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  • Why does python use 'magic methods'?

    - by Greg Beech
    I've been playing around with Python recently, and one thing I'm finding a bit odd is the extensive use of 'magic methods', e.g. to make its length available an object implements a method def __len__(self) and then it is called when you write len(obj). I was just wondering why objects don't simply define a len(self) method and have it called directly as a member of the object, e.g. obj.len()? I'm sure there must be good reasons for Python doing it the way it does, but as a newbie I haven't worked out what they are yet.

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  • Using mergedModelFromBundles: and versioning (CoreData)

    - by charlax
    Hi everybody, I'm trying to use the migration feature in CoreData. I've followed the Apple Documentation. I have a problem in the following method: /** Returns the managed object model for the application. If the model doesn't already exist, it is created by merging all of the models found in the application bundle. */ - (NSManagedObjectModel *)managedObjectModel { if (managedObjectModel != nil) { return managedObjectModel; } /* * NSInvalidArgumentException', reason: '*** -[NSCFArray insertObject:atIndex:]: attempt to insert nil' * 2010-02-17 16:27:15.338 Patrimoine[3037:207] */ managedObjectModel = [[NSManagedObjectModel mergedModelFromBundles:nil] retain]; return managedObjectModel; } It appears that there is the same problem on http://iphonedevelopment.blogspot.com/2009/09/core-data-migration-problems.html Yet I did choose the method Apple suggests, by using the menu option "Add Model Version". Do you have any idea?

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  • Traveling Salesman - Nearest Neighbor vs Genetic DEATHMATCH

    - by EvilTeach
    Over the last few days I have noted a few web sites that demonstrated TS solution using genetic algorithms. I am looking for your opinion which is better for this particular problem. Heuristics vs Genetic. By better, I mean will yield a shorter/lower cost path. Explain why you feel the way that you do. Examples, and off-site links are welcome.

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  • Salt question - using a "random salt"

    - by barfoon
    Hey everyone, Further to my question here, I have another question regarding salts. When someone says "use a random salt" to pre/append to a password, does this mean: Creating a static a 1 time randomly generated string of characters, or Creating a string of characters that changes at random every time a password is created? If the salt is random for every user and stored along with the hashed password, how is the original salt ever retrieved back for verification? Thanks!

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  • zoom_changed only triggers once in google maps api version 3 using MVC

    - by fredrik
    Hi, I'm trying to use the MVC objects in google maps version 3. What I can't seem to figure out is why my zoom_changed method is only invoked once. When I first load the map the zoom_changed method is invoked. But not when I zoom on the map. function MarkerWidget (options) { this.setValues(options); this.set('zoom', this.map.zoom); var marker = new google.maps.Marker({ icon : this.icon, mouseOverIcon : this.mouseOverIcon, orgIcon : this.orgIcon }); marker.bindTo('map', this); marker.bindTo('position', this); google.maps.event.addListener(marker, 'mouseover', this.onmouseover); google.maps.event.addListener(marker, 'mouseout', this.onmouseout); } MarkerWidget.prototype = new google.maps.MVCObject(); MarkerWidget.prototype.zoom_changed = function () { $.log(this, new Date()); } Shouldn't the map object fire the zoom event and notify all object's that has "this.set('zoom', this.map.zoom)" ? ..fredrik

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  • Opening SSL URLs with Python

    - by RadiantHex
    Hi folks, I'm using mechanize to navigate pages, it works pretty well. Unfortunately I have a random error come up, by random I mean it occasionally appears. URLError at /test/ urlopen error [Errno 1] _ssl.c:1325: error:140943FC:SSL routines:SSL3_READ_BYTES:sslv3 alert bad record mac I really need help on this one :) any ideas?

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  • Retrieve input and output parameters for SQL stored procs and functions?

    - by Darth Continent
    For a given SQL stored proc or function, I'm trying to obtain its input and output parameters, where applicable, in a Winforms app I'm creating to browse objects and display their parameters and other attributes. So far I've discovered the SQL system function object_definition, which takes a given sysobjects.id and returns the text of that object; also discovered via search this post which describes extracting the parameters in the context of a app using the ADO.NET method DeriveParameters in conjunction with some caching for better performance; and for good measure found some helpful system stored procs from this earlier post on Hidden Features of SQL Server. I'm leaning towards implementing the DeriveParameters method in my C# app, since parsing the output of object_definition seems messy, and I haven't found a hidden feature in that post so far that would do the trick. Is DeriveParameters applicable to both functions and stored procs for purposes of retreiving their parameters, and if so, could someone please provide an example?

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  • WebCrawling Dynamic Links

    - by Jojo
    Hi Everyone, Anybody has any idea on crawling websites that have dynamic pages/queries? I mean if I click a certain link, it has different values every I try to reload it in a web browser. Now my webcrawler could not download the contents of these pages. Please advise.

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  • php smart learner

    - by rajesh1984
    Is there a possibility to create a html or a php page that will count redirects? I mean, let's say you have a page with a link in it. I want the page to count how many times the link is clicked per ip adress or username. The counting would be reported into a log file or text document.

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  • How to draw a full ellipse in a StreamGeometry in WPF?

    - by romkyns
    The only method in a StreamGeometryContext that seems related to ellipses is the ArcTo method. Unfortunately it is heavily geared to joining lines rather than drawing ellipses. In particular, the position of the arc is determined by a starting and ending point. For a full ellipse the two coincide obviously, and the exact orientation becomes undefined. So far the best way of drawing an ellipse centered on 100,100 of size 10,10 that I found is like this: using (var ctx = geometry.Open()) { ctx.BeginFigure(new Point(100+5, 100), isFilled: true, isClosed: true); ctx.ArcTo( new Point(100 + 5*Math.Cos(0.01), 100 + 5*Math.Sin(0.01)), // need a small angle but large enough that the ellipse is positioned accurately new Size(10/2, 10/2), // docs say it should be 10,10 but in practice it appears that this should be half the desired width/height... 0, true, SweepDirection.Counterclockwise, true, true); } Which is pretty ugly, and also leaves a small "flat" area (although not visible at normal zoom levels). How else might I draw a full ellipse using StreamGeometryContext?

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  • Deadlock in Java

    - by israkir
    Long time ago, I saved a sentence from a Java reference book: "Java has no mechanism to handle deadlock. it won't even know deadlock occurred." (Head First Java 2nd Edition, p.516) So, what is about it? Is there a way to catch deadlock case in Java? I mean, is there a way that our code understands a deadlock case occurred?

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  • Entity Framework in n-layered application - Lazy loading vs. Eager loading patterns

    - by Marconline
    Hi all. This questions doesn't let me sleep as it's since one year I'm trying to find a solution but... still nothing happened in my mind. Probably you can help me, because I think this is a very common issue. I've a n-layered application: presentation layer, business logic layer, model layer. Suppose for simplicity that my application contains, in the presentation layer, a form that allows a user to search for a customer. Now the user fills the filters through the UI and clicks a button. Something happens and the request arrives to presentation layer to a method like CustomerSearch(CustomerFilter myFilter). This business logic layer now keeps it simple: creates a query on the model and gets back results. Now the question: how do you face the problem of loading data? I mean business logic layer doesn't know that that particular method will be invoked just by that form. So I think that it doesn't know if the requesting form needs just the Customer objects back or the Customer objects with the linked Order entities. I try to explain better: our form just wants to list Customers searching by surname. It has nothing to do with orders. So the business logic query will be something like: (from c in ctx.CustomerSet where c.Name.Contains(strQry) select c).ToList(); now this is working correctly. Two days later your boss asks you to add a form that let you search for customers like the other and you need to show the total count of orders created by each customer. Now I'd like to reuse that query and add the piece of logic that attach (includes) orders and gets back that. How would you front this request? Here is the best (I think) idea I had since now. I'd like to hear from you: my CustomerSearch method in BLL doesn't create the query directly but passes through private extension methods that compose the ObjectQuery like: private ObjectQuery<Customer> SearchCustomers(this ObjectQuery<Customer> qry, CustomerFilter myFilter) and private ObjectQuery<Customer> IncludeOrders(this ObjectQuery<Customer> qry) but this doesn't convince me as it seems too complex. Thanks, Marco

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  • How does NHibernate handle cascade="all-delete-orphan"?

    - by Johannes Rudolph
    I've been digging around the NHibernate sources a little, trying to understand how NHibernate implements removing child elements from a collection. I think I've already found the answer, but I'd ideally like this to be confirmed by someone familiar with the matter. So far I've found AbstractPersistentCollection (base class for all collection proxies) has a static helper method called GetOrphans to find orphans by comparing the current collection with a snapshot. The existence of this method suggests NHibernate tries to find all oprhaned elements and then deletes them by key. Is this correct, in terms of the generated SQL?

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  • Can we use spring FTL based form validations with any controller other than SimpleFormController

    - by Adhir Aima
    Hi, Because of some design specification we have to extend all controllers in spring MVC from a class that extends AbstractCommandController. I am trying to include the spring FTL based form validations in my FTL file, but it gives me an error like Method public org.springframework.web.servlet.support.BindStatus org.springframework.web.servlet.support.RequestContext.getBindStatus(java.lang.String) throws java.lang.IllegalStateException threw an exception when invoked on org.springframework.web.servlet.support.RequestContext@b05cd7 with arguments of types [java.lang.String,] The problematic instruction: == assignment: status=springMacroRequestContext.getBindStatus(path) [on line 120, column 9 in spring.ftl] in user-directive spring.bind [on line 47, column 33 in myProfile.ftl] Java backtrace for programmers: freemarker.template.TemplateModelException: Method public org.springframework.web.servlet.support.BindStatus org.springframework.web.servlet.support.RequestContext.getBindStatus(java.lang.String) throws java.lang.IllegalStateException threw an exception when invoked on org.springframework.web.servlet.support.RequestContext@b05cd7 with arguments of types [java.lang.String,] I have put the command name properly in the controller class and in the controller class, neither the specified name nor the default "command" works. Some help please. And would be much appreciated if it comes with an example. Thanks in advance, Adhir Aima

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  • Implications of using many USB web cameras

    - by Martin
    I'm looking into connecting multiple low resolution USB webcams to a single computer. What implications might this have on performance? How does, for example, four 320x240 cameras fare against a single 640x480 camera? I'm not well versed in the architecture of the USB interface, what are the performance caveats? By performance I mean how would it affect the time to read the image data from multiple cameras compared to a single one.

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  • Java Connections netstat -ano

    - by ikurtz
    I am new to java and I have been testing my application all day long. I just did netstat -ano and it gave me a huge listing of active connections (listening, established) does this mean when i close my appliation these connections are not being shutdown (close())? here is a screenshot: any advise on how to go about closing the connection when im done with it? i am trying to close the connection best to my knowledge but it appears im not doing enough. thanks for your time.

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  • How to evaluate query by DBMS?

    - by Kevinniceguy
    Sorry...I mean what question will be for this query? SELECT SUM(price) FROM Room r, Hotel h WHERE r.hotelNo = h.hotelNo and hotelName = 'Paris Hilton' and roomNo NOT IN (SELECT roomNo FROM Booking b, Hotel h WHERE (dateFrom <= CURRENT_DATE AND dateTo >= CURRENT_DATE) AND b.hotelNo = h.hotelNo AND hotelName = 'Paris Hilton');

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  • JAVA Classes in Game programming.

    - by Gabriel A. Zorrilla
    I'm doing a little strategy game to help me learn Java in a fun way. The thing is I visioned the units as objects that would self draw on the game map (using images and buffering) and would react to the mouse actions with listeners attached to them. Now, based on some tutorials I've been reading regarding basic game programming, all seems to be drawn in the Graphics method of my Map class. If a new unit emerges, i just update the Map.Graphics method, it's not as easy as making a new Unit object which would self draw... In this case, I'd be stuck with a whole bunch of Map methods instead of using classes for rendering new things. So my question is, is it possible to use classes for rendering units, interface objects, etc, or i'll have to create methods and just do some kind of structural programming instead of object oriented? I'm a little bit confused and I'd like to have a mental blueprint of how things would be organized. Thanks!

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  • Rail test case fixtures not loading

    - by Deano
    Rails appears to not be loading any fixtures for unit or functional tests. I have a simple 'products.yml' that parses and appears correct: ruby: title: Programming Ruby 1.9 description: Ruby is the fastest growing and most exciting dynamic language out there. If you need to get working programs delivered fast, you should add Ruby to your toolbox. price: 49.50 image_url: ruby.png My controller functional test begins with: require 'test_helper' class ProductsControllerTest < ActionController::TestCase fixtures :products setup do @product = products(:one) @update = { :title => 'Lorem Ipsum' , :description => 'Wibbles are fun!' , :image_url => 'lorem.jpg' , :price => 19.95 } end According to the book, Rails should "magically" load the fixtures (as my test_helper.rb has fixtures :all in it. I also added the explicit fixtures load (seen above). Yes Rails complains: user @ host ~/Dropbox/Rails/depot > rake test:functionals (in /Somewhere/Users/user/Dropbox/Rails/depot) /System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/bin/ruby -Ilib:test "/System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/lib/ruby/gems/1.8/gems/rake-0.8.3/lib/rake/rake_test_loader.rb" "test/functional/products_controller_test.rb" Loaded suite /System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/lib/ruby/gems/1.8/gems/rake-0.8.3/lib/rake/rake_test_loader Started EEEEEEE Finished in 0.062506 seconds. 1) Error: test_should_create_product(ProductsControllerTest): NoMethodError: undefined method `products' for ProductsControllerTest:Class /test/functional/products_controller_test.rb:7 2) Error: test_should_destroy_product(ProductsControllerTest): NoMethodError: undefined method `products' for ProductsControllerTest:Class /test/functional/products_controller_test.rb:7 ... I did come across the other Rails test fixture question http://stackoverflow.com/questions/1547634/rails-unit-testing-doesnt-load-fixtures, but that leads to a plugin issue (something to do with the order of loading fixtures). BTW, I am developing on Mac OS X 10.6 with Rail 2.3.5 and Ruby 1.8.7, no additional plugins (beyond the base install). Any pointers on how to debug, why the magic of Rails appears to be failing here? Is it a version problem? Can I trace code into the libraries and find the answer? There are so many "mixin" modules I can't find where the fixtures method really lives.

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  • ShowDialog won't run

    - by clawson
    I've come across a situation where I try to run a simple line of code in a method Dim res As DialogResult = frmOptions.ShowDialog() but nothing happens. The dialog box will not appear. If I run this method from another location in the code it executes fine (i.e. displays the form in dialog mode and code executes fine thereafter). Hence, it may be the way in which I arrive at this code that is causing my problem, but I cannot see to find what is wrong. When I pause the debugger the line of code is highlighted in green but I can't see to step over it or into it. Any idea what may cause this to happen, or what I should be looking for that might be causing the problem?? Thanks for the help!

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  • JPQL (JPA) search substring

    - by JavaBeginner
    Hi, Im facing simple problem with searching entities by some (sub)string, which they might contain. E.g. I have users user1, usr2, useeeer3, user4 and I will enter to search window "use" and I expect to return user1, useeer3, user4. Im sure you know what I mean now. Is there any construction in JPA (JQPL)? It would be nice to search using WHERE somehow in named queries. Something like "SELECT u FROM User u WHERE u.nickname contains :substring"

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  • Why does /MANIFESTUAC:NO work?

    - by Eamon
    Windows 7, C++, VS2008 I have a COM DLL that needs to be registered using "runas administrator" (it is a legacy app that writes to the registry) The DLL is used by a reports app which instantiates it using CoCreateInstance. This failed unless I also ran the reports app as administrator; until I changed the linker setting from /MANIFESTUAC to /MANIFESTUAC:NO Can anyone tell me why this works? Does it mean that I can write apps that bypass the UAC using this setting?

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