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  • Space in DIV ??

    - by alex
    Hello all, Is it possible to avoid the spaces X & Y (see image)? There is no padding in CSS! <html> <head> <title>Prova WIDGET</title> <link rel="stylesheet" href="jquery-ui-1.8.1.custom/css/ui-lightness/jquery-ui-1.8.1.custom.css" type="text/css"> <script src="jquery-ui-1.8.1.custom/development-bundle/jquery-1.4.2.js" type="text/javascript"></script> <script src="jquery-ui-1.8.1.custom/js/jquery-ui-1.8.1.custom.min.js" type="text/javascript"></script> <script type="text/javascript"> $(themify); function themify(){ $("#pulsante").addClass("ui-button ui-button-text-only ui-widget ui-state-default ui-corner-all"); //ui-button-text } </script> <style>#test{display:none}</style> <script type="text/javascript"> function rendiVisibile(){ if(document.getElementById("test").style.display = "none"){ $("#test").css({"width":"100px","float":"right","text-align":"center"}); $("#test").show("slide",{},1000); } } </script> </head> <body> <h2 class="ui-widget-header">Tentativo widget con DIV</h2> <form action=""> <input type="button" value="Submit" id="pulsante" onclick="rendiVisibile()";><br/></br> <div id="test" class="ui-widget ui-widget-content ui-corner-all"> <h3 class="ui-widget-header ui-corner-all">CIAO</h3> <p class="ui-widget-content ui-corner-all">Un saluto</p> </div> </form> </body> </html>

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  • Any socket programmers out there? How can I obtain the IPv4 address of the client?

    - by Dr Dork
    Hello! I'm prepping for a simple work project and am trying to familiarize myself with the basics of socket programming in a Unix dev environment. At this point, I have some basic server side code setup to listen for incoming TCP connection requests from clients after the parent socket has been created and is set to listen... int sockfd, newfd; unsigned int len; socklen_t sin_size; char msg[]="Test message sent"; char buf[MAXLEN]; int st, rv; struct addrinfo hints, *serverinfo, *p; struct sockaddr_storage client; char ip[INET6_ADDRSTRLEN]; . . //parent socket creation and listen code omitted for simplicity . //wait for connection requests from clients while(1) { //Returns the socketID and address of client connecting to socket if( ( newfd = accept(sockfd, (struct sockaddr *)&client, &len) ) == -1 ){ perror("Accept"); exit(-1); } if( (rv = recv(newfd, buf, MAXLEN-1, 0 )) == -1) { perror("Recv"); exit(-1); } struct sockaddr_in *clientAddr = ( struct sockaddr_in *) get_in_addr((struct sockaddr *)&client); inet_ntop(client.ss_family, clientAddr, ip, sizeof ip); printf("Receive from %s: query type is %s\n", ip, buf); if( ( st = send(newfd, msg, strlen(msg), 0)) == -1 ) { perror("Send"); exit(-1); } //ntohs is used to avoid big-endian and little endian compatibility issues printf("Send %d byte to port %d\n", ntohs(clientAddr->sin_port) ); close(newfd); } } I found the get_in_addr function online and placed it at the top of my code and use it to obtain the IP address of the client connecting... // get sockaddr, IPv4 or IPv6: void *get_in_addr(struct sockaddr *sa) { if (sa->sa_family == AF_INET) { return &(((struct sockaddr_in*)sa)->sin_addr); } return &(((struct sockaddr_in6*)sa)->sin6_addr); } but the function always returns the IPv6 IP address since thats what the sa_family property is set as. My question is, is the IPv4 IP address stored anywhere in the data I'm using and, if so, how can I access it? Thanks so much in advance for all your help!

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  • JSON or YAML encoding in GWT/Java on both client and server

    - by KennethJ
    I'm looking for a super simple JSON or YAML library (not particularly bothered which one) written in Java, and can be used in both GWT on the client, and in its original Java form on the server. What I'm trying to do is this: I have my models, which are shared between the client and the server, and these are the primary source of data interchange. I want to design the web service in between to be as simple as possible, and decided to take the RESTful approach. My problem is that I know our application will grow substantially in the future, and writing all the getters, setters, serialization, factories, etc. by hand fills me with absolute dread. So in order to avoid it, I decided to implement annotations to keep track of attributes on the models. The reason I can't just serialize everything directly, using GWT's own one, or one which works through reflection, is because we need a certain amount of logic going on in the serialization process. I.e. whether references to other models get serialized during the serialization of the original model, or whether an ID is just passed, and general simple things like that. I've then written an annotation processor to preprocess my shared models and generate an implementing class with all the getters, setters, serialization, lazy-loading, etc. To make a long story short, I need some type of simple YAML or JSON library, which allows me to encode and decode manually, so I can generate this code through my annotation processor. I have had a look around the interwebs, but every single one I ran into supported some reflection which, while all fine and dandy, make it pretty much useless for GWT. And in the case of GWT's own JSON library, it uses JSNI for speed purposes, making it useless server side. One solution I did think about involved writing writing two sets of serialization methods on the models, one for the client and one for the server, but I'd rather not do that. Also, I'm pretty new to GWT, and even though I have done a lot of Java, it was back in the 1.2 days, so it's a bit rusty. So if you think I'm going about this problem completely the wrong way, I'm open to suggestions.

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  • How to scroll table view with toolbar at the top of the view

    - by Jakub
    Hello, I have a view with a toolbar at the top and a table view with text fields in it's cells. When I want to edit the text fields placed in the bottom of the table view the keyboard is hiding the text field being edited (as the table view is not scrolled up). I tried to implement http://cocoawithlove.com/2008/10/sliding-uitextfields-around-to-avoid.html but this makes my whole view move up (the toolbar and the table view) while I would like to have the toobar at the top of the view for the whole time. I modified the mentioned code to something like this: - (void)textFieldDidBeginEditing:(UITextField *)textField { CGRect textFieldRect = [tableView.window convertRect:textField.bounds fromView:textField]; CGRect viewRect = [tableView.window convertRect:tmpTableView.bounds fromView:tableView]; CGFloat midline = textFieldRect.origin.y + 0.5 * textFieldRect.size.height; CGFloat numerator = midline - viewRect.origin.y - MINIMUM_SCROLL_FRACTION * viewRect.size.height; CGFloat denominator = (MAXIMUM_SCROLL_FRACTION - MINIMUM_SCROLL_FRACTION) * viewRect.size.height; CGFloat heightFraction = numerator / denominator; if (heightFraction < 0.0) { heightFraction = 0.0; } else if (heightFraction > 1.0) { heightFraction = 1.0; } UIInterfaceOrientation orientation = [[UIApplication sharedApplication] statusBarOrientation]; if (orientation == UIInterfaceOrientationPortrait || orientation == UIInterfaceOrientationPortraitUpsideDown) { animatedDistance = floor(PORTRAIT_KEYBOARD_HEIGHT * heightFraction); } else { animatedDistance = floor(LANDSCAPE_KEYBOARD_HEIGHT * heightFraction); } CGRect viewFrame = tableView.frame; viewFrame.origin.y -= animatedDistance; [UIView beginAnimations:nil context:NULL]; [UIView setAnimationBeginsFromCurrentState:YES]; [UIView setAnimationDuration:KEYBOARD_ANIMATION_DURATION]; [tableView setFrame:viewFrame]; [UIView commitAnimations]; } and - (void)textFieldDidEndEditing:(UITextField *)textField { CGRect viewFrame = tableView.frame; viewFrame.origin.y += animatedDistance; [UIView beginAnimations:nil context:NULL]; [UIView setAnimationBeginsFromCurrentState:YES]; [UIView setAnimationDuration:KEYBOARD_ANIMATION_DURATION]; [tableView setFrame:viewFrame]; [UIView commitAnimations]; } This made my toolbar stay at the top, but unfortunately the table view overlays the toolbar and the toolbar is not visible. Any ideas how to solve this?

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  • Objective-c design advice for use of different data sources, swapping between test and live

    - by user200341
    I'm in the process of designing an application that is part of a larger piece of work, depending on other people to build an API that the app can make use of to retrieve data. While I was thinking about how to setup this project and design the architecture around it, something occurred to me, and I'm sure many people have been in similar situations. Since my work is depending on other people to complete their tasks, and a test server, this slows work down at my end. So the question is: What's the best practice for creating test repositories and classes, implementing them, and not having to depend on altering several places in the code to swap between the test classes and the actual repositories / proper api calls. Contemplate the following scenario: GetDataFromApiCommand *getDataCommand = [[GetDataFromApiCommand alloc]init]; getDataCommand.delegate = self; [getDataCommand getData]; Once the data is available via the API, "GetDataFromApiCommand" could use the actual API, but until then a set of mock data could be returned upon the call of [getDataCommand getData] There might be multiple instances of this, in various places in the code, so replacing all of them wherever they are, is a slow and painful process which inevitably leads to one or two being overlooked. In strongly typed languages we could use dependency injection and just alter one place. In objective-c a factory pattern could be implemented, but is that the best route to go for this? GetDataFromApiCommand *getDataCommand = [GetDataFromApiCommandFactory buildGetDataFromApiCommand]; getDataCommand.delegate = self; [getDataCommand getData]; What is the best practices to achieve this result? Since this would be most useful, even if you have the actual API available, to run tests, or work off-line, the ApiCommands would not necessarily have to be replaced permanently, but the option to select "Do I want to use TestApiCommand or ApiCommand". It is more interesting to have the option to switch between: All commands are test and All command use the live API, rather than selecting them one by one, however that would also be useful to do for testing one or two actual API commands, mixing them with test data. EDIT The way I have chosen to go with this is to use the factory pattern. I set up the factory as follows: @implementation ApiCommandFactory + (ApiCommand *)newApiCommand { // return [[ApiCommand alloc]init]; return [[ApiCommandMock alloc]init]; } @end And anywhere I want to use the ApiCommand class: GetDataFromApiCommand *getDataCommand = [ApiCommandFactory newApiCommand]; When the actual API call is required, the comments can be removed and the mock can be commented out. Using new in the message name implies that who ever uses the factory to get an object, is responsible for releasing it (since we want to avoid autorelease on the iPhone). If additional parameters are required, the factory needs to take these into consideration i.e: [ApiCommandFactory newSecondApiCommand:@"param1"]; This will work quite well with repositories as well.

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  • Should I add try/catch around when casting on an attribute of JSP implicit object?

    - by Michael Mao
    Hi all: Basically what I mean is like this: List<String[]> routes = (List<String[]>)application.getAttribute("routes"); For the above code, it tries to get an attribute named "routes" from the JSP implicit object - application. But as everyone knows, after this line of code, routes may very well contains a null - which means this application hasn't got an attribute named "routes". Is this "casting on null" good programming practice in Java or not? Basically I try to avoid exceptions such as java.io.InvalidCastException I reckon things like this are more as "heritage" of Java 1.4 when generic types were not introduced to this language. So I guess everything stored in application attributes as Objects (Similar to traditional ArrayList). And when you do "downcast", there might be invalid casts. What would you do in this case? Update: Just found that although in the implicit object application I did store a List of String arrays, when I do this : List<double[]> routes = (List<double[]>)application.getAttribute("routes"); It doesn't produce any error... And I felt not comfortable already... And even with this code: out.print(routes.get(0)); It does print out something strange : [Ljava.lang.String;@18b352f Am I printing a "pointer to String"? I can finally get an exception like this: out.print(routes.get(0)[1]); with error : java.lang.ClassCastException: [Ljava.lang.String; Because it was me to add the application attribute, I know which type should it be cast to. I feel this is not "good enough", what if I forget the exact type? I know there are still some cases where this sort of thing would happen, such as in JSP/Servlet when you do casting on session attributes. Is there a better way to do this? Before you say:"OMG, why you don't use Servlets???", I should justify my reason as this: - because my uni sucks, its server can only work with Servlets generated by JSP, and I don't really want to learn how to fix issues like that. look at my previous question on this , and this is uni homework, so I've got no other choice, forget all about war, WEB-INF,etc, but "code everything directly into JSP" - because the professors do that too. :)

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  • Best way to test for a variable's existence in PHP; isset() is clearly broken

    - by chazomaticus
    From the isset() docs: isset() will return FALSE if testing a variable that has been set to NULL. Basically, isset() doesn't check for whether the variable is set at all, but whether it's set to anything but NULL. Given that, what's the best way to actually check for the existence of a variable? I tried something like: if(isset($v) || @is_null($v)) (the @ is necessary to avoid the warning when $v is not set) but is_null() has a similar problem to isset(): it returns TRUE on unset variables! It also appears that: @($v === NULL) works exactly like @is_null($v), so that's out, too. How are we supposed to reliably check for the existence of a variable in PHP? Edit: there is clearly a difference in PHP between variables that are not set, and variables that are set to NULL: <?php $a = array('b' => NULL); var_dump($a); PHP shows that $a['b'] exists, and has a NULL value. If you add: var_dump(isset($a['b'])); var_dump(isset($a['c'])); you can see the ambiguity I'm talking about with the isset() function. Here's the output of all three of these var_dump()s: array(1) { ["b"]=> NULL } bool(false) bool(false) Further edit: two things. One, a use case. An array being turned into the data of an SQL UPDATE statement, where the array's keys are the table's columns, and the array's values are the values to be applied to each column. Any of the table's columns can hold a NULL value, signified by passing a NULL value in the array. You need a way to differentiate between an array key not existing, and an array's value being set to NULL; that's the difference between not updating the column's value and updating the column's value to NULL. Second, Zoredache's answer, array_key_exists() works correctly, for my above use case and for any global variables: <?php $a = NULL; var_dump(array_key_exists('a', $GLOBALS)); var_dump(array_key_exists('b', $GLOBALS)); outputs: bool(true) bool(false) Since that properly handles just about everywhere I can see there being any ambiguity between variables that don't exist and variables that are set to NULL, I'm calling array_key_exists() the official easiest way in PHP to truly check for the existence of a variable. (Only other case I can think of is for class properties, for which there's property_exists(), which, according to its docs, works similarly to array_key_exists() in that it properly distinguishes between not being set and being set to NULL.)

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  • Using empty row as default in a ComboBox with Style "DropDownList"?

    - by Pesche Helfer
    Hi board I am trying to write a method, that takes a ComboBox, a DataTable and a TextBox as arguments. The purpose of it is to filter the members displayed in the ComboBox according to the TextBox.Text. The DataTable contains the entire list of possible entries that will then be filtered. For filtering, I create a DataView of the DataTable, add a RowFilter and then bind this View to the ComboBox as DataSource. To prevent the user from typing into the ComboBox, I choose the DropDownStyle DropDownList. That’s working fine so far, except that the user should also be able to choose nothing / empty line. In fact, this should be the default member to be displayed (to prevent choosing a wrong member by accident, if the user clicks through the dialog too fast). I tried to solve this problem by adding a new Row to the view. While this works for some cases, the main issue here is that any DataTable can be passed to the method. If the DataTable contains columns that cannot be null and don’t contain a default value, I suppose I will raise an error by adding an empty row. A possibility would be to create a view that contains only the column that is defined as DisplayMember, and the one that is defined as ValueMember. Alas, this can’t be done with a view in C#. I would like to avoid creating a true copy of the DataTable at all cost, since who knows how big it will get with time. Do you have any suggestions how to get around this problem? Instead of a view, could I create an object containing two members and assign the DisplayMember and the ValueMember to these members? Would the members be passed as reference (what I hope) or would true copied be created (in which case it would not be a solution)? Thank you very much for your help! Best regards public static void ComboFilter(ComboBox cb, DataTable dtSource, TextBox filterTextBox) { cb.DropDownStyle = ComboBoxStyle.DropDownList; string displayMember = cb.DisplayMember; DataView filterView = new DataView(dtSource); filterView.AddNew(); filterView.RowFilter = displayMember + " LIKE '%" + filterTextBox.Text + "%'"; cb.DataSource = filterView; }

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  • Serialization of non-required fields in protobuf-net

    - by David Hedlund
    I have a working java client that is communicating with Google, through ProtoBuf serialized messages. I am currently trying to translate that client into C#. I have a .proto file where the parameter appId is an optional string. Its default value in the C# representation as generated by the protobuf-net library is an empty string, just as it is in the java representation of the same file. message AppsRequest { optional AppType appType = 1; optional string query = 2; optional string categoryId = 3; optional string appId = 4; optional bool withExtendedInfo = 6; } I find that when I explicitly set appId to "" in the java client, the client stops working (403 Bad Request from Google). When I explicitly set appId to null in the java client, everything works, but only because hasAppId is being set to false (I'm uncertain as to how that affects the serialization). In the C# client, I always get 403 responses. I don't see any logic behind the distinction between not setting a value, and setting the default value, that seems to make all the difference in the java client. Since the output is always a binary stream, I am not sure if the successful java messages are being serialized with an empty string, or not serialized at all. In the C# client, I've tried setting IsRequired to true on the ProtoMember attribute, to force them to serialize, and I've tried setting the default value to null, and explicitly set "", so I'm quite sure I've tried some configuration where the value is being serialized. I've also played around with ProtoBuf.ProtoIgnore and at some point, removing the appId parameter altogether, but I haven't been able to avoid the 403 errors in C#. I've tried manually copying the serialized string from java, and that resolved my issues, so I'm certain that the rest of the HTTP Request is working, and the error can be traced to the serialized object. My serialization is simply this: var clone = ProtoBuf.Serializer.DeepClone(request); MemoryStream ms = new MemoryStream(2000); ProtoBuf.Serializer.Serialize(ms, clone); var bytearr = ms.ToArray(); string encodedData = Convert.ToBase64String(bytearr); I'll admit to not being quite sure about what DeepClone does. I've tried both with and without it...

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  • JQuery validation not working for checkbox group

    - by Chris Halcrow
    I'm having trouble getting JQuery validation to work with a set of checkboxes. I'm generating the checkboxes using an ASP.NET checkboxlist, and I've used JQuery to set the 'name' attribute to the same thing for each checkbox in the list. Here's the code that gets written to the browser. I'm setting the 'validate' attribute on the 1st checkbox to set the rule that at least one checkbox must be selected. The JQuery validation works for all other elements on the form, but not for the checkbox list. I'm also using a JQuery form wizard on the page which triggers validation for each 'page' of the form, so I don't have control over how the validation is called. <input id="ContentPlaceHolder1_MainContent_AreaOfInterest_0" class="ui-wizard-content ui-helper-reset ui-state-default" type="checkbox" value="Famine" name="hello[]" validate="required:true, minlength:1"> <label for="ContentPlaceHolder1_MainContent_AreaOfInterest_0">Famine</label> <br> <input id="ContentPlaceHolder1_MainContent_AreaOfInterest_1" class="ui-wizard-content ui-helper-reset ui-state-default" type="checkbox" value="Events Volunteer" name="hello[]"> <label for="ContentPlaceHolder1_MainContent_AreaOfInterest_1">Events Volunteer</label> Any ideas on what's going wrong? There are lots of examples of JQuery scripts that will do the validation, however I'm trying to avoid this as I'm generating the checkboxlist server side by a custom control so that it can be re-used across different pages that may or may not have JQuery enabled. I'm trying to enable the JQuery validation whilst being as unobtrusive as possible, so that pages will still work even if JQuery is disabled. Here are the relevant JQuery inclusions and JQuery initialisation script for the form wizard. I'm not using any initialisation code for JQuery validation: <script type="text/javascript" src="../js/formwizard/js/bbq.js"></script> <script type="text/javascript" src="../js/formwizard/js/jquery.form.js"></script> <script type="text/javascript" src="../js/formwizard/js/jquery.form.wizard.js"></script> <script type="text/javascript" src="../js/formwizard/js/jquery.validate.js"></script> <script type="text/javascript"> $(document).ready(function () { $("#form1").formwizard({ validationEnabled: true, focusFirstInput: true }); }); </script>

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  • What are the weaknesses of this user authentication method?

    - by byronh
    I'm developing my own PHP framework. It seems all the security articles I have read use vastly different methods for user authentication than I do so I could use some help in finding security holes. Some information that might be useful before I start. I use mod_rewrite for my MVC url's. Passwords are sha1 and md5 encrypted with 24 character salt unique to each user. mysql_real_escape_string and/or variable typecasting on everything going in, and htmlspecialchars on everything coming out. Step-by step process: Top of every page: session_start(); session_regenerate_id(); If user logs in via login form, generate new random token to put in user's MySQL row. Hash is generated based on user's salt (from when they first registered) and the new token. Store the hash and plaintext username in session variables, and duplicate in cookies if 'Remember me' is checked. On every page, check for cookies. If cookies set, copy their values into session variables. Then compare $_SESSION['name'] and $_SESSION['hash'] against MySQL database. Destroy all cookies and session variables if they don't match so they have to log in again. If login is valid, some of the user's information from the MySQL database is stored in an array for easy access. So far, I've assumed that this array is clean so when limiting user access I refer to user.rank and deny access if it's below what's required for that page. I've tried to test all the common attacks like XSS and CSRF, but maybe I'm just not good enough at hacking my own site! My system seems way too simple for it to actually be secure (the security code is only 100 lines long). What am I missing? I've also spent alot of time searching for the vulnerabilities with mysql_real_escape string but I haven't found any information that is up-to-date (everything is from several years ago at least and has apparently been fixed). All I know is that the problem was something to do with encoding. If that problem still exists today, how can I avoid it? Any help will be much appreciated.

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  • Endianness conversion and g++ warnings

    - by SuperBloup
    I've got the following C++ code : template <int isBigEndian, typename val> struct EndiannessConv { inline static val fromLittleEndianToHost( val v ) { union { val outVal __attribute__ ((used)); uint8_t bytes[ sizeof( val ) ] __attribute__ ((used)); } ; outVal = v; std::reverse( &bytes[0], &bytes[ sizeof(val) ] ); return outVal; } inline static void convertArray( val v[], uint32_t size ) { // TODO : find a way to map the array for (uint32_t i = 0; i < size; i++) for (uint32_t i = 0; i < size; i++) v[i] = fromLittleEndianToHost( v[i] ); } }; Which work and has been tested (without the used attributes). When compiling I obtain the following errors from g++ (version 4.4.1) || g++ -Wall -Wextra -O3 -o t t.cc || t.cc: In static member function 'static val EndiannessConv<isBigEndian, val>::fromLittleEndianToHost(val)': t.cc|98| warning: 'used' attribute ignored t.cc|99| warning: 'used' attribute ignored || t.cc: In static member function 'static val EndiannessConv<isBigEndian, val>::fromLittleEndianToHost(val) [with int isBigEndian = 1, val = double]': t.cc|148| instantiated from here t.cc|100| warning: unused variable 'outVal' t.cc|100| warning: unused variable 'bytes' I've tried to use the following code : template <int size, typename valType> struct EndianInverser { /* should not compile */ }; template <typename valType> struct EndianInverser<4, valType> { static inline valType reverseEndianness( const valType &val ) { uint32_t castedVal = *reinterpret_cast<const uint32_t*>( &val ); castedVal = (castedVal & 0x000000FF << (3 * 8)) | (castedVal & 0x0000FF00 << (1 * 8)) | (castedVal & 0x00FF0000 >> (1 * 8)) | (castedVal & 0xFF000000 >> (3 * 8)); return *reinterpret_cast<valType*>( &castedVal ); } }; but it break when enabling optimizations due to the type punning. So, why does my used attribute got ignored? Is there a workaround to convert endianness (I rely on the enum to avoid type punning) in templates?

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  • Normalizing Item Names & Synonyms

    - by RabidFire
    Consider an e-commerce application with multiple stores. Each store owner can edit the item catalog of his store. My current database schema is as follows: item_names: id | name | description | picture | common(BOOL) items: id | item_name_id | picture | price | description | picture item_synonyms: id | item_name_id | name | error(BOOL) Notes: error indicates a wrong spelling (eg. "Ericson"). description and picture of the item_names table are "globals" that can optionally be overridden by "local" description and picture fields of the items table (in case the store owner wants to supply a different picture for an item). common helps separate unique item names ("Jimmy Joe's Cheese Pizza" from "Cheese Pizza") I think the bright side of this schema is: Optimized searching & Handling Synonyms: I can query the item_names & item_synonyms tables using name LIKE %QUERY% and obtain the list of item_name_ids that need to be joined with the items table. (Examples of synonyms: "Sony Ericsson", "Sony Ericson", "X10", "X 10") Autocompletion: Again, a simple query to the item_names table. I can avoid the usage of DISTINCT and it minimizes number of variations ("Sony Ericsson Xperia™ X10", "Sony Ericsson - Xperia X10", "Xperia X10, Sony Ericsson") The down side would be: Overhead: When inserting an item, I query item_names to see if this name already exists. If not, I create a new entry. When deleting an item, I count the number of entries with the same name. If this is the only item with that name, I delete the entry from the item_names table (just to keep things clean; accounts for possible erroneous submissions). And updating is the combination of both. Weird Item Names: Store owners sometimes use sentences like "Harry Potter 1, 2 Books + CDs + Magic Hat". There's something off about having so much overhead to accommodate cases like this. This would perhaps be the prime reason I'm tempted to go for a schema like this: items: id | name | picture | price | description | picture (... with item_names and item_synonyms as utility tables that I could query) Is there a better schema you would suggested? Should item names be normalized for autocomplete? Is this probably what Facebook does for "School", "City" entries? Is the first schema or the second better/optimal for search? Thanks in advance! References: (1) Is normalizing a person's name going too far?, (2) Avoiding DISTINCT

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  • assign member based on string value

    - by Aperion
    I need start off with code because I am not sure what terminology to use. Lets say I have the following code: class Node { public: void Parse(rapidxml::xml_node<> *node) { for (rapidxml::xml_attribute<> *attr = node->first_attribute(); attr; attr = attr->next_attribute()) { std::stringstream converter; converter << attr->value(); if( !strcmp(attr->name(), "x") ) converter >> x; else if( !strcmp(attr->name(),"y") ) converter >> y; else if( !strcmp(attr->name(), "z") ) converter >> z; } } private: float x; float y; float z; }; What I can't stand is the repetition of if( !strcmp(attr-name(), "x") ) converter x; I feel that this is error prone and monotonous, but I cannot think of another way to map a string value to a member assignment. What are some other approaches one can take to avoid code such as this? The only other possible alternative I could think of was to use a hashmap, but that runs into problems with callbacks This is the best I could up with but it's not as flexible as I'd like: class Node { Node() : x(0.0f), y(0.0f), z(0.0f) { assignmentMap["x"] = &x; assignmentMap["y"] = &y; assignmentMap["z"] = &z; } public: void Parse(rapidxml::xml_node<> *node) { for (rapidxml::xml_attribute<> *attr = node->first_attribute(); attr; attr = attr->next_attribute()) { if( !attr->name() ) continue; std::stringstream converter; converter << attr->value(); converter >> *assignmentMap[attr->name()]; } } private: float x; float y; float z; std::map<std::string, float*> assignmentMap; };

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  • Is this a valid pattern for raising events in C#?

    - by Will Vousden
    Update: For the benefit of anyone reading this, since .NET 4, the lock is unnecessary due to changes in synchronization of auto-generated events, so I just use this now: public static void Raise<T>(this EventHandler<T> handler, object sender, T e) where T : EventArgs { if (handler != null) { handlerCopy(sender, e); } } And to raise it: SomeEvent.Raise(this, new FooEventArgs()); Having been reading one of Jon Skeet's articles on multithreading, I've tried to encapsulate the approach he advocates to raising an event in an extension method like so (with a similar generic version): public static void Raise(this EventHandler handler, object @lock, object sender, EventArgs e) { EventHandler handlerCopy; lock (@lock) { handlerCopy = handler; } if (handlerCopy != null) { handlerCopy(sender, e); } } This can then be called like so: protected virtual void OnSomeEvent(EventArgs e) { this.someEvent.Raise(this.eventLock, this, e); } Are there any problems with doing this? Also, I'm a little confused about the necessity of the lock in the first place. As I understand it, the delegate is copied in the example in the article to avoid the possibility of it changing (and becoming null) between the null check and the delegate call. However, I was under the impression that access/assignment of this kind is atomic, so why is the lock necessary? Update: With regards to Mark Simpson's comment below, I threw together a test: static class Program { private static Action foo; private static Action bar; private static Action test; static void Main(string[] args) { foo = () => Console.WriteLine("Foo"); bar = () => Console.WriteLine("Bar"); test += foo; test += bar; test.Test(); Console.ReadKey(true); } public static void Test(this Action action) { action(); test -= foo; Console.WriteLine(); action(); } } This outputs: Foo Bar Foo Bar This illustrates that the delegate parameter to the method (action) does not mirror the argument that was passed into it (test), which is kind of expected, I guess. My question is will this affect the validity of the lock in the context of my Raise extension method? Update: Here is the code I'm now using. It's not quite as elegant as I'd have liked, but it seems to work: public static void Raise<T>(this object sender, ref EventHandler<T> handler, object eventLock, T e) where T : EventArgs { EventHandler<T> copy; lock (eventLock) { copy = handler; } if (copy != null) { copy(sender, e); } }

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  • Myself throwing NullReferenceException... needs help

    - by Amit Ranjan
    I know it might be a weird question and its Title too, but i need your help. I am a .net dev , working on platform for the last 1.5 years. I am bit confused on the term usually we say " A Good Programmer ". I dont know ,what are the qualities of a good programmer ? Is the guy who writes a bug free code? or Can develop applications solely? or blah blah blah...lots of points. I dont know... But as far i am concerned , I know I am not a good programmer, still in learning phase an needs a lot to learn in coming days. So you guys are requested to please help me with this two problems of mine My first problem is regarding the proper Error Handling, which is a most debatable aspect of programming. We all know we use ` try { } catch { } finally { } ` in our code to manage exception. But even if I use try { } catch(exception ex) { throw ex } finally { } , different guys have different views. I still dont know the good way to handle errors. I can write code, use try-catch but still i feel I lacks something. When I saw the codes generated by .net fx tools even they uses throw ex or `throw new Exception("this is my exception")`.. I am just wondering what will be the best way to achieve the above. All means the same thing but why we avoid something. If it has some demerits then it must be made obselete.Anyways I still dont have one [how to handle errors efficiently?]. I generally follow the try-catch(execoption ex){throw ex}, and usually got stucked in debates with leads why you follow this why not that... 2.Converting your entire code blocks in modules using Design patterns of some OOPs concepts. How do you guys decide what architeture or pattern will be the best for my upcoming application based on its working, flow etc. I need to know what you guys can see that I can't. Since I know , I dont have that much experience but I can say, with my experience that experience doesnot comes either from degree/certificates or success you made instead it cames from failures you faced or got stucking situations. Pleas help me out.

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  • How does Sentry aggregate errors?

    - by Hugo Rodger-Brown
    I am using Sentry (in a django project), and I'd like to know how I can get the errors to aggregate properly. I am logging certain user actions as errors, so there is no underlying system exception, and am using the culprit attribute to set a friendly error name. The message is templated, and contains a common message ("User 'x' was unable to perform action because 'y'"), but is never exactly the same (different users, different conditions). Sentry clearly uses some set of attributes under the hood to determine whether to aggregate errors as the same exception, but despite having looked through the code, I can't work out how. Can anyone short-cut my having to dig further into the code and tell me what properties I need to set in order to manage aggregation as I would like? [UPDATE 1: event grouping] This line appears in sentry.models.Group: class Group(MessageBase): """ Aggregated message which summarizes a set of Events. """ ... class Meta: unique_together = (('project', 'logger', 'culprit', 'checksum'),) ... Which makes sense - project, logger and culprit I am setting at the moment - the problem is checksum. I will investigate further, however 'checksum' suggests that binary equivalence, which is never going to work - it must be possible to group instances of the same exception, with differenct attributes? [UPDATE 2: event checksums] The event checksum comes from the sentry.manager.get_checksum_from_event method: def get_checksum_from_event(event): for interface in event.interfaces.itervalues(): result = interface.get_hash() if result: hash = hashlib.md5() for r in result: hash.update(to_string(r)) return hash.hexdigest() return hashlib.md5(to_string(event.message)).hexdigest() Next stop - where do the event interfaces come from? [UPDATE 3: event interfaces] I have worked out that interfaces refer to the standard mechanism for describing data passed into sentry events, and that I am using the standard sentry.interfaces.Message and sentry.interfaces.User interfaces. Both of these will contain different data depending on the exception instance - and so a checksum will never match. Is there any way that I can exclude these from the checksum calculation? (Or at least the User interface value, as that has to be different - the Message interface value I could standardise.) [UPDATE 4: solution] Here are the two get_hash functions for the Message and User interfaces respectively: # sentry.interfaces.Message def get_hash(self): return [self.message] # sentry.interfaces.User def get_hash(self): return [] Looking at these two, only the Message.get_hash interface will return a value that is picked up by the get_checksum_for_event method, and so this is the one that will be returned (hashed etc.) The net effect of this is that the the checksum is evaluated on the message alone - which in theory means that I can standardise the message and keep the user definition unique. I've answered my own question here, but hopefully my investigation is of use to others having the same problem. (As an aside, I've also submitted a pull request against the Sentry documentation as part of this ;-)) (Note to anyone using / extending Sentry with custom interfaces - if you want to avoid your interface being use to group exceptions, return an empty list.)

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  • Migrating from hand-written persistence layer to ORM

    - by Sergey Mikhanov
    Hi community, We are currently evaluating options for migrating from hand-written persistence layer to ORM. We have a bunch of legacy persistent objects (~200), that implement simple interface like this: interface JDBC { public long getId(); public void setId(long id); public void retrieve(); public void setDataSource(DataSource ds); } When retrieve() is called, object populates itself by issuing handwritten SQL queries to the connection provided using the ID it received in the setter (this usually is the only parameter to the query). It manages its statements, result sets, etc itself. Some of the objects have special flavors of retrive() method, like retrieveByName(), in this case a different SQL is issued. Queries could be quite complex, we often join several tables to populate the sets representing relations to other objects, sometimes join queries are issued on-demand in the specific getter (lazy loading). So basically, we have implemented most of the ORM's functionality manually. The reason for that was performance. We have very strong requirements for speed, and back in 2005 (when this code was written) performance tests has shown that none of mainstream ORMs were that fast as hand-written SQL. The problems we are facing now that make us think of ORM are: Most of the paths in this code are well-tested and are stable. However, some rarely-used code is prone to result set and connection leaks that are very hard to detect We are currently squeezing some additional performance by adding caching to our persistence layer and it's a huge pain to maintain the cached objects manually in this setup Support of this code when DB schema changes is a big problem. I am looking for an advice on what could be the best alternative for us. As far as I know, ORMs has advanced in last 5 years, so it might be that now there's one that offers an acceptable performance. As I see this issue, we need to address those points: Find some way to reuse at least some of the written SQL to express mappings Have the possibility to issue native SQL queries without the necessity to manually decompose their results (i.e. avoid manual rs.getInt(42) as they are very sensitive to schema changes) Add a non-intrusive caching layer Keep the performance figures. Is there any ORM framework you could recommend with regards to that?

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  • Howto access thread data outside a thread

    - by Quandary
    Question: I start the MS Text-to-speech engine in a thread, in order to avoid a crash on DLL_attach. It starts fine, and the text to speech engine gets initialized, but I can't access ISpVoice outside the thread. How can I access ISpVoice outside the thread ? It's a global variable after all... #include <windows.h> #include <sapi.h> #include "XPThreads.h" ISpVoice * pVoice = NULL; unsigned long init_engine_thread(void* param) { Sleep(5000); printf("lolthread\n"); //HRESULT hr = CoInitializeEx(NULL, COINIT_MULTITHREADED); HRESULT hr = CoInitialize(NULL); if(FAILED(hr) ) { MessageBox(NULL, TEXT("Failed To Initialize"), TEXT("Error"), 0); char buffer[2000] ; sprintf(buffer, "An error occured: 0x%08X.\n", hr); FILE * pFile = fopen ( "c:\\temp\\CoInitialize_dll.txt" , "w" ); fwrite (buffer , 1 , strlen(buffer) , pFile ); fclose (pFile); } else { printf("trying to create instance.\n"); //HRESULT hr = CoCreateInstance(CLSID_SpVoice, NULL, CLSCTX_ALL, IID_ISpVoice, (void **) &pVoice); //hr = CoCreateInstance(CLSID_SpVoice, NULL, CLSCTX_ALL, IID_ISpVoice, (void **) &pVoice); //HRESULT hr = CoCreateInstance(__uuidof(ISpVoice), NULL, CLSCTX_INPROC_SERVER, IID_ISpVoice, (void **) &pVoice); HRESULT hr = CoCreateInstance(__uuidof(SpVoice), NULL, CLSCTX_ALL, IID_ISpVoice, (void **) &pVoice); if( SUCCEEDED( hr ) ) { printf("Succeeded\n"); hr = pVoice->Speak(L"The text to speech engine has been successfully initialized.", 0, NULL); } else { printf("failed\n"); MessageBox(NULL, TEXT("Failed To Create COM instance"), TEXT("Error"), 0); char buffer[2000] ; sprintf(buffer, "An error occured: 0x%08X.\n", hr); FILE * pFile = fopen ( "c:\\temp\\CoCreateInstance_dll.txt" , "w" ); fwrite (buffer , 1 , strlen(buffer) , pFile ); fclose (pFile); } } if(pVoice != NULL) { pVoice->Release(); pVoice = NULL; } CoUninitialize(); return NULL; } XPThreads* ptrThread = new XPThreads(init_engine_thread); BOOL APIENTRY DllMain( HMODULE hModule, DWORD ul_reason_for_call, LPVOID lpReserved) { switch (ul_reason_for_call) { case DLL_PROCESS_ATTACH: //init_engine(); LoadLibrary(TEXT("ole32.dll")); ptrThread->Run(); break; case DLL_THREAD_ATTACH: break; case DLL_THREAD_DETACH: break; case DLL_PROCESS_DETACH: break; } return TRUE; }

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  • Is it ok to dynamic cast "this" as a return value?

    - by Panayiotis Karabassis
    This is more of a design question. I have a template class, and I want to add extra methods to it depending on the template type. To practice the DRY principle, I have come up with this pattern (definitions intentionally omitted): template <class T> class BaseVector: public boost::array<T, 3> { protected: BaseVector<T>(const T x, const T y, const T z); public: bool operator == (const Vector<T> &other) const; Vector<T> operator + (const Vector<T> &other) const; Vector<T> operator - (const Vector<T> &other) const; Vector<T> &operator += (const Vector<T> &other) { (*this)[0] += other[0]; (*this)[1] += other[1]; (*this)[2] += other[2]; return *dynamic_cast<Vector<T> * const>(this); } } template <class T> class Vector : public BaseVector<T> { public: Vector<T>(const T x, const T y, const T z) : BaseVector<T>(x, y, z) { } }; template <> class Vector<double> : public BaseVector<double> { public: Vector<double>(const double x, const double y, const double z); Vector<double>(const Vector<int> &other); double norm() const; }; I intend BaseVector to be nothing more than an implementation detail. This works, but I am concerned about operator+=. My question is: is the dynamic cast of the this pointer a code smell? Is there a better way to achieve what I am trying to do (avoid code duplication, and unnecessary casts in the user code)? Or am I safe since, the BaseVector constructor is private?

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  • how to develop a program to minimize errors in human transcription of hand written surveys

    - by Alex. S.
    I need to develop custom software to do surveys. Questions may be of multiple choice, or free text in a very few cases. I was asked to design a subsystem to check if there is any error in the manual data entry for the multiple choices part. We're trying to speed up the user data entry process and to minimize human input differences between digital forms and the original questionnaires. The surveys are filled with handwritten marks and text by human interviewers, so it's possible to find hard to read marks, or also the user could accidentally select a different value in some question, and we would like to avoid that. The software must include some automatic control to detect possible typing differences. Each answer of the multiple choice questions has the same probability of being selected. This question has two parts: The GUI. The most simple thing I have in mind is to implement the most usable design of the questions display: use of large and readable fonts and space generously the choices. Is there something else? For faster input, I would like to use drop down lists (favoring keyboard over mouse). Given the questions are grouped in sections, I would like to show the answers selected for the questions of that section, but this could slow down the process. Any other ideas? The error checking subsystem. What else can I do to minimize or to check human typos in the multiple choice questions? Is this a solvable problem? is there some statistical methodology to check values that were entered by the users are the same from the hand filled forms? For example, let's suppose the survey has 5 questions, and each has 4 options. Let's say I have n survey forms filled in paper by interviewers, and they're ready to be entered in the software, then how to minimize the accidental differences that can have the manual transcription of the n surveys, without having to double check everything in the 5 questions of the n surveys? My first suggestion is that at the end of the processing of all the hand filled forms, the software could choose some forms randomly to make a double check of the responses in a few instances, but on what criteria can I make this selection? This validation would be enough to cover everything in a significant way? The actual survey is nation level and it has 56 pages with over 200 questions in total, so it will be a lot of hand written pages by many people, and the intention is to reduce the likelihood of errors and to optimize speed in the data entry process. The surveys must filled in paper first, given the complications of taking laptops or handhelds with the interviewers.

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  • How to Work Around Limitations in Generic Type Constraints in C#?

    - by Jose
    Okay I'm looking for some input, I'm pretty sure this is not currently supported in .NET 3.5 but here goes. I want to require a generic type passed into my class to have a constructor like this: new(IDictionary<string,object>) so the class would look like this public MyClass<T> where T : new(IDictionary<string,object>) { T CreateObject(IDictionary<string,object> values) { return new T(values); } } But the compiler doesn't support this, it doesn't really know what I'm asking. Some of you might ask, why do you want to do this? Well I'm working on a pet project of an ORM so I get values from the DB and then create the object and load the values. I thought it would be cleaner to allow the object just create itself with the values I give it. As far as I can tell I have two options: 1) Use reflection(which I'm trying to avoid) to grab the PropertyInfo[] array and then use that to load the values. 2) require T to support an interface like so: public interface ILoadValues { void LoadValues(IDictionary values); } and then do this public MyClass<T> where T:new(),ILoadValues { T CreateObject(IDictionary<string,object> values) { T obj = new T(); obj.LoadValues(values); return obj; } } The problem I have with the interface I guess is philosophical, I don't really want to expose a public method for people to load the values. Using the constructor the idea was that if I had an object like this namespace DataSource.Data { public class User { protected internal User(IDictionary<string,object> values) { //Initialize } } } As long as the MyClass<T> was in the same assembly the constructor would be available. I personally think that the Type constraint in my opinion should ask (Do I have access to this constructor? I do, great!) Anyways any input is welcome.

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  • How to implement a tagging plugin for jQuery

    - by anxiety
    Goal: To implement a jQuery plugin for my rails app (or write one myself, if necessary) that creates a "box" around text after a delimiter is typed. Example: With tagging on SO, the user begins typing a tag, then selects one from the drop-down list provided. The input field recognizes that a tag has been selected, puts a space and then is ready for the next tag. Similarly, I am attempting to use this plugin to put a box around the previously entered tag before moving to to accept the next tag/input. The instructions in the README.txt seem simple enough, however I have been receiving a $(".tagbox").tagbox is not a function error when debugging my app with firebug. Here is what I have in my application.js: $(document).ready( function(){ $('.tagbox').tagbox({ separator: /\[,]/, // specifying comma separation for <code>tags</code> }); }); And here is my _form.html.erb: <% form_for @tag do |f| %> <%= f.error_messages %> <p> <%= f.label :name %><br /> <%= text_field :tag, :name, { :method => :get, :class => "tagbox" } %> </p> <p><%= f.submit "Submit" %></p> <% end %> I have omitted some other code (namely the implementation of an autocomplete plugin) existing within my _form.html.erb and application.js for sake of readability. The inclusion or exclusion of this omitted code does not affect the performance of this plugin. I have included all of the necessary files for the tagbox plugin (as well as application.js after all other included JS files) within the javascript_include_tag in my application.html.erb file. I'm pretty much confused as to why I'd be getting this "not a function" error when jquery.tagbox.js clearly defines the function and is included in the head of my html page in question. I've been struggling with this plugin for longer than I'd like to admit, so any help would really be appreciated. And, of course, I'm open to any other plugins or from-scratch suggestions you may have in mind.. This tagbox plugin does not seem to have a wealth of documentation or any currently working examples. Also to note, I'm trying to avoid using jrails. Thanks for your time

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  • Embedded "Smart" character LCD driver. Is this a good idea?

    - by chris12892
    I have an embedded project that I am working on, and I am currently coding the character LCD driver. At the moment, the LCD driver only supports "dumb" writing. For example, let's say line 1 has some text on it, and I make a call to the function that writes to the line. The function will simply seek to the beginning of the line and write the text (plus enough whitespace to erase whatever was last written). This is well and good, but I get the feeling it is horribly inefficient sometimes, since some lines are simply: "Some-reading: some-Value" Rather than "brute force" replacing the entire line, I wanted to develop some code that would figure out the best way to update the information on the LCD. (just as background, it takes 2 bytes to seek to any char position. I can then begin writing the string) My idea was to first have a loop. This loop would compare the input to the last write, and in doing so, it would cover two things: A: Collect all the differences between the last write and the input. For every contiguous segment (be it same or different) add two bytes to the byte count. This is referenced in B to determine if we are wasting serial bandwidth. B: The loop would determine if this is really a smart thing to do. If we end up using more bytes to update the line than to "brute force" the line, then we should just return and let the brute force method take over. We should exit the smart write function as soon as this condition is met to avoid wasting time. The next part of the function would take all the differences, seek to the required char on the LCD, and write them. Thus, if we have a string like this already on the LCD: "Current Temp: 80F" and we want to update it to "Current Temp: 79F" The function will go through and see that it would take less bandwidth to simply seek to the "8" and write "79". The "7" will cover the "8" and the "9" will cover the "0". That way, we don't waste time writing out the entire string. Does this seem like a practical idea?

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  • Implementing coroutines in Java

    - by JUST MY correct OPINION
    This question is related to my question on existing coroutine implementations in Java. If, as I suspect, it turns out that there is no full implementation of coroutines currently available in Java, what would be required to implement them? As I said in that question, I know about the following: You can implement "coroutines" as threads/thread pools behind the scenes. You can do tricksy things with JVM bytecode behind the scenes to make coroutines possible. The so-called "Da Vinci Machine" JVM implementation has primitives that make coroutines doable without bytecode manipulation. There are various JNI-based approaches to coroutines also possible. I'll address each one's deficiencies in turn. Thread-based coroutines This "solution" is pathological. The whole point of coroutines is to avoid the overhead of threading, locking, kernel scheduling, etc. Coroutines are supposed to be light and fast and to execute only in user space. Implementing them in terms of full-tilt threads with tight restrictions gets rid of all the advantages. JVM bytecode manipulation This solution is more practical, albeit a bit difficult to pull off. This is roughly the same as jumping down into assembly language for coroutine libraries in C (which is how many of them work) with the advantage that you have only one architecture to worry about and get right. It also ties you down to only running your code on fully-compliant JVM stacks (which means, for example, no Android) unless you can find a way to do the same thing on the non-compliant stack. If you do find a way to do this, however, you have now doubled your system complexity and testing needs. The Da Vinci Machine The Da Vinci Machine is cool for experimentation, but since it is not a standard JVM its features aren't going to be available everywhere. Indeed I suspect most production environments would specifically forbid the use of the Da Vinci Machine. Thus I could use this to make cool experiments but not for any code I expect to release to the real world. This also has the added problem similar to the JVM bytecode manipulation solution above: won't work on alternative stacks (like Android's). JNI implementation This solution renders the point of doing this in Java at all moot. Each combination of CPU and operating system requires independent testing and each is a point of potentially frustrating subtle failure. Alternatively, of course, I could tie myself down to one platform entirely but this, too, makes the point of doing things in Java entirely moot. So... Is there any way to implement coroutines in Java without using one of these four techniques? Or will I be forced to use the one of those four that smells the least (JVM manipulation) instead?

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