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• Can you force a crash if a write occurs to a given memory location with finer than page granularity?

  - by Joseph Garvin

  I'm writing a program that for performance reasons uses shared memory (alternatives have been evaluated, and they are not fast enough for my task, so suggestions to not use it will be downvoted). In the shared memory region I am writing many structs of a fixed size. There is one program responsible for writing the structs into shared memory, and many clients that read from it. However, there is one member of each struct that clients need to write to (a reference count, which they will update atomically). All of the other members should be read only to the clients. Because clients need to change that one member, they can't map the shared memory region as read only. But they shouldn't be tinkering with the other members either, and since these programs are written in C++, memory corruption is possible. Ideally, it should be as difficult as possible for one client to crash another. I'm only worried about buggy clients, not malicious ones, so imperfect solutions are allowed. I can try to stop clients from overwriting by declaring the members in the header they use as const, but that won't prevent memory corruption (buffer overflows, bad casts, etc.) from overwriting. I can insert canaries, but then I have to constantly pay the cost of checking them. Instead of storing the reference count member directly, I could store a pointer to the actual data in a separate mapped write only page, while keeping the structs in read only mapped pages. This will work, the OS will force my application to crash if I try to write to the pointed to data, but indirect storage can be undesirable when trying to write lock free algorithms, because needing to follow another level of indirection can change whether something can be done atomically. Is there any way to mark smaller areas of memory such that writing them will cause your app to blow up? Some platforms have hardware watchpoints, and maybe I could activate one of those with inline assembly, but I'd be limited to only 4 at a time on 32-bit x86 and each one could only cover part of the struct because they're limited to 4 bytes. It'd also make my program painful to debug ;)

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• Jquery Autocomplete plugin with Django (Trey Piepmeier solution)

  - by Sally

  So, I'm basing my code on Trey's solution on: http://solutions.treypiepmeier.com/2009/12/10/using-jquery-autocomplete-with-django/ The script is: <script> $(function() { $('#id_members').autocomplete('{{ object.get_absolute_url }}members/lookup', { dataType: 'json', width: 200, parse: function(data) { return $.map(data, function(row) { return { data:row, value:row[1], result:row[0] }; }); } }).result( function(e, data, value) { $("#id_members_pk").val(value); } ); } ); </script> The views.py: def members_lookup(request, pid): results = [] if request.method == "GET": if request.GET.has_key(u'q'): value = request.GET[u'q'] # Ignore queries shorter than length 1 if len(value) > 2: model_results = Member.objects.filter( Q(user__first_name__icontains=value) | Q(user__last_name__icontains=value) ) results = [ (x.user.get_full_name(), x.id) for x in model_results ] json = simplejson.dumps(results) print json return HttpResponse(json, mimetype='application/json') The problem is: It stops refining the search results after the initial lookup. For example: If I set len(value) 2, after I type the 3rd character it will give me a list of suggestions. But if I keep on typing the 4th or 5th character, the list of suggestions doesn't change. Any suggestions on why this is?

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• Internet Explorer Warning when embedding Youtube on HTTPS site?

  - by pellepim

  Our application is run over HTTPS which rarely presents any problems for us. When it comes to youtube however, the fact that they do not present any content over SSL connections is giving us some head ache when trying to embed clips. Mostly because of Internet Explorers famous little warning message: "Do you want to view only the webpage content that was delivered securely? This page contains content that will not be delivered using a secure HTTPS ... etc" I've tried to solve this in several ways. The most promising one was to use the ProxyPass functionality in Apache to map to YouTube. Like this: ProxyPass: /youtube/ http://www.youtube.com ProxyPassReverse: /youtube/ http://www.youtube.com This gets rid of the annoying warning. However, the youtube SWF fails to start streaming The SWF i manage to load into the browser simply states : "An error occurred, please try again later". Potential solutions are perhaps: Download youtube FLV:s and serve them out of own domain (gah) Use custom FLV-player and stream only FLV:s from youtube over a https proxy? Update 10 March: I've tried to use Googles Youtube API for ActionScript to load a player. It looked promising at first and I was able to load a player through my https:// proxy. However, the SWF that is loaded contains loads of explicit calls to different non-ssl urls to create authentication links for the FLV-stream and for loading different crossdomain policies. It really seems like we're not supposed to access flv-streams directly. This makes it very hard to bypass the Internet Explorer warning, short of ripping out the FLV:s from youtube and serving them out of your own domain. There are solutions out there for downloading youtubes FLV:s. But that is not compliant with the Youtube terms of use and is really not an option for us.

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• How to transform coordinate from WGS84 to a coordinate in a projection in PROJ.4?

  - by Sanoj

  I have a GPS-coordinate in WGS84 that I would like to transform to a map-projection coordinate in SWEREF99 TM using PROJ.4 in Java or proj4js in JavaScript. Its hard to find documentation for PROJ.4 and how to us it. If you have a good link, please post it as a comment. The PROJ.4 parameters for SWEREF99 TM is +proj=utm +zone=33 +ellps=GRS80 +towgs84=0,0,0,0,0,0,0 +units=m +no_defs I have tried to use a PROJ.4 Java library and tried this code and values: String[] proj4_w = new String[] { "+proj=utm", "+zone=33", "+ellps=GRS80", "+towgs84=0,0,0,0,0,0,0", "+units=m", "+no_defs" }; Projection proj = ProjectionFactory.fromPROJ4Specification(proj4_w); Point2D.Double testLatLng = new Point2D.Double(55.0000, 12.7500); Point2D.Double testProjec = proj.transform(testLatLng, new Point2D.Double()); This give me the point Point2D.Double[5197915.86288144, 1822635.9083898761] but I should be N: 6097106.672, E: 356083.438 What am I doing wrong? and what method and parameters should I use instead? The correct values is taken from Lantmäteriet. I am not sure if proj.transform(testLatLng, new Point2D.Double()); is the right method to use.

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• Hibernate bit array to entity mapping

  - by teabot

  I am trying to map a normalized Java model to a legacy database schema using Hibernate 3.5. One particular table encodes a foreign keys in a one-to-many relationship as a bit array column. Consider tables 'person' and 'clubs' that describes people's affiliations to clubs: person .----.------. club: .----.---------.---------------------------. | id | name | | id | name | members | binary(members) | |----+------| |----+---------|---------+-----------------| | 1 | Bob | | 10 | Cricket | 0 | 000 | | 2 | Joe | | 11 | Tennis | 5 | 101 | | 3 | Sue | | 12 | Cooking | 7 | 111 | '----'------' | 13 | Golf | 3 | 100 | '----'---------'---------'-----------------' So hopefully it is clear that person.id is used as the bit index in the bit array club.members. In this example the members column tells us that: no one is a member of Cricket, Bob/Sue - Tennis, Bob/Sue/Joe - Cooking and Sue - Golf. In my Java domain I'd like to declare this with entities like so: class Person { private int id; private String name; ... } class Club { private Set<Person> members; private int id; private String name; ... } I am assuming that I must use a UserType implementation but have been unable to find any examples where the items described by the user type are references to entities - not literal field values - or composites thereof. Additionally I am aware that I'll have to consider how the person entities are fetched when a club instance is loaded. Can anyone tell me how I can tame this legacy schema with Hibernate?

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• Java anagram recursion List<List<String>> only storing empty lists<Strings>

  - by Riff Rafffer

  Hi In this recursion method i am trying to find all anagrams and add it to a List but what happens when i run this code is it just returns alot of empty Lists. private List<List<String>> findAnagrams(LetterInventory words, ArrayList<String> anagram, int max, Map<String, LetterInventory> smallDict, int level, List<List<String>> result) { ArrayList<String> solvedWord = new ArrayList<String>(); LetterInventory shell; LetterInventory shell2; if (level < max || max == 0) { Iterator<String> it = smallDict.keySet().iterator(); while (it.hasNext()) { String k = it.next(); shell = new LetterInventory(k); shell2 = words; if (shell2.subtract(shell) != null) { anagram.add(k); shell2 = words.subtract(shell); if (shell2.isEmpty()) { //System.out.println(anagram.toString()); it prints off fine here result.add(anagram); // but doesnt add here } else findAnagrams(shell2, anagram, max, smallDict, level + 1, result); anagram.remove(anagram.size()-1); } } } return results; }

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• iPhone: Remove annotation from MKMapView which is in another view

  - by Nic Hubbard

  I have two views. The first is a MKMapView with some annotations. Clicking a UIButton pushes a second view on the stack. This has a UITableView with a list of annotations which correspond to the map annotations. So, when you click the delete button, how can I call my MKMapView which is in another view, so that I can remove the annotation. My MKMapView is declared in my app delegate, as well as my current class. I am trying to use the following, but it is not working: RideAppDelegate *appDelegate = (RideAppDelegate *)[[UIApplication sharedApplication] delegate]; Annotation *ano; CLLocationCoordinate2D anoPoint; anoPoint.latitude = [[eventToDelete valueForKey:@"latitude"] doubleValue]; anoPoint.longitude = [[eventToDelete valueForKey:@"longitude"] doubleValue]; ano = [[[Annotation alloc] init] autorelease]; ano.coordinate = anoPoint; [appDelegate.ridesMap removeAnnotation: ano]; [appDelegate release]; I must be trying to access the MKMapView of my other view incorrectly?

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• Designing a fluent Javascript interface to abstract away the asynchronous nature of AJAX

  - by Anurag

  How would I design an API to hide the asynchronous nature of AJAX and HTTP requests, or basically delay it to provide a fluid interface. To show an example from Twitter's new Anywhere API: // get @ded's first 20 statuses, filter only the tweets that // mention photography, and render each into an HTML element T.User.find('ded').timeline().first(20).filter(filterer).each(function(status) { $('div#tweets').append('<p>' + status.text + '</p>'); }); function filterer(status) { return status.text.match(/photography/); } vs this (asynchronous nature of each call is clearly visible) T.User.find('ded', function(user) { user.timeline(function(statuses) { statuses.first(20).filter(filterer).each(function(status) { $('div#tweets').append('<p>' + status.text + '</p>'); }); }); }); It finds the user, gets their tweet timeline, filters only the first 20 tweets, applies a custom filter, and ultimately uses the callback function to process each tweet. I am guessing that a well designed API like this should work like a query builder (think ORMs) where each function call builds the query (HTTP URL in this case), until it hits a looping function such as each/map/etc., the HTTP call is made and the passed in function becomes the callback. An easy development route would be to make each AJAX call synchronous, but that's probably not the best solution. I am interested in figuring out a way to make it asynchronous, and still hide the asynchronous nature of AJAX.

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• In Ruby, what is good way to filter all the methods of an object that contain the word "time" in it?

  - by Jian Lin

  I tried the following and it was partly working: >> s.methods.map {|n| n if n =~ /time/} => [nil, nil, nil, nil, nil, nil, nil, nil, "skip_time_zone_conversion_for_attri butes", nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, ni l, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, ni l, "timestamped_migrations", nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, n il, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, n il, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, n il, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, n il, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, "time_zone_aware _attributes", nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, n il, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, "default_timezone", nil, n il, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, n il, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, n il, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, n il, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, "recor d_timestamps", nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil] >> s.methods.each {|n| p n if n =~ /time/} "skip_time_zone_conversion_for_attributes" "timestamped_migrations" "time_zone_aware_attributes" "default_timezone" "record_timestamps" => ["extended_by", "before_create", "vote_ids=", "save_without_dirty", "_delete" , "touch", "daemonize", "after_destroy", "skip_time_zone_conversion_for_attribut es", "methods", "send", "to_query", "becomes", "after_validation", "store_full_s ti_class?", "save_with_transactions!", "autosave_associated_records_for_votes", "require_library_or_gem", "enum_for", "taint", "instance_variable_defined?", "ac [...] and the rest of the whole array >> s.methods.filter {|n| n =~ /time/} NoMethodError: undefined method `filter' for #<Array:0x4de6b00> from (irb):93

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• Why do you have to explicitly specify scope with friendly_id?

  - by nfm

  I'm using the friendly_id gem. I also have my routes nested: # config/routes.rb map.resources :users do |user| user.resources :events end So I have URLs like /users/nfm/events/birthday-2009. In my models, I want the event title to be scoped to the username, so that both nfm and mrmagoo can have events birthday-2009 without them being slugged. # app/models/event.rb def Event < ActiveRecord::Base has_friendly_id :title, :use_slug => true, :scope => :user belongs_to :user ... end I'm also using has_friendly_id :username in my User model. However, in my controller, I'm only pulling out events pertinent to the user who is logged in (current_user): def EventsController < ApplicationController def show @event = current_user.events.find(params[:id]) end ... end This doesn't work; I get the error ActiveRecord::RecordNotFound; expected scope but got none. # This works @event = current_user.events.find(params[:id], :scope => 'nfm') # This doesn't work, even though User has_friendly_id, so current_user.to_param _should_ return "nfm" @event = current_user.events.find(params[:id], :scope => current_user) # But this does work! @event = current_user.events.find(params[:id], :scope => current_user.to_param) SO, why do I need to explicitly specify :scope if I'm restricting it to current_user.events anyway? And why does current_user.to_param need to be called explicitly? Can I override this?

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• Proper way to validate model in ASP.NET MVC 2 and ViewModel apporach

  - by adrin

  I am writing an ASP.NET MVC 2 application using NHibernate and repository pattern. I have an assembly that contains my model (business entities), moreover in my web project I want to use flattened objects (possibly with additional properties/logic) as ViewModels. These VMs contain UI-specific metadata (eg. DisplayAttribute used by Html.LabelFor() method). The problem is that I don't know how to implement validation so that I don't repeat myself throughout various tiers (specifically validation rules are written once in Model and propagated to ViewModel). I am using DataAnnotations on my ViewModel but this means no validation rules are imposed on the Model itself. One approach I am considering is deriving ViewModel objects from business entities adding new properties/overriding old ones, thus preserving validation metadata between the two however this is an ugly workaround. I have seen Automapper project which helps to map properties, but I am not sure if it can handle ASP.NET MVC 2 validation metadata properly. Is it difficult to use custom validation framework in asp.net mvc 2? Do you have any patterns that help to preserve DRY in regard to validation?

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• Makefile : Build in a separate directory tree

  - by Simone Margaritelli

  My project (an interpreted language) has a standard library composed by multiple files, each of them will be built into an .so dynamic library that the interpreter will load upon user request (with an import directive). Each source file is located into a subdirectory representing its "namespace", for instance : The build process has to create a "build" directory, then when each file is compiling has to create its namespace directory inside the "build" one, for instance, when compiling std/io/network/tcp.cc he run an mkdir command with mkdir -p build/std/io/network The Makefile snippet is : STDSRC=stdlib/std/hashing/md5.cc \ stdlib/std/hashing/crc32.cc \ stdlib/std/hashing/sha1.cc \ stdlib/std/hashing/sha2.cc \ stdlib/std/io/network/http.cc \ stdlib/std/io/network/tcp.cc \ stdlib/std/io/network/smtp.cc \ stdlib/std/io/file.cc \ stdlib/std/io/console.cc \ stdlib/std/io/xml.cc \ stdlib/std/type/reflection.cc \ stdlib/std/type/string.cc \ stdlib/std/type/matrix.cc \ stdlib/std/type/array.cc \ stdlib/std/type/map.cc \ stdlib/std/type/type.cc \ stdlib/std/type/binary.cc \ stdlib/std/encoding.cc \ stdlib/std/os/dll.cc \ stdlib/std/os/time.cc \ stdlib/std/os/threads.cc \ stdlib/std/os/process.cc \ stdlib/std/pcre.cc \ stdlib/std/math.cc STDOBJ=$(STDSRC:.cc=.so) all: stdlib stdlib: $(STDOBJ) .cc.so: mkdir -p `dirname $< | sed -e 's/stdlib/stdlib\/build/'` $(CXX) $< -o `dirname $< | sed -e 's/stdlib/stdlib\/build/'`/`basename $< .cc`.so $(CFLAGS) $(LDFLAGS) I have two questions : 1 - The problem is that the make command, i really don't know why, doesn't check if a file was modified and launch the build process on ALL the files no matter what, so if i need to build only one file, i have to build them all or use the command : make path/to/single/file.so Is there any way to solve this? 2 - Any way to do this in a "cleaner" way without have to distribute all the build directories with sources? Thanks

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• Neo4j Reading data / performing shortest path calculations on stored data

  - by paddydub

  I'm using the Batch_Insert example to insert Data into the database How can i read this data back from the database. I can't find any examples of how i do this. public static void CreateData() { // create the batch inserter BatchInserter inserter = new BatchInserterImpl( "var/graphdb", BatchInserterImpl.loadProperties( "var/neo4j.props" ) ); Map<String,Object> properties = new HashMap<String,Object>(); properties.put( "name", "Mr. Andersson" ); properties.put( "age", 29 ); long node1 = inserter.createNode( properties ); properties.put( "name", "Trinity" ); properties.remove( "age" ); long node2 = inserter.createNode( properties ); inserter.createRelationship( node1, node2, DynamicRelationshipType.withName( "KNOWS" ), null ); inserter.shutdown(); } I would like to store graph data in the database, graph.makeEdge( "s", "c", "cost", (double) 7 ); graph.makeEdge( "c", "e", "cost", (double) 7 ); graph.makeEdge( "s", "a", "cost", (double) 2 ); graph.makeEdge( "a", "b", "cost", (double) 7 ); graph.makeEdge( "b", "e", "cost", (double) 2 ); Dijkstra<Double> dijkstra = getDijkstra( graph, 0.0, "s", "e" ); What is the best method to store this kind data with 10000's of edges. Then run the Dijskra algorighm to find shortest path calculations using the stored graph data.

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• Wildcard subdomain .htaccess and Codeigniter

  - by Gautam

  Hi All, I am trying to create the proper .htaccess that would allow me to map as such: http://domain.com/ --> http://domain.com/home http://domain.com/whatever --> http://domain.com/home/whatever http://user.domain.com/ --> http://domain.com/user http://user.domain.com/whatever --> http://domain.com/user/whatever/ Here, someone would type in the above URLs, however internally, it would be redirecting as if it were the URL on the right. Also the subdomain would be dynamic (that is, http://user.domain.com isn't an actual subdomain but would be a .htaccess rewrite) Also /home is my default controller so no subdomain would internally force it to /home controller and any paths following it (as shown in #2 example above) would be the (catch-all) function within that controller. Like wise if a subdomain is passed it would get passed as a (catch-all) controller along with any (catch-all) functions for it (as shown in #4 example above) Hopefully I'm not asking much here but I can't seem to figure out the proper .htaccess or routing rules (in Codeigniter) for this. httpd.conf and hosts are setup just fine. EDIT #1 Here's my .htaccess that is coming close but is messing up at some point: RewriteEngine On RewriteBase / RewriteCond %{SCRIPT_FILENAME} !-d RewriteCond %{SCRIPT_FILENAME} !-f RewriteCond %{HTTP_HOST} ^([a-z0-9-]+).domain [NC] RewriteRule (.*) index.php/%1/$1 [QSA] RewriteCond $1 !^(index\.php|images|robots\.txt) RewriteRule ^(.*)$ /index.php/$1 [L,QSA] With the above, when I visit: http://test.domain/abc/123 this is what I notice in $_SERVER var (I've removed some of the fields): Array ( [REDIRECT_STATUS] => 200 [SERVER_NAME] => test.domain [REDIRECT_URL] => /abc/123 [QUERY_STRING] => [REQUEST_URI] => /abc/123 [SCRIPT_NAME] => /index.php [PATH_INFO] => /test/abc/123 [PATH_TRANSLATED] => redirect:\index.php\test\test\abc\123\abc\123 [PHP_SELF] => /index.php/test/abc/123 ) You can see the PATH_TRANSLATED is not properly being formed and I think that may be screwing things up?

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• Batch Geocoding with Garmin Mapsource

  - by Mike Trader

  Please Note: I AM NOT LOOKING FOR AN ALTERNATIVE SOLUTION I lost track of this effort years ago but have need to geocode thousands of addresses nightly. I must use the very accurate database sitting on the machine, installed when the Nuvi map update installed Mapsource. When I contacted Garmin years ago, they expressed an interest in providing an API for this, but then I heard nothing and did not follow up. Their database is provided by navtec? I believe. Anyone have experience with that format? I posted on the Garmin Developer forum a while ago, but its a little lethargic over there :) Has anyone done this? Does anyone know how it might be done without an API; meaning database structure and calls? I'll take a solution in any language. Added: Garmin has expressed an interest in making this available to me. They just have not done it. I do not know the database format. I am NOT looking for an online solution or any other "alternative". This question is very specific. Contact Info: MikeTrader2 A T gmail D O T com Added: I offered a 400 pt bounty for this. Jeff Atwood then offered 400pts also. If you would like to see a solution to this, vote up the question and I will chase up Garmin and show there is interest in finally providing this. Please Note: I AM NOT LOOKING FOR AN ALTERNATIVE SOLUTION

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• nested form collection_select new value overwriting previous selected values

  - by bharath

  Nested form <%= nested_form_for(@bill) do |f| %> <p><%= f.link_to_add "Add Product", :bill_line_items %> </p> Partial of bill line items <%= javascript_include_tag 'bill'%> <%= f.hidden_field :bill_id %> <%- prices = Hash[Product.all.map{|p| [p.id, p.price]}].to_json %> <%= f.label :product_id %> <%= f.collection_select :product_id ,Product.all,:id,:name, :class => 'product', :prompt => "Select a Product", input_html: {data: {prices: prices}}%> <br/ > <%= f.label :price, "price"%> <%= f.text_field :price, :size=>20, :class =>"price" %><br/> bill.js jQuery(document).ready(function(){ jQuery('.product').change(function() { var product_id = jQuery(this).val(); var price = eval(jQuery(this).data("prices"))[product_id]; jQuery('.price').val(price); }); }); Rails 3.2 Issue: Second click on Add Product & on selecting the product When we select the second product the price of second product is overwriting on the price of the first selected product. Request help.

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• A dynamic array of class "landmark", inside another single class "landmarks"

  - by pinnacler

  I'm working on a robot localization simulator and I created a class called "landmark". The end result is going to be a robot that is always centered and always faces the top of the screen. As it turns, the birds eye view map will rotate around the robot. To accomplish this, I'm assuming I can rotate one class and have all elements inside rotate as well. So, the landmark class has properties x,y, label, and radius. This is suppose to simulate a tree location in a forest. To test everything, I need "forest data," and I wrote a script to generate 100 trees in a 100m x 100m area. The script automatically generates values within an acceptable range for x,y, radius. The generated data is stored in an object called tempForest and is 100x3. Ideally, I want to create a class called "landmarks" (plural) that has 100 landmark instances inside. How would I instantiate 100 instances of landmark in one instance of landmarks using that randomly generated data? Ideally, I'd just type treeBeacons = landmarks(); and it would randomly populate 100 (user definable, set in config file) instances with x, y, radius data. I'm not sure how to deal with a dynamic array of class "Landmark", inside another single class "landmarks." Any ideas?

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• Why use SQL database?

  - by martinthenext

  I'm not quite sure stackoverflow is a place for such a general question, but let's give it a try. Being exposed to the need of storing application data somewhere, I've always used MySQL or sqlite, just because it's always done like that. As it seems like the whole world is using these databases, most of all software products, frameworks, etc. It is rather hard for a beginning developer like me to ask a question - why? Ok, say we have some object-oriented logic in our application, and objects are related to each other somehow. We need to map this logic to the storage logic, so we need relations between database objects too. This leads us to using relational database and I'm ok with that - to put it simple, our database rows sometimes will need to have references to other tables' rows. But why do use SQL language for interaction with such a database? SQL query is a text message. I can understand this is cool for actually understanding what it does, but isn't it silly to use text table and column names for a part of application that no one ever seen after deploynment? If you had to write a data storage from scratch, you would have never used this kind of solution. Personally, I would have used some 'compiled db query' bytecode, that would be assembled once inside a client application and passed to the database. And it surely would name tables and colons by id numbers, not ascii-strings. In the case of changes in table structure those byte queries could be recompiled according to new db schema, stored in XML or something like that. What are the problems of my idea? Is there any reason for me not to write it myself and to use SQL database instead?

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• ViewModel updates after Model server roundtrip

  - by Pavel Savara

  I have stateless services and anemic domain objects on server side. Model between server and client is POCO DTO. The client should become MVVM. The model could be graph of about 100 instances of 20 different classes. The client editor contains diverse tab-pages all of them live-connected to model/viewmodel. My problem is how to propagate changes after server round-trip nice way. It's quite easy to propagate changes from ViewModel to DTO. For way back it would be possible to throw away old DTO and replace it whole with new one, but it will cause lot of redrawing for lists/DataTemplates. I could gather the server side changes and transmit them to client side. But the names of fields changed would be domain/DTO specific, not ViewModel specific. And the mapping seems nontrivial to me. If I should do it imperative way after round-trip, it would break SOC/modularity of viewModels. I'm thinking about some kind of mapping rule engine, something like automappper or emit mapper. But it solves just very plain use-cases. I don't see how it would map/propagate/convert adding items to list or removal. How to identify instances in collections so it could merge values to existing instances. As well it should propagate validation/error info. Maybe I should implement INotifyPropertyChanged on DTO and try to replay server side events on it ? And then bind ViewModel to it ? Would binding solve the problems with collection merges nice way ? Is EventAgregator from PRISM useful for that ? Is there any event record-replay component ? Is there better client side pattern for architecture with server side logic ?

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• get lattitude and longitude of a place against its zipcode

  - by yunas

  Hello i have used the following code to get the location of the particular place on map using the following piece of code NSString * urlString = [[NSString alloc] initWithFormat:@"http://maps.google.com/maps/geo?key=%@&output=xml&q=%@",GoogleMapsAPIKey,[placeName stringByAddingPercentEscapesUsingEncoding:NSUTF8StringEncoding]]; result: <?xml version="1.0" encoding="UTF-8" ?> <kml xmlns="http://earth.google.com/kml/2.0"><Response> <name>postdam</name> <Status> <code>200</code> <request>geocode</request> </Status> <Placemark id="p1"> <address>Potsdam, Germany</address> <AddressDetails Accuracy="4" xmlns="urn:oasis:names:tc:ciq:xsdschema:xAL:2.0"><Country><CountryNameCode>DE</CountryNameCode><CountryName>Deutschland</CountryName><AdministrativeArea><AdministrativeAreaName>Brandenburg</AdministrativeAreaName><SubAdministrativeArea><SubAdministrativeAreaName>Potsdam</SubAdministrativeAreaName><Locality><LocalityName>Potsdam</LocalityName></Locality></SubAdministrativeArea></AdministrativeArea></Country></AddressDetails> <ExtendedData> <LatLonBox north="52.4513968" south="52.3424614" east="13.1866602" west="12.9305414" /> </ExtendedData> <Point><coordinates>13.0586008,52.3969627,0</coordinates></Point> </Placemark> </Response></kml> but now i want to get the information agianst the zipcode how to do that using the maps.google.com ???

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• Binary search in a sorted (memory-mapped ?) file in Java

  - by sds

  I am struggling to port a Perl program to Java, and learning Java as I go. A central component of the original program is a Perl module that does string prefix lookups in a +500 GB sorted text file using binary search (essentially, "seek" to a byte offset in the middle of the file, backtrack to nearest newline, compare line prefix with the search string, "seek" to half/double that byte offset, repeat until found...) I have experimented with several database solutions but found that nothing beats this in sheer lookup speed with data sets of this size. Do you know of any existing Java library that implements such functionality? Failing that, could you point me to some idiomatic example code that does random access reads in text files? Alternatively, I am not familiar with the new (?) Java I/O libraries but would it be an option to memory-map the 500 GB text file (I'm on a 64-bit machine with memory to spare) and do binary search on the memory-mapped byte array? I would be very interested to hear any experiences you have to share about this and similar problems.

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• remove text in parentheses and the parentheses using .filter() or .slice()

  - by liz

  i have a table with code like this: <tr> <th scope="row">5-17</th> <td>23.6 (22.0-24.0)</td> <td>18.0 (17-20.0)</td> </tr> <tr> <th scope="row">Total 0-17</th> <td>20.6 (8-15.6)</td> <td>16.1 (22.2-24.0)</td> </tr> i am using the following function to find the contents of the table cells and bring it into an array: var l1 = $('#datatable td:nth-child(2)').map(function() { return $(this).text(); }).get(); the table fragment's id is "datatable". this returns properly, however i am putting this array into jqPlot and it cant read the stuff between the parentheses or the parentheses themselves. i need the data to remain in the table however because we are displaying both the table and the chart. i cant reformat (add spans around the content i want to remove etc) because these tables are being generated by another piece of software. i think what i need to do is either slice off after the space or use a regex to find and remove. not sure how to proceed with either of these. thanks!

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• video calling (center)

  - by rrejc

  We are starting to develop a new application and I'm searching for information/tips/guides on application architecture. Application should: read the data from an external (USB) device send the data to the remote server (through internet) receive the data from the remote server perform a video call with to the calling (support) center receive a video call call from the calling (support) center support touch screens In addition: some of the data should also be visible through the web page. So I was thinking about: On the server side: use the database (probably MS SQL) use ORM (nHibernate) to map the data from the DB to the domain objects create a layer with business logic in C# create a web (WCF) services (for client application) create an asp.net mvc application (for item 7.) to enable data view through the browser On the client side I would use WPF 4 application which will communicate with external device and the wcf services on the server. So far so good. Now the problem begins. I have no idea how to create a video call (outgoing or incoming) part of the application. I believe that there is no problem to communicate with microphone, speaker, camera with WPF/C#. But how to communicate with the call center? What protocol and encoding should be used? I think that I will need to create some kind of server which will: have a list of operators in the calling center and track which operator is occupied and which operator is free have a list of connected end users receive incoming calls from end users and delegate call to free operator delegate calls from calling center to the end user Any info, link, anything on where to start would be much appreciated. Many thanks!

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• Add new types to Go

  - by nevalu

  I'm trying add new types for that been managed/used as in Go core types. To create new types is anything very interesting to validate data before of send it to a non-SQL DBMS or to check data from a form. Go uses univeral constants to define them at global level: var DateType = universe.DefineType("date", universePos, &dateType{}) In this case they're defined to be called from a package like types: var Date = &dateType{} I get these errors: test.go:58: o.lit undefined (cannot refer to unexported field lit) test.go:62: *dateType is not Type missing Pos() token.Position The code is based on: http://github.com/tav/go/blob/master/src/pkg/exp/eval/value.go http://github.com/tav/go/blob/master/src/pkg/exp/eval/type.go package main import ( "exp/eval" "fmt" // "go/token" ) // http://github.com/tav/go/blob/master/src/pkg/exp/eval/value.go type DateValue interface { eval.Value Get(*eval.Thread) string Set(*eval.Thread, string) } /* Date */ type dateV string func (v *dateV) String() string { return fmt.Sprint(*v) } func (v *dateV) Assign(t *eval.Thread, o eval.Value) { *v = dateV(o.(DateValue).Get(t)) } func (v *dateV) Get(*eval.Thread) string { return string(*v) } func (v *dateV) Set(t *eval.Thread, x string) { *v = dateV(x) } // http://github.com/tav/go/blob/master/src/pkg/exp/eval/type.go type Type interface { eval.Type // isDate returns true if this is a date type. isDate() bool } /* Common type */ type commonType struct{} // added func (commonType) isDate() bool { return false } /* Date */ type dateType struct { commonType } // * It should not be an universal constant //var universePos = token.Position{"<universe>", 0, 0, 0} // added //var DateType = universe.DefineType("date", universePos, &dateType{}) var Date = &dateType{} func (t *dateType) compat(o Type, conv bool) bool { t2, ok := o.lit().(*dateType) return ok && t == t2 } func (t *dateType) lit() Type { return t } func (t *dateType) isDate() bool { return true } func (t *dateType) String() string { return "<date>" } func (t *dateType) Zero() eval.Value { res := dateV("") return &res } /* Named types */ /* type NamedType struct { eval.NamedType Def Type }*/ type NamedType struct { // added // token.Position Name string // Underlying type. If incomplete is true, this will be nil. // If incomplete is false and this is still nil, then this is // a placeholder type representing an error. Def Type // True while this type is being defined. incomplete bool methods map[string]eval.Method } func (t *NamedType) isDate() bool { return t.Def.isDate() } /* *********************** */ func main() { print("foo") }

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• Which PHP library I should choose to work with CouchDB?

  - by Guss

  I want to try playing with CouchDB for a new project I'm writing (as a hobby, not part of my job). I'm well versed in PHP, but I haven't programmed with CouchDB at all, and also I have little experience with non-SQL databases. From looking at CouchDB's "Getting Started with PHP" document they recommend using a third-party library or writing your own client using their RESTful HTTP API. I think I'd rather not mess with writing protocol implementations myself at this point, but what is your experience with writing PHP to work with CouchDB? I haven't tested any of the alternatives yet, but I looked at: PHPillow : I'm interested in the way they implement ORM. I wasn't planning to do ORM, but my problem domain probably map well to that method. PHP Object Freezer: seems like a poor man's ORM - I can use it to implement an actual ORM, or just as an easy store/retrieve document API but it seems too primitive. PHP-on-Couch : Also a bit simple, but they have an interesting API for views and from the documentation it looks usable enough. PHP CouchDB Extension : From the listed options this looks like it has the best chance of making it into the PHP mainline itself, and also has the most complete API. Any opinion one wish to share on each library is welcome.

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