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• Which third party website thumbnailing services do you use?

  - by Ben Delarre

  I've got a requirement for showing thumbnails of arbitrary websites. I need to be able to show small thumbnails (120px by 90px), and larger thumbnails of around 480px wide. I'll need to specify the queue and invalid placeholder images and preferably have a pingback when the queued images are processed so I can respond appropriately. I'd also need a simple API I can use either directly embedded in my HTML, or from a simple web request to queue the images. I've been looking at various services ranging from low-fi services, to large scale ones - here's some examples: www.bitpixels.com Uses Google AppEngine, seems like a prototype or a toy. Free! www.websnapr.com Tried using this, made a free account and requested a thumbnail. Waited a few minutes and refreshed a couple of times, and ended up having the account banned. Free is tricky yes, but if I can't try it out successfully I'm disinclined to pay. www.shrinktheweb.com Free account seems to be very quick. Lots of documentation on the site, and even covers local caching of the images to your own server (documentation mostly in PHP). Quality of thumbnails look good, and there appear to be sufficient options for setting thumbnail placeholder images and parameters for altering how the thumbnailing is done. Also supports large 'screenshots' of URLs - very useful for me. Discovered the PRO pricing is an à la carte menu, allowing me to select just the features I want and keep the monthly cost low. Excellent stuff, have decided to use this service. www.thumbalizr.com Good coverage of thumbnail sizes and control options - even allowing specification for browser width when thumbnailing. No ping-back, but I can live without that. Supports local caching of images with PHP API, would prefer .NET, but can port it if necessary. Looks like a fairly professional service but seems fairly expensive for the number of thumbnails you get to generate. apologies for lack of proper linking - spam protection! I'm not entirely convinced by any of them, and since this will be a long term service I'd like some stability and support. I'm willing to pay for the service, but I'd want something that fulfills most if not all of my requirements for that. I should also mention that we're hosted on Windows under IIS, so local solutions involving Xvfb and the like sadly can't be used for this project. So my question is: what services do you use? How have they panned out, are you happy with them?

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• Silverlight ControlTemplate and F#

  - by akaphenom

  Has anybody had any success incorporating a Silverlight ControlTemplate into an F# Silverlight application. I am trying to add transitions to the Navgiation.Frame element and following along on with a C# example: http://www.davidpoll.com/2009/07/19/silverlight-3-navigation-adding-transitions-to-the-frame-control The downloaded source uses the MSBUILD:Compile option on the template XAML and the file is included as a "Page"... ILDASM doesn't show any object created for the XAML; In my project I incldued it as a "Resource" (same as I have done for my pages) and referenced it in app.xaml: <Application xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" x:Class="Module1.MyApp"> <Application.Resources> <ResourceDictionary> <ResourceDictionary.MergedDictionaries> <ResourceDictionary Source="/FSSilverlightApp;component/TransitioningFrame.xaml"/> </ResourceDictionary.MergedDictionaries> </ResourceDictionary> </Application.Resources> </Application> the TransitioningFrame.xaml is as follows: <ResourceDictionary xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" xmlns:navigation="clr-namespace:System.Windows.Controls;assembly=System.Windows.Controls.Navigation" xmlns:toolkit="clr-namespace:System.Windows.Controls;assembly=System.Windows.Controls.Layout.Toolkit"> <ControlTemplate x:Key="TransitioningFrame" TargetType="navigation:Frame"> <Border Background="{TemplateBinding Background}" BorderBrush="{TemplateBinding BorderBrush}" BorderThickness="{TemplateBinding BorderThickness}" HorizontalAlignment="{TemplateBinding HorizontalContentAlignment}" VerticalAlignment="{TemplateBinding VerticalContentAlignment}"> <toolkit:TransitioningContentControl Content="{TemplateBinding Content}" Cursor="{TemplateBinding Cursor}" Margin="{TemplateBinding Padding}" HorizontalAlignment="{TemplateBinding HorizontalContentAlignment}" VerticalAlignment="{TemplateBinding VerticalContentAlignment}" HorizontalContentAlignment="{TemplateBinding HorizontalContentAlignment}" VerticalContentAlignment="{TemplateBinding VerticalContentAlignment}" Transition="DefaultTransition" /> </Border> </ControlTemplate> </ResourceDictionary> My page objects all load their respective xaml with the follwoing code: type Page1() as this = inherit UriUserControl("/FSSilverlightApp;component/Page1.xaml") do Application.LoadComponent(this, base.uri) and somewhere in app startup: let p1 = new Page1() I donot have a comparable piece for the ControlTemplate - though I was hoping the application object and App.xaml would pull it in magically (as an aside, the reliance on this magic has made setting up a 100% f# silverlight application rather tricky - as nearly all the published articles I find are based around wizards and short cuts - very little on the acual plumbing - ugh). Any advice or thougts on the subject are appreciated.

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• python Socket.IO client for sending broadcast messages to TornadIO2 server

  - by Alp

  I am building a realtime web application. I want to be able to send broadcast messages from the server-side implementation of my python application. Here is the setup: socketio.js on the client-side TornadIO2 server as Socket.IO server python on the server-side (Django framework) I can succesfully send socket.io messages from the client to the server. The server handles these and can send a response. In the following i will describe how i did that. Current Setup and Code First, we need to define a Connection which handles socket.io events: class BaseConnection(tornadio2.SocketConnection): def on_message(self, message): pass # will be run if client uses socket.emit('connect', username) @event def connect(self, username): # send answer to client which will be handled by socket.on('log', function) self.emit('log', 'hello ' + username) Starting the server is done by a Django management custom method: class Command(BaseCommand): args = '' help = 'Starts the TornadIO2 server for handling socket.io connections' def handle(self, *args, **kwargs): autoreload.main(self.run, args, kwargs) def run(self, *args, **kwargs): port = settings.SOCKETIO_PORT router = tornadio2.TornadioRouter(BaseConnection) application = tornado.web.Application( router.urls, socket_io_port = port ) print 'Starting socket.io server on port %s' % port server = SocketServer(application) Very well, the server runs now. Let's add the client code: <script type="text/javascript"> var sio = io.connect('localhost:9000'); sio.on('connect', function(data) { console.log('connected'); sio.emit('connect', '{{ user.username }}'); }); sio.on('log', function(data) { console.log("log: " + data); }); </script> Obviously, {{ user.username }} will be replaced by the username of the currently logged in user, in this example the username is "alp". Now, every time the page gets refreshed, the console output is: connected log: hello alp Therefore, invoking messages and sending responses works. But now comes the tricky part. Problems The response "hello alp" is sent only to the invoker of the socket.io message. I want to broadcast a message to all connected clients, so that they can be informed in realtime if a new user joins the party (for example in a chat application). So, here are my questions: How can i send a broadcast message to all connected clients? How can i send a broadcast message to multiple connected clients that are subscribed on a specific channel? How can i send a broadcast message anywhere in my python code (outside of the BaseConnection class)? Would this require some sort of Socket.IO client for python or is this builtin with TornadIO2? All these broadcasts should be done in a reliable way, so i guess websockets are the best choice. But i am open to all good solutions.

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• XSLT 1.0 grouping to reformat element defined by date into element defined by task

  - by Daniel

  Hi folks, I have a tricky XSLT transformation and I'd like your advise My xml is formatted as below: <Person> <name>John</name> <date>June12</date> <workTime taskID=1>34</workTime> <workTime taskID=2>12</workTime> </Person> <Person> <name>John</name> <date>June12</date> <workTime taskID=1>21</workTime> <workTime taskID=2>11</workTime> </Person> The output xml should be: <Person> <name>John</name> <taskID>1</taskID> <workTime> <date>June12</date> <time>34</time> </worTime> <workTime> <date>June13</date> <time>21</time> </worTime> </Person> <Person> <name>John</name> <taskID>2</taskID> <workTime> <date>June12</date> <time>12</time> </worTime> <workTime> <date>June13</date> <time>11</time> </worTime> </Person> Essentially, as an input, a "Person" object gathers all the task/workTime for a specific date. As an output, I want the "Person" object to gather the date/workTime for a specific task. I need to use XLST 1.0. I've been trying to use grouping with key but get very puzzled. Appreciate your help. Daniel

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• IDs necessary in update script not being stored (or even seen!?) (PHP MySQL)

  - by Derek

  Hi guys, I really need help with this one...have spent 3 hours trying to figure it out... Basically, I have 3 tables necessary for this function to work (the query and PHP)... Authors, Books and Users. An author can have many books, and a user can have many books - that's it. When the admin user selects to update a book, they are presented with a form, displaying the current data within the fields, very straight forward... However there is one tricky part, the admin user can change the author for a book (incase they make a mistake) and also change the user for which the book is associated with. When I select to update the single book information I am not getting any values what so ever for author_id or user_id. Meaning that when the user updates the book info, the associations with the user and author is being scrapped altogether (when before there was an association)... I cannot see why this is happening because I can clearly see the IDs for the users and authors for my option values (this is because they are in select dropdowns). Here is what my sql to retrieve the user ID is: SELECT user_id, name FROM users and then i have my select options which brings up all the users in the system: <label>This book belongs to:</label> <select name="name" id="name"> <option value="<?php echo $row['user_id']?>" SELECTED><?php echo $row['name']?> - Current</option> <?php while($row = mysql_fetch_array($result)) { ?> <option value="<?php echo $row['user_id']; if (isset($_POST['user_id']));?>"><?php echo $row['name']?></option> <?php } ?> In the presented HTML form, I can select the users (by name) and within the source code I can see the IDs (for the value) matching against the names of the users. Finally, in my script that performs the update, I have this: $book_id = $_POST['book_id']; $bookname = $_POST['bookname']; $booklevel = $_POST['booklevel']; $author_id = $_POST['author_id']; $user_id = $_POST['user_id']; $sql = "UPDATE books SET bookname= '".$bookname."', booklevel= '".$booklevel."', author_id='".$author_id."', user_id= '".$user_id."' WHERE book_id = ".$book_id; The result of this query returns no value for either author_id or user_id... Obviously in this question I have given the information for the user stuff (with the HTML being displayed) but im guessing that I have the same problem with authors aswell... How can I get these ID's passed to the script so that the change can be acknowledge!! :(

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• Any way to speed up this hierarchical query?

  - by RenderIn

  I've got a serious performance problem with a hierarchical query that I can't seem to fix. I am modeling several organization charts in my database, each representing a virtual organization within our company. For example, we have several temporary committees that are created from time to time and there may be a Committee Organizer role at the top of this virtual hierarchy, with several people assigned to the Committee Member role beneath the organizer. Some of our virtual organizations have many levels and several branches at each level. I have a single table in which I represent all the role assignments. i.e. a ROLE_ID column and a PARENT_ROLE_ID column which is a foreign key to the ROLE_ID column. For each assignment we also store as a column the location in the company where this person has the assignment. For example, the Committee Organizer would have a company-level/ CEO assignment, while the committee members would have department-level assignments such as ACCOUNTING, MARKETING, etc. So to model the organizer/member relationship for two individuals we would have: ROLE_ID = 4 PARENT_ROLE_ID = NULL EMPLOYEE_NUMBER = 213423 COMPANY_LOCATION = CEO ROLE_ID = 5 PARENT_ROLE_ID = 4 EMPLOYEE_NUMBER = 838221 COMPANY_LOCATION = ACCOUNTING Here's where things get tricky. I have an application that every person in the organization can log in to. When they log in they should be able to view all the virtual organizations in our company. e.g. the committee members should be able to see the committee organizer and vice-versa. However, only the committee organizer should be able to edit the committee members. The difficulty is in determining whether an individual (who can have multiple role assignments) has edit access for each other assignment. While this seems simple in the example, consider a virtual organization in which we have President at the top, 5 departments directly beneath him, 2 subdepartments below each department. We only want people in the Accounting department to be able to edit individuals in the subdepartments belonging to the Accounting department. They should not have edit access to anybody in the Marketing department or its subdepartments. To determine edit access when a user views a virtual organization in our company I run a query that executes two inline views: A) Hierarchically query for all assignments in this virtual organization and using SYS_CONNECT_BY_PATH to store the entire path to each user/role/company_location and B) Hierarchically retrieve all the assignments the individual logged in has and using the SYS_CONNECT_BY_PATH to store the entire path to each of these assignments. The result of the query is all the records from A) plus a boolean determined by joining with B) which flags whether the logged in user has edit access for each record. Indexes don't seem to be helping... it simply appears that there is too much processing going on to separate all the records and then determine edit access. One issue is that I can't store the SYS_CONNECT_BY_PATH and index it... determining whether an individual record has edit access consists of comparing if: test_record_sys_path LIKE individual_record_sys_path || '%' Is a materialized view the answer?

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• What's the correct way to use Cakephp urls?

  - by Pichan

  Hello all, it's my first post here :) I'm having some difficulties with dealing with urls and parameters. I've gone through the router class api documentation over and over again and found nothing useful. First of all, I'd like to know if there is any 'universal' format in CakePHP(1.3) for handling urls. I'm currently handling all my urls as simple arrays(in the format that Router::url and $html-link accepts) and it's easy as long as I only need to pass them as arguments to cake's own methods. It usually gets tricky if I need something else. Mainly I'm having problems with converting string urls to the basic array format. Let's say I want to convert $arrayUrl to string and than again into url: $arrayUrl=array('controller'=>'SomeController','action'=>'someAction','someValue'); $url=Router::url($arrayUrl); //$url is now '/path/to/site/someController/someAction/someValue' $url=Router::normalize($url); //remove '/path/to/site' $parsed=Router::parse($url); /*$parsed is now Array( [controller] => someController [action] => someAction [named] => Array() [pass] => Array([0] => someValue) [plugin] => ) */ That seems an awful lot of code to do something as simple as to convert between 2 core formats. Also, note that $parsed is still not in the same as $arrayUrl. Of course I could tweak $parsed manually and actually I've done that a few times as a quick patch but I'd like to get to the bottom of this. I also noticed that when using prefix routing, $this-params in controller has the prefix embedded in the action(i.e. [action] = 'admin_edit') and the result of Router::parse() does not. Both of course have the prefix in it's own key. To summarize, how do I convert an url between any of these 3(or 4, if you include the prefix thing) mentioned formats the right way? Of course it would be easy to hack my way through this, but I'd still like to believe that cake is being developed by a bunch of people who have a lot more experience and insight than me, so I'm guessing there's a good reason for this "perceived misbehavior". I've tried to present my problem as good as I can, but due to my rusty english skills, I had to take a few detours :) I'll explain more if needed.

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• Recursive N-way merge/diff algorithm for directory trees?

  - by BobMcGee

  What algorithms or Java libraries are available to do N-way, recursive diff/merge of directories? I need to be able to generate a list of folder trees that have many identical files, and have subdirectories with many similar files. I want to be able to use 2-way merge operations to quickly remove as much redundancy as possible. Goals: Find pairs of directories that have many similar files between them. Generate short list of directory pairs that can be synchronized with 2-way merge to eliminate duplicates Should operate recursively (there may be nested duplicates of higher-level directories) Run time and storage should be O(n log n) in numbers of directories and files Should be able to use an embedded DB or page to disk for processing more files than fit in memory (100,000+). Optional: generate an ancestry and change-set between folders Optional: sort the merge operations by how many duplicates they can elliminate I know how to use hashes to find duplicate files in roughly O(n) space, but I'm at a loss for how to go from this to finding partially overlapping sets between folders and their children. EDIT: some clarification The tricky part is the difference between "exact same" contents (otherwise hashing file hashes would work) and "similar" (which will not). Basically, I want to feed this algorithm at a set of directories and have it return a set of 2-way merge operations I can perform in order to reduce duplicates as much as possible with as few conflicts possible. It's effectively constructing an ancestry tree showing which folders are derived from each other. The end goal is to let me incorporate a bunch of different folders into one common tree. For example, I may have a folder holding programming projects, and then copy some of its contents to another computer to work on it. Then I might back up and intermediate version to flash drive. Except I may have 8 or 10 different versions, with slightly different organizational structures or folder names. I need to be able to merge them one step at a time, so I can chose how to incorporate changes at each step of the way. This is actually more or less what I intend to do with my utility (bring together a bunch of scattered backups from different points in time). I figure if I can do it right I may as well release it as a small open source util. I think the same tricks might be useful for comparing XML trees though.

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• random, Graphics point ,searching- algorithm, via dual for loop set

  - by LoneXcoder

  hello and thanks for joining me in my journey to the custom made algorithm for "guess where the pixel is" this for Loop set (over Point.X, Point.Y), is formed in consecutive/linear form: //Original\initial Location Point initPoint = new Point(150, 100); // No' of pixels to search left off X , and above Y int preXsrchDepth, preYsrchDepth; // No' of pixels to search to the right of X, And Above Y int postXsrchDepth, postYsrchDepth; preXsrchDepth = 10; // will start search at 10 pixels to the left from original X preYsrchDepth = 10; // will start search at 10 pixels above the original Y postXsrchDepth = 10; // will stop search at 10 pixels to the right from X postYsrchDepth = 10; // will stop search at 10 pixels below Y int StopXsearch = initPoint.X + postXsrchDepth; //stops X Loop itarations at initial pointX + depth requested to serch right of it int StopYsearch = initPoint.Y + postYsrchDepth; //stops Y Loop itarations at initial pointY + depth requested below original location int CountDownX, CountDownY; // Optional not requierd for loop but will reports the count down how many iterations left (unless break; triggerd ..uppon success) Point SearchFromPoint = Point.Empty; //the point will be used for (int StartX = initPoint.X - preXsrchDepth; StartX < StopXsearch; StartX++) { SearchFromPoint.X = StartX; for (int StartY = initPoint.Y - preYsrchDepth; StartY < StpY; StartY++) { CountDownX = (initPoint.X - StartX); CountDownY=(initPoint.Y - StartY); SearchFromPoint.Y = StartY; if (SearchSuccess) { same = true; AAdToAppLog("Search Report For: " + imgName + "Search Completed Successfully On Try " + CountDownX + ":" + CountDownY); break; } } } <-10 ---- -5--- -1 X +1--- +5---- +10 what i would like to do is try a way of instead is have a little more clever approach <+8---+5-- -8 -5 -- +2 +10 X -2 - -10 -8-- -6 ---1- -3 | +8 | -10 Y +1 -6 | | +9 .... I do know there's a wheel already invented in this field (even a full-trailer truck amount of wheels (: ) but as a new programmer, I really wanted to start of with a simple way and also related to my field of interest in my project. can anybody show an idea of his, he learnt along the way to Professionalism in algorithm /programming having tests to do on few approaches (kind'a random cleverness...) will absolutely make the day and perhaps help some others viewing this page in the future to come it will be much easier for me to understand if you could use as much as possible similar naming to variables i used or implenet your code example ...it will be Greatly appreciated if used with my code sample, unless my metod is a realy flavorless. p.s i think that(atleast as human being) the tricky part is when throwing inconsecutive numbers you loose track of what you didn't yet use, how do u take care of this too . thanks allot in advance looking forward to your participation !

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• How to catch 'exceptions' for out of order execution in Workflow Foundation 4?

  - by Alex Key

  Hi, I am attempting to model a worklfow using a "WCF Workflow Service" in .net / vs 2010 that needs to handle out of order execution gracefully (but not allow it - if thath makes sense!?) For example I have 2 receive activities one called Initialize and the other called GetValue inside a FlowChart. In most cases Initialize should be called first and GetValue after (as modled in the flow chart). However if GetValue is executed before Initialize I do not want to return an "out of order" exception (although when I look at the WCF test client, I can't actually see an exception). But instead a custom exception saying something like "you must initialize first". In theory I could model this with lots of parallel activities and conditions to check if Initialized / Running / Terminated etc. But the business process I am modelling if very very similar to a state machine... except it must handle people executing things in the wrong order. Ideally I would like to catch the "out of order" exception (thought I don't think it's really an exception as such), check the 'exception' to see which function was attempted to run and then handle it. I have done some research around enabling AllowBufferedReceive. However I don't want to be able to execute out of order (I don't think), but instead give a detailed response if it does happen. I've looked at the new beta state machine template for WF 4 - but i'm not sure if it does what i'm after? I'm not sure if I have the wrong end of the stick, so any help would be greatly appreciated. [EDIT] To help clarify... Sorry it's a tricky one to explain. The standard I am trying to implement (the e-learning standard SCORM RTE) is structured like a state machine i.e. certain functions can only be executed in certain states. However the standard specifies that if the calling clients tries to execute a function that it is not meant to, then a warning should be issued... for example "you cannot use GetValue(), because you have not yet Initialized". Ideally I'd like to structure the workflow as the theoretical state machine and not need to have to use multiple if/else's to handle all the scenarios where something could be executed out-of-order. I'd like to catch a out-of-order exception (but I don't think there is such an exception - as it's not in the debugger) and rethrow it.

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• usercontrol hosted in IE renders as a textbox

  - by coxymla

  On my ongoing saga to mirror the hosting of a legacy app on a clean box, I've hit my next snag. One page relies on a big .NET UserControl that on the new machine renders only as a big, greyed out textarea (greyed out vertical scrollbar on the right hand edge. Inspecting the source shows the expected object tag.) This is particularly tricky because nobody seems to know much about hosted UserControls and all the discussions data back to 2002-2004. The page is quite simple: <%@ Page language="c#" Codebehind="DataExport.aspx.cs" AutoEventWireup="false" Inherits="yyyyy.Web.DataExport" %> <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN" > <html> <head> <title>DataExport</title> <link rel="Configuration" href="/xxxxx/yyyyy/DataExport.config"> </head> <body style="margin:0px;padding:0px;overflow:hidden"> <OBJECT id="DataExport" style="WIDTH: 100%; HEIGHT: 100%; position:absolute; left: 0px; top:0px" classid="yyyyy.Common.dll#yyyyy.Controls.DataExport" VIEWASTEXT> </OBJECT> </body> </html> The config file referenced: <?xml version="1.0" encoding="utf-8" ?> <configuration> <configSections> <sectionGroup name="yyyyy"> <section name="dataExport" type="yyyyy.Controls.DataExportSectionHandler,yyyyy.Common" /> </sectionGroup> </configSections> <yyyyy> <dataExport> <layoutFile>http://vm2/xxxxx/yyyyy/layout.xml</layoutFile> <webServiceUrl>http://vm2/xxxxx/yyyyy/services/yyyyy.asmx</webServiceUrl> </dataExport> </yyyyy> </configuration> What I've checked: Security permissions should be OK, the site is trusted and adding a URL exception to grant FullTrust doesn't change anything. Config file is acessible over the web, layout.xml is accessible, ASMX shows the expected command list Machine.config grants GET permission for the usercontrol.config file. What perhaps looks fishy to me: The DataExport UserControl references Aspose.Excel to generate the spreadsheets it exports. When I navigate to the page and get a blank textbox, then run gacutil /ldl, nothing is in the local download cache. On the working machine, running the same command after viewing the page shows a laundry list of DLLs including the control DLL and the Aspose DLL.

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• Difficulty adding widgets to django form.

  - by codingJoe

  I have a django app that tracks activities that can benefit a classroom. Using the django examples, I was able to build a form to enter this data. But when I try to add widgets to that form, things get tricky. What I want is a calendar widget that lets the user enter the 'activity_date' field using a widget. If I use Admin interface. The AdminDateWidget works fine. however. This particular user isn't allowed access to the admin interface so I need a different way to present this widget. Also I couldn't figure out how to make the bring the admin widget over into non-admin pages. So I tried a custom widget. This is the first custom widget I've built, so I'm not quite sure what is supposed to be going on here. Any Expert Advice? How do I get my date widget to work? # The Model class Activity(models.Model): activity_date = models.DateField() activity_type = models.CharField(max_length=50, choices=ACTIVITY_TYPES) activity_description = models.CharField(max_length=200) activity_duration= models.DecimalField(decimal_places=2, max_digits=4) est_attendance = models.IntegerField("Estimated attendance") # The Form class ActivityForm(forms.ModelForm): # The following line causes lockup if enabled. # With the DateTimeWidget removed, the form functions correctly except that there is no widget. #activity_date = forms.DateField(label=_('Date'), widget=DateTimeWidget) ##!!! Point of Error !!! class Meta: model = Activity fields = ('activity_date', 'activity_type', 'activity_description', 'activity_duration', 'est_attendance') def __init__(self, *args, **kwargs): super(ActivityForm, self).__init__(*args, **kwargs) instance = getattr(self, 'instance', None) edit_aid = kwargs.get('edit_aid', False) # On a different approach, the following also didn't work. #self.fields['activity_date'].widget = widgets.AdminDateWidget() # The Widget # Example referenced: http://djangosnippets.org/snippets/391/ calbtn = u""" <button id="calendar-trigger">...</button> <img src="%s/site_media/images/icon_calendar.gif" alt="calendar" id="%s_btn" style="cursor: pointer; border: 1px solid #8888aa;" title="Select date and time" onmouseover="this.style.background='#444444';" onmouseout="this.style.background=''" /> <script type="text/javascript"> Calendar.setup({ trigger : "calendar-trigger", inputField : "%s" }); </script>""" class DateTimeWidget(forms.widgets.TextInput): dformat = '%Y-%m-%d %H:%M' def render(self, name, value, attrs=None): print "DTWgt render name=%s, value=%s" % name, value if value is None: value = '' final_attrs = self.build_attrs(attrs, type=self.input_type, name=name) if value != '': try: final_attrs['value'] = \ force_unicode(value.strftime(self.dformat)) except: final_attrs['value'] = \ force_unicode(value) if not final_attrs.has_key('id'): final_attrs['id'] = u'%s_id' % (name) id = final_attrs['id'] jsdformat = self.dformat #.replace('%', '%%') cal = calbtn % (settings.MEDIA_URL, id, id, jsdformat, id) a = u'<input%s />%s' % (forms.util.flatatt(final_attrs), cal) print "render return %s " % a return mark_safe(a) def value_from_datadict(self, data, files, name): print "DTWgt value_from_datadict" dtf = forms.fields.DEFAULT_DATETIME_INPUT_FORMATS empty_values = forms.fields.EMPTY_VALUES value = data.get(name, None) if value in empty_values: return None if isinstance(value, datetime.datetime): return value if isinstance(value, datetime.date): return datetime.datetime(value.year, value.month, value.day) for format in dtf: try: return datetime.datetime(*time.strptime(value, format)[:6]) except ValueError: continue return None

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• UTF-8 GET using Indy 10.5.8.0 and Delphi XE2

  - by Bogdan Botezatu

  I'm writing my first Unicode application with Delphi XE2 and I've stumbled upon an issue with GET requests to an Unicode URL. Shortly put, it's a routine in a MP3 tagging application that takes a track title and an artist and queries Last.FM for the corresponding album, track no and genre. I have the following code: function GetMP3Info(artist, track: string) : TMP3Data //<---(This is a record) var TrackTitle, ArtistTitle : WideString; webquery : WideString; [....] WebQuery := UTF8Encode('http://ws.audioscrobbler.com/2.0/?method=track.getcorrection&api_key=' + apikey + '&artist=' + artist + '&track=' + track); //[processing the result in the web query, getting the correction for the artist and title] // eg: for artist := Bucovina and track := Mestecanis, the corrected values are //ArtistTitle := Bucovina; // TrackTitle := Mestecani?; //Now here is the tricky part: webquery := UTF8Encode('http://ws.audioscrobbler.com/2.0/?method=track.getInfo&api_key=' + apikey + '&artist=' + unescape(ArtistTitle) + '&track=' + unescape(TrackTitle)); //the unescape function replaces spaces (' ') with '+' to comply with the last.fm requests [some more processing] end; The webquery looks in a TMemo just right (http://ws.audioscrobbler.com/2.0/?method=track.getInfo&api_key=e5565002840xxxxxxxxxxxxxx23b98ad&artist=Bucovina&track=Mestecani?) Yet, when I try to send a GET() to the webquery using IdHTTP (with the ContentEncoding property set to 'UTF-8'), I see in Wireshark that the component is GET-ing the data to the ANSI value '/2.0/?method=track.getInfo&api_key=e5565002840xxxxxxxxxxxxxx23b98ad&artist=Bucovina&track=Mestec?ni?' Here is the full headers for the GET requests and responses: GET /2.0/?method=track.getInfo&api_key=e5565002840xxxxxxxxxxxxxx23b98ad&artist=Bucovina&track=Mestec?ni? HTTP/1.1 Content-Encoding: UTF-8 Host: ws.audioscrobbler.com Accept: text/html, */* Accept-Encoding: identity User-Agent: Mozilla/5.0 (Windows; U; Windows NT 6.1; en-US; rv:1.9.2.23) Gecko/20110920 Firefox/3.6.23 SearchToolbar/1.22011-10-16 20:20:07 HTTP/1.0 400 Bad Request Date: Tue, 09 Oct 2012 20:46:31 GMT Server: Apache/2.2.22 (Unix) X-Web-Node: www204 Access-Control-Allow-Origin: * Access-Control-Allow-Methods: POST, GET, OPTIONS Access-Control-Max-Age: 86400 Cache-Control: max-age=10 Expires: Tue, 09 Oct 2012 20:46:42 GMT Content-Length: 114 Connection: close Content-Type: text/xml; charset=utf-8; <?xml version="1.0" encoding="utf-8"?> <lfm status="failed"> <error code="6"> Track not found </error> </lfm> The question that puzzles me is am I overseeing anything related to setting the property of the tidhttp control? How can I stop the well-formated URL i'm composing in the application from getting wrongfully sent to the server? Thanks.

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• I could use some help with my SQL command

  - by SuperSpy

  I've got a database table called 'mesg' with the following structure: receiver_id | sender_id | message | timestamp | read Example: 2 *(«me)* | 6 *(«nice girl)* | 'I like you, more than ghoti' | yearsago | 1 *(«seen it)* 2 *(«me)* | 6 *(«nice girl)* | 'I like you, more than fish' | now | 1 *(«seen it)* 6 *(«nice girl)* | 2 *(«me)* | 'Hey, wanna go fish?' | yearsago+1sec | 0 *(«she hasn't seen it)* It's quite a tricky thing that I want to achieve. I want to get: the most recent message(=ORDER BY time DESC) + 'contact name' + time for each 'conversation'. Contact name = uname WHERE uid = 'contact ID' (the username is in another table) Contact ID = if(sessionID*(«me)*=sender_id){receiver_id}else{sender_id} Conversation is me = receiver OR me = sender For example: From: **Bas Kreuntjes** *(« The message from bas is the most recent)* Hey $py, How are you doing... From: **Sophie Naarden** *(« Second recent)* Well hello, would you like to buy my spam? ... *(«I'll work on that later >p)* To: **Melanie van Deijk** *(« My message to Melanie is 3th)* And? Did you kiss him? ... That is a rough output. QUESTION: Could someone please help me setup a good SQL command. This will be the while loup <?php $sql = "????"; $result = mysql_query($sql); while($fetch = mysql_fetch_assoc($result)){ ?> <div class="message-block"> <h1><?php echo($fetch['uname']); ?></h1> <p><?php echo($fetch['message']); ?></p> <p><?php echo($fetch['time']); ?></p> </div> <?php } ?> I hope my explanation is good enough, if not, please tell me. Please don't mind my English, and the Dutch names (I am Dutch myself) Feel free to correct my English UPDATE1: Best I've got until now: But I do not want more than one conversation to show up... u=user table m=message table SELECT u.uname, m.message, m.receiver_uid, m.sender_uid, m.time FROM m, u WHERE (m.receiver_uid = '$myID' AND u.uid = m.sender_uid) OR (m.sender_uid = '$myID' AND u.uid = m.receiver_uid) ORDER BY time DESC;

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• What are the Options for Storing Hierarchical Data in a Relational Database?

  - by orangepips

  Good Overviews One more Nested Intervals vs. Adjacency List comparison: the best comparison of Adjacency List, Materialized Path, Nested Set and Nested Interval I've found. Models for hierarchical data: slides with good explanations of tradeoffs and example usage Representing hierarchies in MySQL: very good overview of Nested Set in particular Hierarchical data in RDBMSs: most comprehensive and well organized set of links I've seen, but not much in the way on explanation Options Ones I am aware of and general features: Adjacency List: Columns: ID, ParentID Easy to implement. Cheap node moves, inserts, and deletes. Expensive to find level (can store as a computed column), ancestry & descendants (Bridge Hierarchy combined with level column can solve), path (Lineage Column can solve). Use Common Table Expressions in those databases that support them to traverse. Nested Set (a.k.a Modified Preorder Tree Traversal) First described by Joe Celko - covered in depth in his book Trees and Hierarchies in SQL for Smarties Columns: Left, Right Cheap level, ancestry, descendants Compared to Adjacency List, moves, inserts, deletes more expensive. Requires a specific sort order (e.g. created). So sorting all descendants in a different order requires additional work. Nested Intervals Combination of Nested Sets and Materialized Path where left/right columns are floating point decimals instead of integers and encode the path information. Bridge Table (a.k.a. Closure Table: some good ideas about how to use triggers for maintaining this approach) Columns: ancestor, descendant Stands apart from table it describes. Can include some nodes in more than one hierarchy. Cheap ancestry and descendants (albeit not in what order) For complete knowledge of a hierarchy needs to be combined with another option. Flat Table A modification of the Adjacency List that adds a Level and Rank (e.g. ordering) column to each record. Expensive move and delete Cheap ancestry and descendants Good Use: threaded discussion - forums / blog comments Lineage Column (a.k.a. Materialized Path, Path Enumeration) Column: lineage (e.g. /parent/child/grandchild/etc...) Limit to how deep the hierarchy can be. Descendants cheap (e.g. LEFT(lineage, #) = '/enumerated/path') Ancestry tricky (database specific queries) Database Specific Notes MySQL Use session variables for Adjacency List Oracle Use CONNECT BY to traverse Adjacency Lists PostgreSQL ltree datatype for Materialized Path SQL Server General summary 2008 offers HierarchyId data type appears to help with Lineage Column approach and expand the depth that can be represented.

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• Memory corruption in System.Move due to changed 8087CW mode (png + stretchblt)

  - by André Mussche

  I have strange a memory corruption problem. After many hours debugging and trying I think I found something. For example: I do a simple string assignment: sTest := 'SET LOCK_TIMEOUT '; However, the result sometimes becomes: sTest = 'SET LOCK'#0'TIMEOUT ' So, the _ gets replaced by an 0 byte. I have seen this happening once (reproducing is tricky, dependent on timing) in the System.Move function, when it uses the FPU stack (fild, fistp) for fast memory copy (in case of 9 till 32 bytes to move): ... @@SmallMove: {9..32 Byte Move} fild qword ptr [eax+ecx] {Load Last 8} fild qword ptr [eax] {Load First 8} cmp ecx, 8 jle @@Small16 fild qword ptr [eax+8] {Load Second 8} cmp ecx, 16 jle @@Small24 fild qword ptr [eax+16] {Load Third 8} fistp qword ptr [edx+16] {Save Third 8} ... Using the FPU view and 2 memory debug views (Delphi - View - Debug - CPU - Memory) I saw it going wrong... once... could not reproduce however... This morning I read something about the 8087CW mode, and yes, if this is changed into $27F I get memory corruption! Normally it is $133F: The difference between $133F and $027F is that $027F sets up the FPU for doing less precise calculations (limiting to Double in stead of Extended) and different infiniti handling (which was used for older FPU’s, but is not used any more). Okay, now I found why but not when! I changed the working of my AsmProfiler with a simple check (so all functions are checked at enter and leave): if Get8087CW = $27F then //normally $1372? if MainThreadID = GetCurrentThreadId then //only check mainthread DebugBreak; I "profiled" some units and dll's and bingo (see stack): Windows.StretchBlt(3372289943,0,0,514,345,4211154027,0,0,514,345,13369376) pngimage.TPNGObject.DrawPartialTrans(4211154027,(0, 0, 514, 345, (0, 0), (514, 345))) pngimage.TPNGObject.Draw($7FF62450,(0, 0, 514, 345, (0, 0), (514, 345))) Graphics.TCanvas.StretchDraw((0, 0, 514, 345, (0, 0), (514, 345)),$7FECF3D0) ExtCtrls.TImage.Paint Controls.TGraphicControl.WMPaint((15, 4211154027, 0, 0)) So it is happening in StretchBlt... What to do now? Is it a fault of Windows, or a bug in PNG (included in D2007)? Or is the System.Move function not failsafe?

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• iPhone Image Resources, ICO vs PNG, app bundle filesize

  - by Jasarien

  My application has a collection of around 1940 icons that are used throughout. They're currently in ICO and new images provided to me come in ICO format too. I have noticed that they contain a 16x16 and 32x32 representation of each icon in one file. Each file is roughly 4KB in filesize (as reported by finder, but ls reports that they vary from being ~1000 bytes to 5000 bytes) A very small number of these icons only contain the 32x32 representation, and as a result are only around 700 bytes in size. Currently I am bundling these icons with my application and they are inflating the size of the app a bit more than I would like. Altogether, the images total just about 25.5MB. Xcode must do some kind of compression because the resulting app bundle is about 12.4MB. Compressing this further into a ZIP (as it would be when submitted to the App Store), results in a final file of 5.8MB. I'm aware that the maximum limit for over the air App Store downloads has been raised to 20MB since the introduction of the iPad (I'm not sure if that extends to iPhone apps as well as iPad apps though, if not the limit would be 10MB). My worry is that new icons are going to be added (sometimes up to 10 icons per week), and will continue to inflate the app bundle over time. What is the best way to distribute these icons with my app? Things I've tried and not had much success with: Converting the icons from ICO to PNG: I tried this in the hopes that the pngcrush utility would help out with the filesize. But it appears that it doesn't make much of a difference between a normal PNG and a crushed png (I believe it just optimises the image for display on the iPhone's GPU rather than compress it's size). Also in going from ICO to PNG actually increased the size of the icon file... Zipping the images, and then uncompressing them on first run. While this did reduce the overall image sizes, I found that the effort needed to unzip them, copy them to the documents folder and ensure that duplication doesn't happen on upgrades was too much hassle to be worth the benefit. Also, on original and 3G iPhones unzipping and copying around 25MB of images takes too long and creates a bad experience... Things I've considered but not yet tried: Instead of distributing the icons within the app bundle, host them online, and download each icon on demand (it depends on the user's data as to which icons will actually be displayed and when). Issues with this is that bandwidth costs money, and image downloads will be bandwidth intensive. However, my app currently has a small userbase of around 5,500 users (of which I estimate around 1500 to be active based on Flurry stats), and I have a huge unused bandwidth allowance with my current hosting package. So I'm open to thoughts on how to solve this tricky issue.

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• Cepstral Analysis for pitch detection

  - by Ohmu

  Hi! I'm looking to extract pitches from a sound signal. Someone on IRC just explain to me how taking a double FFT achieves this. Specifically: take FFT take log of square of absolute value (can be done with lookup table) take another FFT take absolute value I am attempting this using vDSP I can't understand how I didn't come across this technique earlier. I did a lot of hunting and asking questions; several weeks worth. More to the point, I can't understand why I didn't think of it. I am attempting to achieve this with vDSP library. it looks as though it has functions to handle all of these tasks. However, I'm wondering about the accuracy of the final result. I have previously used a technique which scours the frequency bins of a single FFT for local maxima. when it encounters one, it uses a cunning technique (the change in phase since the last FFT) to more accurately place the actual peak within the bin. I am worried that this precision will be lost with this technique I'm presenting here. I guess the technique could be used after the second FFT to get the fundamental accurately. But it kind of looks like the information is lost in step 2. as this is a potentially tricky process, could someone with some experience just look over what I'm doing and check it for sanity? also, I've heard there is an alternative technique involving fitting a quadratic over neighbouring bins. Is this of comparable accuracy? if so, I would favour it, as it doesn't involve remembering bin phases. so questions: does this approach makes sense? Can it be improved? I'm a bit worried about And the log square component; there seems to be a vDSP function to do exactly that: vDSP_vdbcon however, there is no indication it precalculates a log-table -- I assume it doesn't, as the FFT function requires an explicit pre-calculation function to be called and passed into it. and this function doesn't. Is there some danger of harmonics being picked up? is there any cunning way of making vDSP pull out the maxima, biggest first? Can anyone point me towards some research or literature on this technique? the main question: is it accurate enough? Can the accuracy be improved? I have just been told by an expert that the accuracy IS INDEED not sufficient. Is this the end of the line? Pi PS I get SO annoyed (npi) when I want to create tags, but cannot. :| I have suggested to the maintainers that SO keep track of attempted tags, but I'm sure I was ignored. we need tags for vDSP, accelerate framework, cepstral analysis

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• What is the best practice to segment c#.net projects based on a single base project

  - by Anthony

  Honestly, I can't word my question any better without describing it. I have a base project (with all its glory, dlls, resources etc) which is a CMS. I need to use this project as a base for othe custom bake projects. This base project is to be maintained and updated among all custom bake projects. I use subversion (Collabnet and Tortise SVN) I have two questions: 1 - Can I use subversion to share the base project among other projects What I mean here is can I "Checkout" the base project into another "Checked Out" project and have both update and commit seperatley. So, to paint a picture, let's say I am working on a custom project and I modify the core/base prject in some way (which I know will suit the others) can I then commit those changes and upon doing so when I update the base project in the other "Checked out" resources will it pull the changes? In short, I would like not to have to manually deploy updated core files whenever I make changes into each seperate project. 2 - If I create a custom file (let's say an webcontrol or aspx page etc) can I have it compile seperatley from the base project Another tricky one to explain. When I publish my web application it creates DLLs based on the namespaces of projects attached to it. So I may have a number of DLLs including the "Website's" namespace DLL, which could simply be website. I want to be able to make a seperate, custom, control which does not compile into those DLLs as the custom files should not rely on those DLLS to run. Is it as simple to set a seperate namespace for those files like CustomFiles.ProjectName for example? Think of the whole idea as adding modules to the .NET project, I don't want the module's code in any of the core DLLs but I do need for module to be able to access the core dlls. (There is no need for the core project to access the module code as it should be one way only in theory, though I reckon it woould not be possible anyway without using JSON/SOAP or something like that, maybe I am wrong.) I want to create a pluggable environment much like that of Joomla/Wordpress as since PHP generally doesn't have to be compiled first I see this is the reason why all this is possible/easy. The idea is to allow pluggable themes, modules etc etc. (I haven't tried simply adding .NET themes after compile/publish but I am assuming this is possible anyway? OR does the compiler need to reference items in the files?)

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• how to bind the image dynamically for datagrid in.cs

  - by prince23

  hi, this is my xaml code. <sdk:DataGrid x:Name="dgMarks" CanUserResizeColumns="False" SelectionMode="Single" AutoGenerateColumns="False" VerticalAlignment="Top" IsReadOnly="True" Margin="13,44,0,0" RowDetailsVisibilityChanged="dgMarks_RowDetailsVisibilityChanged" RowDetailsVisibilityMode="Collapsed" Height="391" HorizontalAlignment="Left" Width="965" SelectionChanged="dgMarks_SelectionChanged" VerticalScrollBarVisibility="Visible" > <sdk:DataGrid.Columns> <sdk:DataGridTemplateColumn> <sdk:DataGridTemplateColumn.CellTemplate> <DataTemplate> <Button x:Name="myButton" Click="ExpandMarks_Click"> <TextBlock Text="{Binding Level}" TextWrapping="NoWrap" ></TextBlock> <Image x:Name="imgMarks" Stretch="None"/> </Button> </DataTemplate> </sdk:DataGridTemplateColumn.CellTemplate> </sdk:DataGridTemplateColumn> <sdk:DataGridTemplateColumn Header="Name" Visibility="Collapsed"> <sdk:DataGridTemplateColumn.CellTemplate> <DataTemplate > <sdk:Label Content="{Binding Name}"/> </DataTemplate> </sdk:DataGridTemplateColumn.CellTemplate> </sdk:DataGridTemplateColumn> <sdk:DataGridTemplateColumn Header="Marks" Width="80"> <sdk:DataGridTemplateColumn.CellTemplate> <DataTemplate> <sdk:Label Content="{Binding Marks}"/> </DataTemplate> </sdk:DataGridTemplateColumn.CellTemplate> </sdk:DataGridTemplateColumn> </sdk:DataGrid.Columns> </sdk:DataGrid> from database i am getting these values name marks Level abc 23 0 xyz 67 1 yu 56 0 aa 89 1 here i am binding these values for datagrid. i have an tricky thing to be done .based on the level i should be binding image if level value is 1 then bind the image. if level value is 0 then do not bind the image for that row i know this is how we need to handle but where should i write this code in which events? Image imgLevel = (Image)templateTrendScore.FindName("imgMarks"); if (level1==1) { imgLevel .Source = new BitmapImage(new Uri("/Images/image1.JPG", UriKind.Relative)); } any help would be great thanks in advance

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• To Interface or Not?: Creating a polymorphic model relationship in Ruby on Rails dynamically..

  - by Globalkeith

  Please bear with me for a moment as I try to explain exactly what I would like to achieve. In my Ruby on Rails application I have a model called Page. It represents a web page. I would like to enable the user to arbitrarily attach components to the page. Some examples of "components" would be Picture, PictureCollection, Video, VideoCollection, Background, Audio, Form, Comments. Currently I have a direct relationship between Page and Picture like this: class Page < ActiveRecord::Base has_many :pictures, :as => :imageable, :dependent => :destroy end class Picture < ActiveRecord::Base belongs_to :imageable, :polymorphic => true end This relationship enables the user to associate an arbitrary number of Pictures to the page. Now if I want to provide multiple collections i would need an additional model: class PictureCollection < ActiveRecord::Base belongs_to :collectionable, :polymorphic => true has_many :pictures, :as => :imageable, :dependent => :destroy end And alter Page to reference the new model: class Page < ActiveRecord::Base has_many :picture_collections, :as => :collectionable, :dependent => :destroy end Now it would be possible for the user to add any number of image collections to the page. However this is still very static in term of the :picture_collections reference in the Page model. If I add another "component", for example :video_collections, I would need to declare another reference in page for that component type. So my question is this: Do I need to add a new reference for each component type, or is there some other way? In Actionscript/Java I would declare an interface Component and make all components implement that interface, then I could just have a single attribute :components which contains all of the dynamically associated model objects. This is Rails, and I'm sure there is a great way to achieve this, but its a tricky one to Google. Perhaps you good people have some wise suggestions. Thanks in advance for taking the time to read and answer this.

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• What IPC method should I use between Firefox extension and C# code running on the same machine?

  - by Rory

  I have a question about how to structure communication between a (new) Firefox extension and existing C# code. The firefox extension will use configuration data and will produce other data, so needs to get the config data from somewhere and save it's output somewhere. The data is produced/consumed by existing C# code, so I need to decide how the extension should interact with the C# code. Some pertinent factors: It's only running on windows, in a relatively controlled corporate environment. I have a windows service running on the machine, built in C#. Storing the data in a local datastore (like sqlite) would be useful for other reasons. The volume of data is low, e.g. 10kb of uncompressed xml every few minutes, and isn't very 'chatty'. The data exchange can be asynchronous for the most part if not completely. As with all projects, I have limited resources so want an option that's relatively easy. It doesn't have to be ultra-high performance, but shouldn't add significant overhead. I'm planning on building the extension in javascript (although could be convinced otherwise if really necessary) Some options I'm considering: use an XPCOM to .NET/COM bridge use a sqlite db: the extension would read from and save to it. The c# code would run in the service, populating the db and then processing data created by the service. use TCP sockets to communicate between the extension and the service. Let the service manage a local data store. My problem with (1) is I think this will be tricky and not so easy. But I could be completely wrong? The main problem I see with (2) is the locking of sqlite: only a single process can write data at a time so there'd be some blocking. However, it would be nice generally to have a local datastore so this is an attractive option if the performance impact isn't too great. I don't know whether (3) would be particularly easy or hard ... or what approach to take on the protocol: something custom or http. Any comments on these ideas or other suggestions? UPDATE: I was planning on building the extension in javascript rather than c++

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• Simplifying const Overloading?

  - by templatetypedef

  Hello all- I've been teaching a C++ programming class for many years now and one of the trickiest things to explain to students is const overloading. I commonly use the example of a vector-like class and its operator[] function: template <typename T> class Vector { public: T& operator[] (size_t index); const T& operator[] (size_t index) const; }; I have little to no trouble explaining why it is that two versions of the operator[] function are needed, but in trying to explain how to unify the two implementations together I often find myself wasting a lot of time with language arcana. The problem is that the only good, reliable way that I know how to implement one of these functions in terms of the other is with the const_cast/static_cast trick: template <typename T> const T& Vector<T>::operator[] (size_t index) const { /* ... your implementation here ... */ } template <typename T> T& Vector<T>::operator[] (size_t index) { return const_cast<T&>(static_cast<const Vector&>(*this)[index]); } The problem with this setup is that it's extremely tricky to explain and not at all intuitively obvious. When you explain it as "cast to const, then call the const version, then strip off constness" it's a little easier to understand, but the actual syntax is frightening,. Explaining what const_cast is, why it's appropriate here, and why it's almost universally inappropriate elsewhere usually takes me five to ten minutes of lecture time, and making sense of this whole expression often requires more effort than the difference between const T* and T* const. I feel that students need to know about const-overloading and how to do it without needlessly duplicating the code in the two functions, but this trick seems a bit excessive in an introductory C++ programming course. My question is this - is there a simpler way to implement const-overloaded functions in terms of one another? Or is there a simpler way of explaining this existing trick to students? Thanks so much!

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• Ajax page.replace_html problems with partials in Rails

  - by Chris Power

  Hello, I am having a problem with a pretty simple AJAX call in rails. I have a blog-style application and each post has a "like" feature. I want to be able to increment the "like" on each post in the index using AJAX onclick. I got it to work; however, the DOM is a bit tricky here, because no matter what partial its looking at, it will only update the TOP partial. so if I click "like" on post #2, it will update and replace the "likes" on post #1 instead. Code for _post partial: <some code here...> <div id="postcontent"> Posted <%= post.created_at.strftime("%A, %b %d")%> <br /> </div> <div id="postlikes"> <%= link_to_remote 'Like', :url => {:controller => 'posts', :action => 'like_post', :id => post.id}%> <%= post.like %> </div> code for _postlikes partial: <div id="postlikes"> <%= link_to_remote 'Like', :url => {:controller => 'posts', :action => 'like_post', :id => @post.id}%> <%= @post.like %> </div> </div> like_post.rjs code: page.replace_html "postlikes", :partial => "postlikes", :object => @post page.visual_effect :highlight, "postlikes", :duration => 3 So this all works properly for the first "postcontent" div. But this is an index of posts, so if I wanted to updated the second "postcontent" div on the page, it will still replace the html of the first. I understand the problem, I just don't know how to fix it :) Thanks in advance!

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• IntentService android download and return file to Activity

  - by Andrew G

  I have a fairly tricky situation that I'm trying to determine the best design for. The basics are this: I'm designing a messaging system with a similar interface to email. When a user clicks a message that has an attachment, an activity is spawned that shows the text of that message along with a paper clip signaling that there is an additional attachment. At this point, I begin preloading the attachment so that when the user clicks on it - it loads more quickly. currently, when the user clicks the attachment, it prompts with a loading dialog until the download is complete at which point it loads a separate attachment viewer activity, passing in the bmp byte array. I don't ever want to save attachments to persistent storage. The difficulty I have is in supporting rotation as well as home button presses etc. The download is currently done with a thread and handler setup. Instead of this, I'd like the flow to be the following: User loads message as before, preloading begins of attachment as before (invisible to user). When the user clicks on the attachment link, the attachment viewer activity is spawned right away. If the download was done, the image is displayed. If not, a dialog is shown in THIS activity until it is done and can be displayed. Note that ideally the download never restarts or else I've wasted cycles on the preload. Obviously I need some persistent background process that is able to keep downloading and is able to call back to arbitrarily bonded Activities. It seems like the IntentService almost fits my needs as it does its work in a background thread and has the Service (non UI) lifecycle. However, will it work for my other needs? I notice that common implementations for what I want to do get a Messenger from the caller Activity so that a Message object can be sent back to a Handler in the caller's thread. This is all well and good but what happens in my case when the caller Activity is Stopped or Destroyed and the currently active Activity (the attachment viewer) is showing? Is there some way to dynamically bind a new Activity to a running IntentService so that I can send a Message back to the new Activity? The other question is on the Message object. Can I send arbitrarily large data back in this package? For instance, rather than send back that "The file was downloaded", I need to send back the byte array of the downloaded file itself since I never want to write it to disk (and yes this needs to be the case). Any advice on achieving the behavior I want is greatly appreciated. I've not been working with Android for that long and I often get confused with how to best handle asynchronous processes over the course of the Activity lifecycle especially when it comes to orientation changes and home button presses...

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