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  • Need help with an xpath query!

    - by gerrod
    Can anyone help with the following XPath question? Given the node-set: <table> <rows> <row> <value column="Product">Coal</value> <value column="Quantity">10000</value> </row> <row> <value column="Product">Iron</value> <value column="Quantity">5000</value> </row> <row> <value column="Product">Ore</value> <value column="Quantity">4000</value> </row> </rows> </table> I want to query to find the node sub-set with a given product name. Note that the product name is being supplied by an attribute of the current node being processed (i.e. "@name"). So when the @name attribute has the value of "Coal" I would expect this to be returned: <row> <value column="Product">Coal</value> <value column="Quantity">10000</value> </row> This is what I've come up with; I know it's wrong, because I don't get anything back. $table/rows/row[value[@column='Product'][text()=@name]] </code>

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  • Which pattern to use for logging? Dependency Injection or Service Locator?

    - by andlju
    Consider this scenario. I have some business logic that now and then will be required to write to a log. interface ILogger { void Log(string stuff); } interface IDependency { string GetInfo(); } class MyBusinessObject { private IDependency _dependency; public MyBusinessObject(IDependency dependency) { _dependency = dependency; } public string DoSomething(string input) { // Process input var info = _dependency.GetInfo(); var intermediateResult = PerformInterestingStuff(input, info); if (intermediateResult== "SomethingWeNeedToLog") { // How do I get to the ILogger-interface? } var result = PerformSomethingElse(intermediateResult); return result; } } How would you get the ILogger interface? I see two main possibilities; Pass it using Dependency Injection on the constructor. Get it via a singleton Service Locator. Which method would you prefer, and why? Or is there an even better pattern? Update: Note that I don't need to log ALL method calls. I only want to log a few (rare) events that may or may not occur within my method.

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  • Can a custom MFC window/dialog be a template class?

    - by John
    There's a bunch of special macros that MFC uses when creating dialogs, and in my quick tests I'm getting weird errors trying to compile a template dialog class. Is this likely to be a big pain to achieve? Here's what I tried: MyDlg.h template <class W> class CMyDlg : public CDialog { typedef CDialog super; DECLARE_DYNAMIC(CMyDlg <W>) public: CMyDlg (CWnd* pParent); // standard constructor virtual ~CMyDlg (); // Dialog Data enum { IDD = IDD_MYDLG }; protected: virtual void DoDataExchange(CDataExchange* pDX); // DDX/DDV support DECLARE_MESSAGE_MAP() private: W *m_pWidget; //W will always be a CDialog }; IMPLEMENT_DYNAMIC(CMyDlg<W>, super) <------------------- template <class W> CMyDlg<W>::CMyDlg(CWnd* pParent) : super(CMyDlg::IDD, pParent) { m_pWidget = new W(this); } I get a whole bunch of errors but main one appears to be: error C2955: 'CMyDlg' : use of class template requires template argument list I tried using some specialised template versions of macros but it doesn't help much, other errors change but this one remains. Note my code is all in one file, since C++ templates don't like .h/.cpp like normal.

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  • before filter not working as expected

    - by Jimmy
    Hey guys I have a ruby on rails app with a before filter setup in my application controller to ensure only the owner can edit a document, but my permission check is always failing even when it shouldn't. Here is the code: def get_logged_in_user id = session[:user_id] unless id.nil? @current_user = User.find(id) end end def require_login get_logged_in_user if @current_user.nil? session[:original_uri] = request.request_uri flash[:notice] = "You must login first." redirect_to login end end def check_current_user_permission require_login logger.debug "user id is #{params[:user_id]}" logger.debug "current user id is #{session[:user_id]}" if session[:user_id] != params[:user_id] flash[:notice] = "You don't have permission to do that." redirect_to :controller => 'home' end end The code to note is in the check_current_user_permission. Here is an example of my log output: user id is 3 current user id is 3 Redirected to http://localhost:3000/home Filter chain halted as [:check_current_user_permission] rendered_or_redirected. Can anyone shed some light into why this is failing? Obviously the user_id of 3 is equal to the session's user_id of 3. What is going wrong?

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  • MySQL PHP | "SELECT FROM table" using "alphanumeric"-UUID. Speed vs. Indexed Integer / Indexed Char

    - by dropson
    At the moment, I select rows from 'table01' using: SELECT * FROM table01 WHERE UUID = 'whatever'; The UUID column is a unique index. I know this isn't the fastest way to select data from the database, but the UUID is the only row-identifier that is available to the front-end. Since I have to select by UUID, and not ID, I need to know what of these two options I should go for, if say the table consists of 100'000 rows. What speed differences would I look at, and would the index for the UUID grow to large, and lag the DB? Get the ID before doing the "big" select 1. $id = "SELECT ID FROM table01 WHERE UUID = '{alphanumeric character}'"; 2. $rows = SELECT * FROM table01 WHERE ID = $id; Or keep it the way it is now, using the UUID. 1. SELECT FROM table01 WHERE UUID '{alphanumeric character}'; Side note: All new rows are created by checking if the system generated uniqueid exists before trying to insert a new row. Keeping the column always unique. The "example" table. CREATE TABLE Table01 ( ID int NOT NULL PRIMARY KEY, UUID char(15), name varchar(100), url varchar(255), `date` datetime ) ENGINE = InnoDB; CREATE UNIQUE INDEX UUID ON Table01 (UUID);

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  • How do I set an og:type for the first time without losing likes?

    - by Travis
    When I first created my site, I neglected to add the Open Graph tags that Facebook recommends (http://developers.facebook.com/docs/opengraph/), and the site now has about 1200 Facebook likes through a fb:comments widget. http://graph.facebook.com/http://feedtheanimalssamples.com/ shows this: { "id": "http://feedtheanimalssamples.com/", "shares": 1204 } Recently, I've added added the following OG tags: <meta property="fb:app_id" content="59193243341" /> <meta property="og:title" content="Girl Talk - Feed The Animals Samples (old)" /> <meta property="og:image" content="http://feedtheanimalssamples.com/fta_small.png" /> <meta property="og:url" content="http://feedtheanimalssamples.com" /> But when I add the og:type tag: <meta property="og:type" content="website" /> and Lint the site, I lose all my likes. http://graph.facebook.com/http://feedtheanimalssamples.com/ starts showing this: { "id": "170545342993850", "name": "Girl Talk - Feed The Animals Samples", "picture": "http://profile.ak.fbcdn.net/hprofile-ak-snc4/188039_170545342993850_3277642_s.jpg", "link": "http://www.facebook.com/pages/Girl-Talk-Feed-The-Animals-Samples/170545342993850", "category": "Website", "website": "http://feedtheanimalssamples.com/", "description": "Interactively identifies the samples in the 2008 album 'Feed The Animals' by mashup artist Girl Talk.", "likes": 1 } (Note the "likes": 1.) So: How do I set the og:type without losing my likes? I'm trying to let my likers know that I've created a new and improved site. I'm following the instuctions at http://developers.facebook.com/blog/post/397 under "Publishing to Connected Users via Graph API", but using that API apparently requires specifying an og:type. Thanks!

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  • Automatically converting an A* into a B*

    - by Xavier Nodet
    Hi, Suppose I'm given a class A. I would like to wrap pointers to it into a small class B, some kind of smart pointer, with the constraint that a B* is automatically converted to an A* so that I don't need to rewrite the code that already uses A*. I would therefore want to modify B so that the following compiles... struct A { void foo() {} }; template <class K> struct B { B(K* k) : _k(k) {} //operator K*() {return _k;} //K* operator->() {return _k;} private: K* _k; }; void doSomething(A*) {} void test() { A a; A* pointer_to_a (&a); B<A> b (pointer_to_a); //b->foo(); // I don't need those two... //doSomething(b); B<A>* pointer_to_b (&b); pointer_to_b->foo(); // 'foo' : is not a member of 'B<K>' doSomething(pointer_to_b); // 'doSomething' : cannot convert parameter 1 from 'B<K> *' to 'A *' } Note that B inheriting from A is not an option (instances of A are created in factories out of my control)... Is it possible? Thanks.

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  • JavaCC: How can I specify which token(s) are expected in certain context?

    - by java.is.for.desktop
    Hello, everyone! I need to make JavaCC aware of a context (current parent token), and depending on that context, expect different token(s) to occur. Consider the following pseudo-code: TOKEN <abc> { "abc*" } // recognizes "abc", "abcd", "abcde", ... TOKEN <abcd> { "abcd*" } // recognizes "abcd", "abcde", "abcdef", ... TOKEN <element1> { "element1" "[" expectOnly(<abc>) "]" } TOKEN <element2> { "element2" "[" expectOnly(<abcd>) "]" } ... So when the generated parser is "inside" a token named "element1" and it encounter "abcdef" it recognizes it as <abc>, but when its "inside" a token named "element2" it recognizes the same string as <abcd>. element1 [ abcdef ] // aha! it can only be <abc> element2 [ abcdef ] // aha! it can only be <abcd> If I'm not wrong, it would behave similar to more complex DTD definitions of an XML file. So, how can one specify, in which "context" which token(s) are valid/expected? NOTE: It would be not enough for my real case to define a kind of "hierarchy" of tokens, so that "abcdef" is always first matched against <abcd> and than <abc>. I really need context-aware tokens.

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  • Generate regular expression to match strings from the list A, but not from list B

    - by Vlad
    I have two lists of strings ListA and ListB. I need to generate a regular expression that will match all strings in ListA and will not match any string in ListB. The strings could contain any combination of characters, numbers and punctuation. If a string appears on ListA it is guaranteed that it will not be in the ListB. If a string is not in either of these two lists I don't care what the result of the matching should be. The lists typically contain thousands of strings, and strings are fairly similar to each other. I know the trivial answer to this question, which is just generate a regular expression of the form (Str1)|(Str2)|(Str3) where StrN is the string from ListA. But I am looking for a more efficient way to do this. Ideal solution would be some sort of tool that will take two lists and generate a Java regular expression for this. Update 1: By "efficient", I mean to generate expression that is shorter than trivial solution. The ideal algorithm would generate the shorted possible expression. Here are some examples. ListA = { C10 , C15, C195 } ListB = { Bob, Billy } The ideal expression would be /^C1.+$/ Another example, note the third element of ListB ListA = { C10 , C15, C195 } ListB = { Bob, Billy, C25 } The ideal expression is /^C[^2]{1}.+$/ The last example ListA = { A , D ,E , F , H } ListB = { B , C , G , I } The ideal expression is the same as trivial solution which is /^(A|D|E|F|H)$/ Also, I am not looking for the ideal solution, anything better than trivial would help. I was thinking along the lines of generating the list of trivial solutions, and then try to merge the common substrings while watching that we don't wander into ListB territory. *Update 2: I am not particularly worried about the time it takes to generate the RegEx, anything under 10 minutes on the modern machine is acceptable

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  • Is it possible to load an entire SQL Server CE database into RAM?

    - by DanM
    I'm using LinqToSql to query a small SQL Server CE database. I've noticed that any operations involving sub-properties are disappointingly slow. For example, if I have a Customer table that is referenced by an Order table via a foreign key, LinqToSql will automatically create an EntitySet<Order> property. This is a nice convenience, allowing me to do things like Customer.Order.Where(o => o.ProductName = "Stopwatch"), but for some reason, SQL Server CE hangs up pretty bad when I try to do stuff like this. One of my queries, which isn't really that complicated takes 3-4 seconds to complete. I can get the speed up to acceptable, even fast, if I just grab the two tables individually and convert them to List<Customer> and List<Order>, then join then manually with my own query, but this is throwing out a lot of the appeal of LinqToSql. So, I'm wondering if I can somehow get the whole database into RAM and just query that way, then occasionally save it. Is this possible? How? If not, is there anything else I can do to boost the performance? Note: My database in its initial state is about 250K and I don't expect it to grow to more than 1-2Mb. So, loading the data into RAM certainly wouldn't be a problem from a memory point of view.

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  • Purpose of singletons in programming

    - by thecoshman
    This is admittedly a rather loose question. My current understanding of singletons is that they are a class that you set up in such a way that only one instance is ever created. This sounds a lot like a static class to me. The main differnce being that with a static class you don't / can't instance it, you just use it such as Math.pi(). With a singletong class, you would still need to do something like singleton mySingleton = new singleton(); mysingleton.set_name("foo"); singleton otherSingleton = new singleton(); // correct me if i am wrong, but mysingleton == othersingleton right now, yes? // this the following should happen? otherSingleston.set_name("bar"); mysingleton.report_name(); // will output "bar" won't it? Please note, I am asking this language independently, more about the concept. So I am not so worried about actually how to coed such a class, but more why you would wan't to and what thing you would need to consider.

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  • Creating simple calculator with bison & flex in C++ (not C)

    - by ak91
    Hey, I would like to create simple C++ calculator using bison and flex. Please note I'm new to the creating parsers. I already found few examples in bison/flex but they were all written in C. My goal is to create C++ code, where classes would contain nodes of values, operations, funcs - to create AST (evaluation would be done just after creating whole AST - starting from the root and going forward). For example: my_var = sqrt(9 ** 2 - 32) + 4 - 20 / 5 my_var * 3 Would be parsed as: = / \ my_var + / \ sqrt - | / \ - 4 / / \ / \ ** 32 20 5 / \ 9 2 and the second AST would look like: * / \ my_var 3 Then following pseudocode reflects AST: ast_root = create_node('=', new_variable("my_var"), exp) where exp is: exp = create_node(OPERATOR, val1, val2) but NOT like this: $$ = $1 OPERATOR $3 because this way I directly get value of operation instead of creation the Node. I believe the Node should contain type (of operation), val1 (Node), val2 (Node). In some cases val2 would be NULL, like above mentioned sqrt which takes in the end one argument. Right? It will be nice if you can propose me C++ skeleton (without evaluation) for above described problem (including *.y file creating AST) to help me understand the way of creating/holding Nodes in AST. Code can be snipped, just to let me get the idea. I'll also be grateful if you point me to an existing (possibly simple) example if you know any. Thank you all for your time and assistance!

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  • C# Application process hangs after some time

    - by Chris
    Hi, I implemented a simple C# application which inserts about 350000 records into the database. This used to work well and the process took approximately 20 minutes. I created a progress bar which lets you know approximately the progress of the records insertion. When the progress bar reaches about 75% it stops progressing. I have to manually terminate the program as the process doesn't seem to complete. If I use less data (like 10000), the progress bar finishes and the process is completed. However when I try to insert all the records, this won't happen any more. Note that if I wait longer to terminate the program manually, more records would have been inserted. For example, if I terminate the program after 15 minutes, 200000 records are inserted, whereas if I terminate the program after 20 minutes, 250000 records are inserted. This program is using a single thread. In face I can't do anything else until the process is complete. Does this have anything to do with threading or processes? Any feedback will be greatly appreciated. Thanks.

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  • Defining and using controller methods in ember.js

    - by OriginalEXE
    first of all, I am total noob when it comes to OOP in JS, this is new to me so treat me like a noob. I am building my first ember.js application and I am stuck (not the first time but I would get unstuck by myself, this is a tough one though). I have two models: forms entries Entries is of course in (one to many) relationship to forms, so each form can have as many properties. Form properties: id : DS.attr( 'number' ), title : DS.attr( 'string' ), views : DS.attr( 'number' ), conversion : DS.attr( 'number' ), entries : DS.hasMany( 'entry' ) Entry properties: id : DS.attr( 'number' ), parent_id: DS.belongsTo( 'form' ) Now, I have forms route that displays all forms in tabled view, and each table row has some info like form id, name etc. and that works great. What I wanted to do is display the number of entries each form has. I figured I should do that via controller, so here is my controller now: // Form controller App.FormController = Ember.ObjectController.extend({ entriescount: function() { var entries = this.get( 'store').find( 'entry' ); return entries.filterBy( 'parent_id', this.get( 'id' ) ).get( 'length' ); }.property( '[email protected]_id') }); Now for some reason, when I use {{entriescount}} in {{#each}} loop, this returns nothing. It also returns nothing in single form route. Note that in both cases, {{title}} for example works. I am wondering, am I going the right way by using controller for this, and how do I get controller to output the data. Thanks

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  • FileNotFoundExcecption while inserting image into SDCard.

    - by Are
    Hi, I want to insert images into my SDCard.So I used below code m_cImagePath = "/sdcard/"+ String.format("%d.jpg", System.currentTimeMillis()); FileOutputStream lObjOutStream = null; try { lObjOutStream = new FileOutputStream(m_cImagePath); if (null != lObjOutStream && null != finalBitmap) { finalBitmap.compress(Bitmap.CompressFormat.JPEG, 85, lObjOutStream); lObjOutStream.close(); }catch(FileNotFoundException fe){ fe.printStackTrace(); } Sometimes it is giving FileNotFoundException even my SDCard had memory.When I remove some images from sdcard again it is working smoothly.Why this Happend?How can i know that file is inserted successfully in SDCard and Is there any functionality in Java1.5 to know available space of the SDCard like java 1.6?How can i know file length which is not before inserting into the SDCard(I searched in google and found that "when the file is not physically there then file.length() always gives 0" ).But before inserting i want to know the length of the file.Then Comparing this space to available SDCard space is simple. Note :I had an idea to use Unix command df sdcard using in Runtime class to found SDCard space. Please give me an idea in this problem. Regards, Android Developer

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  • PHP: Extract direct sub directory from path string

    - by Nebs
    I need to extract the name of the direct sub directory from a full path string. For example, say we have: $str = "dir1/dir2/dir3/dir4/filename.ext"; $dir = "dir1/dir2"; Then the name of the sub-directory in the $str path relative to $dir would be "dir3". Note that $dir never has '/' at the ends. So the function should be: $subdir = getsubdir($str,$dir); echo $subdir; // Outputs "dir3" If $dir="dir1" then the output would be "dir2". If $dir="dir1/dir2/dir3/dir4" then the output would be "" (empty). If $dir="" then the output would be "dir1". Etc.. Currently this is what I have, and it works (as far as I've tested it). I'm just wondering if there's a simpler way since I find I'm using a lot of string functions. Maybe there's some magic regexp to do this in one line? (I'm not too good with regexp unfortunately). function getsubdir($str,$dir) { // Remove the filename $str = dirname($str); // Remove the $dir if(!empty($dir)){ $str = str_replace($dir,"",$str); } // Remove the leading '/' if there is one $si = stripos($str,"/"); if($si == 0){ $str = substr($str,1); } // Remove everything after the subdir (if there is anything) $lastpart = strchr($str,"/"); $str = str_replace($lastpart,"",$str); return $str; } As you can see, it's a little hacky in order to handle some odd cases (no '/' in input, empty input, etc). I hope all that made sense. Any help/suggestions are welcome.

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  • Why are argument substitutions not replaced during rescanning?

    - by James McNellis
    Consider the following macro definitions and invocation: #define x x[0] #define y(arg) arg y(x) This invocation expands to x[0] (tested on Visual C++ 2010, g++ 4.1, mcpp 2.7.2, and Wave). Why? Specifically, why does it not expand to x[0][0]? During macro replacement, A parameter in the replacement list...is replaced by the corresponding argument after all macros contained therein have been expanded. Before being substituted, each argument’s preprocessing tokens are completely macro replaced (C++03 §16.3.1/1). Evaluating the macro invocation, we take the following steps: The function-like macro y is invoked with x as the argument for its arg parameter The x in the argument is macro-replaced to become x[0] The arg in the replacement list is replaced by the macro-replaced value of the argument, x[0] The replacement list after substitution of all the parameters is x[0]. After all parameters in the replacement list have been substituted, the resulting preprocessing token sequence is rescanned...for more macro names to replace (C++03 §16.3.4/1). If the name of the macro being replaced is found during this scan of the replacement list...it is not replaced. Further, if any nested replacements encounter the name of the macro being replaced, it is not replaced (C++03 §16.3.4/2). The replacement list x[0] is rescanned (note that the name of the macro being replaced is y): x is identified as an object-like macro invocation x is replaced by x[0] Replacement stops at this point because of the rule in §16.3.4/2 preventing recursion. The replacement list after rescanning is x[0][0]. I have clearly misinterpreted something since all of the preprocessors I've tested say I am wrong. In addition, this example is a piece of a larger example in the C++0x FCD (at §16.3.5/5) and it too says that the expected replacement is x[0]. Why is x not replaced during rescanning? C99 and C++0x effectively have the same wording as C++03 in the quoted sections.

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  • Visual Studio internal project references not always working

    - by Chris
    I am using Visual Studio and a solution with 10 or so projects in (mostly VB, some C#) which have various dependencies set up. Usually when I compile the solution it works fine. Occasionally when I do it I get a build error saying that one of the projects referenced is the wrong version (I think always the same one, possibly may be two that can cause problems). In this case going to the solution explorer and right clicking on the mentioned project and saying "rebuild" followed by another full build makes it work fine. I assume there is something set up wrong somewhere but I didn't set up the solution myself initially and a quick look through doesn't show anything immediately wrong. It feels like there is some kind of race condition, that VS is internally setting the version number of the project it needs before that project has been rebuilt and thus gets it wrong or something like that but I'm sure VS should handle all this sort of thing properly. Can anybody please suggest places that I could check for whether this has been correctly set up... And I should finally note that since I don't have reliable repro of this I may not be able to respond to questions too quickly. For example the obvious one of "Could you give the exact error message" will have to wait since I didn't think to copy it this morning, it was only after I cleared it up with the above steps that I thought to post here. Similarly any solutions may take a while to confirm.

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  • Login failed for user ''. The user is not associated with a trusted SQL Server connection

    - by Tony_Henrich
    My web service app on my Windows XP box is trying to log in to my sql server 2005 database on the same box. The machine is part of a domain. I am logged in in the domain and I am an admin on my machine. I am using Windows Authentication in my connection string as in "Server=myServerAddress;Database=myDataBase;Trusted_Connection=True". SQLServer is configured for both types of authentication (mixed mode) and accepts remote connections and accepts tcp and named pipes protocols. Integrated authentication is enabled in IIS and with and without anonymous access. 'Everyone' has access to computer from network setting in local security settings. ASPNET is a user in the sql server and has access to the daatabase. user is mapped to the login. The app works fine for other developers which means the app shouldn't be changed (It's not new code). So it seems it's my machine which has an issue. I am getting the error "Login failed for user ''. The user is not associated with a trusted SQL Server connection" Note the blank user name. Why am I getting this error when both the app and database are on my machine? I can use SQL Server authentication but don't want to. I can connect to the database using SSMS and my Windows credentials. It might be related to setspn, kerberos, delegation, AD. I am not sure what further checks to make?

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  • JSON onFailure issue

    - by Mikey1980
    I’m having trouble getting a AJAX/JSON function to work correctly. I had this function grabbing value from a drop down box but now I want to use an anchor tag to set it's value. I thought it would be easy to just use the onClick event to pass string to the function I was using for the drop down box but I get the alert in JSON onFailure event even though data gets added to MySQL. I tried removing the alert from onFailure event but then it doesn't add the data. The drop down still continues work work fine, no alerts. (I should note that removing the alert also broke my drop down box) 1st I add an onClick event… <a href="<?php echo Settings::get('app.webroot'); ?>?view=schedule&action=questions" onmouseout="MM_swapImgRestore();" onmouseover="MM_swapImage('bre','','template/images/schedule/bre_f2.gif',1)" onclick="assignCallType('testing')";> 2nd I check main.js.php function assignCallType(type) { alert(type); new Request.JSON({ url: "ajax.php", onSuccess: function(rtndata,txt){ if (rtndata['STATUS'] != 'OK') alert('Status was not okay'); }, onFailure : function () { alert("onFailure") } }).get({ 'action': 'assignCallType', 'call_type': type }); } 3rd Ajax.php: the variable is back in PHP and values get added to MySQL but I get the Alert in the JSON onFailure event if ($_GET['action'] == "assignCallType") { if ($USER->isInsideSales()) { $call_type = $_GET['call_type']; $_SESSION['callinfo']->setCallType($call_type); $_SESSION['callinfo']->save($callid); echo json_encode(array('STATUS'=>'OK')); } else { echo json_encode(array('STATUS'=>'DENIED')); } } Any idea where I am going wrong. The only difference between this and the working drop down is how the function was called, I used onchange="assignCallType(this.value)".

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  • multiple models in Rails with a shared interface

    - by dfondente
    I'm not sure of the best structure for a particular situation in Rails. We have several types of workshops. The administration of the workshops is the same regardless of workshop type, so the data for the workshops is in a single model. We collect feedback from participants about the workshops, and the questionnaire is different for each type of workshop. I want to access the feedback about the workshop from the workshop model, but the class of the associated model will depend on the type of workshop. If I was doing this in something other than Rails, I would set up an abstract class for WorkshopFeedback, and then have subclasses for each type of workshop: WorkshopFeedbackOne, WorkshopFeedbackTwo, WorkshopFeedbackThree. I'm unsure how to best handle this with Rails. I currently have: class Workshop < ActiveRecord::Base has_many :workshop_feedbacks end class Feedback < ActiveRecord::Base belongs_to :workshop has_many :feedback_ones has_many :feedback_twos has_many :feedback_threes end class FeedbackOne < ActiveRecord::Base belongs_to :feedback end class FeedbackTwo < ActiveRecord::Base belongs_to :feedback end class FeedbackThree < ActiveRecord::Base belongs_to :feedback end This doesn't seem like to the cleanest way to access the feedback from the workshop model, as accessing the correct feedback will require logic investigating the Workshop type and then choosing, for instance, @workshop.feedback.feedback_one. Is there a better way to handle this situation? Would it be better to use a polymorphic association for feedback? Or maybe using a Module or Mixin for the shared Feedback interface? Note: I am avoiding using Single Table Inheritance here because the FeedbackOne, FeedbackTwo, FeedbackThree models do not share much common data, so I would end up with a large sparsely populated table with STI.

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  • How to delete ProgIDs from other user accounts when uninstalling from Windows?

    - by Mordachai
    I've been investigating "how should a modern windows c++ application register its file types" with Windows (see http://stackoverflow.com/questions/2828637/c-how-do-i-correctly-register-and-unregister-file-type-associations-for-our-ap). And having combed through the various MSDN articles on the subject, the summary appears to be as follows: The installer (elevated) should register the global ProgID HKLM\Software\Classes\my-app.my-doc[.version] (e.g. HKLM\Software\Classes\TextPad.text) The installer also configures default associations for its document types (e.g. .myext) and points this to the aforementioned global ProgID in HKLM. NOTE: a user interface should be provided here to allow the user to either accept all default associations, or to customize which associations should be set. The application, running standard (unelevated), should provide a UI for allowing the current user to set their personal associations as is available in the installer, except that these associations are stored in HKCU\Software\Classes (per user, not per machine). The UN-installer is then responsible for deleting all registered ProgIDs (but should leave the actual file associations alone, as Windows is smart enough to handle associations pointing to missing ProgIDs, and this is the specified desired behavior by MSDN). So that schema sounds reasonable to me, except when I consider #4: How does an uninstaller, running elevated for a given user account, delete any per-user ProgIDs created in step #3 for other users? As I understand things, even in elevated mode, an uninstaller cannot go into another user's registry hive and delete items? Or can it? Does it have to load each given user hive first? What are the rules here? Thanks for any insight you might have to offer! EDIT: See below for the solution (My question was founded in confusion)

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  • How to convert a byte array of 19200 bytes in size where each byte represents 4 pixels (2 bits per p

    - by Klinger
    I am communicating with an instrument (remote controlling it) and one of the things I need to do is to draw the instrument screen. In order to get the screen I issue a command and the instrument replies with an array of bytes that represents the screen. Below is what the instrument manual has to say about converting the response to the actual screen: The command retrieves the framebuffer data used for the display. It is 19200 bytes in size, 2-bits per pixel, 4 pixels per byte arranged as 320x240 characteres. The data is sent in RLE encoded form. To convert this data into a BMP for use in Windows, it needs to be turned into a 4BPP. Also note that BMP files are upside down relative to this data, i.e. the top display line is the last line in the BMP. I managed to unpack the data, but now I am stuck on how to actually go from the unpacked byte array to a bitmap. My background on this is pretty close to zero and my searches have not revealed much either. I am looking for directions and/or articles I could use to help me undestand how to get this done. Any code or even pseudo code would also help. :-) So, just to summarize it all: How to convert a byte array of 19200 bytes in size, where each byte represents 4 pixels (2 bits per pixel), to a bitmap arranged as 320x240 characters. Thanks in advance.

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  • What collection object is appropriate for fixed ordering of values?

    - by makerofthings7
    Scenario: I am tracking several performance counters and have a CounterDescription[] correlate to DataSnapshot[]... where CounterDescription[n] describes the data loaded within DataSnapshot[n]. I want to expose an easy to use API within C# that will allow for the easy and efficient expansion of the arrays. For example CounterDescription[0] = Humidity; DataSnapshot[0] = .9; CounterDescription[1] = Temp; DataSnapshot[1] = 63; My upload object is defined like this: Note how my intent is to correlate many Datasnapshots with a dattime reference, and using the offset of the data to refer to its meaning. This was determined to be the most efficient way to store the data on the back-end, and has now reflected itself into the following structure: public class myDataObject { [DataMember] public SortedDictionary<DateTime, float[]> Pages { get; set; } /// <summary> /// An array that identifies what each position in the array is supposed to be /// </summary> [DataMember] public CounterDescription[] Counters { get; set; } } I will need to expand each of these arrays (float[] and CounterDescription[] ), but whatever data already exists must stay in that relative offset. Which .NET objects support this? I think Array[] , LinkedList<t>, and List<t> Are able to keep the data fixed in the right locations. What do you think?

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  • crash when using stl vector at instead of operator[]

    - by Jamie Cook
    I have a method as follows (from a class than implements TBB task interface - not currently multithreading though) My problem is that two ways of accessing a vector are causing quite different behaviour - one works and the other causes the entire program to bomb out quite spectacularly (this is a plugin and normally a crash will be caught by the host - but this one takes out the host program as well! As I said quite spectacular) void PtBranchAndBoundIterationOriginRunner::runOrigin(int origin, int time) const // NOTE: const method { BOOST_FOREACH(int accessMode, m_props->GetAccessModes()) { // get a const reference to appropriate vector from member variable // map<int, vector<double>> m_rowTotalsByAccessMode; const vector<double>& rowTotalsForAccessMode = m_rowTotalsByAccessMode.find(accessMode)->second; if (origin != 129) continue; // Additional debug constrain: I know that the vector only has one non-zero element at index 129 m_job->Write("size: " + ToString(rowTotalsForAccessMode.size())); try { // check for early return... i.e. nothing to do for this origin if (!rowTotalsForAccessMode[origin]) continue; // <- this works if (!rowTotalsForAccessMode.at(origin)) continue; // <- this crashes } catch (...) { m_job->Write("Caught an exception"); // but its not an exception } // do some other stuff } } I hate not putting in well defined questions but at the moment my best phrasing is : "WTF?" I'm compiling this with Intel C++ 11.0.074 [IA-32] using Microsoft (R) Visual Studio Version 9.0.21022.8 and my implementation of vector has const_reference operator[](size_type _Pos) const { // subscript nonmutable sequence #if _HAS_ITERATOR_DEBUGGING if (size() <= _Pos) { _DEBUG_ERROR("vector subscript out of range"); _SCL_SECURE_OUT_OF_RANGE; } #endif /* _HAS_ITERATOR_DEBUGGING */ _SCL_SECURE_VALIDATE_RANGE(_Pos < size()); return (*(_Myfirst + _Pos)); } (Iterator debugging is off - I'm pretty sure) and const_reference at(size_type _Pos) const { // subscript nonmutable sequence with checking if (size() <= _Pos) _Xran(); return (*(begin() + _Pos)); } So the only difference I can see is that at calls begin instead of simply using _Myfirst - but how could that possibly be causing such a huge difference in behaviour?

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