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  • How to make a good programming interview?

    - by luckyluke
    I am doing interviews with from time to time to recruit some not bad people. And I really think I AM NOT doing to correct Job. I work in a company when We have to do a lot o DB programming, .NET programming, Java programming, so we need people who are open minded and not focused on a particular tech. Afterall language is a notation, You have to understand what is going under the hood. I ask people about their project, ask them some coding questions (believe me a SQL question involving a CROSS JOIN is hard), let them write some code, ask them about oo design, ask them how they update their knowledge, and stay up to date, do they have FUN when they code (at least sometimes). Hell I even give them a coding solution for home (3 hours max) to see how they think and code. And yet my hit rate at hiring junior member (those who live over the initial 3 months) is just about 33%. So my question, how do YOU make the good interviews, because I think my hit rate is to low? Do you have any best-practices(should be at least 60-70%)? p.s. And i noticed that: the best programmers are lazy, but motivated, just being lazy is not enough:) But people who write the best code are attentive to details:)

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  • Capturing time intervals when somebody was online? How would you impement this feature?

    - by Kirzilla
    Hello, Our aim is to build timelines saying about periods of time when user was online. (It really doesn't matter what user we are talking about and where he was online) To get information about onliners we can call API method, someservice.com/api/?call=whoIsOnline whoIsOnline method will give us a list of users currently online. But there is no API method to get information about who IS NOT online. So, we should build our timelines using information we got from whoIsOnline. Of course there will be a measurement error (we can't track information in realtime). Let's suppose that we will call whoIsOnline method every 2 minutes (yes, we will run our script by cron every 2 minutes). For example, calling whoIsOnline at 08:00 will return Peter_id Michal_id Andy_id calling whoIsOnline at 08:02 will return Michael_id Andy_id George_id As you can see, Peter has gone offline, but we have new onliner - George. Available instruments are Db(MySQL) / text files / key-value storage (Redis/memcache); feel free to choose any of them (or even all of them). So, we have to get information like this George_id was online... 12 May: 08:02-08:30, 12:40-12:46, 20:14-22:36 11 May: 09:10-12:30, 21:45-23:00 10 May: was not online And now question... How would you store information to implement such timelines? How would you query/calculate information about periods of time when user was online? Additional information.. You cannot update information about offline users, only users who are "currently" online. Solution should be flexible: timeline information could be represented relating to any timezone. We should keep information only for last 7 days. Every user seen online is automatically getting his own identifier in our database. Uff.. it was really hard for me to write it because my English is pretty bad, but I hope my question will be clear for you. Thank you.

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  • ASP.NET 2.0 and COM Port Communication

    - by theaviator
    ASP.NET 2.0 and COM Port Communication Hello Guys, I have a managed DLL which communicates with the devices attached on COM/Serial ports. The desktop Winforms application sends requests on ports and receives/stores data in memory. In Winforms app I have added a reference to DLL and I am using the methods. This works well. Now, there is a situation where I need to show this data from serial/com port on a web-page. And also users should be able to send requests to the ports using this DLL. I have made a web app in ASP.NET (2.0). Added a reference to the DLL. I am able to use this DLL, the DLL communicates on the COM upon button click on web-page and also the response is shown on web page. However I am not happy with the approach and strongly feel that this is a bad approach. Also the development server crashes after 3 -4 requests. What is the best approach in this scenario. If I use a windows service then how would my ASP.net app will communicate with the Weindows service. Or can this be easily done using WCF. I have not used WCF any time nor any of .net remoting technique. Please suggest me the best architecture in this scenario. Thank you

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  • Windows 7 theme for WPF?

    - by DanM
    Is there any way to make a WPF app look like it's running on Windows 7 even if it's running on XP? I'm looking for some kind of theme I can just paste in. I'm aware of the themes project on Codeplex (http://www.codeplex.com/wpfthemes), but it lacks support for DataGrid, which is something I critically need. I was thinking maybe the Windows 7 theme would just be an easy port, or exists in some file somewhere already. Any information you have (even if it's bad news) would be much appreciated. Update Using @Lars Truijens idea, I was able to get the Windows 7 look for the major controls, but unfortunately it did not work for the WPF Toolkit DataGrid control, which I need. DataGrid looks like this with Aero theme DataGrid should look like this So, I'm still looking for a solution to this problem if anyone has any ideas. Maybe someone has built an extension to the Aero theme that covers the WPF toolkit controls? Again, any information you have is much appreciated. Update 2 - Problem solved! To get the Aero theme to work with WPF Toolkit controls, you just need to add a second Aero dictionary, so your App.xaml should now look like this. <Application.Resources> ... <ResourceDictionary> <ResourceDictionary.MergedDictionaries> <ResourceDictionary Source="/PresentationFramework.Aero;component/themes/Aero.NormalColor.xaml" /> <ResourceDictionary Source="pack://application:,,,/WPFToolkit;component/Themes/Aero.NormalColor.xaml" /> ... </ResourceDictionary.MergedDictionaries> </ResourceDictionary> </Application.Resources> Also, I would recommend turning the gridlines off in your DataGrid controls (because they look horrible): <DataGrid GridLinesVisibility="None" ...>

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  • Programming test for ASP.NET C# developer job - Opinions please!

    - by Indy
    Hi all, We are hiring a .NET C# developer and I have developed a technical test for the candidates to complete. They have an hour and it has two parts, some knowledge based questions covering asp.net, C# and SQL and a small practical test. I'd appreciate feedback on the test, is it sufficient to test the programmers ability? What would you change if anything? Part One. What the are events fired as part of the ASP.NET Page lifecycle. What interesting things can you do at each? How does ViewState work and why is it either useful or bad? What is a common way to create web services in ASP.NET 2.0? What is the GAC? What is boxing? What is a delegate? The C# keyword .int. maps to which .NET type? Explain the difference between a Stored Procedure and a Trigger? What is an OUTER Join? What is @@IDENTITY? Part Two: You are provided with the Northwind Database and the attached DB relationship diagram. Please create a page which provides users with the following functionality. You don’t need to be too concerned with the presentation detail of the page. Select a customer from a list, and see all the orders placed by that customer. For the same customer, find all their orders which are Beverages and the quantity is more than 5. I was aware of setting the right balance of difficulty on this as there is an hour's test. I was able to complete the practical test in under 30 mins using SQLDatasource and the query designer in visual studio and the test questions, I am looking to see how they approach it logically and whether they use the tools available. Many thanks!

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  • Localizing DataAnnotations Custom Validator

    - by Gabe G
    Hello SO, I'm currently working in an MVC 2 app which has to have everything localized in n-languages (currently 2, none of them english btw). I validate my model classes with DataAnnotations but when I wanted to validate a DateTime field found out that the DataTypeAttribute returns always true, no matter it was a valid date or not (that's because when I enter a random string "foo", the IsValid() method checks against "01/01/0001 ", dont know why). Decided to write my own validator extending ValidationAtribute class: public class DateTimeAttribute : ValidationAttribute { public override bool IsValid(object value) { DateTime result; if (value.ToString().Equals("01/01/0001 0:00:00")) { return false; } return DateTime.TryParse(value.ToString(), out result); } } Now it checks OK when is valid and when it's not, but my problem starts when I try to localize it: [Required(ErrorMessageResourceType = typeof(MSG), ErrorMessageResourceName = "INS_DATA_Required")] [CustomValidation.DateTime(ErrorMessageResourceType = typeof(MSG), ErrorMessageResourceName = "INS_DATA_DataType")] public DateTime INS_DATA { get; set; } If I put nothing in the field I get a localized MSG (MSG being my resource class) for the key=INS_DATA_Required but if I put a bad-formatted date I get the "The value 'foo' is not valid for INS_DATA" default message and not the localized MSG. What am I misssing?

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  • Catching 'Last Record' in Coldfusion for IE javascript bug

    - by Simon Hume
    I'm using ColdFusion to pull UK postcodes into an array for display on a Google Map. This happens dynamically from a SQL database, so the numbers can range from 1 to 100+ the script works great, however, in IE (groan) it decides to display one point way off line, over in California somewhere. I fixed this issue in a previous webapp, this was due to the comma between each array item still being present at the end. Works fine in Firefox, Safari etc, but not IE. But, that one was using a set 10 records, so was easy to fix. I just need a little if statement to wrap around my comma to hide it when it hits the last record. I can't seem to get it right. Any tips/suggestions? here is the line of code in question: var address = [<cfloop query="getApplicant"><cfif getApplicant.dbHomePostCode GT ""><cfoutput>'#getApplicant.dbHomePostCode#',</cfoutput></cfif> </cfloop>]; Hopefully someone can help with this rather simple request. I'm just having a bad day at the office!

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  • using indexer to retrieve Linq to SQL object from datastore

    - by fearofawhackplanet
    class UserDatastore : IUserDatastore { ... public IUser this[Guid userId] { get { User user = (from u in _dataContext.Users where u.Id == userId select u).FirstOrDefault(); return user; } } ... } One of the developers in our team is arguing that an indexer in the above situation is not appropriate and that a GetUser(Guid id) method should be prefered. The arguments being that: 1) We aren't indexing into an in-memory collection, the indexer is basically performing a hidden SQL query 2) Using a Guid in an indexer is bad (FxCop flagged this also) 3) Returning null from an indexer isn't normal behaviour 4) An API user generally wouldn't expect any of this behaviour I agree to an extent with (most of) these points. But I'm also inclined to argue that one of the characteristics of Linq is to abstract the database access to make it appear that you're simply working with a bunch of collections, even though the lazy evaluation paradigm means those collections aren't evaluated until you run a query over them. It doesn't seem inconsistent to me to access the datastore in the same manner as if it was a concrete in-memory collection here. Also bearing in mind this is an inherited codebase which uses this pattern extensively and consistently, is it worth the refactoring? I accept that it might have been better to use a Get method from the start, but I'm not yet convinced that it's completely incorrect to be using an indexer. I'd be interested to hear all opinions, thanks.

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  • Ideas for a rudimentary software licensing implementation

    - by Ross
    I'm trying to decide how to implement a very basic licensing solution for some software I wrote. The software will run on my (hypothetical) clients' machines, with the idea being that the software will immediately quit (with a friendly message) if the client is running it on greater-than-n machines (n being the number of licenses they have purchased). Additionally, the clients are non-tech-savvy to the point where "basic" is good enough. Here is my current design, but given that I have little to no experience in the topic, I wanted to ask SO before I started any development on it: A remote server hosts a MySQL database with a table containing two columns: client-key and license quantity The client-side application connects to the MySQL database on startup, offering it's client-key that I've put into a properties file packaged into the distribution (I would create a new distribution for each new client) Chances are, I'll need a second table to store validation history, so that with some short logic, the software can decide if it can be run on a given machine (maybe a sliding window of n machines using the software per 24 hours) If the software cannot establish a connection to the MySQL database, or decides that it's over the n allowed machines per day, it closes The connection info for the remote server hosting the MySQL database should be hard-coded into the app? (That sounds like a bad idea, but otherwise they could point it to some other always-validates-to-success server) I think that about covers my initial design. The intent being that while it certainly isn't full-proof, I think I've made it at least somewhat difficult to create an easily-sharable cracking solution. Also, I can easily adjust the license amount for a given client/key pair. I gotta figure this has been done a million times before, so tell me about a better solution that's just as simple to implement and provides the same (low) amount of security. In the event that external libraries are used, I prefer Java, as that's what the software has been written in.

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  • What should a developer know before building a public web site?

    - by Joel Coehoorn
    What things should a programmer implementing the technical details of a web site address before making the site public? If Jeff Atwood can forget about HttpOnly cookies, sitemaps, and cross-site request forgeries all in the same site, what important thing could I be forgetting as well? I'm thinking about this from a web developer's perspective, such that someone else is creating the actual design and content for the site. So while usability and content may be more important than the platform, you the programmer have little say in that. What you do need to worry about is that your implementation of the platform is stable, performs well, is secure, and meets any other business goals (like not cost too much, take too long to build, and rank as well with Google as the content supports). Think of this from the perspective of a developer who's done some work for intranet-type applications in a fairly trusted environment, and is about to have his first shot and putting out a potentially popular site for the entire big bad world wide web. Also: I'm looking for something more specific than just a vague "web standards" response. I mean, HTML, JavaScript, and CSS over HTTP are pretty much a given, especially when I've already specified that you're a professional web developer. So going beyond that, Which standards? In what circumstances, and why? Provide a link to the standard's specification. This question is community wiki, so please feel free to edit that answer to add links to good articles that will help explain or teach each particular point.

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  • What's the deal with Java's public fields?

    - by Annan
    I've been reading two articles (1)(2) on javaworld.com about how all class fields should be private and getter/setter methods are just as bad. An object should act on the data it has rather than allowing access to it. I'm currently working on a University assignment for Connect Four. In designing the program the Agents playing the Game need access to the Board's state (so they can decide what to move). They also need to pass this move to the Game so it can validate it as a legal move. And during deciding what to move pieces are grouped into Threats with a start and end Points. Board, Threat and Point objects don't really do anything. They are just there to store related data that can be accessed in a human readable way. At the start of design I was representing Points on the board as two element int arrays, however that got annoying when creating points or referencing components of them. So, the class: public class Point { public int x; public int y; public Point(int x, int y){ this.x = x; this.y = y; } } Perfect in every way I can think of. Except it breaks every rule I've learned. Have I sinned?

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  • How can I find out why a website looks different when I upload it to IIS ?

    - by UXdesigner
    Good day... I've been working on a website project, that requires to be on a Microsoft IIS Web Server. It is HTML, pure HTML, with really nice CSS, web-standards, etc. I open this website using in my computer, using Firefox, IE 8.0, Safari, Google Chrome and it looks fine everywhere. But as I upload it to the Microsoft IIS server, it changes a few things. for example: the main menu, which is a navigation bar that has dropdowns, seems to change it's line-height for some reason, and it is bigger. Some <h3> or <h2> Alignment seems wrong as well... And the lines that are supposed to surround the photographs in the website (like a frame - dotted line) won't appear. But all the rest of the CSS is loading perfectly fine. I don't think it's a path problem as everything is loading fine. But this is making me look bad and it is very important to have this done as soon as possible. Can someone give me good suggestions on what to look at ? The IIS permissions seem fine. I'm not a big Microsoft fan...but I have to develop the website there. Also, I uploaded the site to my apache server and it worked wonders. I wish I could change the policies in this corporation, but I can't. Thank you so much for your kind help.

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  • parameter for xcodebuild for using latest sdk.

    - by Maciek Sawicki
    I using ant exec task to execute xcodebuild to build some iOS projects hudson. I would like to be able to crate script that way that allows not to specify sdk version, because after updating sdk on hudson slave or my iOS projects all my projects failing.... There is is nice option in xcode since sdk 4.2 in target setup Base SDK - Latest iOS and I don't have to provide -sdk param in xcodebuild command, but then (i think) it's taken from xcode project and it's bad because then some one can change target from simulator to device accidentally during commit. I need something that is constant. I will prefer not to use env variable because I would like to be able to run this ant task also on dev machines and would like not have to renember about setting it on all machines. Unfortunately xcodebuild -showsdk gives only: Mac OS X SDKs: Mac OS X 10.4 -sdk macosx10.4 Mac OS X 10.5 -sdk macosx10.5 Mac OS X 10.6 -sdk macosx10.6 iOS SDKs: iOS 4.2 -sdk iphoneos4.2 iOS Simulator SDKs: Simulator - iOS 3.2 -sdk iphonesimulator3.2 Simulator - iOS 4.0 -sdk iphonesimulator4.0 Simulator - iOS 4.1 -sdk iphonesimulator4.1 Simulator - iOS 4.2 -sdk iphonesimulator4.2 I need something like -sdk iphoneosLatest. My only idea is to pare output of xcodebuild -showsdk with some script, but I don't like this idea.

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  • extjs how to make a nested child using xTemplate when we don't know how deep is it?

    - by Ebo the gordon
    first, sorry if my english bad,.... in my script, variable tplData below is dynamic,... (lets say it generates from database) so, every chid, can have another child. and so on,.... now, i'm stack how to iteration it,.. var tplData = [{ name : 'Naomi White' },{ name : 'Yoko Ono' },{ name : 'John Smith', child : [{ name:'Michael (John\'s son)', child: [{ name : 'Brad (Michael\'s son,John\'s grand son)' },{ name : 'Brid (Michael\'s son,John\'s grand son)', child: [{ name:'Buddy (Brid\'s son,Michael\'s grand son)' }] },{ name : 'Brud (Michael\'s son,John\'s grand son)' }] }] }]; var myTpl = new Ext.XTemplate( '<tpl for=".">', '<div style="background-color: {color}; margin: 10px;">', '<b> Name :</b> {name}<br />', // how to make this over and over every child (while it has ) '<tpl if="typeof child !=\'undefined\'">', '<b> Child : </b>', '<tpl for="child">', '{name} <br />', '</tpl>', '</tpl>', /////////////////////////////////////// '</div>', '</tpl>' ); myTpl.compile(); myTpl.overwrite(document.body, tplData);

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  • REST API error return good practices

    - by Remus Rusanu
    I'm looking for guidance on good practices when it comes to return errors from a REST API. I'm working on a new API so I can take it any direction right now. My content type is XML at the moment, but I plan to support JSON in future. I am now adding some error cases, like for instance a client attempts to add a new resource but has exceeded his storage quota. I am already handling certain error cases with HTTP status codes (401 for authentication, 403 for authorization and 404 for plain bad request URIs). I looked over the blessed HTTP error codes but none of the 400-417 range seems right to report application specific errors. So at first I was tempted to return my application error with 200 OK and a specific XML payload (ie. Pay us more and you'll get the storage you need!) but I stopped to think about it and it seems to soapy (/shrug in horror). Besides it feels like I'm splitting the error responses into distinct cases, as some are http status code driven and other are content driven. So what is the SO crowd recommendation? Good practices (please explain why!) and also, from a client pov, what kind of error handling in the REST API makes life easier for the client code?

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  • Using Git to work with subversion: Ignoring modifications to tracked files

    - by Chris Nicola
    I am currently working with a subversion repository but I am using git to work locally on my machine. It makes work much easier, but it also makes some of the bad behavior going on in the subversion repo quite glaring and that creates problems for me. There is a somewhat complex local build process after pulling down the code and it creates (and unfortunately modifies) a number of files. Obviously these changes are not meant to be committed back to the repository. Unfortunately the build process is actually modifying some tracked files (yes, most likely because someone mistakenly committed these build artifacts at some point to the subversion repository). Since these are modifications adding them to my ignore file does nothing for me. I can avoid checking these changes back it, I simple don't stage or commit them, but having unstaged local changes means I can't rebase without first cleaning them up. What I would like to know is if there any way to ignore future changes to a set of tracked files? Alternatively, is there another way to handle the problem I am having, or will I just have to tell whoever checked in these files to clean them up?

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  • Why does adding Crossover to my Genetic Algorithm gives me worse results?

    - by MahlerFive
    I have implemented a Genetic Algorithm to solve the Traveling Salesman Problem (TSP). When I use only mutation, I find better solutions than when I add in crossover. I know that normal crossover methods do not work for TSP, so I implemented both the Ordered Crossover and the PMX Crossover methods, and both suffer from bad results. Here are the other parameters I'm using: Mutation: Single Swap Mutation or Inverted Subsequence Mutation (as described by Tiendil here) with mutation rates tested between 1% and 25%. Selection: Roulette Wheel Selection Fitness function: 1 / distance of tour Population size: Tested 100, 200, 500, I also run the GA 5 times so that I have a variety of starting populations. Stop Condition: 2500 generations With the same dataset of 26 points, I usually get results of about 500-600 distance using purely mutation with high mutation rates. When adding crossover my results are usually in the 800 distance range. The other confusing thing is that I have also implemented a very simple Hill-Climbing algorithm to solve the problem and when I run that 1000 times (faster than running the GA 5 times) I get results around 410-450 distance, and I would expect to get better results using a GA. Any ideas as to why my GA performing worse when I add crossover? And why is it performing much worse than a simple Hill-Climb algorithm which should get stuck on local maxima as it has no way of exploring once it finds a local max?

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  • PostgreSQL insert on primary key failing with contention, even at serializable level

    - by Steven Schlansker
    I'm trying to insert or update data in a PostgreSQL db. The simplest case is a key-value pairing (the actual data is more complicated, but this is the smallest clear example) When you set a value, I'd like it to insert if the key is not there, otherwise update. Sadly Postgres does not have an insert or update statement, so I have to emulate it myself. I've been working with the idea of basically SELECTing whether the key exists, and then running the appropriate INSERT or UPDATE. Now clearly this needs to be be in a transaction or all manner of bad things could happen. However, this is not working exactly how I'd like it to - I understand that there are limitations to serializable transactions, but I'm not sure how to work around this one. Here's the situation - ab: => set transaction isolation level serializable; a: => select count(1) from table where id=1; --> 0 b: => select count(1) from table where id=1; --> 0 a: => insert into table values(1); --> 1 b: => insert into table values(1); --> ERROR: duplicate key value violates unique constraint "serial_test_pkey" Now I would expect it to throw the usual "couldn't commit due to concurrent update" but I'm guessing since the inserts are different "rows" this does not happen. Is there an easy way to work around this?

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  • Represent multiple Null/Generic objects in an ActiveRecord association?

    - by slothbear
    I have a Casefile model that belongs_to a Doctor. In additional to all the "real" doctors, there are several generic Doctors: "self-treated", "not specified", and "removed" (it used to have a real doctor, but no longer does). I suspect there will be even more generic values in the future. I started with special "doctors" in the database, generated from seed. The generic Doctors only need to respond to the "name" and "real_doctor?" methods. This worked with one, was strained with two, and now feels completely broken. I want to change the behavior and can't figure out how to test it, a bad sign. Creating all the generic objects for testing is also trouble, including fake values to pass validation of the required Doctor attributes. The Null Object pattern works well for one generic object. The "name" method could check casefile.doctor.nil? and return "self-treated", as demonstrated by Craig Ambrose. What pattern should I use when there are multiple generic objects with very limited state?

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  • Unit testing and mocking email sender in Python with Google AppEngine

    - by CVertex
    I'm a newbie to python and the app engine. I have this code that sends an email based on request params after some auth logic. in my Unit tests (i'm using GAEUnit), how do I confirm an email with specific contents were sent? - i.e. how do I mock the emailer with a fake emailer to verify send was called? class EmailHandler(webapp.RequestHandler): def bad_input(self): self.response.set_status(400) self.response.headers['Content-Type'] = 'text/plain' self.response.out.write("<html><body>bad input </body></html>") def get(self): to_addr = self.request.get("to") subj = self.request.get("subject") msg = self.request.get("body") if not mail.is_email_valid(to_addr): # Return an error message... # self.bad_input() pass # authenticate here message = mail.EmailMessage() message.sender = "[email protected]" message.to = to_addr message.subject = subj message.body = msg message.send() self.response.headers['Content-Type'] = 'text/plain' self.response.out.write("<html><body>success!</body></html>") And the unit tests, import unittest from webtest import TestApp from google.appengine.ext import webapp from email import EmailHandler class SendingEmails(unittest.TestCase): def setUp(self): self.application = webapp.WSGIApplication([('/', EmailHandler)], debug=True) def test_success(self): app = TestApp(self.application) response = app.get('http://localhost:8080/[email protected]&body=blah_blah_blah&subject=mySubject') self.assertEqual('200 OK', response.status) self.assertTrue('success' in response) # somehow, assert email was sent

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  • WPF tree data binding

    - by Am
    Hi, I have a well defined tree repository. Where I can rename items, move them up, down, etc. Add new and delete. The data is stored in a table as follows: Index Parent Label Left Right 1 0 root 1 14 2 1 food 2 7 3 2 cake 3 4 4 2 pie 5 6 5 1 flowers 8 13 6 5 roses 9 10 7 5 violets 11 12 Representing the following tree: (1) root (14) (2) food (7) (8) flowers (13) (3) cake (4) (5) pie (6) (9) roeses (10) (11) violets (12) or root food cake pie flowers roses violets Now, my problem is how to represent this in a bindable way, so that a TreeView can handle all the possible data changes? Renaming is easy, all I need is to make the label an updatble field. But what if a user moves flowers above food? I can make the relevant data changes, but they cause a complete data change to all other items in the tree. And all the examples I found of bindable hierarchies are good for non static trees.. So my current (and bad) solution is to reload the displayed tree after relocation change. Any direction will be good. Thanks

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  • Convert a Unit Vector to a Quaternion

    - by Hmm
    So I'm very new to quaternions, but I understand the basics of how to manipulate stuff with them. What I'm currently trying to do is compare a known quaternion to two absolute points in space. I'm hoping what I can do is simply convert the points into a second quaternion, giving me an easy way to compare the two. What I've done so far is to turn the two points into a unit vector. From there I was hoping I could directly plug in the i j k into the imaginary portion of the quaternion with a scalar of zero. From there I could multiply one quaternion by the other's conjugate, resulting in a third quaternion. This third quaternion could be converted into an axis angle, giving me the degree by which the original two quaternions differ by. Is this thought process correct? So it should just be [ 0 i j k ]. I may need to normalize the quaternion afterwards, but I'm not sure about that. I have a bad feeling that it's not a direct mapping from a vector to a quaternion. I tried looking at converting the unit vector to an axis angle, but I'm not sure this would work, since I don't know what angle to give as an input.

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  • Base class deleted before subclass during python __del__ processing

    - by Oddthinking
    Context I am aware that if I ask a question about Python destructors, the standard argument will be to use contexts instead. Let me start by explaining why I am not doing that. I am writing a subclass to logging.Handler. When an instance is closed, it posts a sentinel value to a Queue.Queue. If it doesn't, a second thread will be left running forever, waiting for Queue.Queue.get() to complete. I am writing this with other developers in mind, so I don't want a failure to call close() on a handler object to cause the program to hang. Therefore, I am adding a check in __del__() to ensure the object was closed properly. I understand circular references may cause it to fail in some circumstances. There's not a lot I can do about that. Problem Here is some simple example code: explicit_delete = True class Base: def __del__(self): print "Base class cleaning up." class Sub(Base): def __del__(self): print "Sub-class cleaning up." Base.__del__(self) x = Sub() if explicit_delete: del x print "End of thread" When I run this I get, as expected: Sub-class cleaning up. Base class cleaning up. End of thread If I set explicit_delete to False in the first line, I get: End of thread Sub-class cleaning up. Exception AttributeError: "'NoneType' object has no attribute '__del__'" in <bound method Sub.__del__ of <__main__.Sub instance at 0x00F0B698>> ignored It seems the definition of Base is removed before the x._del_() is called. The Python Documentation on _del_() warns that the subclass needs to call the base-class to get a clean deletion, but here that appears to be impossible. Can you see where I made a bad step?

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  • High performance text file parsing in .net

    - by diamandiev
    Here is the situation: I am making a small prog to parse server log files. I tested it with a log file with several thousand requests (between 10000 - 20000 don't know exactly) What i have to do is to load the log text files into memory so that i can query them. This is taking the most resources. The methods that take the most cpu time are those (worst culprits first): string.split - splits the line values into a array of values string.contains - checking if the user agent contains a specific agent string. (determine browser ID) string.tolower - various purposes streamreader.readline - to read the log file line by line. string.startswith - determine if line is a column definition line or a line with values there were some others that i was able to replace. For example the dictionary getter was taking lots of resources too. Which i had not expected since its a dictionary and should have its keys indexed. I replaced it with a multidimensional array and saved some cpu time. Now i am running on a fast dual core and the total time it takes to load the file i mentioned is about 1 sec. Now this is really bad. Imagine a site that has tens of thousands of visits a day. It's going to take minutes to load the log file. So what are my alternatives? If any, cause i think this is just a .net limitation and i can't do much about it.

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  • How to handle SalesForce WSDL files for sandbox and production sites in ASP.Net?

    - by Traveling Tech Guy
    I need to authenticate users and get info about them from an ASP.Net application. Since I have 2 sites (sandbox, production) and 2 org IDs - I needed to generate 2 SalesForce WSDL files. I diffed the 2 files (each about 600kb in size) and while they are 95% the same, there are enough differences strewn all over the place - enough for me to need to use them both. I added both as web references to my solution, and here's where my problem starts.Obviously, I cannot use both references in the same file, as they contain the same classes/functions. I had to write a quick-and-dirty solution over the weekend, so I just created 2 classes - each using a different web reference - but otherwise the exact functionality, and I use the appropriate one, based on the URL the user is coming from. This works well, but strikes me as a bad (read: quick-and-dirty) solution. My question: is there any way to do one or more of the following: change the web reference on the fly? use both web references in the same file, but put one in a different namespace? find a better solution to the whole situation? I nd up with a huge XmlSerializer.dll (3mb!) - probably due to using both huge WSDL files. Thanks for your time.

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