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  • How to prevent google chrome from caching my inputs, esp hidden ones when user click back?

    - by melaos
    hi there, i have an asp.net mvc app which have quite a few hidden inputs to keep values around and formatting their names so that i can use the Model binding later when i submit the form. i stumble into a weird bug with chrome which i don't have with IE or Firefox when the user submits the form and click on the back button, i find that chrome will keep my hidden input values as well. this whole chunk is generated via javascript hence i believe chrome is caching this. function addProductRow(productId, productName) { if (productName != "") { //use guid to ensure that the row never repeats var guid = $.Guid.New(); var temp = parseFloat($(".tboProductCount").val()); //need the span to workaround for chrome var szHTML = "<tr valign=\"top\" id=\"productRow\"><td class=\"productIdCol\"><input type=\"hidden\" id=productRegsID" + temp + "\" name=\"productRegs[" + temp + "].productId\" value=\"" + productId + "\"/>" + "<span id=\"spanProdID" + temp + "\" name=\"spanProdID" + temp + "\" >" + productId + "</span>" + "</td>" //+ "<td><input type=\"text\" id=\"productRegName\" name=\"productRegs[" + temp + "].productName\" value=\"" + productName + "\" class=\"productRegName\" size=\"50\" readonly=\"readonly\"/></td>" + "<td><span id=\"productRegName\" name=\"productRegs[" + temp + "].productName\" class=\"productRegName\">"+ productName + "<\span></td>" + "<td id=\"" + guid + "\" class=\"productrowguid\" \>" + "<input type=\"text\" size=\"20\" id=\"productSerialNo" + temp + "\" name=\"productRegs[" + temp + "].serialNo\" value=\"" + "\" class=\"productSerialNo\" maxlength=\"18\" />" + "<a class=\"fancybox\" id=\"btnImgSerialNo" + temp + "\" href=\"#divSerialNo" + temp + "\"><img class=\"btnImgSerialNo\" src=\"Images/landing_14.gif\" /></a>" + "<span id=\"snFlag" + temp + "\" class=\"redWarning\"></span></td>" + "<td><input type=\"text\" id=\"productRegDate" + temp + "\" name=\"productRegs[" + temp + "].PurchaseDate\" readonly=\"readonly\" />" + "<span id=\"snRegDate" + temp + "\" class=\"redWarning\"></span></td>" + "<td align=\"center\"><img style=\"cursor:pointer\" id=\"btnImgDelete\" src=\"Images/btn_remove.gif\" onclick=\"javascript:removeProductRow('" + guid + "')\" /><div style=\"display:none;\"><div id=\"divSerialNo" + temp + "\" style=\"font-family:verdana;font-size:11px;width:600px\">" + serialnumbergeneral + "<br /><br />" + getSNImageByCategory(productId) + "</div></div></td>" + "</tr>"; $(".ProductRegistrationTable").append(szHTML); $("a.fancybox").fancybox(); //initialization $("#productRegDate" + temp).datepicker({ minDate: new Date(1996, 1 - 1, 1), maxDate: 0 }); //sanity check //s7test alert('1 '+$("#spanProdID" + temp)); alert('2 '+$("#productRegsID" + temp)); } //end function addNewProductRow i need the id to be refreshed when the user select a new product, but putting another span tag beside it shows that the span will have the new id will the hidden input will still have the previous id. is there an elegant way to workaround this issue? thanks

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  • Having trouble wrapping functions in the linux kernel

    - by Corey Henderson
    I've written a LKM that implements Trusted Path Execution (TPE) into your kernel: https://github.com/cormander/tpe-lkm I run into an occasional kernel OOPS (describe at the end of this question) when I define WRAP_SYSCALLS to 1, and am at my wit's end trying to track it down. A little background: Since the LSM framework doesn't export its symbols, I had to get creative with how I insert the TPE checking into the running kernel. I wrote a find_symbol_address() function that gives me the address of any function I need, and it works very well. I can call functions like this: int (*my_printk)(const char *fmt, ...); my_printk = find_symbol_address("printk"); (*my_printk)("Hello, world!\n"); And it works fine. I use this method to locate the security_file_mmap, security_file_mprotect, and security_bprm_check functions. I then overwrite those functions with an asm jump to my function to do the TPE check. The problem is, the currently loaded LSM will no longer execute the code for it's hook to that function, because it's been totally hijacked. Here is an example of what I do: int tpe_security_bprm_check(struct linux_binprm *bprm) { int ret = 0; if (bprm->file) { ret = tpe_allow_file(bprm->file); if (IS_ERR(ret)) goto out; } #if WRAP_SYSCALLS stop_my_code(&cs_security_bprm_check); ret = cs_security_bprm_check.ptr(bprm); start_my_code(&cs_security_bprm_check); #endif out: return ret; } Notice the section between the #if WRAP_SYSCALLS section (it's defined as 0 by default). If set to 1, the LSM's hook is called because I write the original code back over the asm jump and call that function, but I run into an occasional kernel OOPS with an "invalid opcode": invalid opcode: 0000 [#1] SMP RIP: 0010:[<ffffffff8117b006>] [<ffffffff8117b006>] security_bprm_check+0x6/0x310 I don't know what the issue is. I've tried several different types of locking methods (see the inside of start/stop_my_code for details) to no avail. To trigger the kernel OOPS, write a simple bash while loop that endlessly starts a backgrounded "ls" command. After a minute or so, it'll happen. I'm testing this on a RHEL6 kernel, also works on Ubuntu 10.04 LTS (2.6.32 x86_64). While this method has been the most successful so far, I have tried another method of simply copying the kernel function to a pointer I created with kmalloc but when I try to execute it, I get: kernel tried to execute NX-protected page - exploit attempt? (uid: 0). If anyone can tell me how to kmalloc space and have it marked as executable, that would also help me solve the above problem. Any help is appreciated!

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  • Primary language - C++/Qt, C#, Java?

    - by Airjoe
    I'm looking for some input, but let me start with a bit of background (for tl;dr skip to end). I'm an IT major with a concentration in networking. While I'm not a CS major nor do I want to program as a vocation, I do consider myself a programmer and do pretty well with the concepts involved. I've been programming since about 6th grade, started out with a proprietary game creation language that made my transition into C++ at college pretty easy. I like to make programs for myself and friends, and have been paid to program for local businesses. A bit about that- I wrote some programs for a couple local businesses in my senior year in high school. I wrote management systems for local shops (inventory, phone/pos orders, timeclock, customer info, and more stuff I can't remember). It definitely turned out to be over my head, as I had never had any formal programming education. It was a great learning experience, but damn was it crappy code. Oh yeah, by the way, it was all vb6. So, I've used vb6 pretty extensively, I've used c++ in my classes (intro to programming up to algorithms), used Java a little bit in another class (had to write a ping client program, pretty easy) and used Java for some simple Project Euler problems to help learn syntax and such when writing the program for the class. I've also used C# a bit for my own simple personal projects (simple programs, one which would just generate an HTTP request on a list of websites and notify if one responded unexpectedly or not at all, and another which just held a list of things to do and periodically reminded me to do them), things I would've written in vb6 a year or two ago. I've just started using Qt C++ for some undergrad research I'm working on. Now I've had some formal education, I [think I] understand organization in programming a lot better (I didn't even use classes in my vb6 programs where I really should have), how it's important to structure code, split into functions where appropriate, document properly, efficiency both in memory and speed, dynamic and modular programming etc. I was looking for some input on which language to pick up as my "primary". As I'm not a "real programmer", it will be mostly hobby projects, but will include some 'real' projects I'm sure. From my perspective: QtC++ and Java are cross platform, which is cool. Java and C# run in a virtual machine, but I'm not sure if that's a big deal (something extra to distribute, possibly a bit slower? I think Qt would require additional distributables too, right?). I don't really know too much more than this, so I appreciate any help, thanks! TL;DR Am an avocational programmer looking for a language, want quick and straight forward development, liked vb6, will be working with database driven GUI apps- should I go with QtC++, Java, C#, or perhaps something else?

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  • Marshalling non-Blittable Structs from C# to C++

    - by Greggo
    I'm in the process of rewriting an overengineered and unmaintainable chunk of my company's library code that interfaces between C# and C++. I've started looking into P/Invoke, but it seems like there's not much in the way of accessible help. We're passing a struct that contains various parameters and settings down to unmanaged codes, so we're defining identical structs. We don't need to change any of those parameters on the C++ side, but we do need to access them after the P/Invoked function has returned. My questions are: What is the best way to pass strings? Some are short (device id's which can be set by us), and some are file paths (which may contain Asian characters) Should I pass an IntPtr to the C# struct or should I just let the Marshaller take care of it by putting the struct type in the function signature? Should I be worried about any non-pointer datatypes like bools or enums (in other, related structs)? We have the treat warnings as errors flag set in C++ so we can't use the Microsoft extension for enums to force a datatype. Is P/Invoke actually the way to go? There was some Microsoft documentation about Implicit P/Invoke that said it was more type-safe and performant. For reference, here is one of the pairs of structs I've written so far: C++ /** Struct used for marshalling Scan parameters from managed to unmanaged code. */ struct ScanParameters { LPSTR deviceID; LPSTR spdClock; LPSTR spdStartTrigger; double spinRpm; double startRadius; double endRadius; double trackSpacing; UINT64 numTracks; UINT32 nominalSampleCount; double gainLimit; double sampleRate; double scanHeight; LPWSTR qmoPath; //includes filename LPWSTR qzpPath; //includes filename }; C# /// <summary> /// Struct used for marshalling scan parameters between managed and unmanaged code. /// </summary> [StructLayout(LayoutKind.Sequential)] public struct ScanParameters { [MarshalAs(UnmanagedType.LPStr)] public string deviceID; [MarshalAs(UnmanagedType.LPStr)] public string spdClock; [MarshalAs(UnmanagedType.LPStr)] public string spdStartTrigger; public Double spinRpm; public Double startRadius; public Double endRadius; public Double trackSpacing; public UInt64 numTracks; public UInt32 nominalSampleCount; public Double gainLimit; public Double sampleRate; public Double scanHeight; [MarshalAs(UnmanagedType.LPWStr)] public string qmoPath; [MarshalAs(UnmanagedType.LPWStr)] public string qzpPath; }

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  • Stored procedure performance randomly plummets; trivial ALTER fixes it. Why?

    - by gWiz
    I have a couple of stored procedures on SQL Server 2005 that I've noticed will suddenly take a significantly long time to complete when invoked from my ASP.NET MVC app running in an IIS6 web farm of four servers. Normal, expected completion time is less than a second; unexpected anomalous completion time is 25-45 seconds. The problem doesn't seem to ever correct itself. However, if I ALTER the stored procedure (even if I don't change anything in the procedure, except to perhaps add a space to the script created by SSMS Modify command), the completion time reverts to expected completion time. IIS and SQL Server are running on separate boxes, both running Windows Server 2003 R2 Enterprise Edition. SQL Server is Standard Edition. All machines have dual Xeon E5450 3GHz CPUs and 4GB RAM. SQL Server is accessed using its TCP/IP protocol over gigabit ethernet (not sure what physical medium). The problem is present from all web servers in the web farm. When I invoke the procedure from a query window in SSMS on my development machine, the procedure completes in normal time. This is strange because I was under the impression that SSMS used the same SqlClient driver as in .NET. When I point my development instance of the web app to the production database, I again get the anomalous long completion time. If my SqlCommand Timeout is too short, I get System.Data.SqlClient.SqlException: Timeout expired. The timeout period elapsed prior to completion of the operation or the server is not responding. Question: Why would performing ALTER on the stored procedure, without actually changing anything in it, restore the completion time to less than a second, as expected? Edit: To clarify, when the procedure is running slow for the app, it simultaneously runs fine in SSMS with the same parameters. The only difference I can discern is login credentials (next time I notice the behavior, I'll be checking from SSMS with the same creds). The ultimate goal is to get the procs to sustainably run with expected speed without requiring occasional intervention. Resolution: I wanted to to update this question in case others are experiencing this issue. Following the leads of the answers below, I was able to consistently reproduce this behavior. In order to test, I utilize sp_recompile and pass it one of the susceptible sprocs. I then initiate a website request from my browser that will invoke the sproc with atypical parameters. Lastly, I initiate a website request to a page that invokes the sproc with typical parameters, and observe that the request does not complete because of a SQL timeout on the sproc invocation. To resolve this on SQL Server 2005, I've added OPTIMIZE FOR hints to my SELECT. The sprocs that were vulnerable all have the "all-in-one" pattern described in this article. This pattern is certainly not ideal but was a necessary trade-off given the timeframe for the project.

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  • What is GC holes?

    - by tianyi
    I wrote a long TCP connection socket server in C#. Spike in memory in my server happens. I used dotNet Memory Profiler(a tool) to detect where the memory leaks. Memory Profiler indicates the private heap is huge, and the memory is something like below(the number is not real,what I want to show is the GC0 and GC2's Holes are very very huge, the data size is normal): Managed heaps - 1,500,000KB Normal heap - 1400,000KB Generation #0 - 600,000KB Data - 100,000KB "Holes" - 500,000KB Generation #1 - xxKB Data - 0KB "Holes" - xKB Generation #2 - xxxxxxxxxxxxxKB Data - 100,000KB "Holes" - 700,000KB Large heap - 131072KB Large heap - 83KB Overhead/unused - 130989KB Overhead - 0KB Howerver, what is GC hole? I read an article about the hole: http://kaushalp.blogspot.com/2007/04/what-is-gc-hole-and-how-to-create-gc.html The author said : The code snippet below is the simplest way to introduce a GC hole into the system. //OBJECTREF is a typedef for Object*. { PointerTable *pTBL = o_pObjectClass->GetPointerTable(); OBJECTREF aObj = AllocateObjectMemory(pTBL); OBJECTREF bObj = AllocateObjectMemory(pTBL); //WRONG!!! “aObj” may point to garbage if the second //“AllocateObjectMemory” triggered a GC. DoSomething (aOb, bObj); } All it does is allocate two managed objects, and then does something with them both. This code compiles fine, and if you run simple pre-checkin tests, it will probably “work.” But this code will crash eventually. Why? If the second call to “AllocateObjectMemory” triggers a GC, that GC discards the object instance you just assigned to “aObj”. This code, like all C++ code inside the CLR, is compiled by a non-managed compiler and the GC cannot know that “aObj” holds a root reference to an object you want kept live. ======================================================================== I can't understand what he explained. Does the sample mean aObj becomes a wild pointer after GC? Is it mean { aObj = (*aObj)malloc(sizeof(object)); free(aObj); function(aObj);? } ? I hope somebody can explain it.

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  • Modify audio pitch of recorded clip (m4v)

    - by devcube
    I'm writing an app in which I'm trying to change the pitch of the audio when I'm recording a movie (.m4v). Or by modifying the audio pitch of the movie afterwards. I want the end result to be a movie (.m4v) that has the original length (i.e. same visual as original) but with modified sound pitch, e.g. a "chipmunk voice". A realtime conversion is to prefer if possible. I've read alot about changing audio pitch in iOS but most examples focus on playback, i.e. playing the sound with a different pitch. In my app I'm recording a movie (.m4v / AVFileTypeQuickTimeMovie) and saving it using standard AVAssetWriter. When saving the movie I have access to the following elements where I've tried to manipulate the audio (e.g. modify the pitch): audio buffer (CMSampleBufferRef) audio input writer (AVAssetWriterAudioInput) audio input writer options (e.g. AVNumberOfChannelsKey, AVSampleRateKey, AVChannelLayoutKey) asset writer (AVAssetWriter) I've tried to hook into the above objects to modify the audio pitch, but without success. I've also tried with Dirac as described here: Real Time Pitch Change In iPhone Using Dirac And OpenAL with AL_PITCH as described here: Piping output from OpenAL into a buffer And the "BASS" library from un4seen: Change Pitch/Tempo In Realtime I haven't found success with any of the above libs, most likely because I don't really know how to use them, and where to hook them into the audio saving code. There seems to be alot of librarys that have similar effects but focuses on playback or custom recording code. I want to manipulate the audio stream I've already got (AVAssetWriterAudioInput) or modify the saved movie clip (.m4v). I want the video to be unmodifed visually, i.e. played at the same speed. But I want the audio to go faster (like a chipmunk) or slower (like a ... monster? :)). Do you have any suggestions how I can modify the pitch in either real time (when recording the movie) or afterwards by converting the entire movie (.m4v file)? Should I look further into Dirac, OpenAL, SoundTouch, BASS or some other library? I want to be able to share the movie to others with modified audio, that's the reason I can't rely on modifying the pitch for playback only. Any help is appreciated, thanks!

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  • Learning... anything really

    - by WebDevHobo
    I'm particularly interested in Windows PowerShell, but here's a somewhat more general complaint: When asking for help on learning something new, be it a small subject on PHP or understanding a class in Java, what usually happens is that people direct me towards the documentation pages. What I'm looking for is somewhat of a course. A deep explanation of why something works the way it does. I know my basic programming, like Java and C#. I've never seen C or C++, though I have seen a bit of assembler. I know what the Stack and Heap are, how boxing and unboxing works, why you have to deep-copy an array instead of copying the pointer and some other things. Windows PowerShell on the other hand, I know nothing about. And I notice that when reading the small document or some code, I usually forget what it does or why it works. What I am looking for is preferably, a nice tutorial that explains the beginnings, the concepts, and goes to more difficult things at a steady pace. The only thing documentation can do is explain what a function does. That's no good to me since I don't know what I want to do yet. I could read about a thousand functions, and forget about most of them, because I don't need to implement them right after it. Randomly wandering through the documentation doesn't do me any good. So conclude, what is a good tutorial on Windows Powershell? One which explains in clear language what is happening, one which builds on previous things learned. I don't think googling this is a good idea. Doing a Google search on this would turn up numerous tutorials. And experience tells me that you have to look long and hard to find the gem you're looking for. That's why I'm asking here. Because this is the place where you can find more experienced people. Many of the PowerShell guys among you will know the good ones already, and by asking you, I avoid wasting time that could be spent learning. So to summarize: I will not google this!

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  • Accordion nonfunctional in Opera

    - by nona
    While working as expected in all other browsers, opera refuses to tween the height of content. oddly enough, as i sat annoyed rapidly clicking it over and over again, if it's closed, and you select some text, and keep clicking the same spot long enough, sometimes it pops open. lol. seriously. ahh, it seems to sometimes open the first time clicked after the page is loaded. wth? the javascript: window.addEvent('domready', function(){ var content_height = [];i=0; $$( '.bio_accordion' ).each(function(item){ i++; content_height.push(item.getElement('.moreInfo').offsetHeight); var thisSlider = new Fx.Slide( item.getElement( '.moreInfo' ), { mode: 'horizontal' } ); thisSlider.hide(); item.getElement('.moreInfo').set('tween').tween('height', '0px'); var morph = new Fx.Morph(item.getElement( '.divToggle' )); var selected = 0; item.getElement( '.divToggle' ).addEvents({ 'mouseenter': function(){ if(!selected) this.morph('.div_highlight'); }, 'mouseleave': function(){ if(!selected) { this.morph('.divToggle'); } }, 'click': function(){ if (!selected){ if (this.getElement('.symbol').innerHTML == '+') this.getElement('.symbol').innerHTML = '-'; else this.getElement('.symbol').innerHTML = '+'; item.getElement('.moreInfo').set('tween', { duration: 1500, transition: Fx.Transitions.Bounce.easeOut }).tween('height', content_height[i]); selected = 1; thisSlider.slideIn(); } else{ if (this.getElement('.symbol').innerHTML == '+') this.getElement('.symbol').innerHTML = '-'; else this.getElement('.symbol').innerHTML = '+'; thisSlider.slideOut(); item.getElement('.moreInfo').set('tween', { duration: 1000, transition: Fx.Transitions.Bounce.easeOut }).tween('height', '0px'); selected = 0; } } }); } ); }); the html: <div class="bio_accordion"> <div class="divToggle">test<span class="symbol">-</span></div> <div class="moreInfo" style="margin-left:10px;"> aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa asdfasdfasdfasdfasdfasdfasdfasdfasdfasdfasdf aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa asdfasdfasdfasdfasdfasdfasdfasdfasdfasdfasdf aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa asdfasdfasdfasdfasdfasdfasdfasdfasdfasdfasdf </div> </div> the css: .bio_accordion { padding:0px; margin:0px; } .divToggle { cursor: pointer; color: #ffffff; background-color:#1089b5; padding: 8px; } .div_highlight { padding-left:30px; padding-right:30px; background-color:#096687; } .moreInfo { padding: 2px; padding-top:15px; padding-bottom:15px; overflow: hidden; } .symbol { float:right; }

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  • Saving JQuery Draggable Sitemap Values Correctly

    - by mdolon
    I am trying to implement Boagworld's Sitemap tutorial, however I am running into difficulty trying to correctly save the child/parent relationships. The HTML is as follows, however populated with other items as well: <input type="hidden" name="sitemap-order" id="sitemap-order" value="" /> <ul id=”sitemap”> <li id="1"> <dl> <dt><a href=”#”>expand/collapse</a> <a href=”#”>Page Title</a></dt> <dd>Text Page</dd> <dd>Published</dd> <dd><a href=”#”>delete</a></dd> </dl> <ul><!–child pages–></ul> </li> </ul> And here is the JQuery code: $('#sitemap li').prepend('<div class="dropzone"></div>'); $('#sitemap li').draggable({ handle: ' > dl', opacity: .8, addClasses: false, helper: 'clone', zIndex: 100 }); var order = ""; $('#sitemap dl, #sitemap .dropzone').droppable({ accept: '#sitemap li', tolerance: 'pointer', drop: function(e, ui) { var li = $(this).parent(); var child = !$(this).hasClass('dropzone'); //If this is our first child, we'll need a ul to drop into. if (child && li.children('ul').length == 0) { li.append('<ul/>'); } //ui.draggable is our reference to the item that's been dragged. if (child) { li.children('ul').append(ui.draggable); }else { li.before(ui.draggable); } //reset our background colours. li.find('dl,.dropzone').css({ backgroundColor: '', backgroundColor: '' }); li.find('.dropzone').css({ height: '8px', margin: '0' }); // THE PROBLEM: var parentid = $(this).parent().attr('id'); menuorder += ui.draggable.attr('id')+'=>'+parentid+','; $("#sitemap-order").val(order); }, over: function() { $(this).filter('dl').css({ backgroundColor: '#ccc' }); $(this).filter('.dropzone').css({ backgroundColor: '#aaa', height: '30px', margin: '5px 0'}); }, out: function() { $(this).filter('dl').css({ backgroundColor: '' }); $(this).filter('.dropzone').css({ backgroundColor: '', height: '8px', margin: '0' }); } }); When moving items into the top-level (without parents), the parentid value I get is of the first list item (the parent container), so I can never remove the parent value and have a top-level item. Is there a no-brainer answer that I'm just not seeing right now? Any help is appreciated.

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  • How to pass operators as parameters

    - by Rodion Ingles
    I have to load an array of doubles from a file, multiply each element by a value in a table (different values for different elements), do some work on it, invert the multiplication (that is, divide) and then save the data back to file. Currently I implement the multiplication and division process in two separate methods. Now there is some extra work behind the scenes but apart from the specific statements where the multiplication/division occurs, the rest of the code is identical. As you can imagine, with this approach you have to be very careful making any changes. The surrounding code is not trivial, so its either a case of manually editing each method or copying changes from one method to the other and remembering to change the * and / operators. After too many close calls I am fed up of this and would like to make a common function which implements the common logic and two wrapper functions which pass which operator to use as a parameter. My initial approach was to use function pointers: MultiplyData(double data) { TransformData(data, &(operator *)); } DivideData(double data) { TransformData(data, &(operator /)); } TransformData(double data, double (*func)(double op1, double op2)) { /* Do stuff here... */ } However, I can't pass the operators as pointers (is this because it is an operator on a native type?), so I tried to use function objects. Initially I thought that multiplies and divides functors in <functional> would be ideal: MultiplyData(double data) { std::multiplies<double> multFunct; TransformData(data, &multFunct); } DivideData(double data) { std::divides<double> divFunct; TransformData(data, &divFunct); } TransformData(double data, std::binary_function<double, double, double> *funct) { /* Do stuff here... */ } As you can see I was trying to use a base class pointer to pass the functor polymorphically. The problem is that std::binary_function does not declare an operator() member for the child classes to implement. Is there something I am missing, or is the solution to implement my own functor heirarchy (which really seems more trouble than it is worth)?

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  • template pass by const reference

    - by 7vies
    Hi, I've looked over a few similar questions, but I'm still confused. I'm trying to figure out how to explicitly (not by compiler optimization etc) and C++03-compatible avoid copying of an object when passing it to a template function. Here is my test code: #include <iostream> using namespace std; struct C { C() { cout << "C()" << endl; } C(const C&) { cout << "C(C)" << endl; } ~C() { cout << "~C()" << endl; } }; template<class T> void f(T) { cout << "f<T>" << endl; } template<> void f(C c) { cout << "f<C>" << endl; } // (1) template<> void f(const C& c) { cout << "f<C&>" << endl; } // (2) int main() { C c; f(c); return 0; } (1) accepts the object of type C, and makes a copy. Here is the output: C() C(C) f<C> ~C() ~C() So I've tried to specialize with a const C& parameter (2) to avoid this, but this simply doesn't work (apparently the reason is explained in this question). Well, I could "pass by pointer", but that's kind of ugly. So is there some trick that would allow to do that somehow nicely? EDIT: Oh, probably I wasn't clear. I already have a templated function template<class T> void f(T) {...} But now I want to specialize this function to accept a const& to another object: template<> void f(const SpecificObject&) {...} But it only gets called if I define it as template<> void f(SpecificObject) {...}

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  • mysql timeout - c/C++

    - by user1262876
    Guys i'm facing a problem with this code, the problem is the timeout by timeout i mean the time it takes the program to tell me if the server is connected or not. If i use my localhost i get the answer fast, but when i connect to outside my localhost it takes 50sc - 1.5 min to response and the program frezz until it done. HOw can i fix the frezzing, or make my own timeout, like if still waiting after 50sc, tell me connection failed and stop? please use codes as help, becouse i would understand it better, thanks for any help i get PS: USING MAC #include "mysql.h" #include <stdio.h> #include <stdlib.h> // Other Linker Flags: -lmysqlclient -lm -lz // just going to input the general details and not the port numbers struct connection_details { char *server; char *user; char *password; char *database; }; MYSQL* mysql_connection_setup(struct connection_details mysql_details) { // first of all create a mysql instance and initialize the variables within MYSQL *connection = mysql_init(NULL); // connect to the database with the details attached. if (!mysql_real_connect(connection,mysql_details.server, mysql_details.user, mysql_details.password, mysql_details.database, 0, NULL, 0)) { printf("Conection error : %s\n", mysql_error(connection)); exit(1); } return connection; } MYSQL_RES* mysql_perform_query(MYSQL *connection, char *sql_query) { // send the query to the database if (mysql_query(connection, sql_query)) { printf("MySQL query error : %s\n", mysql_error(connection)); exit(1); } return mysql_use_result(connection); } int main() { MYSQL *conn; // the connection MYSQL_RES *res; // the results MYSQL_ROW row; // the results row (line by line) struct connection_details mysqlD; mysqlD.server = (char*)"Localhost"; // where the mysql database is mysqlD.user = (char*)"root"; // the root user of mysql mysqlD.password = (char*)"123456"; // the password of the root user in mysql mysqlD.database = (char*)"test"; // the databse to pick // connect to the mysql database conn = mysql_connection_setup(mysqlD); // assign the results return to the MYSQL_RES pointer res = mysql_perform_query(conn, (char*) "SELECT * FROM me"); printf("MySQL Tables in mysql database:\n"); while ((row = mysql_fetch_row(res)) !=NULL) printf("%s - %s\n", row[0], row[1], row[2]); // <-- Rows /* clean up the database result set */ mysql_free_result(res); /* clean up the database link */ mysql_close(conn); return 0; }

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  • unable to trigger event in IE during clonning

    - by Abhimanyu
    Following is the code which will clone a set of div with their events(onclick) which is working fine for FF but in case of IE it is not firing events associated with each div. <html> <head> <style type='text/css'> .firstdiv{ border:1px solid red; } </style> <script language="JavaScript"> function show_tooltip(idx,condition,ev) { alert(idx +"=="+condition+"=="+ev); } function createCloneNode () { var cloneObj = document.getElementById("firstdiv").cloneNode(true); document.getElementById("maindiv").appendChild(cloneObj); } function init(){ var mainDiv = document.createElement("div"); mainDiv.id = 'maindiv'; var firstDiv = document.createElement("div"); firstDiv.id ='firstdiv'; firstDiv.className ='firstdiv'; for(var j=0;j<4;j++) { var summaryDiv = document.createElement("div"); summaryDiv.id = "sDiv"+j summaryDiv.className ='summaryDiv'; summaryDiv.onmouseover = function() {this.setAttribute("style","text-decoration:underline;cursor:pointer;");} summaryDiv.onmouseout = function() {this.setAttribute("style","text-decoration:none;");} summaryDiv.setAttribute("onclick", "show_tooltip("+j+",'view_month',event)"); summaryDiv.innerHTML = 'Div'+j; firstDiv.appendChild(summaryDiv); } mainDiv.appendChild(firstDiv); var secondDiv = document.createElement("div"); var linkDiv = document.createElement("div"); linkDiv.innerHTML ='create clone of above element'; linkDiv.onclick = function() { createCloneNode(); } secondDiv.appendChild(linkDiv); mainDiv.appendChild(secondDiv); document.body.appendChild(mainDiv); } </script> </head> <body> <script language="JavaScript"> init() </script> </body> </html> can anybody tell me whats the problem in above code please correct me..

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  • Are Objective-C initializers allowed to share the same name?

    - by NattKatt
    I'm running into an odd issue in Objective-C when I have two classes using initializers of the same name, but differently-typed arguments. For example, let's say I create classes A and B: A.h: #import <Cocoa/Cocoa.h> @interface A : NSObject { } - (id)initWithNum:(float)theNum; @end A.m: #import "A.h" @implementation A - (id)initWithNum:(float)theNum { self = [super init]; if (self != nil) { NSLog(@"A: %f", theNum); } return self; } @end B.h: #import <Cocoa/Cocoa.h> @interface B : NSObject { } - (id)initWithNum:(int)theNum; @end B.m: #import "B.h" @implementation B - (id)initWithNum:(int)theNum { self = [super init]; if (self != nil) { NSLog(@"B: %d", theNum); } return self; } @end main.m: #import <Foundation/Foundation.h> #import "A.h" #import "B.h" int main (int argc, const char * argv[]) { NSAutoreleasePool * pool = [[NSAutoreleasePool alloc] init]; A *a = [[A alloc] initWithNum:20.0f]; B *b = [[B alloc] initWithNum:10]; [a release]; [b release]; [pool drain]; return 0; } When I run this, I get the following output: 2010-04-26 20:44:06.820 FnTest[14617:a0f] A: 20.000000 2010-04-26 20:44:06.823 FnTest[14617:a0f] B: 1 If I reverse the order of the imports so it imports B.h first, I get: 2010-04-26 20:45:03.034 FnTest[14635:a0f] A: 0.000000 2010-04-26 20:45:03.038 FnTest[14635:a0f] B: 10 For some reason, it seems like it's using the data type defined in whichever @interface gets included first for both classes. I did some stepping through the debugger and found that the isa pointer for both a and b objects ends up the same. I also found out that if I no longer make the alloc and init calls inline, both initializations seem to work properly, e.g.: A *a = [A alloc]; [a initWithNum:20.0f]; If I use this convention when I create both a and b, I get the right output and the isa pointers seem to be different for each object. Am I doing something wrong? I would have thought multiple classes could have the same initializer names, but perhaps that is not the case.

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  • Having trouble doing an Update with a Linq to Sql object

    - by Pure.Krome
    Hi folks, i've got a simple linq to sql object. I grab it from the database and change a field then save. No rows have been updated. :( When I check the full Sql code that is sent over the wire, I notice that it does an update to the row, not via the primary key but on all the fields via the where clause. Is this normal? I would have thought that it would be easy to update the field(s) with the where clause linking on the Primary Key, instead of where'ing (is that a word :P) on each field. here's the code... using (MyDatabase db = new MyDatabase()) { var boardPost = (from bp in db.BoardPosts where bp.BoardPostId == boardPostId select bp).SingleOrDefault(); if (boardPost != null && boardPost.BoardPostId > 0) { boardPost.ListId = listId; // This changes the value from 0 to 'x' db.SubmitChanges(); } } and here's some sample sql.. exec sp_executesql N'UPDATE [dbo].[BoardPost] SET [ListId] = @p6 WHERE ([BoardPostId] = @p0) AND .... <snip the other fields>',N'@p0 int,@p1 int,@p2 nvarchar(9),@p3 nvarchar(10),@p4 int,@p5 datetime,@p6 int',@p0=1276,@p1=212787,@p2=N'ttreterte',@p3=N'ttreterte3',@p4=1,@p5='2009-09-25 12:32:12.7200000',@p6=72 Now, i know there's a datetime field in this update .. and when i checked the DB it's value was/is '2009-09-25 12:32:12.720' (less zero's, than above) .. so i'm not sure if that is messing up the where clause condition... but still! should it do a where clause on the PK's .. if anything .. for speed! Yes / no ? UPDATE After reading nitzmahone's reply, I then tried playing around with the optimistic concurrency on some values, and it still didn't work :( So then I started some new stuff ... with the optimistic concurrency happening, it includes a where clause on the field it's trying to update. When that happens, it doesn't work. so.. in the above sql, the where clause looks like this ... WHERE ([BoardPostId] = @p0) AND ([ListId] IS NULL) AND ... <rest snipped>) This doesn't sound right! the value in the DB is null, before i do the update. but when i add the ListId value to the where clause (or more to the point, when L2S add's it because of the optomistic concurrecy), it fails to find/match the row. wtf?

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  • What are the pros and cons of using manual list iteration vs recursion through fail

    - by magus
    I come up against this all the time, and I'm never sure which way to attack it. Below are two methods for processing some season facts. What I'm trying to work out is whether to use method 1 or 2, and what are the pros and cons of each, especially large amounts of facts. methodone seems wasteful since the facts are available, why bother building a list of them (especially a large list). This must have memory implications too if the list is large enough ? And it doesn't take advantage of Prolog's natural backtracking feature. methodtwo takes advantage of backtracking to do the recursion for me, and I would guess would be much more memory efficient, but is it good programming practice generally to do this? It's arguably uglier to follow, and might there be any other side effects? One problem I can see is that each time fail is called, we lose the ability to pass anything back to the calling predicate, eg. if it was methodtwo(SeasonResults), since we continually fail the predicate on purpose. So methodtwo would need to assert facts to store state. Presumably(?) method 2 would be faster as it has no (large) list processing to do? I could imagine that if I had a list, then methodone would be the way to go.. or is that always true? Might it make sense in any conditions to assert the list to facts using methodone then process them using method two? Complete madness? But then again, I read that asserting facts is a very 'expensive' business, so list handling might be the way to go, even for large lists? Any thoughts? Or is it sometimes better to use one and not the other, depending on (what) situation? eg. for memory optimisation, use method 2, including asserting facts and, for speed use method 1? season(spring). season(summer). season(autumn). season(winter). % Season handling showseason(Season) :- atom_length(Season, LenSeason), write('Season Length is '), write(LenSeason), nl. % ------------------------------------------------------------- % Method 1 - Findall facts/iterate through the list and process each %-------------------------------------------------------------- % Iterate manually through a season list lenseason([]). lenseason([Season|MoreSeasons]) :- showseason(Season), lenseason(MoreSeasons). % Findall to build a list then iterate until all done methodone :- findall(Season, season(Season), AllSeasons), lenseason(AllSeasons), write('Done'). % ------------------------------------------------------------- % Method 2 - Use fail to force recursion %-------------------------------------------------------------- methodtwo :- % Get one season and show it season(Season), showseason(Season), % Force prolog to backtrack to find another season fail. % No more seasons, we have finished methodtwo :- write('Done').

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  • help me to choose the best soulotion for my purpose to build my software.

    - by rima
    before answer me plz thinking about the futures of these kind of program and answer me plz. I wanna get some data from oracle server like: 1-get all the function,package,procedure and etc for showing them or drop them & etc... 2-compile my *.sql files,get the result if they have problem & etc... becuz I was beginner in oracle first of all I for solve the second problem I try to connect to sqlPlus by RUN sqlplus and trace the output(I mean,I change the output stream of shell and trace what happend and handle the assigned message to customer. NOW THIS PART SUCCEED. just a little bit I have problem with get all result because the output is asynchronous.any way... [in this case I log in to oracle Server by send argument to the sqlplus by make a process in c#] after that I try to get all function,package or procedure name,but I have problem in speed!so I try to use oracle.DataAccess.dll to connect the database. now I m so confusing about: which way is correct way to build a program that work like Oracle Developer! I do not have any experience for like these program how work. If Your answer is I must use the second way follow this part plz: I search a little bit the Golden,PLedit (Benthic software),I have little bit problem how I must create the connection string?because I thinking about how I can find the host name or port number that oracle work on them?? am I need read the TNSNames.Ora file? IF your answer is I must use the first way follow this part plz: do u have any Idea for how I parse the output?because for example the result of a table is so confusing...[i can handle & program it but I really need someone experience,because the important things to me learn how such software work so nice and with quick response?] All of the has different style in output... If you are not sure Can u help me which book can help me in this way i become expert? becuz for example all the C# write just about how u can connect to DB and the DB books write how u can use this DB program,I looking for a book that give me some Idea how develop an interface for do transaction between these two.not simple send and receive data,for example how write a compiler for them. the language of book is not different for me i know C#,java,VB,sql,Oracle Thanks.

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  • Improving Javascript Load Times - Concatenation vs Many + Cache

    - by El Yobo
    I'm wondering which of the following is going to result in better performance for a page which loads a large amount of javascript (jQuery + jQuery UI + various other javascript files). I have gone through most of the YSlow and Google Page Speed stuff, but am left wondering about a particular detail. A key thing for me here is that the site I'm working on is not on the public net; it's a business to business platform where almost all users are repeat visitors (and therefore with caches of the data, which is something that YSlow assumes will not be the case for a large number of visitors). First up, the standard approach recommended by tools such as YSlow is to concatenate it, compress it, and serve it up in a single file loaded at the end of your page. This approach sounds reasonably effective, but I think that a key part of the reasoning here is to improve performance for users without cached data. The system I currently have is something like this * All javascript files are compressed and loaded at the bottom of the page * All javascript files have far future cache expiration dates, so will remain (for most users) in the cache for a long time * Pages only load the javascript files that they require, rather than loading one monolithic file, most of which will not be required Now, my understanding is that, if the cache expiration date for a javascript file has not been reached, then the cached version is used immediately; there is no HTTP request sent at to the server at all. If this is correct, I would assume that having multiple tags is not causing any performance penalty, as I'm still not having any additional requests on most pages (recalling from above that almost all users have populated caches). In addition to this, not loading the JS means that the browser doesn't have to interpret or execute all this additional code which it isn't going to need; as a B2B application, most of our users are unfortunately stuck with IE6 and its painfully slow JS engine. Another benefit is that, when code changes, only the affected files need to be fetched again, rather than the whole set (granted, it would only need to be fetched once, so this is not so much of a benefit). I'm also looking at using LabJS to allow for parallel loading of the JS when it's not cached. So, what do people think is a better approach? In a similar vein, what do you think about a similar approach to CSS - is monolithic better?

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  • C++ class member functions instantiated by traits

    - by Jive Dadson
    I am reluctant to say I can't figure this out, but I can't figure this out. I've googled and searched Stack Overflow, and come up empty. The abstract, and possibly overly vague form of the question is, how can I use the traits-pattern to instantiate non-virtual member functions? The question came up while modernizing a set of multivariate function optimizers that I wrote more than 10 years ago. The optimizers all operate by selecting a straight-line path through the parameter space away from the current best point (the "update"), then finding a better point on that line (the "line search"), then testing for the "done" condition, and if not done, iterating. There are different methods for doing the update, the line-search, and conceivably for the done test, and other things. Mix and match. Different update formulae require different state-variable data. For example, the LMQN update requires a vector, and the BFGS update requires a matrix. If evaluating gradients is cheap, the line-search should do so. If not, it should use function evaluations only. Some methods require more accurate line-searches than others. Those are just some examples. The original version instantiates several of the combinations by means of virtual functions. Some traits are selected by setting mode bits that are tested at runtime. Yuck. It would be trivial to define the traits with #define's and the member functions with #ifdef's and macros. But that's so twenty years ago. It bugs me that I cannot figure out a whiz-bang modern way. If there were only one trait that varied, I could use the curiously recurring template pattern. But I see no way to extend that to arbitrary combinations of traits. I tried doing it using boost::enable_if, etc.. The specialized state information was easy. I managed to get the functions done, but only by resorting to non-friend external functions that have the this-pointer as a parameter. I never even figured out how to make the functions friends, much less member functions. The compiler (VC++ 2008) always complained that things didn't match. I would yell, "SFINAE, you moron!" but the moron is probably me. Perhaps tag-dispatch is the key. I haven't gotten very deeply into that. Surely it's possible, right? If so, what is best practice?

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  • Casting to derived type problem in C++

    - by GONeale
    Hey there everyone, I am quite new to C++, but have worked with C# for years, however it is not helping me here! :) My problem: I have an Actor class which Ball and Peg both derive from on an objective-c iphone game I am working on. As I am testing for collision, I wish to set an instance of Ball and Peg appropriately depending on the actual runtime type of actorA or actorB. My code that tests this as follows: // Actors that collided Actor *actorA = (Actor*) bodyA->GetUserData(); Actor *actorB = (Actor*) bodyB->GetUserData(); Ball* ball; Peg* peg; if (static_cast<Ball*> (actorA)) { // true ball = static_cast<Ball*> (actorA); } else if (static_cast<Ball*> (actorB)) { ball = static_cast<Ball*> (actorB); } if (static_cast<Peg*> (actorA)) { // also true?! peg = static_cast<Peg*> (actorA); } else if (static_cast<Peg*> (actorB)) { peg = static_cast<Peg*> (actorB); } if (peg != NULL) { [peg hitByBall]; } Once ball and peg are set, I then proceed to run the hitByBall method (objective c). Where my problem really lies is in the casting procedurel Ball casts fine from actorA; the first if (static_cast<>) statement steps in and sets the ball pointer appropriately. The second step is to assign the appropriate type to peg. I know peg should be a Peg type and I previously know it will be actorB, however at runtime, detecting the types, I was surprised to find actually the third if (static_cast<>) statement stepped in and set this, this if statement was to check if actorA was a Peg, which we already know actorA is a Ball! Why would it have stepped here and not in the fourth if statement? The only thing I can assume is how casting works differently from c# and that is it finds that actorA which is actually of type Ball derives from Actor and then it found when static_cast<Peg*> (actorA) is performed it found Peg derives from Actor too, so this is a valid test? This could all come down to how I have misunderstood the use of static_cast. How can I achieve what I need? :) I'm really uneasy about what feels to me like a long winded brute-casting attempt here with a ton of ridiculous if statements. I'm sure there is a more elegant way to achieve a simple cast to Peg and cast to Ball dependent on actual type held in actorA and actorB. Hope someone out there can help! :) Thanks a lot.

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  • CGAffineTransformMakeRotation goes the other way after 180 degrees (-3.14)

    - by TheKillerDev
    So, i am trying to do a very simple disc rotation (2d), according to the user touch on it, just like a DJ or something. It is working, but there is a problem, after certain amount of rotation, it starts going backwards, this amount is after 180 degrees or as i saw in while logging the angle, -3.14 (pi). I was wondering, how can i achieve a infinite loop, i mean, the user can keep rotating and rotating to any side, just sliding his finger? Also a second question is, is there any way to speed up the rotation? Here is my code right now: #import <UIKit/UIKit.h> @interface Draggable : UIImageView { CGPoint firstLoc; UILabel * fred; double angle; } @property (assign) CGPoint firstLoc; @property (retain) UILabel * fred; @end @implementation Draggable @synthesize fred, firstLoc; - (id)initWithFrame:(CGRect)frame { self = [super initWithFrame:frame]; angle = 0; if (self) { // Initialization code } return self; } -(void)handleObject:(NSSet *)touches withEvent:(UIEvent *)event isLast:(BOOL)lst { UITouch *touch =[[[event allTouches] allObjects] lastObject]; CGPoint curLoc = [touch locationInView:self]; float fromAngle = atan2( firstLoc.y-self.center.y, firstLoc.x-self.center.x ); float toAngle = atan2( curLoc.y-(self.center.y+10), curLoc.x-(self.center.x+10)); float newAngle = angle + (toAngle - fromAngle); NSLog(@"%f",newAngle); CGAffineTransform cgaRotate = CGAffineTransformMakeRotation(newAngle); self.transform = cgaRotate; if (lst) angle = newAngle; } -(void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event { UITouch *touch =[[[event allTouches] allObjects] lastObject]; firstLoc = [touch locationInView:self]; }; -(void) touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event { [self handleObject:touches withEvent:event isLast:NO]; }; -(void) touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event { [self handleObject:touches withEvent:event isLast:YES]; } @end And in the ViewController: UIImage *tmpImage = [UIImage imageNamed:@"theDisc.png"]; CGRect cellRectangle; cellRectangle = CGRectMake(-1,self.view.frame.size.height,tmpImage.size.width ,tmpImage.size.height ); dragger = [[Draggable alloc] initWithFrame:cellRectangle]; [dragger setImage:tmpImage]; [dragger setUserInteractionEnabled:YES]; dragger.layer.anchorPoint = CGPointMake(.5,.5); [self.view addSubview:dragger]; I am open to new/cleaner/more correct ways of doing this too. Thanks in advance.

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  • I'm having trouble traversing a newly appended DOM element with jQuery

    - by culov
    I have a form that I want to be used to add entries. Once an entry is added, the original form should be reset to prepare it for the next entry, and the saved form should be duplicated prior to resetting and appended onto a div for 'storedEntries.' This much is working (for the most part), but Im having trouble accessing the newly created form... I need to change the value attribute of the submit button from 'add' to 'edit' so properly communicate what clicking that button should do. heres my form: <div class="newTruck"> <form id="addNewTruck" class='updateschedule' action="javascript:sub(sTime.value, eTime.value, lat.value, lng.value, street.value);"> <b style="color:green;">Opening at: </b> <input id="sTime" name="sTime" title="Opening time" value="Click to set opening time" class="datetimepicker"/> <b style="color:red;">Closing at: </b> <input id="eTime" name= "eTime" title="Closing time" value="Click to set closing time" class="datetimepicker"/> <label for='street'>Address</label> <input type='text' name='street' id='street' class='text' autocomplete='off'/> <input id='submit' class='submit' style="cursor: pointer; cursor: hand;" type="submit" value='Add new stop'/> <div id='suggests' class='auto_complete' style='display:none'></div> <input type='hidden' name='lat' id='lat'/> <input type='hidden' name='lng' id='lng'/> ive tried using a hundred different selectors with jquery to no avail... heres my script as it stands: function cloneAndClear(){ var id = name+now; $j("#addNewTruck").clone(true).attr("id",id).appendTo(".scheduledTrucks"); $j('#'+id).filter('#submit').attr('value', 'Edit'); $j("#addNewTruck")[0].reset(); createPickers(); } the element is properly cloned and inserted into the div, but i cant find a way to access this element... the third line in the script never works. Another problem i am having is that the 'values' in the cloned form revert back to the value in the source of the html rather than what the user inputs. advice on how to solve either of these issues is greatly appreciated!

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  • Refactoring Singleton Overuse

    - by drharris
    Today I had an epiphany, and it was that I was doing everything wrong. Some history: I inherited a C# application, which was really just a collection of static methods, a completely procedural mess of C# code. I refactored this the best I knew at the time, bringing in lots of post-college OOP knowledge. To make a long story short, many of the entities in code have turned out to be Singletons. Today I realized I needed 3 new classes, which would each follow the same Singleton pattern to match the rest of the software. If I keep tumbling down this slippery slope, eventually every class in my application will be Singleton, which will really be no logically different from the original group of static methods. I need help on rethinking this. I know about Dependency Injection, and that would generally be the strategy to use in breaking the Singleton curse. However, I have a few specific questions related to this refactoring, and all about best practices for doing so. How acceptable is the use of static variables to encapsulate configuration information? I have a brain block on using static, and I think it is due to an early OO class in college where the professor said static was bad. But, should I have to reconfigure the class every time I access it? When accessing hardware, is it ok to leave a static pointer to the addresses and variables needed, or should I continually perform Open() and Close() operations? Right now I have a single method acting as the controller. Specifically, I continually poll several external instruments (via hardware drivers) for data. Should this type of controller be the way to go, or should I spawn separate threads for each instrument at the program's startup? If the latter, how do I make this object oriented? Should I create classes called InstrumentAListener and InstrumentBListener? Or is there some standard way to approach this? Is there a better way to do global configuration? Right now I simply have Configuration.Instance.Foo sprinkled liberally throughout the code. Almost every class uses it, so perhaps keeping it as a Singleton makes sense. Any thoughts? A lot of my classes are things like SerialPortWriter or DataFileWriter, which must sit around waiting for this data to stream in. Since they are active the entire time, how should I arrange these in order to listen for the events generated when data comes in? Any other resources, books, or comments about how to get away from Singletons and other pattern overuse would be helpful.

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  • How do I create a safe local development environment?

    - by docgnome
    I'm currently doing web development with another developer on a centralized development server. In the past this has worked alright, as we have two separate projects we are working on and rarely conflict. Now, however, we are adding a third (possible) developer into the mix. This is clearly going to create problems with other developers changes affecting my work and vice versa. To solve this problem, I'm thinking the best solution would be to create a virtual machine to distribute between the developers for local use. The problem I have is when it comes to the database. Given that we all develop on laptops, simply keeping a local copy of the live data is plain stupid. I've considered sanitizing the data, but I can't really figure out how to replace the real data, with data that would be representative of what people actually enter with out repeating the same information over and over again, e.g. everyone's address becomes 123 Testing Lane, Test Town, WA, 99999 or something. Is this really something to be concerned about? Are there tools to help with this sort of thing? I'm using MySQL. Ideally, if I sanitized the db it should be done from a script that I can run regularly. If I do this I'd also need a way to reduce the size of the db itself. (I figure I could select all the records created after x and whack them and all the records in corresponding tables out so that isn't really a big deal.) The second solution I've thought of is to encrypt the hard drive of the vm, but I'm unsure of how practical this is in terms of speed and also in the event of a lost/stolen laptop. If I do this, should the vm hard drive file itself be encrypted or should it be encrypted in the vm? (I'm assuming the latter as it would be portable and doesn't require the devs to have any sort of encryption capability on their OS of choice.) The third is to create a copy of the database for each developer on our development server that they are then responsible to keep the schema in sync with the canonical db by means of migration scripts or what have you. This solution seems to be the simplest but doesn't really scale as more developers are added. How do you deal with this problem?

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