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  • Speeding up templates in GAE-Py by aggregating RPC calls

    - by Sudhir Jonathan
    Here's my problem: class City(Model): name = StringProperty() class Author(Model): name = StringProperty() city = ReferenceProperty(City) class Post(Model): author = ReferenceProperty(Author) content = StringProperty() The code isn't important... its this django template: {% for post in posts %} <div>{{post.content}}</div> <div>by {{post.author.name}} from {{post.author.city.name}}</div> {% endfor %} Now lets say I get the first 100 posts using Post.all().fetch(limit=100), and pass this list to the template - what happens? It makes 200 more datastore gets - 100 to get each author, 100 to get each author's city. This is perfectly understandable, actually, since the post only has a reference to the author, and the author only has a reference to the city. The __get__ accessor on the post.author and author.city objects transparently do a get and pull the data back (See this question). Some ways around this are Use Post.author.get_value_for_datastore(post) to collect the author keys (see the link above), and then do a batch get to get them all - the trouble here is that we need to re-construct a template data object... something which needs extra code and maintenance for each model and handler. Write an accessor, say cached_author, that checks memcache for the author first and returns that - the problem here is that post.cached_author is going to be called 100 times, which could probably mean 100 memcache calls. Hold a static key to object map (and refresh it maybe once in five minutes) if the data doesn't have to be very up to date. The cached_author accessor can then just refer to this map. All these ideas need extra code and maintenance, and they're not very transparent. What if we could do @prefetch def render_template(path, data) template.render(path, data) Turns out we can... hooks and Guido's instrumentation module both prove it. If the @prefetch method wraps a template render by capturing which keys are requested we can (atleast to one level of depth) capture which keys are being requested, return mock objects, and do a batch get on them. This could be repeated for all depth levels, till no new keys are being requested. The final render could intercept the gets and return the objects from a map. This would change a total of 200 gets into 3, transparently and without any extra code. Not to mention greatly cut down the need for memcache and help in situations where memcache can't be used. Trouble is I don't know how to do it (yet). Before I start trying, has anyone else done this? Or does anyone want to help? Or do you see a massive flaw in the plan?

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  • How do large blobs affect SQL delete performance, and how can I mitigate the impact?

    - by Max Pollack
    I'm currently experiencing a strange issue that my understanding of SQL Server doesn't quite mesh with. We use SQL as our file storage for our internal storage service, and our database has about half a million rows in it. Most of the files (86%) are 1mb or under, but even on fresh copies of our database where we simply populate the table with data for the purposes of a test, it appears that rows with large amounts of data stored in a BLOB frequently cause timeouts when our SQL Server is under load. My understanding of how SQL Server deletes rows is that it's a garbage collection process, i.e. the row is marked as a ghost and the row is later deleted by the ghost cleanup process after the changes are copied to the transaction log. This suggests to me that regardless of the size of the data in the blob, row deletion should be close to instantaneous. However when deleting these rows we are definitely experiencing large numbers of timeouts and astoundingly low performance. In our test data set, its files over 30mb that cause this issue. This is an edge case, we don't frequently encounter these, and even though we're looking into SQL filestream as a solution to some of our problems, we're trying to narrow down where these issues are originating from. We ARE performing our deletes inside of a transaction. We're also performing updates to metadata such as file size stats, but these exist in a separate table away from the file data itself. Hierarchy data is stored in the table that contains the file information. Really, in the end it's not so much what we're doing around the deletes that matters, we just can't find any references to low delete performance on rows that contain a large amount of data in a BLOB. We are trying to determine if this is even an avenue worth exploring, or if it has to be one of our processes around the delete that's causing the issue. Are there any situations in which this could occur? Is it common for a database server to come to the point of complete timeouts when many of these deletes are occurring simultaneously? Is there a way to combat this issue if it exists? (cross-posted from StackOverflow )

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  • Warning: Cannot modify header information - headers already sent

    - by Pankaj Khurana
    Hi, I am using code available on http://www.forosdelweb.com/f18/zip-lib-php-archivo-zip-vacio-431133/ for creating zip file. First file-zip.lib.php <?php /* $Id: zip.lib.php,v 1.1 2004/02/14 15:21:18 anoncvs_tusedb Exp $ */ // vim: expandtab sw=4 ts=4 sts=4: /** * Zip file creation class. * Makes zip files. * * Last Modification and Extension By : * * Hasin Hayder * HomePage : www.hasinme.info * Email : [email protected] * IDE : PHP Designer 2005 * * * Originally Based on : * * http://www.zend.com/codex.php?id=535&single=1 * By Eric Mueller <[email protected]> * * http://www.zend.com/codex.php?id=470&single=1 * by Denis125 <[email protected]> * * a patch from Peter Listiak <[email protected]> for last modified * date and time of the compressed file * * Official ZIP file format: http://www.pkware.com/appnote.txt * * @access public */ class zipfile { /** * Array to store compressed data * * @var array $datasec */ var $datasec = array(); /** * Central directory * * @var array $ctrl_dir */ var $ctrl_dir = array(); /** * End of central directory record * * @var string $eof_ctrl_dir */ var $eof_ctrl_dir = "\x50\x4b\x05\x06\x00\x00\x00\x00"; /** * Last offset position * * @var integer $old_offset */ var $old_offset = 0; /** * Converts an Unix timestamp to a four byte DOS date and time format (date * in high two bytes, time in low two bytes allowing magnitude comparison). * * @param integer the current Unix timestamp * * @return integer the current date in a four byte DOS format * * @access private */ function unix2DosTime($unixtime = 0) { $timearray = ($unixtime == 0) ? getdate() : getdate($unixtime); if ($timearray['year'] < 1980) { $timearray['year'] = 1980; $timearray['mon'] = 1; $timearray['mday'] = 1; $timearray['hours'] = 0; $timearray['minutes'] = 0; $timearray['seconds'] = 0; } // end if return (($timearray['year'] - 1980) << 25) | ($timearray['mon'] << 21) | ($timearray['mday'] << 16) | ($timearray['hours'] << 11) | ($timearray['minutes'] << 5) | ($timearray['seconds'] >> 1); } // end of the 'unix2DosTime()' method /** * Adds "file" to archive * * @param string file contents * @param string name of the file in the archive (may contains the path) * @param integer the current timestamp * * @access public */ function addFile($data, $name, $time = 0) { $name = str_replace('', '/', $name); $dtime = dechex($this->unix2DosTime($time)); $hexdtime = 'x' . $dtime[6] . $dtime[7] . 'x' . $dtime[4] . $dtime[5] . 'x' . $dtime[2] . $dtime[3] . 'x' . $dtime[0] . $dtime[1]; eval('$hexdtime = "' . $hexdtime . '";'); $fr = "\x50\x4b\x03\x04"; $fr .= "\x14\x00"; // ver needed to extract $fr .= "\x00\x00"; // gen purpose bit flag $fr .= "\x08\x00"; // compression method $fr .= $hexdtime; // last mod time and date // "local file header" segment $unc_len = strlen($data); $crc = crc32($data); $zdata = gzcompress($data); $zdata = substr(substr($zdata, 0, strlen($zdata) - 4), 2); // fix crc bug $c_len = strlen($zdata); $fr .= pack('V', $crc); // crc32 $fr .= pack('V', $c_len); // compressed filesize $fr .= pack('V', $unc_len); // uncompressed filesize $fr .= pack('v', strlen($name)); // length of filename $fr .= pack('v', 0); // extra field length $fr .= $name; // "file data" segment $fr .= $zdata; // "data descriptor" segment (optional but necessary if archive is not // served as file) $fr .= pack('V', $crc); // crc32 $fr .= pack('V', $c_len); // compressed filesize $fr .= pack('V', $unc_len); // uncompressed filesize // add this entry to array $this -> datasec[] = $fr; // now add to central directory record $cdrec = "\x50\x4b\x01\x02"; $cdrec .= "\x00\x00"; // version made by $cdrec .= "\x14\x00"; // version needed to extract $cdrec .= "\x00\x00"; // gen purpose bit flag $cdrec .= "\x08\x00"; // compression method $cdrec .= $hexdtime; // last mod time & date $cdrec .= pack('V', $crc); // crc32 $cdrec .= pack('V', $c_len); // compressed filesize $cdrec .= pack('V', $unc_len); // uncompressed filesize $cdrec .= pack('v', strlen($name) ); // length of filename $cdrec .= pack('v', 0 ); // extra field length $cdrec .= pack('v', 0 ); // file comment length $cdrec .= pack('v', 0 ); // disk number start $cdrec .= pack('v', 0 ); // internal file attributes $cdrec .= pack('V', 32 ); // external file attributes - 'archive' bit set $cdrec .= pack('V', $this -> old_offset ); // relative offset of local header $this -> old_offset += strlen($fr); $cdrec .= $name; // optional extra field, file comment goes here // save to central directory $this -> ctrl_dir[] = $cdrec; } // end of the 'addFile()' method /** * Dumps out file * * @return string the zipped file * * @access public */ function file() { $data = implode('', $this -> datasec); $ctrldir = implode('', $this -> ctrl_dir); return $data . $ctrldir . $this -> eof_ctrl_dir . pack('v', sizeof($this -> ctrl_dir)) . // total # of entries "on this disk" pack('v', sizeof($this -> ctrl_dir)) . // total # of entries overall pack('V', strlen($ctrldir)) . // size of central dir pack('V', strlen($data)) . // offset to start of central dir "\x00\x00"; // .zip file comment length } // end of the 'file()' method /** * A Wrapper of original addFile Function * * Created By Hasin Hayder at 29th Jan, 1:29 AM * * @param array An Array of files with relative/absolute path to be added in Zip File * * @access public */ function addFiles($files /*Only Pass Array*/) { foreach($files as $file) { if (is_file($file)) //directory check { $data = implode("",file($file)); $this->addFile($data,$file); } } } /** * A Wrapper of original file Function * * Created By Hasin Hayder at 29th Jan, 1:29 AM * * @param string Output file name * * @access public */ function output($file) { $fp=fopen($file,"w"); fwrite($fp,$this->file()); fclose($fp); } } // end of the 'zipfile' class ?> My second file newzip.php <? include("zip.lib.php"); $ziper = new zipfile(); $ziper->addFiles(array("index.htm")); //array of files // the next three lines force an immediate download of the zip file: header("Content-type: application/octet-stream"); header("Content-disposition: attachment; filename=test.zip"); echo $ziper -> file(); ?> I am getting this warning while executing newzip.php Warning: Cannot modify header information - headers already sent by (output started at E:\xampp\htdocs\demo\zip.lib.php:233) in E:\xampp\htdocs\demo\newzip.php on line 6 I am unable to figure out the reason for the same. Please help me on this. Thanks

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  • Sockets receiving null (Android)

    - by Henrik
    I have a android app that is communicating with a server (written in java). Between these two parts I have established a Socket connection and want to send data. The problem I am having is that sometimes, for some users, the information that reaches the server is null. This works (for all phones, all users): Server: int a = Integer.parseInt(in.readLine()); int b = Integer.parseInt(in.readLine()); int c = Integer.parseInt(in.readLine()); int d = Integer.parseInt(in.readLine()); String checksum = in.readLine(); String model = in.readLine(); String device = in.readLine(); String name = in.readLine(); Client: out.println(a); out.println(b); out.println(c); out.println(d); out.println(hash); out.println(Build.MODEL); out.println(Build.DEVICE); String name = fixName(); out.print(name); out.flush(); This does not work (for some users): Server: int a = Integer.parseInt(in.readLine()); String checksum = in.readLine(); String model = in.readLine(); String device = in.readLine(); String name = in.readLine(); String msg = in.readLine(); int version = -1; String test = "hej"; try{ test = in.readLine(); version = Integer.parseInt(test); }catch(Exception e){ e.printStackTrace(); } Client: out.println(a); out.println(hash); out.println(Build.MODEL); out.println(Build.DEVICE); String name = fixName(); if(name == null) name = "John Doe"; out.println(name); String msg = fixMsg(); if(msg == null) name = "nada"; out.println(msg); out.println(curversion); out.flush(); Sometimes, in the second case, the name, msg, and version (the string test) are null at the server side. The catch is triggered because test is null. curversion,a are ints, the rest are strings. Any ideas?

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  • How do I store multiple copies of the same field in Django?

    - by Alistair
    I'm storing OLAC metadata which describes linguistic resources. Many of the elements of the metadata are repeatable -- for example, a resource can have two languages, three authors and four dates associated with it. Is there any way of storing this in one model? It seems like overkill to define a model for each repeatable metadata element -- especially since the models will only have one field: it's value.

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  • Symfony custom route works with frontend_dev.php but not with index.php

    - by dazhall
    Am I missing something or should my custom route work with the index.php (or nothing) instead of frontend_dev.php? I'm getting a 500 error when I go to the model, and a 404 for the show page. My route is: project_show: url: /project/:slug class: sfDoctrineRoute options: { model: Project, type: object } param: { module: project, action: show } Any help would be much appreciated! Thanks! Darren.

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  • dojo layout tutorial dor version 1.7 doesn't work for 1.7.2

    - by Sheena
    This is sortof a continuation to dojo1.7 layout acting screwy. So I made some working widgets and tested them out, i then tried altering my work using the tutorial at http://dojotoolkit.org/documentation/tutorials/1.7/dijit_layout/ to make the layout nice. After failing at that in many interesting ways (thus my last question) I started on a new path. My plan is now to implement the layout tutorial example and then stick in my widgets. For some reason even following the tutorial wont work... everything loads then disappears and I'm left with a blank browser window. Any ideas? It just struck me that it could be browser compatibility issues, I'm working on Firefox 13.0.1. As far as I know Dojo is supposed to be compatible with this... anyway, have some code: HTML: <body class="claro"> <div id="appLayout" class="demoLayout" data-dojo-type="dijit.layout.BorderContainer" data-dojo-props="design: 'headline'"> <div class="centerPanel" data-dojo-type="dijit.layout.ContentPane" data-dojo-props="region: 'center'"> <div> <h4>Group 1 Content</h4> <p>stuff</p> </div> <div> <h4>Group 2 Content</h4> </div> <div> <h4>Group 3 Content</h4> </div> </div> <div class="edgePanel" data-dojo-type="dijit.layout.ContentPane" data-dojo-props="region: 'top'"> Header content (top) </div> <div id="leftCol" class="edgePanel" data-dojo-type="dijit.layout.ContentPane" data-dojo-props="region: 'left', splitter: true"> Sidebar content (left) </div> </div> </body> Dojo Configuration: var dojoConfig = { baseUrl: "${request.static_url('mega:static/js')}", //this is in a mako template tlmSiblingOfDojo: false, packages: [ { name: "dojo", location: "libs/dojo" }, { name: "dijit", location: "libs/dijit" }, { name: "dojox", location: "libs/dojox" }, ], parseOnLoad: true, has: { "dojo-firebug": true, "dojo-debug-messages": true }, async: true }; other js stuff: require(["dijit/layout/BorderContainer", "dijit/layout/TabContainer", "dijit/layout/ContentPane", "dojo/parser"]); css: html, body { height: 100%; margin: 0; overflow: hidden; padding: 0; } #appLayout { height: 100%; } #leftCol { width: 14em; }

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  • How do I use Django to insert a Geometry Field into the database?

    - by alex
    class LocationLog(models.Model): user = models.ForeignKey(User) utm = models.GeometryField(spatial_index=True) This is my database model. I would like to insert a row. I want to insert a circle at point -55, 333. With a radius of 10. How can I put this circle into the geometry field? Of course, then I would want to check which circles overlap a given circle. (my select statement)

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  • Recommended NetBeans UML plugins

    - by Thomas Owens
    It appears that the NetBeans UML plugin has been discontinued, as per a discussion on the NetBeans forums. This was a great, free tool with nice model-code and code-model generation. There are a number of other UML NetBeans plugins out there. However, I've never used any of them. Any suggestions?

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  • Cocoa & Cocoa Touch. How do I create an NSData object from a plain ole pointer?

    - by dugla
    I have malloc'd a whole mess of data in an NSOperation instance. I have a pointer: data = malloc(humungous_amounts_of_god_knows_what); uint8_t* data; How do I package this up as an NSData instance and return it to the main thread? I am assuming that after conversion to an NSData instance I can simply call: free(data); Yes? Also, back on the main thread how do I retrieve the pointer? Thanks, Doug

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  • How do I get the number of objects per day using django?

    - by Keith
    I have a django model with a DateTimeField. class Point(models.Model): somedata = models.CharField(max_length=256) time = models.DateTimeField() I want to get a count of the number of these objects for each day. I can do this with the following SQL query, but don't know how to do it through django. SELECT DATE(`time`), Count(*) FROM `app_point` GROUP BY DATE(`time`) Being able to restrict the results to a date range would also be good.

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  • Django ForeignKey created empty?

    - by Scott Willman
    This seems very basic and I must be missing something, but here goes anyways... With two models like so: class School(models.Model): name = models.CharField("Official School Name", max_length=128) address = models.TextField("Address of the School", max_length=256) mascot = models.CharField("Name of the School Mascot", max_length=128) class StudentProfile(models.Model): name = models.CharField(max_length=128) school = models.ForeignKey(School) If the student gets created before the school, how do I give 'school' a default empty value? Is it blank or null or what? Thanks!

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  • Linking Mapkit with Core Data, Search and user location. Converting annotations from a database in a tableview with search to display in a mapview?

    - by Jon
    Xcode is quite new to me so explanations are appreciated. I am looking to build an application that displays annotations in a mapview (zoomed in on current user location). I want the applications to come from some sort of database rather than manually inputting all the annotations (which is what I'm currently doing) What would be my application type? tab based? window based? i want a tab for a tableview with a list of my annotations and a mapview tab that will show my database of annotations but with the map zoomed in on current location. In a perfect world, it would be great if the user could add favourites from these annotations and keep them in a favourites tableview tab. I'm desperate to work this out and create a fully functional app for a final uni project. i have a working application already but it's nothing like what i am trying to achieve, any help would be much appreciated!!!! Jon (if looked through countless tutorials and as of yet found nothing i can understand to achieve a project like this. Some would call me too ambitious, I just want to make a decent app)

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  • how to retrieve distinct values from multiple columns

    - by ANIL MANE
    Hello Experts, I have a flat text file data which I import into MSSQL table. It creates and table with specified name along with multiple columns as per data file. now I need a query which will return the data and its count. e.g. data file : BREAD,MILK BREAD,DIAPER,BEER,EGGS MILK,DIAPER,BEER,COKE BREAD,MILK,DIAPER,BEER BREAD,MILK,DIAPER,COKE BREAD,ICE,MANGO JUICE,BURGER Result should be BREAD | 5 MILK | 4 DIAPER| 4 and so on.

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  • J2ME/Java: Referencing StringBuffer through Threads

    - by Jemuel Dalino
    This question might be long, but I want to provide much information. Overview: I'm creating a Stock Quotes Ticker app for Blackberry. But I'm having problems with my StringBuffer that contains an individual Stock information. Process: My app connects to our server via SocketConnection. The server sends out a formatted set of strings that contains the latest Stock trade. So whenever a new trade happens, the server will send out an individual Stock Quote of that trade. Through an InputStream I am able to read that information and place each character in a StringBuffer that is referenced by Threads. By parsing based on char3 I am able to determine a set of stock quote/information. char1 - to separate data char3 - means end of a stock quote/information sample stock quote format sent out by our server: stock_quote_name(char 1)some_data(char1)some_data(char1)(char3) My app then parses that stock quote to compare certain data and formats it how it will look like when displayed in the screen. When trades happen gradually(slow) the app works perfectly. However.. Problem: When trades happen too quickly and almost at the same time, My app is not able to handle the information sent efficiently. The StringBuffer has its contents combined with the next trade. Meaning Two stock information in one StringBuffer. field should be: Stock_quote_name some_data some_data sample of what's happening: Stock_quote_name some_data some_dataStock_quote_name some_data some_data here's my code for this part: while (-1 != (data = is.read())) { sb.append((char)data); while(3 != (data = is.read())) { sb.append((char)data); } UiApplication.getUiApplication().invokeLater(new Runnable() { public void run() { try { synchronized(UiApplication.getEventLock()) { SetStringBuffer(sb); DisplayStringBuffer(); RefreshStringBuffer(); } } catch (Exception e) { System.out.println("Error in setting stringbuffer: " + e.toString()); } } }); } public synchronized void DisplayStringBuffer() { try { //parse sb - string buffer ...... } catch(Exception ex) { System.out.println("error in DisplayStringBuffer(): " + ex.toString()); } } public synchronized void SetStringBuffer(StringBuffer dataBuffer) { this.sb =dataBuffer; System.out.println(sb); } public synchronized void RefreshStringBuffer() { this.sb.delete(0, this.sb.length()); } From what I can see, when trades happen very fast, The StringBuffer is not refreshed immediately and still has the contents of the previous trade, when i try to put new data. My Question is: Do you guys have any suggestion on how i can put data into the StringBuffer, without the next information being appended to the first content

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  • MVC: How do i declare the name value using DropDownListFor

    - by frosty
    I have the following dropdownlist in mvc <%= Html.DropDownListFor(c => c.Address.Id, new SelectList(Model.Addresses, "id", "Name", Model.Address.Id), "-- New Address --", new { @name = "[" + orderItemAddressCount + "].AddressId" })%> I'm trying to overwrite the name value on the dropdownlist. this is the markup i get <select id="Address_Id" name="Address.Id"><option value="">-- New Address --</option> This is the markup i want -- New Address -- How do i declare the name value using DropDownListFor?

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  • weird FileField url in admin site

    - by panchicore
    My model class TheFile(models.Model): document = models.FileField(upload_to="archivos") The weird HTML admin link: <a hacking_google_maps_and_google_earth.pdf="" archivos="" media="" localhost:8000="" http:="" href="" target="_blank">archivos/Hacking_Google_Maps_And_Google_Earth.pdf</a> If I firebug-edit the href="" it works :S

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  • get average from set of objects in django

    - by dotty
    Hay, i have a simple rating system for a property. You give it a mark out of 5 (stars). The models are defined like this def Property(models.Model) # stuff here def Rating(models.Model) property = models.ForeignKey(Property) stars = models.IntegerField() What i want to do is get a property, find all the Rating objects, collect them, then get the average 'stars' from them. any ideas how to do this?

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  • Editing Neo Slider to move in one direction

    - by user2106416
    I have a website with brandspace theme from pixelentity. Currently, the slider move from right to left ( auto transition) . But, when the slider reaches the last image, it will go back to the first image by making all previous images sliding back from left to right. I want to make the slider to have a normal transition,i.e. going back to first image but still with the image sliding from right to left. Below is the slider.php code.: <?php $t =& peTheme(); ?> <?php list($pid,$conf,$loop) = $t->template->data(); ?> <?php $w = $t->media->width(940); ?> <?php $h = $t->media->height(300); ?> <div class="peSlider peVolo" data-autopause="disabled" data-plugin="<?php echo apply_filters("pe_theme_slider_plugin","peVolo"); ?>" data-controls-arrows="edges-full" data-controls-bullets="disabled" data-icon-font="enabled"> <?php while ($slide =& $loop->next()): ?> <?php $link = empty($slide->link) ? false: $slide->link; ?> <?php $img = $t->image->resizedImg($slide->img,$w,$h); ?> <div data-delay="4" <?php echo $slide->idx == 0 ? ' class="visible"' : ''; ?>> <?php if (isset($slide->caption)) $t->slider->caption($slide->caption); ?> <?php if ($link): ?> <a href="<?php echo $link ?>" data-flare-gallery="fsGallery<?php echo $pid ?>"> <?php echo $img; ?> </a> <?php else: ?> <?php echo $img; ?> <?php endif; ?> </div> <?php endwhile; ?> </div>

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  • Go - Using a container/heap to implement a priority queue

    - by Seth Hoenig
    In the big picture, I'm trying to implement Dijkstra's algorithm using a priority queue. According to members of golang-nuts, the idiomatic way to do this in Go is to use the heap interface with a custom underlying data structure. So I have created Node.go and PQueue.go like so: //Node.go package pqueue type Node struct { row int col int myVal int sumVal int } func (n *Node) Init(r, c, mv, sv int) { n.row = r n.col = c n.myVal = mv n.sumVal = sv } func (n *Node) Equals(o *Node) bool { return n.row == o.row && n.col == o.col } And PQueue.go: // PQueue.go package pqueue import "container/vector" import "container/heap" type PQueue struct { data vector.Vector size int } func (pq *PQueue) Init() { heap.Init(pq) } func (pq *PQueue) IsEmpty() bool { return pq.size == 0 } func (pq *PQueue) Push(i interface{}) { heap.Push(pq, i) pq.size++ } func (pq *PQueue) Pop() interface{} { pq.size-- return heap.Pop(pq) } func (pq *PQueue) Len() int { return pq.size } func (pq *PQueue) Less(i, j int) bool { I := pq.data.At(i).(Node) J := pq.data.At(j).(Node) return (I.sumVal + I.myVal) < (J.sumVal + J.myVal) } func (pq *PQueue) Swap(i, j int) { temp := pq.data.At(i).(Node) pq.data.Set(i, pq.data.At(j).(Node)) pq.data.Set(j, temp) } And main.go: (the action is in SolveMatrix) // Euler 81 package main import "fmt" import "io/ioutil" import "strings" import "strconv" import "./pqueue" const MATSIZE = 5 const MATNAME = "matrix_small.txt" func main() { var matrix [MATSIZE][MATSIZE]int contents, err := ioutil.ReadFile(MATNAME) if err != nil { panic("FILE IO ERROR!") } inFileStr := string(contents) byrows := strings.Split(inFileStr, "\n", -1) for row := 0; row < MATSIZE; row++ { byrows[row] = (byrows[row])[0 : len(byrows[row])-1] bycols := strings.Split(byrows[row], ",", -1) for col := 0; col < MATSIZE; col++ { matrix[row][col], _ = strconv.Atoi(bycols[col]) } } PrintMatrix(matrix) sum, len := SolveMatrix(matrix) fmt.Printf("len: %d, sum: %d\n", len, sum) } func PrintMatrix(mat [MATSIZE][MATSIZE]int) { for r := 0; r < MATSIZE; r++ { for c := 0; c < MATSIZE; c++ { fmt.Printf("%d ", mat[r][c]) } fmt.Print("\n") } } func SolveMatrix(mat [MATSIZE][MATSIZE]int) (int, int) { var PQ pqueue.PQueue var firstNode pqueue.Node var endNode pqueue.Node msm1 := MATSIZE - 1 firstNode.Init(0, 0, mat[0][0], 0) endNode.Init(msm1, msm1, mat[msm1][msm1], 0) if PQ.IsEmpty() { // make compiler stfu about unused variable fmt.Print("empty") } PQ.Push(firstNode) // problem return 0, 0 } The problem is, upon compiling i get the error message: [~/Code/Euler/81] $ make 6g -o pqueue.6 Node.go PQueue.go 6g main.go main.go:58: implicit assignment of unexported field 'row' of pqueue.Node in function argument make: *** [all] Error 1 And commenting out the line PQ.Push(firstNode) does satisfy the compiler. But I don't understand why I'm getting the error message in the first place. Push doesn't modify the argument in any way.

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  • Struggling with ASP.NET MVC auto-scaffolder template

    - by DanM
    I'm trying to write an auto-scaffolder template for Index views. I'd like to be able to pass in a collection of models or view-models (e.g., IQueryable<MyViewModel>) and get back an HTML table that uses the DisplayName attribute for the headings (th elements) and Html.Display(propertyName) for the cells (td elements). Each row should correspond to one item in the collection. Here's what I have so far: <%@ Control Language="C#" Inherits="System.Web.Mvc.ViewUserControl" %> <% var items = (IQueryable<TestProj.ViewModels.TestViewModel>)Model; // How do I make this generic? var properties = items.First().GetMetadata().Properties .Where(pm => pm.ShowForDisplay && !ViewData.TemplateInfo.Visited(pm)); %> <table> <tr> <% foreach(var property in properties) { %> <th> <%= property.DisplayName %> </th> <% } %> </tr> <% foreach(var item in items) { HtmlHelper itemHtml = ????; // What should I put in place of "????"? %> <tr> <% foreach(var property in properties) { %> <td> <%= itemHtml.Display(property.DisplayName) %> </td> <% } %> </tr> <% } %> </table> Two problems with this: I'd like it to be generic. So, I'd like to replace var items = (IQueryable<TestProj.ViewModels.TestViewModel>)Model; with var items = (IQueryable<T>)Model; or something to that effect. A property Html is automatically created for me when the view is created, but this HtmlHelper applies to the whole collection. I need to somehow create an itemHtml object that applies just to the current item in the foreach loop. I'm not sure how to do this, however, because the constructors for HtmlHelper don't take a Model object. How do I solve these two problems?

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