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• What's the best practice for handling system-specific information under version control?

  - by Joe

  I'm new to version control, so I apologize if there is a well-known solution to this. For this problem in particular, I'm using git, but I'm curious about how to deal with this for all version control systems. I'm developing a web application on a development server. I have defined the absolute path name to the web application (not the document root) in two places. On the production server, this path is different. I'm confused about how to deal with this. I could either: Reconfigure the development server to share the same path as the production Edit the two occurrences each time production is updated. I don't like #1 because I'd rather keep the application flexible for any future changes. I don't like #2 because if I start developing on a second development server with a third path, I would have to change this for every commit and update. What is the best way to handle this? I thought of: Using custom keywords and variable expansion (such as setting the property $PATH$ in the version control properties and having it expanded in all the files). Git doesn't support this because it would be a huge performance hit. Using post-update and pre-commit hooks. Possibly the likely solution for git, but every time I looked at the status, it would report the two files as being changed. Not really clean. Pulling the path from a config file outside of version control. Then I would have to have the config file in the same location on all servers. Might as well just have the same path to begin with. Is there an easy way to deal with this? Am I over thinking it?

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• Any way to define getters for lazy variables in Javascript arrays?

  - by LLer

  I'm trying to add elements to an array that are lazy-evaluated. This means that the value for them will not be calculated or known until they are accessed. This is like a previous question I asked but for objects. What I ended up doing for objects was Object.prototype.lazy = function(var_name, value_function) { this.__defineGetter__(var_name, function() { var saved_value = value_function(); this.__defineGetter__(var_name, function() { return saved_value; }); return saved_value; }); } lazy('exampleField', function() { // the code that returns the value I want }); But I haven't figured out a way to do it for real Arrays. Arrays don't have setters like that. You could push a function to an array, but you'd have to call it as a function for it to return the object you really want. What I'm doing right now is I created an object that I treat as an array. Object.prototype.lazy_push = function(value_function) { if(!this.length) this.length = 0; this.lazy(this.length++, value_function); } So what I want to know is, is there a way to do this while still doing it on an array and not a fake array?

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• C++ class derivation and superconstructor confusion

  - by LukeN

  Hey, in a tutorial C++ code, I found this particular piece of confusion: PlasmaTutorial1::PlasmaTutorial1(QObject *parent, const QVariantList &args) : Plasma::Applet(parent, args), // <- Okay, Plasma = namespace, Applet = class m_svg(this), // <- A member function of class "Applet"? m_icon("document") // <- ditto? { m_svg.setImagePath("widgets/background"); // this will get us the standard applet background, for free! setBackgroundHints(DefaultBackground); resize(200, 200); } I'm not new to object oriented programming, so class derivation and super-classes are nothing complicated, but this syntax here got me confused. The header file defines the class like this: class PlasmaTutorial1 : public Plasma::Applet { Similar to above, namespace Plasma and class Applet. But what's the public doing there? I fear that I already know the concept but don't grasp the C++ syntax/way of doing it. In this question I picked up that these are called "superconstructors", at least that's what stuck in my memory, but I don't get this to the full extend. If we glance back at the first snippet, we see Constructor::Class(...) : NS::SuperClass(...), all fine 'till here. But what are m_svg(this), m_icon("document") doing there? Is this some kind of method to make these particular functions known to the derivated class? Is this part of C++ basics or more immediate? While I'm not completly lost in C++, I feel much more at home in C :) Most of the OOP I have done so far was done in D, Ruby or Python. For example in D I would just define class MyClass : MySuperClass, override what I needed to and call the super class' constructor if I'd need to.

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• A specific data structure

  - by user550413

  Well, this question is a bit specific but I think there is some general idea in it that I can't get it. Lets say I got K servers (which is a constant that I know its size). I have a program that get requests and every request has an id and server id that will handle it. I have n requests - unknown size and can be any number. I need a data structure to support the next operations within the given complexity: GetServer - the function gets the request ID and returns the server id that is supposed to handle this request at the current situation and not necessarily the original server (see below). Complexity: O(log K) at average. KillServer - the function gets as input a server id that should be removed and another server id that all the requests of the removed server should be passed to. Complexity: O(1) at the worst case. -- Place complexity for all the structure is O(K+n) -- The KillServer function made me think using a Union-Find as I can do the union in O(1) as requested but my problem is the first operation. Why it's LogK? Actually, no matter how I "save" the requests if I want to access to any request (lets say it's an AVL tree) so the complexity will be O(log n) at the worst case and said that I can't assume Kn (and probably K Tried thinking about it a couple of hours but I can't find any solution. Known structures that can be used are: B+ tree, AVL tree, skip list, hash table, Union-Find, rank tree and of course all the basics like arrays and such.

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• j_security_check to SSO in different module under Oracle App Server?

  - by thebearinboulder

  I have an existing j2ee application running on Oracle App Server. It is targeted towards paying customers so the content is secured and a SSO module properly intercepts all requests for secured content. Now the company is adding a unbranded public-facing module with a number of unsecured pages. At one point the user is expected to register for a free account and log in to proceed further. Think doctors adding a public-facing site with information for potential patients, or lawyers adding a public-facing site with information for potential clients. There's some information on the session and the usual approach would be to authenticate the user, persist the session information using the now-known user id, invalidate the existing session (to prevent certain types of attacks), the reload the session information before returning to the user. I can't just persist it under the session id since that's about to change. The glitch is that the existing application already has an SSO module and I get a 404 error every time I try to direct to j_security_check. I've tried that, /sso/j_security_check, even http://localhost/sso/j_security_check, all without success. I noticed that an earlier question said that tomcat requires access to a secured page before j_security_check is even visible. I don't know if that's the case with Oracle AS. Ideas? Or is the best approach to continue arguing that we have a different user base so it would be better to handle authentication in our own module anyway?

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• Panel in Windows Forms Application not clearing

  - by SwiftStriker00

  I'm working on my project: [Beer Pong Management System][1], a Windows Forms application. I am currently trying to add a whole tournament mode to it. In a nutshell, I've created a TabControl, with the first tab page with the settings and setup and the second page the brackets. There is a feature for each of the match-ups, that once there is a winner is decided, a yellow cancel button will appear in order to revert the tournament. However my issue is when i click the button the next match-up does not get removed in the series is going. See below: Image Here(not high enough rep to insert image) I have tried to set the MatchUp to null, I've tried dispose(), close(). even Parent.Controls.Remove(). Even after I switch tabs which is supposed to clear all, they still sit there when i come back. I have a feeling I might be loosing a reference or something because I can't even push new teams into them, they just sit there with their buttons. Does anyone have any tips or know of any known issues that might be causing this? Thanks. [1] _http://www.cs.rit.edu/~rmb1201/pages/code.shtml

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• What do I do about a Java program that spawned two instaces of itself?

  - by user288915

  I have a java JAR file that is triggered by a SQL server job. It's been running successfully for months. The process pulls in a structured flat file to a staging database then pushes that data into an XML file. However yesterday the process was triggered twice at the same time. I can tell from a log file that gets created, it looks like the process ran twice simultaneously. This caused a lot of issues and the XML file that it kicked out was malformed and contained duplicate nodes etc. My question is, is this a known issue with Java JVM's spawning multiple instances of itself? Or should I be looking at sql server as the culprit? I'm looking into 'socket locking' or file locking to prevent multiple instances in the future. This is the first instance of this issue that I've ever heard of. More info: The job is scheduled to run every minute. The job triggers a .bat file that contains the java.exe - jar filename.jar The java program runs, scans a directory for a file and then executes a loop to process if the file if it finds one. After it processes the file it runs another loop that kicks out XML messages. I can provide code samples if that would help. Thank you, Kevin

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• Should core application configuration be stored in the database, and if so what should be done to se

  - by Rl

  I'm writing an application around a lot of hierarchical data. Currently the hierarchy is fixed, but it's likely that new items will be added to the hierarchy in the future. (please let them be leaves) My current application and database design is fairly generic and nothing dealing with specific nodes in the hierarchy is hardcoded, with the exception of validation and lookup functions written to retrieve external data from each node's particular database. This pleases me from a design point of view, but I'm nervous at the realization that the entire application rests on a handful of records in the database. I'm also frustrated that I have to enforce certain aspects of data integrity with database triggers rather than by foreign key constraints (an example is where several different nodes in the hierarchy have their own proprietary IDs and I store them in a single column which, when coupled with the node ID can be used to locate the foreign data). I'm starting to wonder whether it may have been appropriate to simply hardcoded these known nodes into the system so that it would be more "type safe" and less generic. How does one know when something should be hardcoded, and when it should be a configuration item? Is it just a cost-benefit analysis of clarity/safety now vs less work later, or am I missing some metric I should be using to determine whether or not this is appropriate. The steps I'm taking to protect these valuable configurations are to add triggers that prevent updates/deletes. The database user that this application uses will only have the ability to manipulate data through stored procedures. What else can I do?

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• switch namespace by if condtion

  - by pascal

  Hi, in my C++ program I have several namespaces that contain several pointers with identical names. I then want a function to choose a namespace according to a parameter. I.e. something like: #include <iostream> namespace ns1{ double x[5]={1,2,3,4,5}; } namespace ns2{ double x[5]={6,7,8,9,10}; } int main(){ int b=1; if(b==1){ using namespace ns1; } if(b==2){ using namespace ns2; } std::cout << x[3] << std::endl; } However, this doesn't work since the compiler complains that x isn't known in that scope. I guess the problem is that "using namespace ..." is only valid within the if-statement. I think that it should be possible to switch namespaces somehow, but cannot find out how... Do you know how to do this without casting all variable separately? int main(){ int b=1; double *x; if(b==1){ x = ns1::x; } if(b==2){ x = ns2::x; } std::cout << x[3] << std::endl; } Cheers, Pascal

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• Triangulation in 3D Space

  - by w3b_wizzard

  Disclaimer: This is for class, however I'm fresh out of ideas and a nudge in the right direction would be much appreciated. Also, this needs to be implemented in raw C, so no fancy libraries can be used. I have to write a search and rescue simulator for submarines, it has to find a probe that is randomly placed in 3D space in a grid from of the MAX_XYZ (100000). The only tools I'm given are a "ping" which will give the magnitude of the distance between a certain sub and the probe. The goal is to optimize the costs of this entire operation so a brute force attempt, like looking at every single coordinate, won't work. Hence I was thinking triangulation. Now, it makes loads of sense to me, place three subs, each one of them uses their ping to get the distance between them and the probe. Since each sub have a known distance relative to one another, it's easy to build the base of a tetrahedron with them, and the results of the ping will point to a certain coordinate, the problem I'm having is how to figure out the elevation, or the height, of the tetrahedron. So what I have as data is the following: Distances between subs (In vector format) Angles between each subs (very easy to compute) Distance between each sub and the probe (3 segments from the base to the peak) Angles inside each of the outer 3 surfaces of the tetrahedron. I tried finding some sort of relationship with the vertices of the tetrahedron and the relative angles in each of them, however all I found had to deal with tetrahedrons built with equilateral triangles, which isn't much help. I have the impression this can be easily solved with trig but either I'm not seeing it or I need more coffee. Any suggestions would be appreciated!

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• Any workarounds for non-static member array initialization?

  - by TomiJ

  In C++, it's not possible to initialize array members in the initialization list, thus member objects should have default constructors and they should be properly initialized in the constructor. Is there any (reasonable) workaround for this apart from not using arrays? [Anything that can be initialized using only the initialization list is in our application far preferable to using the constructor, as that data can be allocated and initialized by the compiler and linker, and every CPU clock cycle counts, even before main. However, it is not always possible to have a default constructor for every class, and besides, reinitializing the data again in the constructor rather defeats the purpose anyway.] E.g. I'd like to have something like this (but this one doesn't work): class OtherClass { private: int data; public: OtherClass(int i) : data(i) {}; // No default constructor! }; class Foo { private: OtherClass inst[3]; // Array size fixed and known ahead of time. public: Foo(...) : inst[0](0), inst[1](1), inst[2](2) {}; }; The only workaround I'm aware of is the non-array one: class Foo { private: OtherClass inst0; OtherClass inst1; OtherClass inst2; OtherClass *inst[3]; public: Foo(...) : inst0(0), inst1(1), inst2(2) { inst[0]=&inst0; inst[1]=&inst1; inst[2]=&inst2; }; }; Edit: It should be stressed that OtherClass has no default constructor, and that it is very desirable to have the linker be able to allocate any memory needed (one or more static instances of Foo will be created), using the heap is essentially verboten. I've updated the examples above to highlight the first point.

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• Why "Content-Length: 0" in POST requests?

  - by stesch

  A customer sometimes sends POST requests with Content-Length: 0 when submitting a form (10 to over 40 fields). We tested it with different browsers and from different locations but couldn't reproduce the error. The customer is using Internet Explorer 7 and a proxy. We asked them to let their system administrator see into the problem from their side. Running some tests without the proxy, etc.. In the meantime (half a year later and still no answer) I'm curious if somebody else knows of similar problems with a Content-Length: 0 request. Maybe from inside some Windows network with a special proxy for big companies. Is there a known problem with Internet Explorer 7? With a proxy system? The Windows network itself? Google only showed something in the context of NTLM (and such) authentication, but we aren't using this in the web application. Maybe it's in the way the proxy operates in the customer's network with Windows logins? (I'm no Windows expert. Just guessing.) I have no further information about the infrastructure.

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• Reference remotely located assembly (web uri) from locally installed application?

  - by moonground.de

  Hi Stackoverflowers! :) We have a .NET application for Windows which is installed locally by Microsoft Installer. Now we have the need to use additional assemblies which are located online at our Web Servers. We'd like to refer to a remote uri like https://www.ourserver.com/OurProductName/ExternalLib.dll and reveal additional functionality, which is described roughly by a known common ("AddIn/Plugin") Interface. These are not 3rd Party Plugins, we just want be able to exchange parts of the application frequently, without the need to have frequent software updates. Our first idea was to add some kind of "remote refence" in Visual Studio by setting the path to the remote assembly uri. But Visual Studio downloaded the assembly immediately to a temporary directory, adding a reference to it. Our second attempt then, is simply using a WebRequest (or WebClient) to retrieve a binary stream of the Assembly, loading it "from image" by using Assembly.Load(...). This actually works, but is not very elegant and requires more additional programming for verification etc. We hoped Clickonce would provide useful techniques but apparently it's suitable for standalone applications only. (Correct me?) Is there a way (.net native or by framework/api) to reference remotely located assemblies? Thanks in advance and have a happy easter!

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• Sys. engineer has decided to dynamically transform all XSLs into DLLs on website build process. DLL

  - by John Sullivan

  Hello, OS: Win XP. Here is my situation. I have a browser based application. It is "wrapped" in a Visual Basic application. Our "Systems Engineer Senior" has decided to spawn DLL files from all of our XSL pages (many of which have duplicate names) upon building a new instance of the website and have the active server pages (ASPX) use the DLL instead. This has created a "known issue" in which ~200 DLL naming conflicts occur and, thus, half of our application is broken. I think a solution to this problem is that, thankfully, we're generating the names of the DLLs and linking them up with our application dynamically. Therefore we can do something kludgy like generate a hash and append it to the end of the DLL file name when we build our website, then always reference the DLL that had some kind of random string / hash appended to its name. Aside from outright renaming the DLLs, is there another way to have multiple DLLs with the same name register for one application? I think the answer is "No, only between different applications using a special technique." Please confirm. Another question I have on my mind is whether this whole idea is a good practice -- converting our XSL pages (which we use in mass -- every time a response from our web app occurs) into DLL functions that call a "function" to do what the XSL page did via an active server page (ASPX), when we were before just sending an XML response to an XSL page via aspx.

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• Cryptography for P2P card game

  - by zephyr

  I'm considering writing a computer adaptation of a semi-popular card game. I'd like to make it function without a central server, and I'm trying to come up with a scheme that will make cheating impossible without having to trust the client. The basic problem as I see it is that each player has a several piles of cards (draw deck, current hand and discard deck). It must be impossible for either player to alter the composition of these piles except when allowed by the game rules (ie drawing or discarding cards), nor should players be able to know what is in their or their oppponent's piles. I feel like there should be some way to use something like public-key cryptography to accomplish this, but I keep finding holes in my schemes. Can anyone suggest a protocol or point me to some resources on this topic? [Edit] Ok, so I've been thinking about this a bit more, and here's an idea I've come up with. If you can poke any holes in it please let me know. At shuffle time, a player has a stack of cards whose value is known to them. They take these values, concatenate a random salt to each, then hash them. They record the salts, and pass the hashes to their opponent. The opponent concatenates a salt of their own, hashes again, then shuffles the hashes and passes the deck back to the original player. I believe at this point, the deck has been randomized and neither player can have any knowledge of the values. However, when a card is drawn, the opponent can reveal their salt, allowing the first player to determine what the original value is, and when the card is played the player reveals their own salt, allowing the opponent to verify the card value.

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• reformatting a matrix in matlab with nan values

  - by Kate

  This post follows a previous question regarding the restructuring of a matrix: re-formatting a matrix in matlab An additional problem I face is demonstrated by the following example: depth = [0:1:20]'; data = rand(1,length(depth))'; d = [depth,data]; d = [d;d(1:20,:);d]; Here I would like to alter this matrix so that each column represents a specific depth and each row represents time, so eventually I will have 3 rows (i.e. days) and 21 columns (i.e. measurement at each depth). However, we cannot reshape this because the number of measurements for a given day are not the same i.e. some are missing. This is known by: dd = sortrows(d,1); for i = 1:length(depth); e(i) = length(dd(dd(:,1)==depth(i),:)); end From 'e' we find that the number of depth is different for different days. How could I insert a nan into the matrix so that each day has the same depth values? I could find the unique depths first by: unique(d(:,1)) From this, if a depth (from unique) is missing for a given day I would like to insert the depth to the correct position and insert a nan into the respective location in the column of data. How can this be achieved?

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• Pass the return type as a parameter in java?

  - by jonderry

  I have some files that contain logs of objects. Each file can store objects of a different type, but a single file is homogeneous -- it only stores objects of a single type. I would like to write a method that returns an array of these objects, and have the array be of a specified type (the type of objects in a file is known and can be passed as a parameter). Roughly, what I want is something like the following: public static <T> T[] parseLog(File log, Class<T> cls) throws Exception { ArrayList<T> objList = new ArrayList<T>(); FileInputStream fis = new FileInputStream(log); ObjectInputStream in = new ObjectInputStream(fis); try { Object obj; while (!((obj = in.readObject()) instanceof EOFObject)) { T tobj = (T) obj; objList.add(tobj); } } finally { in.close(); } return objList.toArray(new T[0]); } The above code doesn't compile (there's an error on the return statement, and a warning on the cast), but it should give you the idea of what I'm trying to do. Any suggestions for the best way to do this?

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• Echo a multidimensional array in PHP

  - by Jennifer

  I have a multidimensional array and I'm trying to find out how to simply "echo" the elements of the array. The depth of the array is not known, so it could be deeply nested. In the case of the array below, the right order to echo would be: This is a parent comment This is a child comment This is the 2nd child comment This is another parent comment This is the array I was talking about: Array ( [0] => Array ( [comment_id] => 1 [comment_content] => This is a parent comment [child] => Array ( [0] => Array ( [comment_id] => 3 [comment_content] => This is a child comment [child] => Array ( [0] => Array ( [comment_id] => 4 [comment_content] => This is the 2nd child comment [child] => Array ( ) ) ) ) ) ) [1] => Array ( [comment_id] => 2 [comment_content] => This is another parent comment [child] => Array ( ) ) )

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• Configuration Error , Finding assembly after I swapped referenced dll out. Visual Studio 2003

  - by TampaRich

  Here is the situation. I had a clean build of my asp.net web application working. I then went into the bin folder under the web app and replaced two referenced dll's with two older version of the same dll's. (Same name etc.) After testing I replaced those dll's back to the new ones and now my application keeps throwing the configuration error === Pre-bind state information === LOG: DisplayName = xxxxx.xxxx.Personalization (Partial) LOG: Appbase = file:///c:/inetpub/wwwroot/appname LOG: Initial PrivatePath = bin Calling assembly : (Unknown). LOG: Policy not being applied to reference at this time (private, custom, partial, or location-based assembly bind). I found this issue on the web and tried all the solutions to it but nothing worked. I then went into all my projects that it references under the solution and cleared out the bin/debug folder in each, I cleared out the obj folder under each and also deleted the temporary files associated with the application. I rebuilt it and it still will not work due to this error Not sure what is causing this or how to fix this issue. I have tried restarting IIS, stopping index services which was said to be a known issue. This is .net framework 1.1 app and visual studio 2003 Any suggestions would be great. Thanks.

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• Use LINQ, to Sort and Filter items in a List<ReturnItem> collection, based on the values within a Li

  - by Daniel McPherson

  This is tricky to explain. We have a DataTable that contains a user configurable selection of columns, which are not known at compile time. Every column in the DataTable is of type String. We need to convert this DataTable into a strongly typed Collection of "ReturnItem" objects so that we can then sort and filter using LINQ for use in our application. We have made some progress as follows: We started with the basic DataTable. We then process the DataTable, creating a new "ReturnItem" object for each row This "ReturnItem" object has just two properties: ID ( string ) and Columns( List(object) ). The properties collection contains one entry for each column, representing a single DataRow. Each property is made Strongly Typed (int, string, datetime, etc). For example it would add a new "DateTime" object to the "ReturnItem" Columns List containing the value of the "Created" Datatable Column. The result is a List(ReturnItem) that we would then like to be able to Sort and Filter using LINQ based on the value in one of the properties, for example, sort on "Created" date. We have been using the LINQ Dynamic Query Library, which gets us so far, but it doesn't look like the way forward because we are using it over a List Collection of objects. Basically, my question boils down to: How can I use LINQ, to Sort and Filter items in a List(ReturnItem) collection, based on the values within a List(object) property which is part of the ReturnItem class?

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• jquery simplemodal close wont work in firefox

  - by junkqwe

  I am using jquery.simplemodal 1.3.5 (i tried older versions) the close button doesnt close the modal in firefox (i tried IE and it work fine) this is the test page i am using: <html> <head> <title>Untitled Page</title> <style> #simplemodal-overlay { background-color:#000; cursor:wait; } #simplemodal-container a.modalCloseImg { background: url(../images/modal_close.png) no-repeat; width:25px; height:29px; display:inline; z-index:3200; position:absolute; top:15px; right:18px; cursor:pointer; } .modala { width: 372px; height: 206px; background: url(../images/modal.png) no-repeat; } </style> </head> <body> test page <script language="javascript" src="http://ajax.googleapis.com/ajax/libs/jquery/1.3.2/jquery.min.js" type="text/javascript"></script> <script language="javascript" src="/include/jquery.simplemodal-1.3.5.js" type="text/javascript"></script> <script type="text/javascript"> $("body").click(function() { $.modal("<div class=\"modala\"><h1>SimpleModal</h1></div>", {overlayClose: true} ); }); </script> </body> </html> what can be the problem? is it a known problem with simplemodal and FF?

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• Storing C++ templated objects as same type

  - by JaredC

  I have a class that is a core component of a performance sensitive code path, so I am trying to optimize it as much as possible. The class used to be: class Widget { Widget(int n) : N(n) {} .... member functions that use the constant value N .... const int N; // just initialized, will never change } The arguments to the constructor are known at compile time, so I have changed this class to a template, so that N can be compiled into the functions: template<int N> class Widget { .... member functions that use N .... } I have another class with a method: Widget & GetWidget(int index); However, after templating Widget, each widget has a different type so I cannot define the function like this anymore. I considered different inheritance options, but I'm not sure that the performance gain from the template would outweigh the cost of inherited function invocations. SO, my question is this: I am pretty sure I want the best of both worlds (compile-time / run-time), and it may not be possible. But, is there a way to gain the performance of knowing N at compile time, but still being able to return Widgets as the same type? Thanks!

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• How to combine two rows and calculate the time difference between two timestamp values in MySQL?

  - by Nadar

  I have a situation that I'm sure is quite common and it's really bothering me that I can't figure out how to do it or what to search for to find a relevant example/solution. I'm relatively new to MySQL (have been using MSSQL and PostgreSQL earlier) and every approach I can think of is blocked by some feature lacking in MySQL. I have a "log" table that simply lists many different events with their timestamp (stored as datetime type). There's lots of data and columns in the table not relevant to this problem, so lets say we have a simple table like this: CREATE TABLE log ( id INT NOT NULL AUTO_INCREMENT, name VARCHAR(16), ts DATETIME NOT NULL, eventtype VARCHAR(25), PRIMARY KEY (id) ) Let's say that some rows have an eventtype = 'start' and others have an eventtype = 'stop'. What I want to do is to somehow couple each "startrow" with each "stoprow" and find the time difference between the two (and then sum the durations per each name, but that's not where the problem lies). Each "start" event should have a corresponding "stop" event occuring at some stage later then the "start" event, but because of problems/bugs/crashed with the data collector it could be that some are missing. In that case I would like to disregard the event without a "partner". That means that given the data: foo, 2010-06-10 19:45, start foo, 2010-06-10 19:47, start foo, 2010-06-10 20:13, stop ..I would like to just disregard the 19:45 start event and not just get two result rows both using the 20:13 stop event as the stop time. I've tried to join the table with itself in different ways, but the key problems for me seems to be to find a way to correctly identify the corresponding "stop" event to the "start" event for the given "name". The problem is exactly the same as you would have if you had table with employees stamping in and out of work and wanted to find out how much they actually were at work. I'm sure there must be well known solutions to this, but I can't seem to find them...

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• Why won't my code segfault on Windows 7?

  - by Trevor

  This is an unusual question to ask but here goes: In my code, I accidentally dereference NULL somewhere. But instead of the application crashing with a segfault, it seems to stop execution of the current function and just return control back to the UI. This makes debugging difficult because I would normally like to be alerted to the crash so I can attach a debugger. What could be causing this? Specifically, my code is an ODBC Driver (ie. a DLL). My test application is ODBC Test (odbct32w.exe) which allows me to explicitly call the ODBC API functions in my DLL. When I call one of the functions which has a known segfault, instead of crashing the application, ODBC Test simply returns control to the UI without printing the result of the function call. I can then call any function in my driver again. I do know that technically the application calls the ODBC driver manager which loads and calls the functions in my driver. But that is beside the point as my segfault (or whatever is happening) causes the driver manager function to not return either (as evidenced by the application not printing a result). One of my co-workers with a similar machine experiences this same problem while another does not but we have not been able to determine any specific differences.

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• Has inheritance become bad?

  - by mafutrct

  Personally, I think inheritance is a great tool, that, when applied reasonably, can greatly simplify code. However, I seems to me that many modern tools dislike inheritance. Let's take a simple example: Serialize a class to XML. As soon as inheritance is involved, this can easily turn into a mess. Especially if you're trying to serialize a derived class using the base class serializer. Sure, we can work around that. Something like a KnownType attribute and stuff. Besides being an itch in your code that you have to remember to update every time you add a derived class, that fails, too, if you receive a class from outside your scope that was not known at compile time. (Okay, in some cases you can still work around that, for instance using the NetDataContract serializer in .NET. Surely a certain advancement.) In any case, the basic principle still exists: Serialization and inheritance don't mix well. Considering the huge list of programming strategies that became possible and even common in the past decade, I feel tempted to say that inheritance should be avoided in areas that relate to serialization (in particular remoting and databases). Does that make sense? Or am messing things up? How do you handle inheritance and serialization?

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