried out a couple of alternatives and would like to hear what you use, and if you have come up with something better? // Simply block-marking N lines by '//' is one way... // <tags> """ anything My editor makes this easy, but it's not really The Thing. It gets easily mixed with actual one-line comments. Then I figured there's native XML support, so: <!-- ... did not work --> Wrapping in XML works, unless you have <tags> within the block: class none { val a= <ignore> ... cannot have //<tags> <here> (not even in end-of-line comments!) </ignore> } The same for multi-line strings seems kind of best, but there's an awful lot of boilerplate (not fashionable in Scala) to please the compiler (less if you're doing this within a class or an object): object none { val ignore= """ This seems like ... <truly> <anything goes> but three "'s of course """ } The 'right' way to do this might be: /*** /* ... works but not properly syntax highlighed in SubEthaEdit (or StackOverflow) */ ***/ ..but that matches the /* and */ only, not i.e. /*** to ***/. This means the comments within the block need to be balanced. And - the current Scala syntax highlighting mode for SubEthaEdit fails miserably on this. As a comparison, Lua has --[==[ matching ]==] and so forth. I think I'm spoilt? So - is there some useful trick I'm overseeing?

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  • URL-Encoded post parameters don't Bind to model

    - by Steven Klein
    I have the following Model namespace ClientAPI.Models { public class Internal { public class ReportRequest { public DateTime StartTime; public DateTime EndTime; public string FileName; public string UserName; public string Password; } } } with the following method: [HttpPost] public HttpResponseMessage GetQuickbooksOFXService(Internal.ReportRequest Request){ return GetQuickbooksOFXService(Request.UserName, Request.Password, Request.StartTime, Request.EndTime, Request.FileName); } My webform looks like this: <form method="POST" action="http://localhost:56772/Internal/GetQuickbooksOFXService" target="_blank"> <input type="text" name="StartTime" value="2013-04-03T00:00:00"> <input type="text" name="EndTime" value="2013-05-04T00:00:00"> <input type="text" name="FileName" value="Export_2013-04-03_to_2013-05-03.qbo"> <input type="text" name="UserName" value="UserName"> <input type="text" name="Password" value="*****"> <input type="submit" value="Submit"></form> My question is: I get into the GetQuickbooksOFXService function but my model has all nulls in it instead something useful. Am I doing something wrong?

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  • string comparision and counting the key in target [closed]

    - by mesun
    Suppose we want to count the number of times that a key string appears in a target string. We are going to create two different functions to accomplish this task: one iterative, and one recursive. For both functions, you can rely on Python's find function - you should read up on its specifications to see how to provide optional arguments to start the search for a match at a location other than the beginning of the string. For example, find("atgacatgcacaagtatgcat","atgc") #returns the value 5, while find("atgacatgcacaagtatgcat","atgc",6) #returns the value 15, meaning that by starting the search at index 6, #the next match is found at location 15. For the recursive version, you will want to think about how to use your function on a smaller version of the same problem (e.g., on a smaller target string) and then how to combine the result of that computation to solve the original problem. For example, given you can find the first instance of a key string in a target string, how would you combine that result with invocation of the same function on a smaller target string? You may find the string slicing operation useful in getting substrings of string.

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  • Is there a better way to change user password in cakephp using Auth?

    - by sipiatti
    Hi, I am learning cakephp by myself. I tried to create a user controller with a changepassword function. It works, but I am not sure if this is the best way, and I could not googled up useful tutorials on this. Here is my code: class UsersController extends AppController { var $name = 'Users'; function login() { } function logout() { $this->redirect($this->Auth->logout()); } function changepassword() { $session=$this->Session->read(); $id=$session['Auth']['User']['id']; $user=$this->User->find('first',array('conditions' => array('id' => $id))); $this->set('user',$user); if (!empty($this->data)) { if ($this->Auth->password($this->data['User']['password'])==$user['User']['password']) { if ($this->data['User']['passwordn']==$this->data['User']['password2']) { // Passwords match, continue processing $data=$this->data; $this->data=$user; $this->data['User']['password']=$this->Auth->password($data['User']['passwordn']); $this->User->id=$id; $this->User->save($this->data); $this->Session->setFlash('Password changed.'); $this->redirect(array('controller'=>'Toners','action' => 'index')); } else { $this->Session->setFlash('New passwords differ.'); } } else { $this->Session->setFlash('Typed passwords did not match.'); } } } } password is the old password, passwordn is the new one, password2 is the new one retyped. Is there any other, more coomon way to do it in cake?

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  • Can't serve HTML5 video through PHP on Safari/Mac (5.0)

    - by JKS
    I'm encountering a strange bug in Safari where, when I serve MP4 video through PHP (to obfuscate the file beneath the document root with a token-based authentication system), Safari for some reason fires the <video>'s onerror event, and the video never loads (I can't get any useful information out of the event object sent to onerror — everything is undefined). When I access the PHP script directly (i.e., the video is not embedded in a page), the video controls appear momentarily before flashing to a QuickTime question mark. When I access the MP4 file directly, it works as expected. What's bizarre is that the embedded video works perfectly in the latest version of Chrome for Mac. Here are the headers when accessed through PHP: Connection:Keep-Alive Content-Disposition:inline; filename="test.mp4" Content-Length:5558749 Content-Type:video/mp4 Date:Tue, 22 Jun 2010 01:24:25 GMT Keep-Alive:timeout=10, max=29 Server:Apache/2.2.15 (CentOS) mod_ssl/2.2.15 0.9.8l DAV/2 mod_auth_passthrough/2.1 FrontPage/5.0.2.2635 X-Powered-By:PHP/5.2.13 And here are the headers when test.mp4 is accessed directly: Accept-Ranges:bytes Connection:Keep-Alive Content-Length:5558749 Content-Type:video/mp4 Date:Tue, 22 Jun 2010 01:26:45 GMT Etag:"1c04757-54d1dd-489944c5a6400" Keep-Alive:timeout=10, max=30 Last-Modified:Tue, 22 Jun 2010 01:25:36 GMT Server:Apache/2.2.15 (CentOS) mod_ssl/2.2.15 0.9.8l DAV/2 mod_auth_passthrough/2.1 FrontPage/5.0.2.2635 The only differing headers are: Accept-Ranges (which I don't think is necessary), Etag, Last-Modified, Content-Disposition, and X-Powered-By. Not only can Chrome handle the PHP-served video fine, but when I use the same script to load the MP4 through a Flash player, it also works fine. I just can't figure out what Safari is choking on. EDIT: Also, when I change the content disposition to "attachment", Safari will download the MP4 file just fine.

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  • Converting Source ASCII Files to JPEGs

    - by CommonsWare
    I publish technical books, in print, PDF, and Kindle/MOBI, with EPUB on the way. The Kindle does not support monospace fonts, which are kinda useful for source code listings. The only way to do monospace fonts is to convert the text (Java source, HTML, XML, etc.) into JPEG images. More specifically, due to pagination issues, a given input ASCII file needs to be split into slices of ~6 lines each, with each slice turned into a JPEG, so listings can span a screen. This is a royal pain. My current mechanism to do that involves: Running expand to set a consistent 2-space tab size, which pipes to... a2ps, which pipes to... A small Perl snippet to add a "%%LanguageLevel: 3\n" line, which pipes to... ImageMagick's convert, to take the (E)PS and make a JPEG out it, with an appropriate background, cropped to 575x148+5+28, etc. That used to work 100% of the time. It now works 95% of the time. The rest of the time, I get convert: geometry does not contain image errors, which I cannot seem to get rid of, in part because I don't understand what the problem is. Before this process, I used to use a pretty-print engine (source-highlight) to get HTML out of the source code...but then the only thing I could find to convert the HTML into JPEGs was to automate screen-grabs from an embedded Gecko engine. Reliability stank, which is why I switched to my current mechanism. So, if you were you, and you needed to turn source listings into JPEG images, in an automated fashion, how would you do it? Bonus points if it offers some sort of pretty-print process (e.g., bolded keywords)! Or, if you know what typically causes convert: geometry does not contain image, that might help. My current process is ugly, but if I could get it back to 100% reliability, that'd be just fine for now. Thanks in advance!

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  • SASS mixin for swapping images / floats on site language (change)

    - by DBUK
    Currently using SASS on a website build. It is my first project using it, tried a little LESS before and liked it. I made a few basic mixins and variables with LESS, super useful stuff! I am trying to get my head around SASS mixins, and syntax, specifically for swapping images when the page changes to a different language, be that with body ID changing or <html lang="en">. And, swapping floats around if, for example, a website changed to chinese. So a mixin where float left is float left unless language is AR and then it becomes float right. With LESS I think it would be something like: .headerBg() when (@lang = en) {background-image:url(../img/hello.png);} .headerBg() when (@lang = it) {background-image:url(../img/ciao.png);} .header {.headerBg(); width: 200px; height:100px} .floatleft() when (@lang = en) { float: left;} .floatleft() when (@lang = ar) { float: right;} .logo {.floatleft();} Its the syntax I am having problems with combined with a brain melting day.

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  • structDelete doesn't effect the shallow copy?

    - by Travis
    I was playing around onError so I tried to create an error using a large xml document object. <cfset variables.XMLByRef = variables.parsedXML.XMLRootElement.XMLChildElement> <cfset structDelete(variables.parsedXML, "XMLRootElement")> <cfset variables.startXMLShortLoop = getTickCount()> <cfloop from = "1" to = "#arrayLen(variables.XMLByRef)#" index = "variables.i"> <cfoutput>#variables.XMLByRef[variables.i].id.xmltext#</cfoutput><br /> </cfloop> <cfset variables.stopXMLShortLoop = getTickCount()> I expected to get an error because I deleted the structure I was referencing. From LiveDocs: Variable Assignment - Creates an additional reference, or alias, to the structure. Any change to the data using one variable name changes the structure that you access using the other variable name. This technique is useful when you want to add a local variable to another scope or otherwise change a variable's scope without deleting the variable from the original scope. instead I got 580df1de-3362-ca9b-b287-47795b6cdc17 25a00498-0f68-6f04-a981-56853c0844ed ... ... ... db49ed8a-0ba6-8644-124a-6d6ebda3aa52 57e57e28-e044-6119-afe2-aebffb549342 Looped 12805 times in 297 milliseconds <cfdump var = "#variables#"> Shows there's nothing in the structure, just parsedXML.xmlRoot.xmlName with the value of XMLRootElement. I also tried <cfset structDelete(variables.parsedXML.XMLRootElement, "XMLChildElement")> as well as structClear for both. More information on deleting from the xml document object. http://help.adobe.com/en_US/ColdFusion/9.0/Developing/WSc3ff6d0ea77859461172e0811cbec22c24-78e3.html Can someone please explain my faulty logic? Thanks.

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  • Are the formatted addresses of a Google location unique?

    - by Hans
    I want our users of a web site to be able to either search and pick an address or mark a location on a map decide how accurate this address/location is I am in the process of implementing the first part with jquery, jquery ui's autocomplete, google map, and google geocoder. For the second part I will generate a radiobutton list based on the address elements/alternatives of the first part on the client side with jquery. My concern, however, is how to convey the choices to the server side. The Google geocoder includes a number of useful metadata that I want to store. A possibility is to store the complete json object in a hidden form field, but I can't trust the users. Such a solution would enable an unfriendly insertion of spam in the data. If the addresses/locations would have a unique identifyer I could store just these and let the server refetch/evaluate the data. The alternative geonames.org web service has such ids. But are for example the formatted addresses of a Google location unique? Any tips?

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  • Void* array casting to float, int32, int16, etc.

    - by Griffin
    Hey guys, I've got an array of PCM data, it could be 16 bit, 24 bit packed, 32 bit, etc.. It could be signed, or unsigned, and it could be 32 or 64 bit floating point. It is currently stored as a "void**" matrix, indexed by channel, then by frame. The goal is to allow my library to take in any PCM format and buffer it, without requiring manipulation of the data to fit a designated structure. If the A/D converter spits out 24 bit packed arrays of interleaved PCM, I need to accept it gracefully. I also need to support 16 bit non interleaved, as well as any permutation of the above formats. I know the bit depth and other information at runtime, and I'm trying to code efficiently while not duplicating code. What I need is an effective way to cast the matrix, put PCM data into the matrix, and then pull it out later. I can cast the matrix to int32_t, or int16_t for the 32 and 16 bit signed PCM respectively, I'll probably have to store the 24 bit PCM in an int32_t for 32 bit, 8 bit byte systems as well. Can anyone recommend a good way to put data into this array, and pull it out later? I'd like to avoid large sections of code which look like: switch( mFormat ) { case 1: // unsigned 8 bit for( int i = 0; i < mChannels; i++ ) framesArray = (uint8_t*)pcm[i]; break; case 2: // signed 8 bit for( int i = 0; i < mChannels; i++ ) framesArray = (int8_t*)pcm[i]; break; case 3: // unsigned 16 bit ... Limitations: I'm working in C/C++, no templates, no RTTI, no STL. Think embedded. Things get trickier when I have to port this to a DSP with 16 bit bytes. Does anybody have any useful macros they might be willing to share? Thanks, -Griff

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  • Database choices

    - by flobadob
    I have a prickly design issue regarding the choice of database technologies to use for a group of new applications. The final suite of applications would have the following database requirements... Central databases (more than one database) using mysql (myst be mysql due to justhost.com). An application to be written which accesses the multiple mysql databases on the web host. This application will also write to local serverless database (sqlite/firebird/vistadb/whatever). Different flavors of this application will be created for windows (.NET), windows mobile, android if possible, iphone if possible. So, the design task is to minimise the quantity of code to achieve this. This is going to be tricky since the languages used are already c# / java (android) and objc (iphone). Not too worried about that, but can the work required to implement the various database access layers be minimised? The serverless database will hold similar data to the mysql server, so some kind of inheritance in the DAL would be useful. Looking at hibernate/nhibernate and there is linq to whatever. So many choices!

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  • Writing a synchronized thread-safety wrapper for NavigableMap

    - by polygenelubricants
    java.util.Collections currently provide the following utility methods for creating synchronized wrapper for various collection interfaces: synchronizedCollection(Collection<T> c) synchronizedList(List<T> list) synchronizedMap(Map<K,V> m) synchronizedSet(Set<T> s) synchronizedSortedMap(SortedMap<K,V> m) synchronizedSortedSet(SortedSet<T> s) Analogously, it also has 6 unmodifiedXXX overloads. The glaring omission here are the utility methods for NavigableMap<K,V>. It's true that it extends SortedMap, but so does SortedSet extends Set, and Set extends Collection, and Collections have dedicated utility methods for SortedSet and Set. Presumably NavigableMap is a useful abstraction, or else it wouldn't have been there in the first place, and yet there are no utility methods for it. So the questions are: Is there a specific reason why Collections doesn't provide utility methods for NavigableMap? How would you write your own synchronized wrapper for NavigableMap? Glancing at the source code for OpenJDK version of Collections.java seems to suggest that this is just a "mechanical" process Is it true that in general you can add synchronized thread-safetiness feature like this? If it's such a mechanical process, can it be automated? (Eclipse plug-in, etc) Is this code repetition necessary, or could it have been avoided by a different OOP design pattern?

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  • Save object in CoreData

    - by John
    I am using CoreData with iPhone SDK. I am making a notes app. I have a table with note objects displayed from my model. When a button is pressed I want to save the text in the textview to the object being edited. How do I do this? I've been trying several things but none seem to work. Thanks EDIT: NSManagedObjectContext *context = [fetchedResultsController managedObjectContext]; NSEntityDescription *entity = [[fetchedResultsController fetchRequest] entity]; NSManagedObject *newManagedObject = [NSEntityDescription insertNewObjectForEntityForName:[entity name] inManagedObjectContext:context]; [newManagedObject setValue:detailViewController.textView.text forKey:@"noteText"]; NSError *error; if (![context save:&error]) { /* Replace this implementation with code to handle the error appropriately. abort() causes the application to generate a crash log and terminate. You should not use this function in a shipping application, although it may be useful during development. If it is not possible to recover from the error, display an alert panel that instructs the user to quit the application by pressing the Home button. */ NSLog(@"Unresolved error %@, %@", error, [error userInfo]); abort(); } The above code saves it correctly but it saves it as a new object. I want it to be saved as the one I have selected in my tableView.

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  • Ajax and JSF 1.1 using hidden iframe with "proxy forms", what do you think about this development st

    - by Steel Plume
    Hi, currently I am using yet 1.1 specs, so I am trying to make simple what is too complex for me :p, managing backing beans with conflicting navigation rules, external params breaking rules and so on... for example when I need a backing bean used by other "views" simply I call it using FacesContext inside other backing beans, but often it's too wired up to JSF navigation/initialization rules to be really usable, and of course more simple is more useful become the FacesContext. So with only a bit of cross browser Javascript (simply a form copy and a read-write on a "proxy" form), I create a sort of proxy form inside the main user page (totally disassociated from JSF navigation rules, but using JSF taglibs). Ajax gives me flexibility on the user interaction, but data is always managed by JSF. Pratically I demand all "fictious" user actions to an hidden "iframe" which build up all needed forms according JSF rules, then a javascript simply clone its form output and put it into the user view level (CSS for showing/hiding real command buttons and making pretty), the user plays around and when he click submit, a script copies all "proxied" form values into the real JSF form inside the "iframe" that invokes the real submit of the form, what it returns is obviously dependent by your choice. Now JSF is really a pleasure :-p My real interest is to know what are your alternative strategy for using pure Ajax and JSF 1.1 without adopting middle layer like ajax4jsf and others, all good choices but too much "plugins" than specs.

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  • In C/C++ mode in Emacs, change face of code in #if 0...#endif block to comment face

    - by pogopop77
    I'm trying to add functionality found in some other code editors to my Emacs configuration, whereby C/C++ code within #if 0...#endif blocks is automatically set to the comment face/font. Based on my testing, cpp-highlight-mode does something like what I want, but requires user action. It seems like tying into the font-lock functionality is the correct option to make the behavior automatic. I have successfully followed examples in the GNU documentation to change the face of single-line regular expressions. For example: (add-hook 'c-mode-common-hook (lambda () (font-lock-add-keywords nil '(("\\<\\(FIXME\\|TODO\\|HACK\\|fixme\\|todo\\|hack\\)" 1 font-lock-warning-face t))))) works fine to highlight debug related keywords anywhere in a file. However, I am having problems matching #if 0...#endif as a multiline regular expression. I found some useful information in this post (How to compose region like ""), that suggested that Emacs must be told specifically to allow for multiline matches. But this code: (add-hook 'c-mode-common-hook (lambda () '(progn (setq font-lock-multiline t) (font-lock-add-keywords nil '(("#if 0\\(.\\|\n\\)*?#endif" 1 font-lock-comment-face t)))))) still does not work for me. Perhaps my regular expression is wrong (though it appears to work using M-x re-builder), I've messed up my syntax, or I'm following the wrong approach entirely. I'm using Aquamacs 2.1 (which is based on GNU Emacs 23.2.50.1) on OS X 10.6.5, if that makes a difference. Any assistance would be appreciated!

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  • HMAC URLs instead of login?

    - by Tres
    In implementing my site (a Rails site if it makes any difference), one of my design priorities is to relieve the user of the need to create yet another username and password while still providing useful per-user functionality. The way I am planning to do this is: User enters information on the site. Information is associated with the user via server-side session. User completes entering information, server sends an access URL via e-mail to the user roughly in the form of: http://siteurl/<user identifier>/<signature: HMAC(secret + salt + user identifier)> User clicks URL, site looks up user ID and salt and computes the HMAC with the server-stored secret and authenticates if the computed HMAC and signature match. My question is: is this a reasonably secure way to accomplish what I'm looking to do? Are there common attacks that would render it useless? Is there a compelling reason to abandon my desire to avoid a username/password? Is there a must-read book or article on the subject? Note that I'm not dealing with credit card numbers or anything exceedingly private, but I would still like to keep the information reasonably secure.

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  • Better language or checking tool?

    - by rwallace
    This is primarily aimed at programmers who use unmanaged languages like C and C++ in preference to managed languages, forgoing some forms of error checking to obtain benefits like the ability to work in extremely resource constrained systems or the last increment of performance, though I would also be interested in answers from those who use managed languages. Which of the following would be of most value? A language that would optionally compile to CLR byte code or to machine code via C, and would provide things like optional array bounds checking, more support for memory management in environments where you can't use garbage collection, and faster compile times than typical C++ projects. (Think e.g. Ada or Eiffel with Python syntax.) A tool that would take existing C code and perform static analysis to look for things like potential null pointer dereferences and array overflows. (Think e.g. an open source equivalent to Coverity.) Something else I haven't thought of. Or put another way, when you're using C family languages, is the top of your wish list more expressiveness, better error checking or something else? The reason I'm asking is that I have a design and prototype parser for #1, and an outline design for #2, and I'm wondering which would be the better use of resources to work on after my current project is up and running; but I think the answers may be useful for other tools programmers also. (As usual with questions of this nature, if the answer you would give is already there, please upvote it.)

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  • class modifier issues in C# with "private" classes

    - by devoured elysium
    I had a class that had lots of methods: public class MyClass { public bool checkConditions() { return checkCondition1() && checkCondition2() && checkCondition3(); } ...conditions methods public void DoProcess() { FirstPartOfProcess(); SecondPartOfProcess(); ThirdPartOfProcess(); } ...process methods } I identified two "vital" work areas, and decided to extract those methods to classes of its own: public class MyClass { private readonly MyClassConditions _conditions = new ...; private readonly MyClassProcessExecution = new ...; public bool checkConditions() { return _conditions.checkConditions(); } public void DoProcess() { _process.DoProcess(); } } In Java, I'd define MyClassConditions and MyClassProcessExecution as package protected, but I can't do that in C#. How would you go about doing this in C#? Setting both classes as inner classes of MyClass? I have 2 options: I either define them inside MyClass, having everything in the same file, which looks confusing and ugly, or I can define MyClass as a partial class, having one file for MyClass, other for MyClassConditions and other for MyClassProcessExecution. Defining them as internal? I don't really like that much of the internal modifier, as I don't find these classes add any value at all for the rest of my program/assembly, and I'd like to hide them if possible. It's not like they're gonna be useful/reusable in any other part of the program. Keep them as public? I can't see why, but I've let this option here. Any other? Name it! Thanks

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  • Questions on Juval Lowy's IDesign C# Coding Standard

    - by Jan
    We are trying to use the IDesign C# Coding standard. Unfortunately, I found no comprehensive document to explain all the rules that it gives, and also his book does not always help. Here are the open questions that remain for me (from chapter 2, Coding Practices): No. 26: Avoid providing explicit values for enums unless they are integer powers of 2 No. 34: Always explicitly initialize an array of reference types using a for loop No. 50: Avoid events as interface members No. 52: Expose interfaces on class hierarchies No. 73: Do not define method-specific constraints in interfaces No. 74: Do not define constraints in delegates Here's what I think about those: I thought that providing explicit values would be especially useful when adding new enum members at a later point in time. If these members are added between other already existing members, I would provide explicit values to make sure the integer representation of existing members does not change. No idea why I would want to do this. I'd say this totally depends on the logic of my program. I see that there is alternative option of providing "Sink interfaces" (simply providing already all "OnXxxHappened" methods), but what is the reason to prefer one over the other? Unsure what he means here: Could this mean "When implementing an interface explicitly in a non-sealed class, consider providing the implementation in a protected virtual method that can be overridden"? (see Programming .NET Components 2nd Edition, end of chapter “Interfaces and Class Hierarchies”). I suppose this is about providing a "where" clause when using generics, but why is this bad on an interface? I suppose this is about providing a "where" clause when using generics, but why is this bad on a delegate?

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  • What's the SQL function for timestamp manipulation?

    - by Eric Leroy
    I'm new to SQL and the time functions are different than mySQL so I'm having a terrible time finding a good site reference with USEFUL timestamp queries. I'm not able to locate the correct way of doing this query in SQL: Id Timestamp ----------------------------------- 1145744 2012-10-10 18:15:11.500 1145743 2012-10-10 18:15:11.313 1145742 2012-10-10 18:15:11.313 1145741 2012-10-10 18:15:11.253 1145740 2012-10-10 18:15:11.190 1145739 2012-10-10 18:15:11.190 1145738 2012-10-10 18:15:11.127 1145737 2012-10-10 18:15:11.067 1145736 2012-10-10 18:15:11.063 1145735 2012-10-10 18:15:10.940 1145734 2012-10-10 18:15:10.817 SELECT * from table WHERE Timestamp ... RANGE I need the range of 2 timestamps so I can select rows by the following parameters: second range minute range hour range day range week range month range year range Is there one function to put in 2 timestamps and get the range? or is this a mix of functions I need? Any good site references would be greatly appriceated. MSDN site isn't helping me isolate the proper way of doing this. I've been searching for about an hour trying to get the last day from 1:30PM to 1:30PM today.

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  • Mysterious Flickering Visual Artifact

    - by Axis
    A flashing bar of red appears at the top of the EAGLView that I have added as a subview in my iPhone app. It flickers on and off (i.e., one frame it's there, the next frame it's not, the next frame it's there again). I have removed a lot of code from my app until I'm essentially left with the stock OpenGL-ES project and a few changes: The glview is not fullscreen; it's a subview. I enabled the depth buffer. I'm not even trying to draw anything. If the glview is fullscreen, or if I disable the depth buffer, then there is no flicker and it works fine. But needless to say, this is a 3D view and I'd like to be able to display it within a larger UIKit view. I'm not sure what code would be useful to post, but here's how I add the glview to my main view: appDelegate.glView.frame = CGRectMake(245, 65, 215, 215); [self.view addSubview:appDelegate.glView]; [appDelegate.glView startAnimation]; Here's my render function: - (void) render { [EAGLContext setCurrentContext:context]; glBindFramebufferOES(GL_FRAMEBUFFER_OES, defaultFramebuffer); glViewport(0, 0, backingWidth, backingHeight); glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); glBindRenderbufferOES(GL_RENDERBUFFER_OES, colorRenderbuffer); [context presentRenderbuffer:GL_RENDERBUFFER_OES]; } It seems pretty obvious to me that the problem lies with the depth buffer somehow, but I'm not sure why. Also, it works fine in the simulator, but not on my iphone. I'm using iPhone OS 3.1. Any ideas on where to look for a problem?

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