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• Mutually exclusive regular expressions

  - by CaptnCraig

  If I have a list of regular expressions, is there an easy way to determine that no two of them will both return a match for the same string? That is, the list is valid if and only if for all strings a maximum of one item in the list will match the entire string. It seems like this will be very hard (maybe impossible?) to prove definitively, but I can't seem to find any work on the subject. The reason I ask is that I am working on a tokenizer that accepts regexes, and I would like to ensure only one token at a time can match the head of the input.

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• Turn database result into array

  - by Industrial

  Hi everyone, I have just made the update/add/delete part for the "Closure table" way of organizing query hierarchical data that are shown on page 70 in this slideshare: http://www.slideshare.net/billkarwin/sql-antipatterns-strike-back My database looks like this: Table Categories: ID Name 1 Top value 2 Sub value1 Table CategoryTree: child parent 1 1 2 2 2 1 However, I have a bit of an issue getting the full tree back as an multidimensional array from a single query. Here's what I would like to get back: array ( 'topvalue' = array ( 'Subvalue', 'Subvalue2', 'Subvalue3' = array ('Subvalue 1', 'Subvalue 2', 'Subvalue 3' ) ); ); Update: Found this link, but I still have a hard time to convert it into an array: http://karwin.blogspot.com/2010/03/rendering-trees-with-closure-tables.html

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• Any way to ask a method for its name?

  - by Andy

  I'm trying to debug an iPhone app I'm working on, and the idea of adding fifty NSLog statements to the various source files gives me the willies. What I'd like to do is write a pair of statements, say NSString *methodName = [self methodName]; NSLog(@"%@", methodName); that I can just paste into each method I need to. Is there a way to do this? Is there some Objective-C construct for asking a method for its name? Or am I gonna have to do this the hard way?

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• How to find the number of inversions in an array ?

  - by Michael

  This is an phone interview question: "Find the number of inversions in an array". I guess they mean O(N*log N) solution since O(N^2) is trivial. I guess it cannot be better than O(N*log N) since sorting is O(N*log N) I have checked a similar question from SO and can summarize the answers as follows: Calculate half the distance the elements should be moved to sort the array : copy the array and sort the copy. For each element of the original array a[i] find it's position j in the sorted copy (binary search) and sum abs(i - j)/2. Modify merge sort : modify merge to count inversions between two sorted arrays (it takes O(N)) and run merge sort with the modified merge. Does it make sense ? Are there other (maybe simpler) solution ? Isn't it too hard for a phone interview ?

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• Database triggers / referential integrity and in-memory caching

  - by Ran Biron

  Do you see database triggers / referential integrity rules being used in a way that changes actual data in the database (changing row w in table x causes a change in row y in table z)? If yes, How does this tie-in with the increasing popularity of in-memory caching (memcache and friends)? After all, these actions occur inside the database but the caching system must be aware of them in order to reflect to correct state (or at least invalidate the possibly changed state). I find it hard to believe that callbacks are implemented for such cases. Does anyone have real-world experience with such a setup / real-world experience with considering such a setup and abandoning it (which way did you go? if caching, how do you enforce integrity?)

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• Java or Python distributed compute job (on a student budget)?

  - by midget_sadhu

  I have a large dataset (c. 40G) that I want to use for some NLP (largely embarrassingly parallel) over a couple of computers in the lab, to which i do not have root access, and only 1G of user space. I experimented with hadoop, but of course this was dead in the water-- the data is stored on an external usb hard drive, and i cant load it on to the dfs because of the 1G user space cap. I have been looking into a couple of python based options (as I'd rather use NLTK instead of Java's lingpipe if I can help it), and it seems distributed compute options look like: Ipython DISCO After my hadoop experience, i am trying to make sure i try and make an informed choice -- any help on what might be more appropriate would be greatly appreciated. Amazon's EC2 etc not really an option, as i have next to no budget.

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• Get license file from a folder in C# project

  - by daft

  I have a license file that I need to access at runtime in order to create pdf-files. After I have created the in memory pdf, I need to call a method on that pdf to set the license, like this: pdf.SetLicense("pathToLicenseFileHere"); The license file is located in the same project as the.cs-file that creates the pdf, but is in a separate folder. I cannot get this simple thing to behave correctly, which makes me a bit sad, since it really shouldn't be that hard. :( I try to set the path like this: string path = @"\Resources\File.lic"; But it just isn't working out for me.

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• Connect android to database

  - by danny

  I am doing a school project where we need to create an android application which needs to connect to a database. the application needs to gain and store information for people's profiles on the database. But unfortunatly we are a little bit stuck at this point because there are numerous ways to link the application such as http request through apache or through the SOAP/REST protocol. But it's really hard to find good instructions or tutorials on the problem since I can't really find them. Maybe that's cause i'm probably using the wrong words on google. Unfortunately I have little relevant information. So if anyone can help me with finding relevant links to good online tutorials or howto's than those are very welcome.

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• Spring+JSP url building best practices

  - by dotsid

  I wonder if there are any good practices for addressing Spring controllers in JSP. Suppose I have controller: @Controller class FooController { // Don't bother about semantic of this query right now @RequestMapping("/search/{applicationId}") public String handleSearch(@PathVariable String applicationId) { [...] } } Of course in JSP I can write: <c:url value="/search/${application.id}" /> But it's very hard to change url then. If you familiar with Rails/Grails then you now how this problem resolved: redirect_to(:controller => 'foo', :action = 'search') But in Spring there is so much UrlMappers. Each UrlMapper have own semantic and binding scheme. Rails alike scheme simply doesn't work (unless you implement it yourself). And my question is: are there any more convenient ways to address controller from JSP in Spring?

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• For anyone with free time: Trying to learn how to replace PHP with Python, failing terribly.

  - by MALON

  I want give web development using Python a shot, but I'm failing hard. I don't even know if I CAN run Python. The webpage for my web host says it supports all kinds of stuff, including Python. I've never touched anything CGI related and this does not appear to be a noob friendly area. Below is all the information I could think of that might be useful: Shared host: Yes Webhost: dibbsonhosting.com Server OS: linux Python installed: Yes (or so says the webhost) mod_python installed: Don't Know WSGI installed: Don't Know Access to http.conf: No Terminal access: No Cpanel: Yes FTP: Yes Django: downloaded latest stable release, not uploaded anywhere, not sure where to put it. DB: MySQL 5.x I really want to use Python for web development! Thanks!

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• What is Restful Routing?

  - by John Baker

  I have been searching pretty hard for info out on the net to explain exactly what Restful routing is but I haven't had any success. There are a lot of resources but not a who lot make sense to me. I'm familiar with Ruby On Rails's routing system and well as how Code Igniter and PhpCake route things but is there more to it than having a centralized location where you give out routes based on a directory structure? Like this: controller/action/id/ Admin/editUser/22 I'd appreciate any help with this, it's had me baffled for months. I just thought of putting it on SO. Thanks

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• "Single NSMutableArray" vs. "Multiple C-arrays" --Which is more Efficient/Practical?

  - by RexOnRoids

  Situation: I have a DAY structure. The DAY structure has three variables or attributes: a Date (NSString*), a Temperature (float), and a Rainfall (float). Problem: I will be iterating through an array of about 5000 DAY structures and graphing a portion of these onto the screen using OpenGL. Question: As far as drawing performance, which is better? I could simply create an NSMutableArray of DAY structures (NSObjects) and iterate on the array on each draw call -- which I think would be hard on the CPU. Or, I could instead manually manage three different C-Arrays -- One for the Date String (2-Dimensional), One for the temperature (1-Dimensional) and One for the Rainfall (1-Dimensional). I could keep track of the current Day by referencing the current index of the iterated C-Arrays.

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• Subdividing 3D mesh into arbitrarily sized pieces

  - by Groky

  I have a mesh defined by 4 points in 3D space. I need an algorithm which will subdivide that mesh into subdivisions of an arbitrary horizontal and vertical size. If the subdivision size isn't an exact divisor of the mesh size, the edge pieces will be smaller. All of the subdivision algorithms I've found only subdivide meshes into exact powers of 2. Does anyone know of one that can do what I want? Failing that, my thoughts about a possible implementation is to rotate the mesh so that it is flat on the Z axis, subdivide in 2D and then translate back into 3D. That's because my mind finds 3D hard ;) Any better suggestions? Using C# if that makes any difference.

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• Examples of fast .NET WPF/WinForms apps?

  - by mythz

  I am currently investigating whether to build a windows application using unmanaged C/C++ or in .NET and would like to know of the kind of performance and responsiveness that is capable with a managed C#/.NET GUI app? Not surprisingly it looks like the fastest most responsive applications (e.g. chrome, spotify, etc) are written in unmanaged C/C++. I've had a hard time finding examples of really good .NET applications and so I would like some help. What's the best example of a fast and responsive .NET windows application?

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• (this == null) in C#!

  - by SLaks

  Due to a bug that was fixed in C# 4, the following program prints true. (Try it in LINQPad) void Main() { new Derived(); } class Base { public Base(Func<string> valueMaker) { Console.WriteLine(valueMaker()); } } class Derived : Base { string CheckNull() { return "Am I null? " + (this == null); } public Derived() : base(() => CheckNull()) { } } In VS2008 in Release mode, in throws an InvalidProgramException. (In Debug mode, it works fine) In VS2010 Beta 2, it doesn't compile (I didn't try Beta 1); I learned that the hard way Is there any other way to make this == null in pure C#?

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• how rspec creates database between specs

  - by timpone

  This is a bit of a naive / simple question. I'm having a hard time finding this info online. Basically, does rspec run rake db:test:prepare between every rspec group? Or is it between every example or model? Or does the schema get loaded once and then truncated between each. I need to add a rake task directly after this call to create a view since they are not supported in schema.rb. Either a link or explanation would be greatly appreciated so that I know where to insert my rake task to create a view. Or whether there is a callback like rake db:test:after_prepare thx

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• Color Themes for Eclipse?

  - by John Stauffer

  I am a recovering Emacs user, who is trying to ease into Eclipse usage. (Since I'm encouraging the rest of the team to use it, I guess I should at least try to get along). My current excuse is that it hurts my eyes. I'm currently using the excellent zenburn theme in emacs, and would love to find it for eclipse. However, I find that changing my color theme every few months makes for a great way to procrastinate, so ideally I'd like to find a repository for eclipse color themes. There don't appear to be any eclipse themes indexed by Google, so all the great themes must be sitting on your hard disk somewhere. Please share them. Thanks

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• Jquery attach show event to select option

  - by John

  Hi, I have a select form element with 5 options. If option 2 is selected I want to display another form input box (this has a style of display:none initially). How can I attach an event to option 2 so that whenever it is selected the input box is shown otherwise it is hidden. I have this currently but this does not handle is option 2 is already selected when the page loads $('#type').change(function(){ var typeSelected = $(this).val(); if (typeSelected == 2) { $('#extraInput').show(); } }); I know I could add another bit of code which checks what is selected on page load but wondered if there was a neater way of doing this. Also something that could handle the hiding of the input box if option 2 is not selected at the start as currently I have just hard-coded style="display:none" onto the input box but I would prefer this to be dynamic. Thanks

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• Web Application - Authentication / Login Framework

  - by user456563

  This is a very simple, probably a most asked question and frequently developed as part of any web application. Say I'm planning to build a web application and some of the functional requirements include (apart from the usual hard hitting security reqs), - Need to have users sign up for a new account profile - Authenticate user using the native app authentication / Facebook or Google or Yahoo or OpenId login - Allow lost password retrieval - Session handling needs Is there an out of the box frameworks (Drupal, Liferay??) that I can use to wrap my application which can be a bunch of JSP's or HTML's with JS? I know I'm asking a very simple and maybe a naive question. But this is a topic every web developer guru will go thru. Any help, advise and pointers much appreciated.

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• CAD/CAM without C++

  - by zaladane

  Hello, Is it possible to do CAD/CAM software without having to use C++? My company developed their software with c/C++ but that was more than 10 years ago. Today,there is a lot of legacy code that switching would force us to get rid of but i was wondering what the actual risks are. We have a lot of mathematical algorithms for toolpath calculations, feature recognition and simulation and 3D Rendering and i was wondering if C# can handles all of that without great performance loss. Is it a utopia to rewrite such algorithms in c# or should that language only deal with UI. We are not talking about game development here (Halo 3 or Call Of Duty) so how much processing does CAD/CAM really need? Can anybody enlighten me on this matter? Most of my colleagues are hardcore C++ programmers and although i program in c++ i love .NET but i am having a hard time selling .NET to them other than basic UI. Does it make sense to consider switching to .NET in such a field, or is it just not a wise idea? Thank you

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• elastic / snaking line algorithm

  - by vhdirk

  Hi everyone I am making a graphics application in which I can edit a polyline by dragging the control point of it. However, I'd like to make it a bit easier to use by making it elastic; When dragging a control point, instead of moving a single point, I'd like the points within a certain distance of that point to be moved as well, depending on how hard the control point is 'pulled'. Does anyone know a simple algorithm for this? It may be quite rudimentary, as the primary requirement is speed. Actually, knowing how to call such behaviour would also be nice, so I can look it up on google. I tried 'snaking' line, but that seems to refer to active contours, which isn't what I'm looking for. Thanks

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• Using css "active tab" technique on single page

  - by flash

  I'm building a navigation system using jquery scrollto. I have my navigation menu in a separate file (( navigation.php )). It is included in 5 locations on the first page (( 5 different sections w/ text following each )). I'm trying to figure out a way to have the current "tab" highlight'd. I could hard code the navigation in each location to ensure it shows up the correct way, but I'd rather use the phpinclude() method. The other issue is that each "tab" has it's own unique color (( cmykd )). Here is the alpha version of what I'm doing (( when you click && the page slides, the "active tab" still stays grey -- I'd like it to be the corresponding color )). Hope this all makes sense && thanks in advance !!

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• Best Practice for Exporting an App's Data to XML via PHP/MySQL?

  - by Alex Cook

  I have an a business app and I want to give my users the ability to export their data at anytime. I'm aware that I can write an XML file semi-manually by doing something like this: http://www.kirupa.com/web/mysql_xml_php.htm But, I thought I'd ask if this is the best practice? Or is there some framework I can use to do this more easily/quickly? Maybe there isn't - it won't be too hard to do it the above way. Also, less importantly - XML is the best format to export to, right? Thanks in advance.

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• XML Architecture

  - by Roflcoptr

  For my application I have to use a undefined number of different detection strategies. A strategy is defined in the following fashion: The AND gate can also be a OR gate. For now, I hard coded all these rules in my code. For better extensability, I'd like to define all the detection startegies respectively rules in a XML file and parse it. But I'm not really sure how I can define such a detection strategy in a XML file. Any hints how to start?

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• How does SWTBOT run a custom eclipse based application? I don't know how to specify my target application

  - by jlisam13

  I have an eclipse based application. I have heard of swtbot however I am having a hard time understanding how exactly does this tool run my application and how would I specify that. This eclipse based application has an executable and various configuration/plugin/features files. I have done the tutorials about swtbot and I have successfully completed them but they all just create a template application to test on. Is this even possible? If not do you guys have any alternatives for UI automation testing on eclipse based apps? Thanks.

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