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  • Does this simple cache class need thread synchronization?

    - by DayOne
    Does this simple cache class need thread synchronization ... if I remove the lock _syncLock statement will encounter any problems? I think i can remove the locks as the references should be updated correctly right? ... BUt i'm think whar happens if client code is iterating over the GetMyDataStructure method and it get replaced? Thanks! public sealed class Cache { private readonly object _syncLock = new object(); private IDictionary<int, MyDataStructure> _cache; public Cache() { Refresh(); } public void Refresh() { lock (_syncLock) { _cache = DAL.GetMyDataStructure(); } } public IDictionary<int, MyDataStructure> **GetMyDataStructure**() { lock (_syncLock) { return _cache; } } }

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  • Unique constraint with nullable column

    - by Álvaro G. Vicario
    I have a table that holds nested categories. I want to avoid duplicate names on same-level items (i.e., categories with same parent). I've come with this: CREATE TABLE `category` ( `category_id` int(10) unsigned NOT NULL AUTO_INCREMENT, `category_name` varchar(100) NOT NULL, `parent_id` int(10) unsigned DEFAULT NULL, PRIMARY KEY (`category_id`), UNIQUE KEY `category_name_UNIQUE` (`category_name`,`parent_id`), KEY `fk_category_category1` (`parent_id`,`category_id`), CONSTRAINT `fk_category_category1` FOREIGN KEY (`parent_id`) REFERENCES `category` (`category_id`) ON DELETE SET NULL ON UPDATE CASCADE ) ENGINE=InnoDB DEFAULT CHARSET=utf8 COLLATE=utf8_spanish_ci Unluckily, category_name_UNIQUE does not enforce my rule for root level categories (those where parent_id is NULL). Is there a reasonable workaround?

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  • animating adding/removing layers on iPhone

    - by magesteve
    On the iPhone, when you add a sub layer to a visible view's layer, using either -addSublayer: or -removeFromSuperlayer, shouldn't that sub layer appear or disappear in an animated manner (ie. fade in or fade out gradually)? My program animates using layers (not views). When I change a property of a layer like position or image content, then the change does animate (layer streaks around it's parent layer, the layer fades from the old image to the new image), so I obviously have the layers & view setup correctly. However, when I add or remove a sub layer, the change occurs instantly; there is no animation. Reading the references, it says that if the layer is visible, the sub layer should animate when adder or removed. What am I doing wrong? Has anyone had a similar problem, and was able to find a solution? Thank you, Steve Sheets

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  • Real world examples of Ecmascript functions returning a Reference?

    - by Bergi
    Read the EcmaScript specification, section 8.7 The Reference Specification Type: The Reference type is used to explain the behaviour of such operators as delete, typeof, and the assignment operators. […] A Reference is a resolved name binding. Function calls are permitted to return references. This possibility is admitted purely for the sake of host objects. No built-in ECMAScript function defined by this specification returns a reference and there is no provision for a user-defined function to return a reference. Those last two sentences impressed me. With this, you could do things like coolHostFn() = value (valid syntax, btw). So my question is: Are there any EcmaScript implementations that define host function objects which result in Reference values?

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  • How can I tell if an ADODB::_RecordsetPtr has already been created?

    - by scottm
    I am trying to write a class that uses ADO to retrieve SQL records. The intent is for the class to maintain one private recordset an other methods move forward, retrieve fields, etc. This is a basic example of my class: class SqlADO { private: ADODB::_RecordsetPtr m_recordset; public: void Open(); //open the connection void Execute(const char* sql); // creates or replaces current recordset void Next(); //moves recordset cursor forward void Field(const char* fieldName); //retrieves field name from current record of the recordset }; My Questions: In the Execute method, how can I check to see that the recordset instance has been created (or do I need to) so that I can close it first? Do you know of any good ADO COM Interop references?

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  • passing Perl method results as a reference

    - by arareko
    Some XML::LibXML methods return arrays instead of references to arrays. Instead of doing this: $self->process_items($xml->findnodes('items/item')); I want to do something like: $self->process_items(\$xml->findnodes('items/item')); So that in process_items() I can dereference the original array instead of creating a copy: sub process_items { my ($self, $items) = @_; foreach my $item (@$items) { # do something... } } I can always store the results of findnodes() into an array and then pass the array reference to my own method, but let's say I want to try a reduced version of my code. Is that the correct syntax for passing the method results or should I use something different? Thanks!

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  • Learning CSS - What is the BEST ONLINE RESOURCE?

    - by Chris Jacob
    The Goal: Use votes to rank nominated sites. The first answer to reach 100+ votes will be accepted. Please answer following these 5 simple rules: ONE SITE per answer. Link to each page if nominating a "series" of resources on a SITE. No "offline" books. Only online resources (tutorials, API references, blogs, screencasts, etc). Don't add "subjective" details/notes in your answer. Add them as a comment to the answer. Don't post duplicates. If your favourite is already listed Up Vote It! Example Answer: Site Name http://www.example.com Example Answer (site with a series of resources): Site Name http://www.example.com Series Name A http://www.example.com/video/a/1 http://www.example.com/video/a/2 Series Name B http://www.example.com/video/b/1

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  • Google CDN not gzipping jquery

    - by thermal7
    If I navigate here: http://ajax.microsoft.com/ajax/jquery/jquery-1.4.2.min.js I download 70k using Firefox 3.6.3 and I can confirm it is sending Accept-Encoding: gzip. If I use the Microsoft one: http://ajax.microsoft.com/ajax/jquery/jquery-1.4.2.min.js I download 30k (and it comes through as Content-Encoding: gzip) I am also experiencing this when using jquery 1.4.2 in regular sites eg jquery.com. Funily enough, stack overflow which references jquery 1.3.2 on the google cdn, is coming through gzipped. Why is this happening? Is it some kind of issue with google or am I missing something? I live in Melbourne, Australia.

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  • How can you deflect a direction/magnitude vector based on a direction/magnitude vector and a collided triangle?

    - by JeanOTF
    So, I have a Triangle-AABB collision algorithm and I have it returning the triangle that the AABB collided with. I was hoping with the 3 vectors of the triangle and the direction/magnitude of the movement would let me determine a deflected vector so that when you run against the wall at an angle you move slower, depending on the angle of collision, but along side the wall. This would remove the sticky collision problem with only moving when there is not a collision. Any suggestions or references would be greatly appreciated! Thanks.

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  • mysql reference result from subquery

    - by iamrohitbanga
    this is what i am doing update t1 set x=a,y=b where a and b are obtained from (select query here) i know the select query the select query returns multiple results which are the same when i use group by or distinct query execution slows down considerably a and b are forward references so mysql reports an error i want to set a equal to the value obtained in the first row and b equal to the value obtained in the first row for the respective columns, to avoid group by. i don't know how to refer to the first result from the select query. how can i achieve all this?

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  • latex table reference

    - by Tim
    Hi, I wrote a long table with a label in a tex file and \input it into my main tex file. The reference in the main tex file to the table, however, does not show the numbering of the table but the one of the next table that are written directly in the main tex file. All long tables that are written directly in the main tex file have correct references. How to fix my problem? Must the label be defined in the same tex file as its reference? Thanks and regards! The label is \label{tab:yy}, and the reference is \ref{tab:yy}, and every table has a distinct label.

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  • How to bring coordination between file system and database?

    - by Lock up
    I am working on a online file management project. We are storing references on the database (sql server) and files data on the on file system. We are facing a problem of coordination between file system and database while we are uploading a file and also in case of deleting a file. First we create a reference in the database or store files on file system. The problem is that if I create a reference in the database first and then store a file on file system, but while storing files on the file system any type of error occur, then the reference for that file is created in the database but no file data exist on the file system. Please give me some solution how to deal with such situation. I am badly in need of it. This case happens also while we deleting a file?

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  • Is foreign key reference from two different primary key from two different tables valid?

    - by arundex
    I have a foreign key that has to refer primary keys of two different tables. Table 1: animal animal_ id (primary key) Table 2: bird bird_ id (primary key) Table 3: Pet_info pet_id, type ENUM ('bird', 'animal') foreign key (pet_ id) references animal(animal_id), bird(bird_id) So, I need to check for pet_id either from animal or bird table depending on the need. Is this valid? Or should I go for some restructuring . . . NOTE: I referred this . . but I'm not sure whether I have to change my existing design

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  • How to use JNI, but only when available for current platform?

    - by Mecki
    What is the common way (or best practice) to optionally use JNI? E.g. I have a Java class and this class is 100% pure Java, so it can run on all platforms. However, on some platforms I'd like to speed up some heavy calculations using JNI - which works fine. Unfortunately I cannot support any existing Java platform in the world. So I guess it is fine to initially only support the big three: Linux, Windows, Mac OS X. So what I'd like to do is to use JNI on those three platforms and use the 100% pure Java version on all other platforms. Now I can think of various ways how to do that (loading class dynamically for example and either loading the JNI class or the pure Java one), but thinking that this is a common issue that thousands of projects had to solve in the past for sure, I'm really surprised to not find any documentation or references to the question how to solve this most elegantly or effectively.

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  • how to get needed data from mysql tables

    - by I Like PHP
    i have 3 tables tbl_faculty(f_id,f_school) tbl_school(s_id,s_city_s_role) tbl_city(c_id,c_name) in one school there may be many teacher(s_role=2) can be appointed, but would be appointed only one principle(s_role=1) first we need to create a school, then we appoint faculty. now i want to appoint principle( where teachers may b already appointed or may b not) so i need all school_id and city name where there is no principle appointed yet references in tables f_school--->s_id s_city---->c_id i used below query but, it show not the exact result i want SELECT s_id,c_name FROM tbl_school LEFT JOIN tbl_city ON c_id=s_city LEFT JOIN tbl_faculty ON f_school=s_id WHERE s_role<>1";

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  • PHP - MySQL - Select runs indefinitely

    - by John
    I have three tables listings: id, pid, beds, baths, etc, etc, etc, db locations: id, pid, zip, lat, lon, etc, etc, etc, db images id, pid, height, width, raw, etc, etc, db id, pid & db are indexed. db just references the mls provider a particular item came from. in images the raw column holds raw image data there are about 15k rows in listings/locations, and about 120k rows in images so there are multiple rows that have the same pid. when i do "select pid from listings" or "select pid from locations" the query completes successfully in about 100ms. when i do "select pid from images" it just hangs in sqlyog and never completes... i was thinking since the raw column contains alot of information that it might be trying to select that too, but my query doesn't try to select that so I can't imagine why it's taking so long... any idea why this is happening??

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  • Different versions in manifest on different machines

    - by Terry777
    Hi guys, Have two machines, both with VS2005 SP1 installed and with the WinSXS showing the same things installed. When one machine builds a particular C++ .dll .vcproj it ends up with <assemblyIdentity type='win32' name='Microsoft.VC80.MFC' version='8.0.50727.762' processorArchitecture='x86' publicKeyToken='1fc8b3b9a1e18e3b' /> in its manifest file. But on the other machine it ends up with <assemblyIdentity type='win32' name='Microsoft.VC80.MFC' version='8.0.50608.0 processorArchitecture='x86' publicKeyToken='1fc8b3b9a1e18e3b' /> even though this machine does not have '8.0.50608.0' libraries listed in its WinSXS. The .dll built on this machine with the older version referenced has some problems. I have ensured both machines have the same latest source code and references etc.. What could be causing it to build with the different reference? Thanks! Terry

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  • SQL where clasue to work with Group by clasue after performing a count()

    - by Matt
    Tried my usual references at w3schools and google. No luck I'm trying to produce the following results. QTY is a derived column | Position | QTY -------------------- 1 Clerk 2 2 Mgr 2 Here's what I'm not having luck with: SELECT Position, Count(position) AS 'QTY' FROM tblemployee Where ('QTY' != 1) GROUP BY Position I know that my Position is set up as varchar(255) Count produces a integer data and my where clasue is accurate so that leads me to believe that that Count() is jamming me up. Please throw up an example so I can reference later. Thanks for the help!

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  • Implementation communication protocols in C/C++

    - by MeThinks
    I am in the process of starting to implement some proprietary communication protocol stack in software but not sure where to start. It is the kind of work I have not done before and I am looking for help in terms of resources for best/recommended approaches. I will be using c/c++ and I am free to use use libraries (BSD/BOOST/Apache) but no GPL. I have used C++ extensively so using the features of C++ is not a problem. The protocol stack has three layers and it is already fully specified and formally verified. So all I need to do is implemented and test it fully in the specified languages. Should also mention that protocol is very simple but can run on different devices over a reliable physical transport layer Any help with references/recommendations will be appreciated. I am willing to use a different language if only to help me understand how to implement them but I will have to eventually resort to the language of choice.

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  • Converting a PHP array to class variables.

    - by animuson
    Simple question, how do I convert an associative array to variables in a class? I know there is casting to do an (object) $myarray or whatever it is, but that will create a new stdClass and doesn't help me much. Are there any easy one or two line methods to make each $key => $value pair in my array into a $key = $value variable for my class? I don't find it very logical to use a foreach loop for this, I'd be better off just converting it to a stdClass and storing that in a variable, wouldn't I? class MyClass { var $myvar; // I want variables like this, so they can be references as $this->myvar function __construct($myarray) { // a function to put my array into variables } }

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  • How can I avoid causing memory leaks in Firefox?

    - by mrdanimal
    It seems that there is a lot of information on memory leaks in IE and how web developers can avoid them, but I can't find much on avoiding leaks in FF. I've found lots of random tips on how end users can tweak their preferences, or tips for extension developers, but little on what I can do as a web developer to make sure my pages don't leak. Am I missing something? It seems lazy to just blame it on the user and say "you've got too many extensions". Or are the major patterns the same as in IE -- circular references and all that? Also, if anyone knows of any tools to troubleshoot leaks in FF, that would be great. I found this: https://addons.mozilla.org/en-US/firefox/addon/2490/ But it's apparently just for chrome and extension development.

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  • GetValue on static field inside nested classes.

    - by Sir Gallahad
    Hi... I have the following class declared. I need to retreive the class structure and the static values without instanciate it. public MyClass() { public static string field = "Value"; public nestedClass() { public static string nestedField = "NestedValue"; } } I've successfuly used GetFields and GetNestedType to recover the class structure and GetValue(null) works fine on field, but not on nestedField. Let me sample: var fi = typeof(MyClass).GetField("field", BindingFlags.Public | BindingFlags.Static); var nt = typeof(MyClass).GetNestedType("nestedClass", BindingFlags.Public); var nfi = nt.GetField("nestedField", BindingFlags.Public | BindingFlags.Static); // All the above references are detected correctly var value = fi.GetValue(null); // until here everything works fine. value == "Value" var nestedValue = nfi.GetValue(null); // this one does not work!! Anyone knows why the last line does not work and how to work around? Thanks.

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  • Fluent mapping help

    - by Matt Thrower
    Hi, This is probably a very simple question but I'm new to nHibernate and I'm having trouble working this out. I have a Page object, which can have many Region objects. I also have a Workflow object. Page and Region objects both have a relationship to Workflow and it's this double association that I'm having trouble with. The PageMap has HasMany(Function(x) x.Regions).Cascade.All() And the RegionMap has: References(Function(x) x.Page) And this all seems to work. But how do I define the relationship between Workflow and these two objects?

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  • C# - Ensuring an assembly is called via a specified assembly

    - by Adam Driscoll
    Is there any built in functionality to determine if an assembly is being called from a particular assembly? I have assembly A which references assembly B. Assembly A exposes PowerShell cmdlets and outputs types that are found within B. Certain methods and properties with in types of exposed by B are of interest to types in assembly A but not of interest to consumers of PowerShell or anyone attempting to load types in B directly and call methods within it. I have looked into InternalsVisibleToAttribute but it would require extensive rework because of the use of interfaces. I was devising a shared key system that would later be obfuscated but that seemed clunky. Is there any way to ensure B is called only by A?

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  • How to run xunit in Visual Studio 2012?

    - by user1978421
    I am very new to unit testing. I have been following the procedures for creating a unit test in visual studio 2012 on http://channel9.msdn.com/Events/TechEd/Europe/2012/DEV214. The test just won't start. And it will prompt me "A project with an Output Type of Class Library cannot be started directly. In order to debug this project, add an executable project to this solution which references the library project. Set an executable project as the startup project. Even though I attached the unit test class code to a console program, the test does not start and the test explorer is empty. In the video, it doesn't need to have any running program. The lady only created a class library, and the test will run. what should I do? Note. there is no "create unit test" on the mouse right click menu

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