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  • Implementation/interface inheritance design question.

    - by Neil G
    I would like to get the stackoverflow community's opinion on the following three design patterns. The first is implementation inheritance; the second is interface inheritance; the third is a middle ground. My specific question is: Which is best? implementation inheritance: class Base { X x() const = 0; void UpdateX(A a) { y_ = g(a); } Y y_; } class Derived: Base { X x() const { return f(y_); } } interface inheritance: class Base { X x() const = 0; void UpdateX(A a) = 0; } class Derived: Base { X x() const { return x_; } void UpdateX(A a) { x_ = f(g(a)); } X x_; } middle ground: class Base { X x() const { return x_; } void UpdateX(A a) = 0; X x_; } class Derived: Base { void UpdateX(A a) { x_ = f(g(a)); } } I know that many people prefer interface inheritance to implementation inheritance. However, the advantage of the latter is that with a pointer to Base, x() can be inlined and the address of x_ can be statically calculated.

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  • Remove duplicate records/objects uniquely identified by multiple attributes

    - by keruilin
    I have a model called HeroStatus with the following attributes: id user_id recordable_type hero_type (can be NULL!) recordable_id created_at There are over 100 hero_statuses, and a user can have many hero_statuses, but can't have the same hero_status more than once. A user's hero_status is uniquely identified by the combination of recordable_type + hero_type + recordable_id. What I'm trying to say essentially is that there can't be a duplicate hero_status for a specific user. Unfortunately, I didn't have a validation in place to assure this, so I got some duplicate hero_statuses for users after I made some code changes. For example: user_id = 18 recordable_type = 'Evil' hero_type = 'Halitosis' recordable_id = 1 created_at = '2010-05-03 18:30:30' user_id = 18 recordable_type = 'Evil' hero_type = 'Halitosis' recordable_id = 1 created_at = '2009-03-03 15:30:00' user_id = 18 recordable_type = 'Good' hero_type = 'Hugs' recordable_id = 1 created_at = '2009-02-03 12:30:00' user_id = 18 recordable_type = 'Good' hero_type = NULL recordable_id = 2 created_at = '2009-012-03 08:30:00' (Last two are not a dups obviously. First two are.) So what I want to do is get rid of the duplicate hero_status. Which one? The one with the most-recent date. I have three questions: How do I remove the duplicates using a SQL-only approach? How do I remove the duplicates using a pure Ruby solution? Something similar to this: http://stackoverflow.com/questions/2790004/removing-duplicate-objects. How do I put a validation in place to prevent duplicate entries in the future?

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  • How to create platform independent 3D video on 3D TV via HDMI 1.4?

    - by artif
    I am writing a real-time, interactive 3D visualization program and at each point in the program, I can compute 2 images (bitmaps) that are meant to look 3D together by means of stereoscopy. How do I get my program to display the image pairs such that they look 3D on a 3D TV? Is there a platform independent way of accomplishing it? (By platform I mean independent of GPU brand, operating system, 3D TV vendor, etc.) If not, which is preferable-- to lock in by GPU, OS, or 3D TV? I suppose I need to be using an HDMI 1.4 cable with the 3D TV? HDMI 1.4 can encode stereoscopy via side-by-side method. But how do I send such an encoded signal to the monitor? What kind of libraries do I use for this sort of thing? Windows DirectShow? If DirectShow is correct, is there a cross platform equivalent available? If anyone asks, yes I have seen this question: http://stackoverflow.com/questions/2811350/generating-3d-tv-stereoscopic-output-programmatically. However, correct me if I am wrong, it does not appear to be what I'm looking for. I do not have an OpenGL or Direct3D program that generates polygons, for which a Nvidia card can do ad-hoc impromptu stereoscopy simply by rendering the scene from 2 slightly offset points of view and then displaying those 2 images on the monitor-- my program already has those image pairs and needs to display them (and they are not the result of rendering polygons). Btw, I have never done any major multimedia programming before and know very little about HDMI, Direct Show, 3D TVs, etc so pardon me if any parts of this question did not make any sense at all.

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  • Python - Checking for membership inside nested dict

    - by victorhooi
    heya, This is a followup questions to this one: http://stackoverflow.com/questions/2901422/python-dictreader-skipping-rows-with-missing-columns Turns out I was being silly, and using the wrong ID field. I'm using Python 3.x here. I have a dict of employees, indexed by a string, "directory_id". Each value is a nested dict with employee attributes (phone number, surname etc.). One of these values is a secondary ID, say "internal_id", and another is their manager, call it "manager_internal_id". The "internal_id" field is non-mandatory, and not every employee has one. (I've simplified the fields a little, both to make it easier to read, and also for privacy/compliance reasons). The issue here is that we index (key) each employee by their directory_id, but when we lookup their manager, we need to find managers by their "internal_id". Before, when employee.keys() was a list of internal_ids, I was using a membership check on this. Now, the last part of my if statement won't work, since the internal_ids is part of the dict values, instead of the key itself. def lookup_supervisor(manager_internal_id, employees): if manager_internal_idis not None and manager_internal_id!= "" and manager_internal_id in employees.keys(): return (employees[manager_internal_id]['mail'], employees[manager_internal_id]['givenName'], employees[manager_internal_id]['sn']) else: return ('Supervisor Not Found', 'Supervisor Not Found', 'Supervisor Not Found') So the first question is, how do I check whether the manager_internal_id is present in the dict's values. I've tried substituting employee.keys() with employee.values(), that didn't work. Also, I'm hoping for something a little more efficient, not sure if there's a way to get a subset of the values, specifically, all the entries for employees[directory_id]['internal_id']. Hopefully there's some Pythonic way of doing this, without using a massive heap of nested for/if loops. My second question is, how do I then cleanly return the required employee attributes (mail, givenname, surname etc.). My for loop is iterating over each employee, and calling lookup_supervisor. I'm feeling a bit stupid/stumped here. def tidy_data(employees): for directory_id, data in employees.items(): # We really shouldnt' be passing employees back and forth like this - hmm, classes? data['SupervisorEmail'], data['SupervisorFirstName'], data['SupervisorSurname'] = lookup_supervisor(data['manager_internal_id'], employees) Thanks in advance =), Victor

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  • Signable, streamable, "readable" archive format?

    - by alexvoda
    Is there any archive format that offers the following: be digitally sign-able with a digital certificate from a trusted source like Verisign - for preventing changes to the file (I am not referring to read only, but in case the file was changed it should no longer be signed telling the user this is not the original file) be stream-able - be able to be opened even if not all of the content has been transfered (also not strictly linearly) be "readable" - be able to read the data without extracting to a temporary folder (AFAIK if you open a file in a zip archive it is extracted first, and this stays true even for zip based formats like OOXML. This is not what I want) be portable - support on at least Windows, Linux and Mac OS X is a must, or at least future support be free of patents - Be open source - also preferably a license that allows commercial use(as far as i know GPL a share-alike licence so it doesn't allow comercial use, BSD on the other hand alows it) Note: Though it may come in handy eventually I can not think right now of a scenario that would require both point 1 and point 2 simultaneously. Or lets leave it a be able to check the signature only when the whole file was downloaded. I am not interested in: being able to be compressed being supported on legacy systems Does any existing archive format fit this description (tar evolutions like DAR and pax come to mind) ? If there is, are there programing libraries available for the above mentioned OSs? If not, would it be hard to create such a thing? EDIT: clarrified piont 5 EDIT 2: added a note to clarify point 1 and 2 P.S.: This is my first question on StackOverflow

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  • How to post to a request using node.js

    - by Mr JSON
    I am trying to post some json to a URL. I saw various other questions about this on stackoverflow but none of them seemed to be clear or work. This is how far I got, I modified the example on the api docs: var http = require('http'); var google = http.createClient(80, 'server'); var request = google.request('POST', '/get_stuff', {'host': 'sever', 'content-type': 'application/json'}); request.write(JSON.stringify(some_json),encoding='utf8'); //possibly need to escape as well? request.end(); request.on('response', function (response) { console.log('STATUS: ' + response.statusCode); console.log('HEADERS: ' + JSON.stringify(response.headers)); response.setEncoding('utf8'); response.on('data', function (chunk) { console.log('BODY: ' + chunk); }); }); When I post this to the server I get an error telling me that it's not of the json format or that it's not utf8, which they should be. I tried to pull the request url but it is null. I am just starting with nodejs so please be nice.

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  • jQuery and jQuery UI (Dual Licensing)

    - by John Hartsock
    OK I have read many posts regarding Dual Licensing using MIT and GPL licenses. But Im curious still, as the wording seems to be inclusive. Many of the Dual Licenses state that the software is licensed using "MIT AND GPL". The "AND" is what confuses me. It seems to me that the word "AND" in the terms, means you will be licensing the product using both licenses. Most of the posts, here on stackoverflow, say you can license the software using one "OR" the other. JQuery specifically states "OR", whereas JQuery UI specifically States "AND". Another Instance of the "AND" would be JQGrid. Im not a lawyer but, it seems to me that a legal interpretation of this would state that use of the software would mean that your using the software under both licenses. Has anyone who has contacted a lawyer gotten clarification or a definitive answer as to what is true? Can you use Dual licensed software products that state "AND" in the terms of agreement under either license?

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  • What's the best way to resolve this scope problem?

    - by Peter Stewart
    I'm writing a program in python that uses genetic techniques to optimize expressions. Constructing and evaluating the expression tree is the time consumer as it can happen billions of times per run. So I thought I'd learn enough c++ to write it and then incorporate it in python using cython or ctypes. I've done some searching on stackoverflow and learned a lot. This code compiles, but leaves the pointers dangling. I tried 'this_node = new Node(...' . It didn't seem to work. And I'm not at all sure how I'd delete all the references as there would be hundreds. I'd like to use variables that stay in scope, but maybe that's not the c++ way. What is the c++ way? class Node { public: char *cargo; int depth; Node *left; Node *right; } Node make_tree(int depth) { depth--; if(depth <= 0) { Node tthis_node("value",depth,NULL,NULL); return tthis_node; } else { Node this_node("operator" depth, &make_tree(depth), &make_tree(depth)); return this_node; } };

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  • Button Template does not render Image clearly.

    - by Akash Kava
    Here is my button template, <Microsoft_Windows_Themes:ButtonChrome x:Name="Chrome" Background="{TemplateBinding Background}" BorderBrush="{TemplateBinding BorderBrush}" RenderDefaulted="{TemplateBinding IsDefaulted}" RenderMouseOver="{TemplateBinding IsMouseOver}" RenderPressed="{TemplateBinding IsPressed}"> <Grid> <Grid.ColumnDefinitions> <ColumnDefinition Width="Auto"/> <ColumnDefinition/> </Grid.ColumnDefinitions> <Image Source="{TemplateBinding ImageSource}" RenderOptions.BitmapScalingMode="NearestNeighbor" SnapsToDevicePixels="True" HorizontalAlignment="Center" VerticalAlignment="Center" Stretch="None" /> <ContentPresenter Grid.Column="1" HorizontalAlignment="{TemplateBinding HorizontalContentAlignment}" Margin="{TemplateBinding Padding}" VerticalAlignment="{TemplateBinding VerticalContentAlignment}" SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}" RecognizesAccessKey="True"/> </Grid> </Microsoft_Windows_Themes:ButtonChrome> Now you can see as per this question My Images are blurry on StackOverflow I tried .. RenderOptions.BitmapScalingMode="NearestNeighbor" On all levels, grid, chrome .. and tried various combinations of SnapsToDevicePixels but images just wont show up correctly. I set Stretch=None, image is aligned at center, still why it stretches automatically? here is the output and its very frustrating. Actual size of the image is 16x16 but I some how figured out by using Windows Maginifier that no matter what I do, the image is actually trying to render as 20x20, for the bigger images its even cropping the right most and bottom part. I think image should be rendered correctly 16x16 when Stretch=None, can anyone clarify whats problem here?

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  • When downloading a file using FileStream, why does page error message refers to aspx page name, not

    - by StuperUser
    After building a filepath (path, below) in a string (I am aware of Path in System.IO, but am using someone else's code and do not have the opportunity to refactor it to use Path). I am using a FileStream to deliver the file to the user (see below): FileStream myStream = new FileStream(path, FileMode.Open, FileAccess.Read); long fileSize = myStream.Length; byte[] Buffer = new byte[(int)fileSize + 1]; myStream.Read(Buffer, 0, (int)myStream.Length); myStream.Close(); Response.ContentType = "application/csv"; Response.AddHeader("content-disposition", "attachment; filename=" + filename); Response.BinaryWrite(Buffer); Response.Flush(); Response.End(); I have seen from: http://stackoverflow.com/questions/736301/asp-net-how-to-stream-file-to-user reasons to avoid use of Response.End() and Response.Close(). I have also seen several articles about different ways to transmit files and have diagnosed and found a solution to the problem (https and http headers) with a colleague. However, the error message that was being displayed was not about access to the file at path, but the aspx file. Edit: Error message is: Internet Explorer cannot download MyPage.aspx from server.domain.tld Internet Explorer was not able to open this Internet site. The requested site is either unavailable or cannot be found. Please try again later. (page name and address anonymised) Why is this? Is it due to the contents of the file coming from the HTTP response .Flush() method rather than a file being accessed at its address?

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  • Facebook offline access step-by-step

    - by Ben
    After searchinge litteraly 1 day on fb and google for an up-to-date and working way to do something seemingly simple: I am looking for a step-by-step explanation to get offline_access for a user for a facebook app and then using this (session key) to retrieve offline & not within a browser friends & profile data. Preferrably doing this in the Fb Java API. Thanks. And yes I did check the facebook wiki. Update: Anyone? this: http://www.facebook.com/authorize.php?api_key=<api-key>&v=1.0&ext_perm=offline_access gives me offline_Access, however how to retrieve the session_key? Why can't facebook just do simple documentation, I mean there are like 600 people working there? The seemingly same question: http://stackoverflow.com/questions/617043/getting-offlineaccess-to-work-with-facebook Does not answer how to retrieve the session key Edit: I am still stuck with that. I guess nobody really tried such a batch access out yet...

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  • Row selection based on subtable data in MySQL

    - by Felthragar
    I've been struggling with this selection for a while now, I've been searching around StackOverflow and tried a bunch of stuff but nothing that helps me with my particular issue. Maybe I'm just missing something obvious. I have two tables: Measurements, MeasurementFlags "Measurements" contain measurements from a device, and each measurement can have properties/attributes attached to them (commonly known as "flags") to signify that the measurement in question is special in some way or another (for instance, one flag may signify a test or calibration measurement). Note: One record per flag! Right, so a record from the "Measurements" table can theoreticly have an unlimited amount of MeasurementFlags attached to it, or it can have none. Now, I need to select records from "Measurements", that have an attached "MeasurementFlag" valued "X", but it must also NOT have a flag valued "Y" attached to it. We're talking about a fairly large database with hundreds of millions of rows, which is why I'm trying to keep all of this logic within one query. Splitting it up would create too many queries, however if it's not possible to do in one query I guess I don't have a choise. Thanks in advance.

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  • key-words highlight in <textarea> (again)

    - by Halst
    Wait, I know! I know that this "syntax highlight in textarea"-question was raised like a million times on stackoverflow! But, please, listen. offtopic: I'm not a web-developer, and technically I'm not a programmer at all. I study mechatronics and deal mostly with control-engineering and digital-hardware. And I'm so pissed off that whenever I want to share some application (that would be helpful in my field) and embed it into the web, I need to know such a crazy amount of technologies, like html, css, javascript, flash, etc.. that takes time, which I could have been spending for the benefit of my own field. Right now I'm playing with hardware-description-languages and I'm writing some Python-libraries to convert one HDL into another. And I wanted to embed such feature on the web: http://xhdl2vhdl.appspot.com/ I wanted to implement some basic syntax highlighting (only keywords highlighting will be enough) so that the code could be readable. But the whole idea highlighting something in textarea is not trivial at all. The other difficulty is that the languages I work with are rare, and there are no out-of-box solutions for them. I tried to dig into these solutions, but they are very complicated for me: http://www.nicolarizzo.com/gamesroom/experimental/CodeEditor.html http://marijn.haverbeke.nl/codemirror/jstest.html and there is no clear descriptions how to use them (for my level of knowledge of web-development). So, is there a simple solution, just to highlight a bunch of key-words in textarea or perform something equivalent? Thank you.

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  • How to access different domain data using Java script

    - by shoaibmohammed
    Hello there, Here is the issue. Suppose there is a DOMAIN A which is going to be the server containing a PHP Script file. The data from Domain A is to be accessed by a Client at DOMAIN B. I know it cannot be accessed directly using JavaScript. So what I did is, in Domain A I created a a JavaScript file as front-end for the PHP Script which AJAXes the PHP and returns the data. But unfortunately it din't work I came across an example having PHP as a Middle Man in the client side. But I donot want to keep any server side PHP code as a middle man in the client side. I just want to give out the Javascript to the client domain. http://stackoverflow.com/questions/578095/how-to-get-data-with-javascript-from-another-server DOMAIN A PHP - data.php <?php echo "Server returns data"; ?> JS - example.js Does the Ajax to the PHP function getData() { //assume ajax is done for data.php and data is retrieved, now return the data return ajaxed_data; } Domain B JS Client includes the example.js file from Domain A in his HTML <script type="text/javascript" src="http://www.DomainA.com/example.js"></script> <script type="text/javascript"> alert(getData()); </script> I hope I have made myself understandable ! Can this be established ? Its something like Google friend connect, what I mean is, just provide JavaScript to the client and thats it. Every thing carried out in server side Thankx for providing this forum

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  • Where in maven project's path should I put configuration files that are not considered resources

    - by Paralife
    I have a simple java maven project. One of my classes when executing needs to load an xml configuration file from the classpath. I dont want to package such xml file when producing the jar but I want to include a default xml file in a zip assemply under a conf subfolder and I also want this default xml to be available in the unit tests to test against it. As I see it there are 2 possible places of this default xml: src/main/resources/conf/default.xml src/main/conf/default.xml Both solutions demand special pom actions: In solution 1, I get the auto copy to target folder during build which means it is available in testing but I also get it in the produced jar which i dont want. In solution 2, I get the jar as I want it(free of the xml) but I manually have to copy the xml to the target folder to be available for testing. (I dont want to add src's subfolders in test classpath. I think it is bad practice). The question is what is the best solution of the two? If the correct is 2, what is the best way to copy it to target folder? Is there any other solution better and more common than those two? (I also read http://stackoverflow.com/questions/465001/where-should-i-put-application-configuration-files-for-a-maven-project but I would like to know the most "correct solution" from the "convention over configuration" point of view and this link provides some configuration type solutions but not any convention oriented. Maybe there isnt one but I ask anyway. Also the solutions provided include AntRun plugin and appAssembler plugin and I wonder if I could do it with out them.)

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  • Java - Problem in deploying Web Application

    - by Yatendra Goel
    I have built a Java Web Application and packed it in a .war file and tested it on my local tomcat server and it is running fine. But when I deployed it on my client's server, it is showing an error. According to the remote server (my client's server), it is not finding a tld file packed in a jar file which I had placed in WEB-INF/lib directory. But when I checked the WEB-INF/lib directory for the jar file, i found that it was there. The contents of META-INF/MANIFEST.MF is as follows: Manifest-Version: 1.0 Class-Path: I think that there is no need to explicitly mention the classpath of WEB-INF/lib directory as it is in the classpath of any web application by default. Then, why the server can't find the jar file in the lib directory when I deployed it on a remote server and why it is working when I deployed the same application on my local server. I posted a question for this at http://stackoverflow.com/questions/2441254/struts-1-struts-taglib-jar-is-not-being-found-by-my-web-application but found that the problem is unusual as nobody could answer it. So my questions are as follows: Q1. Is WEB-INF/lib still remains on the classpath if I leave the classpath entry blank as shown above in the MANIFEST.MF file or I should delete the classpath entry completely from the file or I should explicitly enter Class-Path: /WEB-INF/lib as the classpath entry? Q2. I have JSP pages, Servlets and some helper classes in the web application. Jsp pages are located at the root. Servlets and helper classes are located in WEB-INF/classes folder. So Is there any problem if my helper classes are located in the WEB-INF/classes folder? Note: Please note that this question is not same as my previous question. It is a follow-up question of my previous question. Both the servers (local and remote) are tomcat servers.

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  • Passing arguments and values from HTML to jQuery (events)

    - by Jaroslav Moravec
    What is the practice to pass arguments from HTML to jQuery events function. For example getting id of row from db: <tr class="jq_killMe" id="thisItemId-id"> ... </tr> and jQuery: $(".jq_killMe").click(function () { var tmp = $(this).attr('id).split("-"); var id = tmp[0] // ... } What's the best practise, if I want to pass more than one argument? Is it better not to use jQuery? For example: <tr onclick="killMe('id')"> ... </tr> I didn't find the answer on my question, I will be glad even for links. Thanks. Edit (pre solution) So you suggested two methods to do that: Add custom attributes to element (XHTML) Use attribute ID and parse it by regex Attribute data-* attributes in HTML5 Use hidden children elements I like first solution, but... I would like to (I have to (employer)) produce valid code. Here is a nice question and answers: http://stackoverflow.com/questions/994856/so-what-if-custom-html-attributes-arent-valid-xhtml And the second is not so pretty as the first, but valid. So the compromise is... The third is the solution for future, but here is a lot of CMS where we have to use XHTML or HTML4. (And HTML5 is the long process)

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  • Structuring input of data for localStorage

    - by WmasterJ
    It is nice when there isn't a DB to maintain and users to authenticate. My professor has asked me to convert a recent research project of his that uses Bespin and calculates errors made by users in a code editor as part of his research. The goal is to convert from MySQL to using HTML5 localStorage completely. Doesn't seem so hard to do, even though digging in his code might take some time. Question: I need to store files and state (last placement of cursor and active file). I have already done so by implementing the recommendations in another stackoverflow thread. But would like your input considering how to structure the content to use. My current solution Hashmap like solution with javascript objects: files = {}; // later, saving files[fileName] = data; And then storing in localStorage using some recommendations localStorage.setObject(files): Currently I'm also considering using some type of numeric id. So that names can be changed without any hassle renaming the key in the hashmap. What is your opinion on the way it is solved and would you do it any differently?

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  • Linker error: wants C++ virtual base class destructor

    - by jdmuys
    Hi, I have a link error where the linker complains that my concrete class's destructor is calling its abstract superclass destructor, the code of which is missing. This is using GCC 4.2 on Mac OS X from XCode. I saw http://stackoverflow.com/questions/307352/g-undefined-reference-to-typeinfo but it's not quite the same thing. Here is the linker error message: Undefined symbols: "ConnectionPool::~ConnectionPool()", referenced from: AlwaysConnectedConnectionZPool::~AlwaysConnectedConnectionZPool()in RKConnector.o ld: symbol(s) not found collect2: ld returned 1 exit status Here is the abstract base class declaration: class ConnectionPool { public: static ConnectionPool* newPool(std::string h, short p, std::string u, std::string pw, std::string b); virtual ~ConnectionPool() =0; virtual int keepAlive() =0; virtual int disconnect() =0; virtual sql::Connection * getConnection(char *compression_scheme = NULL) =0; virtual void releaseConnection(sql::Connection * theConnection) =0; }; Here is the concrete class declaration: class AlwaysConnectedConnectionZPool: public ConnectionPool { protected: <snip data members> public: AlwaysConnectedConnectionZPool(std::string h, short p, std::string u, std::string pw, std::string b); virtual ~AlwaysConnectedConnectionZPool(); virtual int keepAlive(); // will make sure the connection doesn't time out. Call regularly virtual int disconnect(); // disconnects/destroys all connections. virtual sql::Connection * getConnection(char *compression_scheme = NULL); virtual void releaseConnection(sql::Connection * theConnection); }; Needless to say, all those members are implemented. Here is the destructor: AlwaysConnectedConnectionZPool::~AlwaysConnectedConnectionZPool() { printf("AlwaysConnectedConnectionZPool destructor call"); // nothing to destruct in fact } and also maybe the factory routine: ConnectionPool* ConnectionPool::newPool(std::string h, short p, std::string u, std::string pw, std::string b) { return new AlwaysConnectedConnectionZPool(h, p, u, pw, b); } I can fix this by artificially making my abstract base class concrete. But I'd rather do something better. Any idea? Thanks

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  • Unable to persist objects in GAE JDO

    - by Basil Dsouza
    Hello Guys, I am completely fresh to both JDO and GAE, and have been struggling to get my data layer to persist any code at all! The issues I am facing may be very simple, but I just cant seem to find any a way no matter what solution I try. Firstly the problem: (Slightly simplified, but still contains all the info necessary) My data model is as such: User: (primary key) String emailID String firstName Car: (primary key) User user (primary key) String registration String model This was the initial datamodel. I implemented a CarPK object to get a composite primary key of the User and the registration. However that ran into a variety of issues. (Which i will save for another time/question) I then changed the design as such: User: (Unchanged) Car: (primary key) String fauxPK (here fauxPK = user.getEmailID() + SEP + registration) User user String registration String model This works fine for the user, and it can insert and retrieve user objects. However when i try to insert a Car Object, i get the following error: "Cannot have a java.lang.String primary key and be a child object" Found the following helpful link about it: http://stackoverflow.com/questions/2063467/persist-list-of-objects Went to the link suggested there, that explains how to create Keys, however they keep talking about "Entity Groups" and "Entity Group Parents". But I cant seem to find any articles or sites that explain what are "Entity Group"s or an "Entity Group Parents" I could try fiddling around some more to figure out if i can store an object somehow, But I am running sort on patience and also would rather understand and implement than vice versa. So i would appreciate any docs (even if its huge) that covers all these points, and preferably has some examples that go beyond the very basic data modeling. And thanks for reading such a long post :)

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  • In Ruby, why does a method invocation not be able to be treated as a unit when "do" and "end" is use

    - by Jian Lin
    The following question is related to http://stackoverflow.com/questions/2127836/ruby-print-inject-do-syntax The question is, can we insist on using DO and END and make it work with puts or p? This works: a = [1,2,3,4] b = a.inject do |sum, x| sum + x end puts b # prints out 10 so, is it correct to say, inject is a class method of the Array class, which takes a block of code, and then returns a number. If so, then it should be no different from calling a function and getting back a return value: b = foo(3) puts b or b = circle.getRadius() puts b In the above two cases, we can directly say puts foo(3) puts circle.getRadius() so, there is no way to make it work directly by using the following 2 ways: a = [1,2,3,4] puts a.inject do |sum, x| sum + x end but it gives ch01q2.rb:7:in `inject': no block given (LocalJumpError) from ch01q2.rb:4:in `each' from ch01q2.rb:4:in `inject' from ch01q2.rb:4 grouping the method call using ( ) doesn't work either: a = [1,2,3,4] puts (a.inject do |sum, x| sum + x end) and this gives: ch01q3.rb:4: syntax error, unexpected kDO_BLOCK, expecting ')' puts (a.inject do |sum, x| ^ ch01q3.rb:4: syntax error, unexpected '|', expecting '=' puts (a.inject do |sum, x| ^ ch01q3.rb:6: syntax error, unexpected kEND, expecting $end end) ^ finally, the following version works: a = [1,2,3,4] puts a.inject { |sum, x| sum + x } but why doesn't the grouping of the method invocation using ( ) work? What if a programmer insists that he uses do and end, can it be made to work directly with p or puts, without an extra temporary variable?

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  • "One or more breakpoints cannot be set and have been disabled. Execution will stop at the beginning

    - by sam
    I set a breakpoint in my code in Visual-C++, but when I run, I see the error mentioned in the title. I know this question has been asked before on Stack Overflow (http://stackoverflow.com/questions/657470/breakpoints-cannot-be-set-and-have-been-disabled-problem), but none of the answers there fully explained the problem I'm seeing. The closest I can see is something about the linker, but I don't understand that - so if someone could explain in more detail that would be great. In my case, I have 2 projects in Visual C++ - the production dsw, and the test code dsw. I have loaded and rebuilt both dsws in debug mode. I want a breakpoint in the production code, which is run via the test scripts. My issue is I get the error message when I run the test code, because the break point is in the production code, which isn't loaded up when the test starts. Near the beginning of the test script there is a mytest_initialize() command. I imagine this goes off and loads up the production dll. Once this line has executed, I can put the breakpoint in my production code and run until I hit it. But it's quite annoying to have to run to this line, set the breakpoint and continue every time I want to run the test. So I think the problem is Visual C++ doesn't realise the two projects are related. Is this a linker issue? What does the linker do and what settings should I change to make this work? Thanks in advance. Apologies if instead I should be appending this question to the existing one, this is my first post so not quite sure how this should work.

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  • Cufon selector problems

    - by meep
    Hello StackOverflow. I am using Cufon (http://cufon.shoqolate.com/generate/) to replace some text in a menu. Problem is that I only need to style the first <li> of the first <ul>. I have tried using: Cufon.replace('#menu ul li > a', { fontFamily: 'Christopherhand', hover: { color: '#99c635'}}); With the > seperator, but it does not work. It still replaces the #menu ul li ul li a This is my markup: <div id="menu"> <ul> <li class="current"> <a href="#1">About JW</a> <ul> <li><a href="#2">Subpage 1</a></li> <li><a href="#3">Subpage 2</a></li> <li><a href="#4">Subpage 3</a></li> <li><a href="#5">Subpage 4</a></li> </ul> </li> <li><a href="#2">Our Products</a></li> <li><a href="#3">Best Recipes</a></li> <li><a href="#4">Health &amp; Diet</a></li> <li><a href="#5">Our Ads</a></li> </ul> </div> Can anyone see the problem? It should work without adding a class to sub <ul>. :-) Thank you.

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  • Use different configurations with Simple Injection

    - by Ruben.Canton
    I'm using the library "Simple Injector" (http://simpleinjector.codeplex.com) and it looks cool and nice. But after building a configuration and use it, now I want to know how to change from one configuration to another. Scenario: Let's imagine I've set up a configuration in the Global Asax and I have the public and global Container there. Now I want to make some tests and I want them to use mock classes so I want to change the configuration. I can, of course, build another configuration and assign it to the global Container created by default, so that every time I run a test the alternative configuration will be set. But on doing that and though I'm in development context the Container is changed for everyone, even for normal requests. I know I'm testing in this context and that shouldn't matter, but I have the feeling that this is not the way for doing this... and I wonder how to change from one configuration to another in the correct way. Note: At Simple Injector documentation says that you can ask questions in stackoverflow so that's why I'm here. =P PD: I'm new in this IoC and DI world so try to be easy with me when explaining it :)

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  • How to generate XML from an Excel VBA macro?

    - by SuperNES
    So, I've got a bunch of content that was delivered to us in the form of Excel spreadsheets. I need to take that content and push it into another system. The other system takes its input from an XML file. I could do all of this by hand (and trust me, management has no problem making me do that!), but I'm hoping there's an easy way to write an Excel macro that would generate the XML I need instead. This seems like a better solution to me, as this is a job that will need to be repeated regularly (we'll be getting a LOT of content in Excel sheets) and it just makes sense to have a batch tool that does it for us. However, I've never experimented with generating XML from Excel spreadsheets before. I have a little VBA knowledge but I'm a newbie to XML. I guess my problem in Googling this is that I don't even know what to Google for. Can anyone give me a little direction to get me started? Does my idea sound like the right way to approach this problem, or am I overlooking something obvious? Thanks StackOverflow!

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