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  • Design problem with callback functions in android

    - by Franz Xaver
    Hi folks! I'm currently developing an app in android that is accessing wifi values, that is, the application needs to scan for all access point and their specific signal strengths. I know that I have to extend the class BroadcastReceiver overwriting the method BroadcastReceiver.onReceive(Context context, Intent intent) which is called when the values are ready. Perhaps there exist solutions provided by the android system itself but I'm relatively new to android so I could need some help. The problem I encountered is that I got one class (an activity, thus controlled by the user) that needs this scan results for two different things (first to save the values in a database or second, to use them for further calculations but not both at one moment!) So how to design the callback system in order to "transport" the scan results from onReceive(Context context, Intent intent) to the operation intended by the user? My first solution was to define enums for each use case (save or use for calculations) which wlan-interested classes have to submit when querying for the values. But that would force the BroadcastReceiverextending class to save the current enum and use it as a parameter in the callback function of the querying class (this querying class needs to know what it asked for when getting backcalled) But that seems to me kind of dirty ;) So anyone a good idea for this?

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  • GCC, functions, and pointer arguments, warning behaviour

    - by James Morris
    I've recently updated to a testing distribution, which is now using GCC 4.4.3. Now I've set everything up, I've returned to coding and have built my project and I get one of these horrible messages: *** glibc detected *** ./boxyseq: free(): invalid pointer: 0x0000000001d873e8 *** I absolutely know what is wrong here, but was rather confused as to when I saw my C code where I call a function which frees a dynamically allocated data structure - I had passed it an incompatible pointer type - a pointer to a completely different data structure. warning: passing argument 1 of 'data_A_free' from incompatible pointer type note: expected 'struct data_A *' but argument is of type 'struct data_B *' I'm confused because I'm sure this would have been an error before and compilation would never have completed. Is this not just going to make life more difficult for C programmers? Can I change it back to an error without making a whole bunch of other warnings errors too? Or am I loosing the plot and it's always been a warning?

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  • PHP anonymous functions scope question

    - by Dan
    Hi, I'm trying to sort an array of objects by a common property, however I cannot get my $property parameter to register in the inner function (I can use it in the outer one OK). The way I read the documentation, it sounded like the parameter would be available, have I misunderstood something? Here is what I have: public static function sortObjectsByProperty($objects, $property) { function compare_object($a, $b) { $a = $a->$property; $b = $b->$property; if ($a->$property == $b->$property) { return 0; } return ($a->$property > $b->$property) ? +1 : -1; } usort($objects, 'compare_object'); return $objects; } Any advice appreciated. Thanks.

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  • How do interpreters functions written in the class C++ in the main

    - by T_Geek
    Hi I'm working on a project about Data structures. In the first , I wrote everything in main but it sounds like C . But as I learned, I tried to thinkk OOP and do as little as possible in my main() methods. I've implemented some opertation in my class like add,delet,find.it's too easy to implement its . class ARB { private: struct BT { int data; BT *l; BT *r; }; struct BT *p; public ARB(); ~ARB(); void del(int n); void add(int n); }; void ARB::del(int num) { //The code ,don't care about it }; main() { // BTR T; T.add(3); T.add(5); }; But I arrived to the big program How can I define a methode which have to use a binary tree and to get a stack STACK ARB::MyFunct(BT* p) { // The code don't care about it } How can I apply it in the main programme main() { // BT T; T.add(3); T.add(5); STACK S; BT* p S=T.MyFunct(p); // error C2664 cannot convert parametre 1 }; **mention :I implement STACK class

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  • Wrapping allocated output parameters with a scoped_ptr/array

    - by Danra
    So, I have some code which looks like this: byte* ar; foo(ar) // Allocates a new[] byte array for ar ... delete[] ar; To make this safer, I used a scoped_array: byte* arRaw; scoped_array ar; foo(arRaw); ar.reset(arRaw); ... // No delete[] The question is, Is there any existing way to do this using just the scoped_array, without using a temporary raw array? I can probably write an in-place "resetter" class, just wondering if the functionality exists and I'm missing it. Thanks, Dan

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  • What is the difference between array parameters in C

    - by STeN
    Hi, what is the difference between following function declarations, which create and return the array in C/C++? Both methods create the array and fill it with proper values and returns true if everything passed. bool getArray(int* array); bool getArray(int* array[]); Thanks Best Regards, STeN

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  • explicit copy constructor or implicit parameter by value

    - by R Samuel Klatchko
    I recently read (and unfortunately forgot where), that the best way to write operator= is like this: foo &operator=(foo other) { swap(*this, other); return *this; } instead of this: foo &operator=(const foo &other) { foo copy(other); swap(*this, copy); return *this; } The idea is that if operator= is called with an rvalue, the first version can optimize away construction of a copy. So when called with a rvalue, the first version is faster and when called with an lvalue the two are equivalent. I'm curious as to what other people think about this? Would people avoid the first version because of lack of explicitness? Am I correct that the first version can be better and can never be worse?

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  • How to Pass Parameters to Activator.CreateInstance<T>()

    - by DaveDev
    Hi guys I want to create an instance of a type that I specify in a generic method that I have. This type has a number of overloaded constructors. I'd like to be able to pass arguments to the constructors, but Activator.CreateInstance<T>() doesn't see to have this as an option. Is there another way to do it? Thanks Dave

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  • How to use Firebug's debugger functions?

    - by TK
    I don't have an experience with any debugger in any language, but I recently found some videos showing Firebug. I'm now playing with Firebug with a script I included an error with. What I understand now is: I can set a breakpoint, which is shown as a red circle. Firebug stops at the breakpoint and gives me 4 options (Continue, Step Into, Step Over and Step Out). What I don't understand are: What is the difference between the 4 options (i.e., Continue, Step Into, Step Over and Step Out)? To me, Step Over is sometimes similar to Step Into... I could be wrong here. I would be grateful if you could explain the differences of the 4 options.

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  • Help needed with Javascript Variable Scope / OOP and Call Back Functions

    - by gargantaun
    I think this issue goes beyond typical variable scope and closure stuff, or maybe I'm an idiot. Here goes anyway... I'm creating a bunch of objects on the fly in a jQuery plugin. The object look something like this function WedgePath(canvas){ this.targetCanvas = canvas; this.label; this.logLabel = function(){ console.log(this.label) } } the jQuery plugin looks something like this (function($) { $.fn.myPlugin = function() { return $(this).each(function() { // Create Wedge Objects for(var i = 1; i <= 30; i++){ var newWedge = new WedgePath(canvas); newWedge.label = "my_wedge_"+i; globalFunction(i, newWedge]); } }); } })(jQuery); So... the plugin creates a bunch of wedgeObjects, then calls 'globalFunction' for each one, passing in the latest WedgePath instance. Global function looks like this. function globalFunction(indicator_id, pWedge){ var targetWedge = pWedge; targetWedge.logLabel(); } What happens next is that the console logs each wedges label correctly. However, I need a bit more complexity inside globalFunction. So it actually looks like this... function globalFunction(indicator_id, pWedge){ var targetWedge = pWedge; someSql = "SELECT * FROM myTable WHERE id = ?"; dbInterface.executeSql(someSql, [indicator_id], function(transaction, result){ targetWedge.logLabel(); }) } There's a lot going on here so i'll explain. I'm using client side database storage (WebSQL i call it). 'dbInterface' an instance of a simple javascript object I created which handles the basics of interacting with a client side database [shown at the end of this question]. the executeSql method takes up to 4 arguments The SQL String an optional arguments array an optional onSuccess handler an optional onError handler (not used in this example) What I need to happen is: When the WebSQL query has completed, it takes some of that data and manipulates some attribute of a particular wedge. But, when I call 'logLabel' on an instance of WedgePath inside the onSuccess handler, I get the label of the very last instance of WedgePath that was created way back in the plugin code. Now I suspect that the problem lies in the var newWedge = new WedgePath(canvas); line. So I tried pushing each newWedge into an array, which I thought would prevent that line from replacing or overwriting the WedgePath instance at every iteration... wedgeArray = []; // Inside the plugin... for(var i = 1; i <= 30; i++){ var newWedge = new WedgePath(canvas); newWedge.label = "my_wedge_"+i; wedgeArray.push(newWedge); } for(var i = 0; i < wedgeArray.length; i++){ wedgeArray[i].logLabel() } But again, I get the last instance of WedgePath to be created. This is driving me nuts. I apologise for the length of the question but I wanted to be as clear as possible. END ============================================================== Also, here's the code for dbInterface object should it be relevant. function DatabaseInterface(db){ var DB = db; this.sql = function(sql, arr, pSuccessHandler, pErrorHandler){ successHandler = (pSuccessHandler) ? pSuccessHandler : this.defaultSuccessHandler; errorHandler = (pErrorHandler) ? pErrorHandler : this.defaultErrorHandler; DB.transaction(function(tx){ if(!arr || arr.length == 0){ tx.executeSql(sql, [], successHandler, errorHandler); }else{ tx.executeSql(sql,arr, successHandler, errorHandler) } }); } // ---------------------------------------------------------------- // A Default Error Handler // ---------------------------------------------------------------- this.defaultErrorHandler = function(transaction, error){ // error.message is a human-readable string. // error.code is a numeric error code console.log('WebSQL Error: '+error.message+' (Code '+error.code+')'); // Handle errors here var we_think_this_error_is_fatal = true; if (we_think_this_error_is_fatal) return true; return false; } // ---------------------------------------------------------------- // A Default Success Handler // This doesn't do anything except log a success message // ---------------------------------------------------------------- this.defaultSuccessHandler = function(transaction, results) { console.log("WebSQL Success. Default success handler. No action taken."); } }

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  • Passing parameters to custom RESTful routes in Rails (using :collection)

    - by dwhite
    I am trying to add a custom route to my RESTful routes using the :collection param on map.resources like so: map.resources :products, :collection => { :tagged => :get } The tagged action takes in a :tag parameter. I am able to link to the URL route using: tagged_products_path(:tag => tag.name). My issue with this is that the URL that this generates: /products/tagged?tag=electronic I would like the tag to be in the URL and not the tag, like so: /products/tagged/electronic Of course this can be accomplished by a separate named route, but I'm wondering if I'm missing something and there is a way to do this with the :collection hash. Thanks in advance for your help -Damien

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  • Nested generator functions in python

    - by Yuval A
    Consider a tuple v = (a,b,c) and a generator function generate(x) which receives an item from the tuple and generates several options for each item. What is the pythonic way of generating a set of all the possible combinations of the result of generate(x) on each item in the tuple? I could do this: v = (a,b,c) for d in generate(v[0]): for e in generate(v[1]): for f in generate(v[2]): print d,e,f but that's just ugly, plus I need a generic solution.

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  • Symfony: Weird routing issue

    - by Tom
    Hi, I've got following URL in symfony (specifics not important): /frontend_dev.php/something/25/apple ... and a routing rule: /something/:id/:word The URL works fine when clicked through to on the site, but not when I type in the URL. Instead, symfony says: Unable to find a matching route to generate url for params "NULL". The weird thing is that I can navigate to this page and it works, but when hitting Enter in the browser address bar, it no longer finds it. Any thoughts on what might be the cause of something like this generally? I should also add that the URL was working fine when typed in the address bar earlier, but doesn't anymore, and I'm not sure what's there that might be interfering with it. Thanks in advance.

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  • URL rewrite with ?lang= parameter

    - by agorom7
    my developer is saying that it is not possible to rewrite url form example.com/name/name/?lang=english to example.com/en/name/name/ is it possible to do or not? if yes, how should it be done? if not, what could be the reasons? we have windows based hosting from maddogdomains (godaddy)

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  • How do I pass parameters between request-scoped beans

    - by smayers81
    This is a question that has been bothering me for sometime. My application uses ICEFaces for our UI framework and Spring 2.5 for Dependency Injection. In addition, Spring actually maintains all of our backing beans, not the ICEFaces framework, so our faces-config is basically empty. Navigation is not even really handled through navigation-rules. We perform manual redirects to new windows using window.open. All of our beans are defined in our appContext file as being request-scoped. I have Page ABC which is backed by BackingBeanABC. Inside that backing bean, I have a parameter say: private Order order; I then have Page XYZ backed by BackingBeanXYZ. When I redirect from page ABC to page XYZ, I want to transfer the 'order' property from ABC to XYZ. The problem is since everything is request-scoped and I'm performing a redirect, I am losing the value of 'description'. There has got to be an easier way to pass objects between beans in request scope during a redirect. Can anyone assist with this issue?

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  • Passing parameters thru Ruby's OAuth

    - by JP
    I'm using Mirven's Twitter OAuth Sinatra example and trying to figure out how I can send a 'next page' parameter with the Oauth request: ie. The user attempts to visit /edit/profile which requires a login so I redirect to /request which deals with login via twitter - I now want to be able to redirect the user to the address they were originally looking for if they log in successfully. I thought I could do this in the .get_request_token line with this code: @request_token = @consumer.get_request_token({:oauth_callback => "http://#{request.host}/auth"},{:next => params['next'] || '/'}) But params has no additional items in the /auth handler. I'm new to OAuth, how would I go about doing this?

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  • wrapp a function whose parameters are out type pointer to structure using swig

    - by pierr
    I have following function : typedef struct tagT{ int a ; int b ; }Point; int lib_a_f_5(Point *out_t) { out_t->a = 20; out_t->b = 30; return 0; } How should I direct the SWIG to generate the correct code for ruby (or lua)? When putting following statement to the interface file : %apply SWIGTYPE Point* {Point *out_t}; I got a warning : liba.i:7: Warning(453): Can't apply (Point *OUTPUT). No typemaps are defined. Did i need to write a typemap? How should I do it?

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  • groovy closure parameters

    - by Don
    Hi, The following example of using the sendMail method provided by the grails mail plugin appears in this book. sendMail { to "[email protected]" subject "Registration Complete" body view:"/foo/bar", model:[user:new User()] } I understand that the code within {} is a closure that is passed to sendMail as a parameter. I also understand that to, subject and body are method calls. I'm trying to figure out what the code that implements the sendMail method would look like, and my best guess is something like this: MailService { String subject String recipient String view def model sendMail(closure) { closure.call() // Code to send the mail now that all the // various properties have been set } to(recipient) { this.recipient = recipient } subject(subject) { this.subject = subject; } body(view, model) { this.view = view this.model = model } } Is this reasonable, or am I missing something? In particular, are the methods invokedwithin the closure (to, subject, body), necessarily members of the same class as sendMail? Thanks, Don

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  • Random Complete System Unresponsiveness Running Mathematical Functions

    - by Computer Guru
    I have a program that loads a file (anywhere from 10MB to 5GB) a chunk at a time (ReadFile), and for each chunk performs a set of mathematical operations (basically calculates the hash). After calculating the hash, it stores info about the chunk in an STL map (basically <chunkID, hash>) and then writes the chunk itself to another file (WriteFile). That's all it does. This program will cause certain PCs to choke and die. The mouse begins to stutter, the task manager takes 2 min to show, ctrl+alt+del is unresponsive, running programs are slow.... the works. I've done literally everything I can think of to optimize the program, and have triple-checked all objects. What I've done: Tried different (less intensive) hashing algorithms. Switched all allocations to nedmalloc instead of the default new operator Switched from stl::map to unordered_set, found the performance to still be abysmal, so I switched again to Google's dense_hash_map. Converted all objects to store pointers to objects instead of the objects themselves. Caching all Read and Write operations. Instead of reading a 16k chunk of the file and performing the math on it, I read 4MB into a buffer and read 16k chunks from there instead. Same for all write operations - they are coalesced into 4MB blocks before being written to disk. Run extensive profiling with Visual Studio 2010, AMD Code Analyst, and perfmon. Set the thread priority to THREAD_MODE_BACKGROUND_BEGIN Set the thread priority to THREAD_PRIORITY_IDLE Added a Sleep(100) call after every loop. Even after all this, the application still results in a system-wide hang on certain machines under certain circumstances. Perfmon and Process Explorer show minimal CPU usage (with the sleep), no constant reads/writes from disk, few hard pagefaults (and only ~30k pagefaults in the lifetime of the application on a 5GB input file), little virtual memory (never more than 150MB), no leaked handles, no memory leaks. The machines I've tested it on run Windows XP - Windows 7, x86 and x64 versions included. None have less than 2GB RAM, though the problem is always exacerbated under lower memory conditions. I'm at a loss as to what to do next. I don't know what's causing it - I'm torn between CPU or Memory as the culprit. CPU because without the sleep and under different thread priorities the system performances changes noticeably. Memory because there's a huge difference in how often the issue occurs when using unordered_set vs Google's dense_hash_map. What's really weird? Obviously, the NT kernel design is supposed to prevent this sort of behavior from ever occurring (a user-mode application driving the system to this sort of extreme poor performance!?)..... but when I compile the code and run it on OS X or Linux (it's fairly standard C++ throughout) it performs excellently even on poor machines with little RAM and weaker CPUs. What am I supposed to do next? How do I know what the hell it is that Windows is doing behind the scenes that's killing system performance, when all the indicators are that the application itself isn't doing anything extreme? Any advice would be most welcome.

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  • What is the scope of JS variables in anonymous functions

    - by smorhaim
    Why does this code returns $products empty? If I test for $products inside the function it does show data... but once it finishes I can't seem to get the data. var $products = new Array(); connection.query($sql, function(err, rows, fields) { if (err) throw err; for(i=0; i< rows.length; i++) { $products[rows[i].source_identifier] = "xyz"; } }); connection.end(); console.log($products); // Shows empty.

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  • JQuery Treeview causes browser crash with certain parameters

    - by IP
    I have the following code, which causes Chrome and Safari to crash (Aw Snap in Chrome) jQuery(".filetree").treeview({ animated: "fast", collapsed: true, unique: true, persist: "cookie", toggle: function() { } }); If I change it to this: jQuery(".filetree").treeview({ animated: "fast", toggle: function() { } }); It doesn't crash...any ideas?

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