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• How to map combinations of things to a relational database?

  - by Space_C0wb0y

  I have a table whose records represent certain objects. For the sake of simplicity I am going to assume that the table only has one row, and that is the unique ObjectId. Now I need a way to store combinations of objects from that table. The combinations have to be unique, but can be of arbitrary length. For example, if I have the ObjectIds 1,2,3,4 I want to store the following combinations: {1,2}, {1,3,4}, {2,4}, {1,2,3,4} The ordering is not necessary. My current implementation is to have a table Combinations that maps ObjectIds to CombinationIds. So every combination receives a unique Id: ObjectId | CombinationId ------------------------ 1 | 1 2 | 1 1 | 2 3 | 2 4 | 2 This is the mapping for the first two combinations of the example above. The problem is, that the query for finding the CombinationId of a specific Combination seems to be very complex. The two main usage scenarios for this table will be to iterate over all combinations, and the retrieve a specific combination. The table will be created once and never be updated. I am using SQLite through JDBC. Is there any simpler way or a best practice to implement such a mapping?

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• How can I include DBNull as a value in my strongly typed dataset?

  - by Beska

  I've created a strongly typed dataset (MyDataSet) in my .NET app. For the sake of simplicity, we'll say it has one DataTable (MyDataTable), with one column (MyCol). MyCol has its DataType property set to "System.Int32", and its AllowDBNull property set to "true". I'd like to manually create a new row, and add it to this dataset. I create the row without a problem, with something like: MyDataSet.MyDataTableRow myRow = MySimpleDataSet.MyDataTable.NewItemRow(); Fine. However, when I try to set the value to DBNull: myRow.MyCol = DBNull.Value; I'm told that I can't do it...that it can't cast that to an int. This makes sense, in a way, since I've defined it to be an int...but then how can I get DBNull in there? Am I not supposed to be able to have DBNull in there? Isn't that what the AllowDBNull property is for? I'm obviously missing something fundemental. Can someone help explain what it is? EDIT: I also tried entering "int?" as the DataType, but Visual Studio throws an error when I enter it, saying that "Column requires a valid DataType."

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• CSS positioning div above another div when not in that order in the HTML

  - by devmode

  Given a template where the HTML cannot be modified because of other requirements, how is it possible to display a div above another div when they are not in that order in the HTML and both divs contain data that could produce a varying height and width. HTML: <div id="wrapper"     <div id="firstDiv"         Content to be below in this situation     </div     <div id="secondDiv"         Content to be above in this situation     </div </div Other elements Hopefully it is obvious that the desired result is: Content to be above in this situation Content to be below in this situation Other elements When the dimensions are fixed it easy to position them where needed, but I need some ideas for when the content is variable. For the sake of this scenario, please just consider the width to be 100% on both. Edit: A CSS solution is the most ideal solution. Thank you for the Javascript options mentioned. Without getting too wordy about what or why (or who) ... I am specifically looking for a CSS only solution (and it will probably have to be met with other solutions if that doesn't pan out). One more ... there are other elements following this. A good suggestion was mentioned given the limited scenario I demonstrated -- given that it might be the best answer, but I am looking to also make sure elements following this aren't impacted.

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• How to build a control programatically?

  - by W_K

  I have custom control written in Java. For the sake of simplicity lets assume that it looks like this: public class HelloworldControl extends UIComponentBase { @Override public void decode(FacesContext context) { String cid = this.getClientId(context); ... super.decode(context); } @Override public void encodeBegin(FacesContext context) throws IOException { ResponseWriter writer = context.getResponseWriter(); writer.writeText("Hello world!", this); // I want a view!! } @Override public void encodeEnd(FacesContext context) throws IOException { ResponseWriter writer = context.getResponseWriter(); ... } public void restoreState(FacesContext context, Object state) { Object values[] = (Object[]) state; ... super.restoreState(context, values[0]); } public Object saveState(FacesContext context) { Object values[] = ... } } I would like to add programatically child control to it. For example I would like a child view control to render a view just under the Hellow world text. How can i do this? What is the standard procedure to build dynamically a control? To put it simply - I want programatically build a hierarchy of standard components and I want to attach it to my control.

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• Split UInt32 (audio frame) into two SInt16s (left and right)?

  - by morgancodes

  Total noob to anything lower-level than Java, diving into iPhone audio, and realing from all of the casting/pointers/raw memory access. I'm working with some example code wich reads a WAV file from disc and returns stereo samples as single UInt32 values. If I understand correctly, this is just a convenient way to return the 32 bits of memory required to create two 16 bit samples. Eventually this data gets written to a buffer, and an audio unit picks it up down the road. Even though the data is written in UInt32-sized chunks, it eventually is interpreted as pairs of 16-bit samples. What I need help with is splitting these UInt32 frames into left and right samples. I'm assuming I'll want to convert each UInt32 into an SInt16, since an audio sample is a signed value. It seems to me that for efficiency's sake, I ought to be able to simply point to the same blocks in memory, and avoid any copying. So, in pseudo-code, it would be something like this: UInt32 myStereoFrame = getFramefromFilePlayer; SInt16* leftChannel = getFirst16Bits(myStereoFrame); SInt16* rightChannel = getSecond16Bits(myStereoFrame); Can anyone help me turn my pseudo into real code?

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• EF in a UserControl can't see the app.config?

  - by Sven

  I just created a user control. This control also makes use of my static Entity Framework class to load two comboboxes. All is well and runs without a problem. Design and runtime are working. Then when I stop the application all the forms that contain my UserControl don't work any more in design time. I just see two errors: Error1: The specified named connection is either not found in the configuration, not intended to be used with the EntityClient provider, or not valid. Error 2: The variable ccArtikelVelden is either undeclared or was never assigned. (ccArtikelVelde is my UserControl) Runtime everything is still working My static EF Repositoy class: public class BSManagerData { private static BSManagerEntities _entities; public static BSManagerEntities Entities { get { if (_entities == null) _entities = new BSManagerEntities(); return _entities; } set { _entities = value; } } } Some logic happening in my UserControl to load the data in the comboboxes: private void LaadCbx() { cbxCategorie.DataSource = (from c in BSManagerData.Entities.Categories select c).ToList(); cbxCategorie.DisplayMember = "Naam"; cbxCategorie.ValueMember = "Id"; } private void cbxCategorie_SelectedIndexChanged(object sender, EventArgs e) { cbxFabrikant.DataSource = from f in BSManagerData.Entities.Fabrikants where f.Categorie.Id == ((Categorie)cbxCategorie.SelectedItem).Id select f; cbxFabrikant.DisplayMember = "Naam"; cbxFabrikant.ValueMember = "Id"; } The only way to make my forms work again, design time, is to comment out the EF part in the UserControl (see above) and rebuild. It's very strange, everything is in the same assembly, same namespace (for the sake of simplicity). Anyone an idea?

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• Is there a way for -webkit-animtion-timing-function to apply to the entire animation instead of each keyframe?

  - by Ken Sykora

  I'm a bit new to animation, so forgive me if I'm missing a huge concept here. I need to animate an arrow that is pointing to a point on a curve, let's just say it's a cubic curve for the sake of this post. The arrow moves along the curve's line, always pointing a few pixels below it. So what I did, is I setup keyframes along the curve's line using CSS3: @-webkit-keyframes ftch { 0% { opacity: 0; left: -10px; bottom: 12px; } 25% { opacity: 0.25; left: 56.5px; bottom: -7px; } 50% { opacity: 0.5; left: 143px; bottom: -20px; } 75% { opacity: 0.75; left: 209.5px; bottom: -24.5px; } 100% { opacity: 1; left: 266px; bottom: -26px; } } However, when I run this animation using -webkit-animation-timing-function: ease-in, it applies that easing to each individual keyframe, which is definitely not what I want. I want the easing to apply to the entire animation. Is there a different way that I should be doing this? Is there some property to apply the easing to the entire sequence rather than each keyframe?

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• Short file names versus long file names in Windows

  - by normski

  I have some code which gets the short name from a file path, using GetShortNameW(), and then later retrieves the long name view GetLongNameA(). The original file is of the form "C:/ProgramData/My Folder/File.ext" However, following conversion to short, then back to long, the filename becomes "C:/Program Files/My Folder/Filename.ext". The short name is of the form "C:/PROGRA~2/MY_FOL~1/FIL~1.EXT" The short name is being incorrectly resolved. The code compiles using VS 2005 on Windows 7 (I cannot upgrade the project to VS2008) Does anybody have any idea why this might be happening? DWORD pathLengthNeeded = ::GetShortPathNameW(aRef->GetFilePath().c_str(), NULL, 0); if(pathLengthNeeded != 0) { WCHAR* shortPath = new WCHAR[pathLengthNeeded]; DWORD newPathNameLength = ::GetShortPathNameW(aRef->GetFilePath().c_str(), shortPath, pathLengthNeeded); if(newPathNameLength != 0) { UI_STRING unicodePath(shortPath); std::string asciiPath = StringFromUserString(unicodePath); pathLengthNeeded = ::GetLongPathNameA(asciiPath.c_str(),NULL, 0); if(pathLengthNeeded != 0) {// convert it back to a long path if possible. For goodness sake can't we use Unicode throughout?F char* longPath = new char[pathLengthNeeded]; DWORD newPathNameLength = ::GetLongPathNameA(asciiPath.c_str(), longPath, pathLengthNeeded); if(newPathNameLength != 0) { std::string longPathString(longPath, newPathNameLength); asciiPath = longPathString; } delete [] longPath; } SetFullPathName(asciiPath); } delete [] shortPath; }

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• Wicket application + Apache + mod_jk - AJP queues are filling up!

  - by nojyarg

  Dear community, We are having a Wicket-based Java application deployed in a production server cluster using Apache (2.2.3) with mod_jk (1.2.30) as load balancing component w/ sticky session and Jboss 5 as application container for the Java application. We are inconsistently seeing an issue in our production environment where our AJP queues between Apache and Jboss as shown in the JMX console fill up with requests to the point where the application server is no longer taking on any new requests. When looking at all involved system components (overall traffic, load db, process list db, load of all clustered application server nodes) nothing points towards a capacity issue which would explain why the calls are being stalled in the AJP queue. Instead all systems appear sufficiently idle. So far, our only remedy to this issue is to restart the appservers and the load balancer which only occasionally clears the AJP queues. We are trying to figure out why the queues are filling up to the point that no calls get returned to the end user although the system is not under a high load. Has anyone else experienced similar problems? Are there any other system metrics we should monitor that could explain the queuing behavior? Is this potentially a mod_jk issue? If so, is it advisable to swap mod_jk with mod_cluster to resolve the issue? Any advice is highly appreciated. If I can provide additional information for the sake of troubleshooting I would be more than willing to do so. /Ben

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• Could this be considered a well-written PHP5 class?

  - by Ben Dauphinee

  I have been learning OOP principals on my own for a while, and taken a few cracks at writing classes. What I really need to know now is if I am actually using what I have learned correctly, or if I could improve as far as OOP is concerned. I have chopped a massive portion of code out of a class that I have been working on for a while now, and pasted it here. To all you skilled and knowledgeable programmers here I ask: Am I doing it wrong? class acl extends genericAPI{ // -- Copied from genericAPI class protected final function sanityCheck($what, $check, $vars){ switch($check){ case 'set': if(isset($vars[$what])){return(1);}else{return(0);} break; } } // --------------------------------- protected $db = null; protected $dataQuery = null; public function __construct(Zend_Db_Adapter_Abstract $db, $config = array()){ $this->db = $db; if(!empty($config)){$this->config = $config;} } protected function _buildQuery($selectType = null, $vars = array()){ // Removed switches for simplicity sake $this->dataQuery = $this->db->select( )->from( $this->config['table_users'], array('tf' => '(CASE WHEN count(*) > 0 THEN 1 ELSE 0 END)') )->where( $this->config['uidcol'] . ' = ?', $vars['uid'] ); } protected function _sanityRun_acl($sanitycheck, &$vars){ switch($sanitycheck){ case 'uid_set': if(!$this->sanityCheck('uid', 'set', $vars)){ throw new Exception(ERR_ACL_NOUID); } $vars['uid'] = settype($vars['uid'], 'integer'); break; } } private function user($action = null, $vars = array()){ switch($action){ case 'exists': $this->_sanityRun_acl('uid_set', $vars); $this->_buildQuery('user_exists_idcheck', $vars); return($this->db->fetchOne($this->dataQuery->__toString())); break; } } public function user_exists($uid){ return($this->user('exists', array('uid' => $uid))); } } $return = $acl_test->user_exists(1);

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• Replacing symbol from object file at compile time. For example swapping out main

  - by Anthony Sottile

  Here's the use case: I have a .cpp file which has functions implemented in it. For sake of example say it has the following: [main.cpp] #include <iostream> int foo(int); int foo(int a) { return a * a; } int main() { for (int i = 0; i < 5; i += 1) { std::cout << foo(i) << std::endl; } return 0; } I want to perform some amount of automated testing on the function foo in this file but would need to replace out the main() function to do my testing. Preferably I'd like to have a separate file like this that I could link in over top of that one: [mymain.cpp] #include <iostream> #include <cassert> extern int foo(int); int main() { assert(foo(1) == 1); assert(foo(2) == 4); assert(foo(0) == 0); assert(foo(-2) == 4); return 0; } I'd like (if at all possible) to avoid changing the original .cpp file in order to do this -- though this would be my approach if this is not possible: do a replace for "(\s)main\s*\(" == "\1__oldmain\(" compile as usual. The environment I am targeting is a linux environment with g++.

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• I've registered my oath about 5 times now, but... (twitteR package R)

  - by user2985989

  I'm attempting to mine twitter data in R, and am having trouble getting started. I created a twitter account, an app in twitter developers, changed the settings to read, write, and access, created my access token, and followed instructions to the letter in registering it: My code: > library(twitteR) > download.file(url="http://curl.haxx.se/ca/cacert.pem", + destfile="cacert.pem") > requestURL <- "https://api.twitter.com/oauth/request_token" > accessURL <- "https://api.twitter.com/oauth/access_token" > authURL <- "https://api.twitter.com/oauth/authorize" > consumerKey <-"my key" #took this part out for privacy's sake > consumerSecret <- "my secret" #this too > twitCred <- OAuthFactory$new(consumerKey=consumerKey, consumerSecret = consumerSecret, requestURL = requestURL, accessURL = accessURL, authURL = authURL) > twitCred$handshake(cainfo="cacert.pem") To enable the connection, please direct your web browser to: https://api.twitter.com/oauth/authorize?oauth_token=zxgHXJkYAB3wQ2IVAeyJjeyid7WK6EGPfouGmlx1c When complete, record the PIN given to you and provide it here: 0010819 > registerTwitterOAuth(twitCred) [1] TRUE > save(list="twitCred", file="twitteR_credentials") And yet, this: > s <- searchTwitter('#United', cainfo="cacert.pem") [1] "Unauthorized" Error in twInterfaceObj$doAPICall(cmd, params, "GET", ...) : Error: Unauthorized I'm about to have a temper tantrum. I'd be extremely grateful if someone could explain to me what is going wrong, or, better yet, how to fix it. Thank you.

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• What is the correct approach to using GWT with persistent objects?

  - by dankilman

  Hi, I am currently working on a simple web application through Google App engine using GWT. It should be noted that this is my first attempt at such a task. I have run into to following problem/dilema: I have a simple Class (getters/setters and nothing more. For the sake of clarity I will refer to this Class as DataHolder) and I want to make it persistent. To do so I have used JDO which required me to add some annotations and more specifically add a Key field to be used as the primary key. The problem is that using the Key class requires me to import com.google.appengine.api.datastore.Key which is ok on the server side, but then I can't use DataHolder on the client side, because GWT doesn't allow it (as far as I know). So I have created a sister Class ClientDataHolder which is almost identical, though it doesn't have all the JDO annotations nor the Key field. Now this actually works but It feels like I'm doing something wrong. Using this approach would require maintaining to separate classes for each entity I wish to have. So my question is: Is there a better way of doing this? Thank you.

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• Sharing rails fragments between formats

  - by Julian

  Hi I'm toying with mobile_fu and want to share some fragments between the different views. E.g. views/ item/ view.html.erb view.mobile.rb shared/ _common.erb In both view.html.erb and view.mobile.erb I want to share the same fragment '_common.erb' without having to specify the format (should you ever have to specify the format inside a fragment? It doesn't seem like The Rails Way?). Let's say for arguments's sake it's because it's in a helper or whatever -- the point is that I need to share fragments in a 'well-defined and Railsy way' across formats. Let's take this fairly innocuous snippet <% render :fragment => 'shared/common' %> I've tried 3 file name conventions: _common.html.erb only works for html /item/view/xx fails with 'shared/_common.erb not found') however _common.erb fails for html and works for mobile (maybe mobile_fu is doing something wacky?) -- same error as for .html.erb version above _common.rhtml does work for both I'm thinking that: that rhtml works for both is a legacy hack and I'm loathe to rename all the shared fragments .rhtml to get the behaviour I want. Any feedback gratefully welcome! Including 'you fundamentally don't understand how Rails works please RTFM here: http://....' :)

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• C++ compiler unable to find function (namespace related)

  - by CS student

  I'm working in Visual Studio 2008 on a C++ programming assignment. We were supplied with files that define the following namespace hierarchy (the names are just for the sake of this post, I know "namespace XYZ-NAMESPACE" is redundant): (MAIN-NAMESPACE){ a bunch of functions/classes I need to implement... (EXCEPTIONS-NAMESPACE){ a bunch of exceptions } (POINTER-COLLECTIONS-NAMESPACE){ Set and LinkedList classes, plus iterators } } The MAIN-NAMESPACE contents are split between a bunch of files, and for some reason which I don't understand the operator<< for both Set and LinkedList is entirely outside of the MAIN-NAMESPACE (but within Set and LinkedList's header file). Here's the Set version: template<typename T> std::ostream& operator<<(std::ostream& os, const MAIN-NAMESPACE::POINTER-COLLECTIONS-NAMESPACE::Set<T>& set) Now here's the problem: I have the following data structure: Set A Set B Set C double num It's defined to be in a class within MAIN-NAMESPACE. When I create an instance of the class, and try to print one of the sets, it tells me that: error C2679: binary '<<' : no operator found which takes a right-hand operand of type 'const MAIN-NAMESPACE::POINTER-COLLECTIONS-NAMESPACE::Set' (or there is no acceptable conversion) However, if I just write a main() function, and create Set A, fill it up, and use the operator- it works. Any idea what is the problem? (note: I tried any combination of using and include I could think of).

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• Adding fields until screen is full

  - by Eric

  For the sake of this question, let us suppose that I want a row of buttons. I want to put as many buttons in that row as I can fit on the screen, but no more. In other words, as long as a prospective button will not be cut off or have its text shortened, add it. It seems that I should be able to do something like: HorizontalFieldManager hfm = new HorizontalFieldManager(); int remainingWidth = Display.getWidth(); int i =0; while(true) { ButtonField bf = new ButtonField("B " + i); remainingWidth -= bf.getWidth(); if(remainingWidth<0) break; hfm.add(bf); i++; } add(hfm); But this doesn't work. bf.getWidth() is always 0. I suspect that this is because the button has not yet been laid out when I query for the width. So, perhaps I could just make sure the buttons are always the same size. But this won't work for a few reasons: Different BB platforms have different looks for buttons and text that will fit on a button on a Curve won't fit on a button on a Storm. 3rd party themes may change the look of buttons, so I can't even count on buttons being a certain size on a certain platform. Is there no way for me to actually check the remaining space before adding a button? It feels like a fairly useful feature; am I just missing something?

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• Powershell: splatting after passing hashtable by reference

  - by user1815871

  Powershell newbie ... I recently learned about splatting — very useful. I ran into a snag when I passed a hash table by reference to a function for splatting purposes. (For brevity's sake — a silly example.) Function AllMyChildren { param ( [ref]$ReferenceToHash } get-childitem @ReferenceToHash.Value # etc.etc. } $MyHash = @{ 'path' = '*' 'include' = '*.ps1' 'name' = $null } AllMyChildren ([ref]$MyHash) Result: an error ("Splatted variables cannot be used as part of a property or array expression. Assign the result of the expression to a temporary variable then splat the temporary variable instead."). Tried this afterward: $newVariable = $ReferenceToHash.Value get-childitem @NewVariable That did work and seemed right per the error message. But: is it the preferred syntax in a case like this? (An oh, look, it actually worked solution isn't always a best practice. My approach here strikes me as "Perl-minded" and perhaps in Powershell passing by value is better, though I don't yet know the syntax for it w.r.t. a hash table.)

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• iPhone SDK Programming - Working with a variable across 2 views

  - by SD

  I have what I hope is a fairly simple question about using the value from a variable across 2 views. I’m new to the iPhone SDK platform and the Model/View/Controller methodology. I’ve got background in VB.Net, some Php, but mostly SQL, so this is new ground for me. I’m building an app that has 3 views. For simplicity’s sake, I’ll call them View1, View2, View3. On View1 I have an NSString variable that I’ve declared in View1.h, and synthesized in View1.m. I’ll call it String1. View1.m uses a UITextField to ask the user for their name and then sets the value of String1 to that name (i.e. "Bill"). I would now like to use the value of String1 in View2. I'm not doing anything other than displaying the value ("Bill"), in a UILabel object in View2. Can someone tell me what the easiest way to accomplish that is? Many thanks in advance….

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• Rails: creating a model in the new action

  - by Joseph Silvashy

  I have an interesting situation, well it's probably not that unique at all, but I'm not totally sure how to tackle it. I have a model, in this case a recipe and the user navigates to the new path /recipes/new however the situation is that I need to be able to have the user upload images and make associations to that model in the new action, but the model doesn't have an ID yet. So I assume I need to rethink my controller, but I don't want to have redirects and whatnot, how can accomplish this? Here is the basic controller, barebones obviously: ... def new # I should be creating the model first, so it has an ID @recipe = Recipe.new end def create @recipe = Recipe.new(params[:recipe]) if @recipe.save redirect_to @recipe else render 'new' end end ... update Perhaps I can have a column thats like state which could have values like new/incomplete/complete or what-have-you. I'm mostly trying to figure out what would also be most efficient for the DB. It would be nice if I could still have a url that said '/new', instead of it be the edit path with the id, for usability sake, but I'm not sure this can be simply accomplished in the new action of my controller. Thoughts?

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• Best way to parse this particular string using awk / sed?

  - by Jack

  Hi, I need to get a particular version string from a file (call it version.lst) and use it to compare another in a shell script. For example sake, the file contains lines that look like this: V1.000 -- build date and other info here -- APP1 V1.000 -- build date and other info here -- APP2 V1.500 -- build date and other info here -- APP3 .. and so on. Let's say I am trying to grab the first version (in this case, V1.000) from APP1. Obviously, the versions can change and I want this to be dynamic. What I have right now works: var = `cat version.lst | grep " -- APP1" | grep -Eo V[0-9].[0-9]{3}` Pipe to grep will get the line containing APP1 and the second pipe to grep will get the version string. However, I hear grep is not the way to do this so I'd like to learn the best way using awk or sed. Any ideas? I am new to both and haven't found a tutorial easy enough to learn the syntax of it. Do they support egrep? Thanks!

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• Member function overloading/template specialization issue

  - by Ferruccio

  I've been trying to call the overloaded table::scan_index(std::string, ...) member function without success. For the sake of clarity, I have stripped out all non-relevant code. I have a class called table which has an overloaded/templated member function named scan_index() in order to handle strings as a special case. class table : boost::noncopyable { public: template <typename T> void scan_index(T val, std::function<bool (uint recno, T val)> callback) { // code } void scan_index(std::string val, std::function<bool (uint recno, std::string val)> callback) { // code } }; Then there is a hitlist class which has a number of templated member functions which call table::scan_index(T, ...) class hitlist { public: template <typename T> void eq(uint fieldno, T value) { table* index_table = db.get_index_table(fieldno); // code index_table->scan_index<T>(value, [&](uint recno, T n)->bool { // code }); } }; And, finally, the code which kicks it all off: hitlist hl; // code hl.eq<std::string>(*fieldno, p1.to_string()); The problem is that instead of calling table::scan_index(std::string, ...), it calls the templated version. I have tried using both overloading (as shown above) and a specialized function template (below), but nothing seems to work. After staring at this code for a few hours, I feel like I'm missing something obvious. Any ideas? template <> void scan_index<std::string>(std::string val, std::function<bool (uint recno, std::string val)> callback) { // code }

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• Type-safe generic data structures in plain-old C?

  - by Bradford Larsen

  I have done far more C++ programming than "plain old C" programming. One thing I sorely miss when programming in plain C is type-safe generic data structures, which are provided in C++ via templates. For sake of concreteness, consider a generic singly linked list. In C++, it is a simple matter to define your own template class, and then instantiate it for the types you need. In C, I can think of a few ways of implementing a generic singly linked list: Write the linked list type(s) and supporting procedures once, using void pointers to go around the type system. Write preprocessor macros taking the necessary type names, etc, to generate a type-specific version of the data structure and supporting procedures. Use a more sophisticated, stand-alone tool to generate the code for the types you need. I don't like option 1, as it is subverts the type system, and would likely have worse performance than a specialized type-specific implementation. Using a uniform representation of the data structure for all types, and casting to/from void pointers, so far as I can see, necessitates an indirection that would be avoided by an implementation specialized for the element type. Option 2 doesn't require any extra tools, but it feels somewhat clunky, and could give bad compiler errors when used improperly. Option 3 could give better compiler error messages than option 2, as the specialized data structure code would reside in expanded form that could be opened in an editor and inspected by the programmer (as opposed to code generated by preprocessor macros). However, this option is the most heavyweight, a sort of "poor-man's templates". I have used this approach before, using a simple sed script to specialize a "templated" version of some C code. I would like to program my future "low-level" projects in C rather than C++, but have been frightened by the thought of rewriting common data structures for each specific type. What experience do people have with this issue? Are there good libraries of generic data structures and algorithms in C that do not go with Option 1 (i.e. casting to and from void pointers, which sacrifices type safety and adds a level of indirection)?

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• Performing an action on Parent/Child elements independently.

  - by Matt Weldon

  I have HTML similar to the following in my page <div id="someDiv"> <img src="foo.gif" class="someImg" /> </div> The wrapper div is set up such that when it is clicked, it's background-color changes using the following jQuery code. $("div").click(function(event){ $(this).css("background-color", "blue"); }); I also have some jQuery associated with my img that will do some other function (for the sake of argument I am going to display and alert box) like so: $("img[class=someImg]").click(function(event){ alert("Image clicked"); }); The issue I have come across is that when I click on the img, the event associated with the div is also triggered. I'm pretty sure that this is due to the way that jQuery (or indeed JavaScript) is handling the two DOM elements - clicking the img would require you to also technically click the div, thus triggering both events. Two questions then really: Is my understanding of the DOM/JavaScript flawed in some way or is this actually how things are occurring? Are there any jQuery methods that would allow me to perform actions on a child element without invoking those associated with its parent?

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• Programmatically Update UITableView in Response to Button Press

  - by Kyle Begeman

  I have a completely custom view that holds a UITableView and a Custom Tab Bar (basically a UIView that contains 6 UIButtons). I am loading data from a plist file, and then I am sorting the data into multiple arrays based on categories (an array for misc items, and array for mail items, etc.) Each button in the tab bar represents a category, and when I press the button I call the custom function "miscSelected" and so on. How can I have the table view completely reload and then display the tableview based on the array selected (select the misc category and the tableview clears itself and loads the misc array data, same for any other category)? The method I have experimented with is created and NSString named "selection" and then in each button function I set selected to equal whatever section I am selecting. In my cellForRoxAtIndexPath method I have this: if ([self.selection isEqualToString:@"All Items"]) { NSArray *mainDataArray = [NSArray arrayWithContentsOfFile:self.plistFile]; NSSortDescriptor *brandDescriptor = [[NSSortDescriptor alloc] initWithKey:@"name" ascending:YES]; NSArray *sortDescriptors = [NSArray arrayWithObject:brandDescriptor]; self.sortedData = [mainDataArray sortedArrayUsingDescriptors:sortDescriptors]; } else if ([self.selection isEqualToString:@"Misc Items"]){ self.sortedData = [NSArray arrayWithContentsOfFile:self.plistFile]; } cell.itemTitle.text = [[self.sortedData objectAtIndex:indexPath.row] objectForKey:@"name"]; For the sake of example and testing I am simply displaying the same data, just one button displays it in alphabetical order and the other does not. This code works only when I start to scroll down and back up, but it does not actually update on button press. Calling myTable reloadData does not do anything either. Any help would be great, thanks!

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• How do I iterate through hierarchical data in a Sql Server 2005 stored proc?

  - by AlexChilcott

  Hi, I have a SqlServer2005 table "Group" similar to the following: Id (PK, int) Name (varchar(50)) ParentId (int) where ParentId refers to another Id in the Group table. This is used to model hierarchical groups such as: Group 1 (id = 1, parentid = null) +--Group 2 (id = 2, parentid = 1) +--Group 3 (id = 3, parentid = 1) +--Group 4 (id = 4, parentid = 3) Group 5 (id = 5, parentid = null) +--Group 6 (id = 6, parentid = 5) You get the picture I have another table, let's call it "Data" for the sake of simplification, which looks something like: Id (PK, int) Key (varchar) Value (varchar) GroupId (FK, int) Now, I am trying to write a stored proc which can get me the "Data" for a given group. For example, if I query for group 1, it returns me the Key-Value-Pairs from Data where groupId = 1. If I query for group 2, it returns the KVPs for groupId = 1, then unioned with those which have groupId = 2 (and duplicated keys are replaced). Ideally, the sproc would also fail gracefully if there is a cycle (ie if group 1's parent is group 2 and group 2's parent is group 1) Has anyone had experience in writing such a sproc, or know how this might be accomplished? Thanks guys, much appreciated, Alex

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