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• Most awkward/misleading method in Java Base API ?

  - by JG

  I was recently trying to convert a string literal into a boolean, when the method "boolean Boolean.getBoolean(String name)" popped out of the auto-complete window. There was also another method ("boolean Boolean.parseBoolean(String s)") appearing right after, which lead me to search to find out what were the differences between these two, as they both seemed to do the same. It turns out that what Boolean.getBoolean(String name) really does is to check if there exists a System property (!) of the given name and if its value is true. I think this is very misleading, as I'm definitely not expecting that a method of Boolean is actually making a call to System.getProperty, and just by looking at the method signature, it sure looks (at least to me) like it should be used to parse a String as a boolean. Sure, the javadoc states it clearly, but I still think the method has a misleading name and is not in the right place. Other primitive type wrappers, such as Integer also have a similar method. Also, it doesn't seem to be a very useful method to belong in the base API, as I think it's not very common to have something like -Darg=true. Maybe it's a good question for a Java position interview: "What is the output of Boolean.getBoolean("true")?". I believe a more appropriate place for those methods would be in the System class, e.g., getPropertyAsBoolean; but again, I still think it's unnecessary to have these methods in the base API. It'd make sense to have these in something like the Properties class, where it's very common to do this kind of type conversions. What do you think of all this ? Also, if there's another "awkward" method that you're aware of, please post it. N.B. I know I can use Boolean.valueOf or Boolean.parseBoolean to convert a string literal into a boolean, but I'm just looking to discuss the API design.

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• gwt seperate modules with no code sharing

  - by Code freak

  Hi, I have to make a web application using GWT. The project has a core module that'll expose a set of apis to be used by other apps; each of these app are unrelated. Each shall be loaded in a separate iframe. My idea was to compile core into core.js and each app shall have its own app1.js app2.js and so on... App1 script type="text/javascript" src="core.js" ></script> script type="text/javascript" src="app1.js" ></script> with this design, due to browser caching, each app laod only the app.js which should be smaller ~20kb in size. Making a core module is straightforward but the apps are problematic. The reason being after compilation, each app contains the entire GWT library - this substantially increases the download size of the complete webapp. Can anyone suggest a way to get aroung this problem ? I've checked similar questions on SO, but failed to find a simple working answer fr the problem. Thanks for any help.

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• Imlpementations of an Interface with Different Types?

  - by b3njamin

  Searched as best I could but unfortunately I've learned nothing relevant; basically I'm trying to work around the following problem in C#... For example, I have three possible references (refA, refB, refC) and I need to load the correct one depending on a configuration option. So far however I can't see a way of doing it that doesn't require me to use the name of said referenced object all through the code (the referenced objects are provided, I can't change them). Hope the following code makes more sense: public ??? LoadedClass; public Init() { /* load the object, according to which version we need... */ if (Config.Version == "refA") { Namespace.refA LoadedClass = new refA(); } else if (Config.Version == "refB") { Namespace.refB LoadedClass = new refB(); } else if (Config.Version == "refC") { Namespace.refC LoadedClass = new refC(); } Run(); } private void Run(){ { LoadedClass.SomeProperty... LoadedClass.SomeMethod(){ etc... } } As you can see, I need the Loaded class to be public, so in my limited way I'm trying to change the type 'dynamically' as I load in which real class I want. Each of refA, refB and refC will implement the same properties and methods but with different names. Again, this is what I'm working with, not by my design. All that said, I tried to get my head around Interfaces (which sound like they're what I'm after) but I'm looking at them and seeing strict types - which makes sense to me, even if it's not useful to me. Any and all ideas and opinions are welcome and I'll clarify anything if necessary. Excuse any silly mistakes I've made in the terminology, I'm learning all this for the first time. I'm really enjoying working with an OOP language so far though - coming from PHP this stuff is blowing my mind :-)

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• `DesignMode` in subcontrols is not set correctly?

  - by affan

  I have a compound control contains nested controls. The problem i am facing is that control read properties from a global setting class which is static and intern read from setting file. To stop individual control from accessing configuration in design mode i added check in each control. If(!DesignMode){ ... //Initialize properties e.g. prop = AppConfig.GetProperty("prop1"); } The problem is that individual control work fine when open in VS. But when i open top control containing nested control i get error by VS designer. The error is that in a nested control DesignMode=false for some reason. I also created a test app and created a simple control within another control to test if there is a problem with VS but it seem to work correctly for any depth of controls. I dont even know how to debug this. For now i comment out the property initializing code and build it and then open designer and there uncomment it and build it again to run it. Did anyone came across this problem or is there any way to fix it.

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• AJAX or a server side framework?

  - by Romansky

  I am working with a friend on building a web site, in general this web site will be a custom web app along with a very custom social network type of thing.. Currently I have a mock-up site that uses simple PHP with AJAX and JSON and JQUERY and I love how it works, I love the way it all fits together. But for a mock-up I did not implement any of the Social Network design patterns such as a login, rating, groups etc.. This brought me to a higher level of decision making requirement, I need to decide if I want to develop all this functionality by hand or use some kind of a framework. I spent this entire day researching, and it would seem that using Drupal and such frameworks will make the Social Network part easy (overlooking the customization requirement for now..) but will make client side Web App development less so. I found some other frameworks that are more developer friendly (customizable) such as Zend and Symfony etc.. but these seem to take allot of the power from the client and implement it in the server side, to me this seems a waste (and an unjustified performance bottleneck) .. Finally I found Aptana Jaxer framework that seems to think the same way I feel. That said it seems a bit under-developed, I didn't find modules for a social network and the community around it seems thin.. (searching Jaxer in StackOverflow returns few results) So other then making server side DB comm a bit simpler it does not help me greatly.. My requirements are a good facility to develop web apps on while containing all the user centric logic usually used for social networks in advance. What would you recommend? EDIT: OK, lats fine tune this question, after considering this abit further, is there a good down loadable source of a social network site in PHP that I can work around in building my web app? (I really like using JQUERY AJAX JSON etc..)

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• Appropriate uses of Monad `fail` vs. MonadPlus `mzero`

  - by jberryman

  This is a question that has come up several times for me in the design code, especially libraries. There seems to be some interest in it so I thought it might make a good community wiki. The fail method in Monad is considered by some to be a wart; a somewhat arbitrary addition to the class that does not come from the original category theory. But of course in the current state of things, many Monad types have logical and useful fail instances. The MonadPlus class is a sub-class of Monad that provides an mzero method which logically encapsulates the idea of failure in a monad. So a library designer who wants to write some monadic code that does some sort of failure handling can choose to make his code use the fail method in Monad or restrict his code to the MonadPlus class, just so that he can feel good about using mzero, even though he doesn't care about the monoidal combining mplus operation at all. Some discussions on this subject are in this wiki page about proposals to reform the MonadPlus class. So I guess I have one specific question: What monad instances, if any, have a natural fail method, but cannot be instances of MonadPlus because they have no logical implementation for mplus? But I'm mostly interested in a discussion about this subject. Thanks! EDIT: One final thought occured to me. I recently learned (even though it's right there in the docs for fail) that monadic "do" notation is desugared in such a way that pattern match failures, as in (x:xs) <- return [] call the monad's fail. It seems like the language designers must have been strongly influenced by the prospect of some automatic failure handling built in to haskell's syntax in their inclusion of fail in Monad.

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• Programming texts and reference material for my Kindle DX, creating the ultimate reference device?

  - by mwilliams

  (Revisiting this topic with the release of the Kindle DX) Having owned both generation Kindle readers and now getting a Kindle DX; I'm very excited for true PDF handling on an e-ink device! An image of _Why's book on my Kindle (from my iPhone). This gives me a device capable of storing hundreds of thousands of pages that are full text search capable in the form factor of a magazine. What references (preferably PDF to preserve things such as code samples) would you recommend? Ultimately I would like reference material for every modern and applicable programming language (C, C++, Objective-C, Python, Ruby, Java, .NET (C#, Visual Basic, ASP.NET), Erlang, SQL references) as well as general programming texts and frameworks (algorithms, design patterns, theory, Rails, Django, Cocoa, ORMs, etc) and anything else that could be thought of. With so many developers here using such a wide array of languages, as a professional in your particular field, what books or references would you recommend to me for my Kindle? Creative Commons material a plus (translate that to free) as well as the material being in the PDF file format. File size is not an issue. If this turns out to be a success, I will update with a follow-up with a compiled list generated from all of the answers. Thanks for the assistance and contributing! UPDATE I have been using the Kindle DX a lot now for technical books. Check out this blog post I did for high resolution photos of different material: http://www.matthewdavidwilliams.com/2009/06/12/technical-document-pdfs-on-the-kindle-dx/

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• SIMPLE PHP MVC Framework [closed]

  - by Allen

  I need a simple and basic MVC example to get me started. I don't want to use any of the available packaged frameworks. I am in need of a simple example of a simple PHP MVC framework that would allow, at most, the basic creation of a simple multi-page site. I am asking for a simple example because I learn best from simple real world examples. Big popular frameworks (such as code igniter) are to much for me to even try to understand and any other "simple" example I have found are not well explained or seem a little sketchy in general. I should add that most examples of simple MVC frameworks I see use mod_rewrite (for URL routing) or some other Apache-only method. I run PHP on IIS. I need to be able to understand a basic MVC framework, so that I could develop my own that would allow me to easily extend functionality with classes. I am at the point where I understand basic design patterns and MVC pretty well. I understand them in theory, but when it comes down to actually building a real world, simple, well designed MVC framework in PHP, I'm stuck. Edit: I just want to note that I am looking for a simple example that an experienced programmer could whip up in under an hour. I mean simple as in bare bones simple. I don't want to use any huge frameworks, I am trying to roll my own. I need a decent SIMPLE example to get me going.

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• How should I return different types in a method based on the value of a string in Java?

  - by Siracuse

  I'm new to Java and I have come to having the following problem: I have created several classes which all implement the interface "Parser". I have a JavaParser, PythonParser, CParser and finally a TextParser. I'm trying to write a method so it will take either a File or a String (representing a filename) and return the appropriate parser given the extension of the file. Here is some psuedo-code of what I'm basically attempting to do: public Parser getParser(String filename) { String extension = filename.substring(filename.lastIndexOf(".")); switch(extension) { case "py": return new PythonParser(); case "java": return new JavaParser(); case "c": return new CParser(); default: return new TextParser(); } } In general, is this the right way to handle this situation? Also, how should I handle the fact that Java doesn't allow switching on strings? Should I use the .hashcode() value of the strings? I feel like there is some design pattern or something for handling this but it eludes me. Is this how you would do it?

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• How can I use a compound condition in a join in Linq?

  - by Gary McGill

  Let's say I have a Customer table which has a PrimaryContactId field and a SecondaryContactId field. Both of these are foreign keys that reference the Contact table. For any given customer, either one or two contacts may be stored. In other words, PrimaryContactId can never be NULL, but SecondaryContactId can be NULL. If I drop my Customer and Contact tables onto the "Linq to SQL Classes" design surface, the class builder will spot the two FK relationships from the Customer table to the Contact table, and so the generated Customer class will have a Contact field and a Contact1 field (which I can rename to PrimaryContact and SecondaryContact to avoid confusion). Now suppose that I want to get details of all the contacts for a given set of customers. If there was always exactly one contact then I could write something like: from customer in customers join contact in contacts on customer.PrimaryContactId equals contact.id select ... ...which would be translated into something like: SELECT ... FROM Customer INNER JOIN Contact ON Customer.FirstSalesPersonId = Contact.id But, because I want to join on both the contact fields, I want the SQL to look something like: SELECT ... FROM Customer INNER JOIN Contact ON Customer.FirstSalesPersonId = Contact.id OR Customer.SecondSalesPersonId = Contact.id How can I write a Linq expression to do that?

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• Auto fit iframe

  - by kevin

  I have a difficulty on design a web page layout. This is my layout structure. <style> #left { float:left; width:600px; min-height:400px; } #right { float:right; width:200px; min-height:400px; } </style> <body> <center> <div id="page"> <div id="left"> <iframe /> </div> <div id="right">right panel</div> <div id="footer">footer</div> </center> </div> </body> How can i make the both left & right div grow when the right div's child increase more than the min height? How can i make the both left & right div grow when the content in the iframe is longer than the min height?

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• QT NOOB: Add action handler for multiple objects of same type.

  - by what

  I have a simple QT application with 10 radio buttons with names radio_1 through radio_10. It is a ui called Selector, and is part of a class called TimeSelector In my header file for this design, i have this: //! [1] class TimeSelector : public QWidget { Q_OBJECT public: TimeSelector(QWidget *parent = 0); private slots: //void on_inputSpinBox1_valueChanged(int value); //void on_inputSpinBox2_valueChanged(int value); private: Ui::Selector ui; }; //! [1] the commented out void_on_inputSpinBox1_valueChanged(int value) is from the tutorial for the simple calculator. I know i can do: void on_radio_1_valueChanged(int value); but I would need 10 functions. I want to be able to make one function that works for everything, and lets me pass in maybe a name of the radio button that called it, or a reference to the radio button so i can work with it and determine who it was. I am very new to QT but this seems like it should be very basic and doable, thanks.

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• How to pass common arguments to Perl modules

  - by Leonard

  I'm not thrilled with the argument-passing architecture I'm evolving for the (many) Perl scripts that have been developed for some scripts that call various Hadoop MapReduce jobs. There are currently 8 scripts (of the form run_something.pl) that are run from cron. (And more on the way ... we expect anywhere from 1 to 3 more for every function we add to hadoop.) Each of these have about 6 identical command-line parameters, and a couple command line parameters that are similar, all specified with Euclid. The implementations are in a dozen .pm modules. Some of which are common, and others of which are unique.... Currently I'm passing the args globally to each module ... Inside run_something.pl I have: set_common_args (%ARGV); set_something_args (%ARGV); And inside Something.pm I have sub set_something_args { (%MYARGS) =@_; } So then I can do if ( $MYARGS{'--needs_more_beer'} ) { $beer++; } I'm seeing that I'm probably going to have additional "common" files that I'll want to pass args to, so I'll have three or four set_xxx_args calls at the top of each run_something.pl, and it just doesn't seem too elegant. On the other hand, it beats passing the whole stupid argument array down the call chain, and choosing and passing individual elements down the call chain is (a) too much work (b) error-prone (c) doesn't buy much. In lots of ways what I'm doing is just object-oriented design without the object-oriented language trappings, and it looks uglier without said trappings, but nonetheless ... Anyone have thoughts or ideas?

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• How to achieve interaction between GUI class with logic class

  - by volting

  Im new to GUI programming, and haven't done much OOP. Im working on a basic calculator app to help me learn GUI design and to brush up on OOP. I understand that anything GUI related should be kept seperate from the logic, but Im unsure how to implement interaction between logic an GUI classes when needed i.e. basically passing variables back and forth... Im using TKinter and when I pass a tkinter variable to my logic it only seems to hold the string PY_VAR0. def on_equal_btn_click(self): self.entryVariable.set(self.entryVariable.get() + "=") calculator = Calc(self.entryVariable) self.entryVariable.set(calculator.calculate()) Im sure that im probably doing something fundamentally wrong and probabaly really stupid, I spent a considerable amount of time experimenting (and searching for answers online) but Im getting no where. Any help would be appreciated. Thanks, V The Full Program (well just enough to show the structure..) import Tkinter class Gui(Tkinter.Tk): def __init__(self,parent): Tkinter.Tk.__init__(self,parent) self.parent = parent self.initialize() def initialize(self): self.grid() self.create_widgets() """ grid config """ #self.grid_columnconfigure(0,weight=1,pad=0) self.resizable(False, False) def create_widgets(self): """row 0 of grid""" """Create Text Entry Box""" self.entryVariable = Tkinter.StringVar() self.entry = Tkinter.Entry(self,width=30,textvariable=self.entryVariable) self.entry.grid(column=0,row=0, columnspan = 3 ) self.entry.bind("<Return>", self.on_press_enter) """create equal button""" equal_btn = Tkinter.Button(self,text="=",width=4,command=self.on_equal_btn_click) equal_btn.grid(column=3, row=0) """row 1 of grid""" """create number 1 button""" number1_btn = Tkinter.Button(self,text="1",width=8,command=self.on_number1_btn_click) number1_btn.grid(column=0, row=1) . . . def on_equal_btn_click(self): self.entryVariable.set(self.entryVariable.get() + "=") calculator = Calc(self.entryVariable) self.entryVariable.set(calculator.calculate()) class Calc(): def __init__(self, equation): self.equation = equation def calculate(self): #TODO: parse string and calculate... return self.equation if __name__ == "__main__": app = Gui(None) app.title('Calculator') app.mainloop()

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• Zend Framework - Deny access to folders other than public folder

  - by Vincent

  All, I have the following Zend application structure: helloworld - application - configs - controllers - models - layouts - include - library - public - .htaccess - index.php - design - .htaccess The .htaccess in the root folder has the following contents: ##################################################### # CONFIGURE media caching # Header unset ETag FileETag None Header unset Last-Modified Header set Expires "Fri, 21 Dec 2012 00:00:00 GMT" Header set Cache-Control "max-age=7200, must-revalidate" SetOutputFilter DEFLATE # ##################################################### ErrorDocument 404 /custom404.php RedirectMatch permanent ^/$ /public/ The .htaccess in the public folder has the following: Options -MultiViews ErrorDocument 404 /custom404.php RewriteEngine on # The leading %{DOCUMENT_ROOT} is necessary when used in VirtualHost context RewriteCond %{DOCUMENT_ROOT}%{REQUEST_FILENAME} -s [OR] RewriteCond %{DOCUMENT_ROOT}%{REQUEST_FILENAME} -l [OR] RewriteCond %{DOCUMENT_ROOT}%{REQUEST_FILENAME} -d RewriteRule ^.*$ - [NC,L] RewriteRule ^.*$ index.php [NC,L] My vhost configuration is as under: <VirtualHost *:80> ServerAdmin [email protected] DocumentRoot "C:\\xampp\\htdocs\\xampp\\helloworld\\" ServerName helloworld ServerAlias helloworld <Directory "C:\\xampp\\htdocs\\xampp\\helloworld\\"> Options Indexes FollowSymLinks AllowOverride all Order Deny,Allow Deny from all Allow from 127.0.0.1 </Directory> </VirtualHost> Currently, if the user visits, http://localhost, my .htaccess files above make sure, the request is routed to http://localhost/public automatically. If the user visits any other folder apart from public folder from the address bar, he gets a directory listing of that folder. How can I make sure to deny the user access to every other folder except the public folder? I want the user to be redirected to the public folder if he visits any other folder. However, if the underlying code requests something from other folders, (ex: ) it should still work.. Thanks

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• Does new JUnit 4.8 @Category render test suites almost obsolete?

  - by grigory

  Given question 'How to run all tests belonging to a certain Category?' and the answer would the following approach be better for test organization? define master test suite that contains all tests (e.g. using ClasspathSuite) design sufficient set of JUnit categories (sufficient means that every desirable collection of sets is identifiable using one or more categories) define targeted test suites based on master test suite and set of categories For example: identify categories for speed (slow, fast), dependencies (mock, database, integration), function (), domain ( demand that each test is properly qualified (tagged) with relevant set of categories. create master test suite using ClasspathSuite (all tests found in classpath) create targeted suites by qualifying master test suite with categories, e.g. mock test suite, fast database test suite, slow integration for domain X test suite, etc. My question is more like soliciting approval rate for such approach vs. classic test suite approach. One unbeatable benefit is that every new test is immediately contained by relevant suites with no suite maintenance. One concern is proper categorization of each test.

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• Three most critical programming concepts

  - by Todd

  I know this has probably been asked in one form or fashion but I wanted to pose it once again within the context of my situation (and probably others here @ SO). I made a career change to Software Engineering some time ago without having an undergrad or grad degree in CS. I've supplemented my undergrad and grad studies in business with programming courses (VB, Java,C, C#) but never performed academic coursework in the other related disciplines (algorithms, design patterns, discrete math, etc.)...just mostly self-study. I know there are several of you who have either performed interviews and/or made hiring decisions. Given recent trends in demand, what would you say are the three most essential Comp Sci concepts that a developer should have a solid grasp of outside of language syntax? For example, I've seen blog posts of the "Absolute minimum X that every programmer must know" variety...that's what I'm looking for. Again if it's truly a redundancy please feel free to close; my feelings won't be hurt. (Closest ones I could find were http://stackoverflow.com/questions/164048/basic-programming-algorithmic-concepts- which was geared towards a true beginner, and http://stackoverflow.com/questions/648595/essential-areas-of-knowledge-which I didn't feel was concrete enough). Thanks in advance all! T.

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• winUserControl in VS2010 - properties are not visible in designer

  - by mj82

  I have a problem with (I suppose) my Visual Studio 2010 Express environment: when I design my own UserControl, in Properties grid I can't see public properties of that control. They are however visible in the project, that reference this control. As it's Express Edition, I create new empty project, then add new UserControl to it. Then, for a test, I put following code: using System; using System.Collections.Generic; using System.ComponentModel; using System.Drawing; using System.Data; using System.Linq; using System.Text; using System.Windows.Forms; namespace Project1 { public partial class UserControl1 : UserControl { private int myNumber; [Browsable(true)] public int MyNumber { get { return myNumber; } set { myNumber = value; } } public UserControl1() { InitializeComponent(); } } } In VS 2008, as I remember, that should be enogh to show MyNumber property in Properties grid, even without [Browsable(true)] attribute. In VS 2010 however, when I double click UserControl1.cs in Solution Explorer and look in Properties, I don't see MyNumber. When I reference and use this control in another project, there is an access to it's properties. I've tried to competly reinstall VS 2010 environment, including SP1, but with no success. Do you have any idea what can be wrong? By the way: none of these attributes are working, either: [Browsable(true)] [EditorBrowsable(EditorBrowsableState.Always)] [DesignerSerializationVisibility(DesignerSerializationVisibility.Content)] [Bindable(true)] Best regards, Marcin

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• PyGTK: Manually render an existing widget at a given Rectangle? (TextView in a custom CellRenderer)

  - by NicDumZ

  Hello! I am trying to draw a TextView into the cell of a TreeView. (Why? I would like to have custom tags on text, so they can be clickable and trigger different actions/popup menus depending on where user clicks). I have been trying to write a customized CellRenderer for this purpose, but so far I failed because I find it extremely difficult to find generic documentation on rendering design in gtk. More than an answer at the specific question (that might be hard/not doable, and I'm not expecting you to do everything for me), I am first looking for documentation on how a widget is rendered, to understand how one is supposed to implement a CellRenderer. Can you share any link that explains, either for gtk or for pygtk, the rendering mechanism? More specifically: size allocation mechanism (should I say protocol?). I understand that a window has a defined size, and then queries its children, saying "my size is w x h, what would be your ideal size, buddy?", and then sometimes shrinks children when all children cant fit together at their ideal sizes. Any specific documentation on that, and on particular on when this happens during rendering? How are rendered "builtin" widgets? What kind of methods do they call on Widget base class? On the parent Window? When? Do they use pango.Layout? can you manually draw a TextView onto a pango.Layout object? This link gives an interesting example showing how you can draw content in a pango.Layout object and use it in a CellRenderer. I guess that I could adapt it if only I understood how TextView widget are rendered. Or perhaps, to put it more simply: given an existing widget instance, how does one render it at a specific gdk.Rectangle? Thanks a lot.

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• Designing model/database for distance between any two locations (that may change)

  - by Yo Ludke

  We should create a web app which has a number of events each with a location (created as user-generated content, so the number of events will be increasingly large). The distance between any events should be available, for example to determine the top 5 closest events and such things. Users may change the locations of events. How should one design the database/model for this (in a scalable way)? I was thinking of doing it with a "distance table" (like so http://www.deutschland-tourist.info/images/entfernungstabelle.gif). Then every time, if a location changes, one row and one column have to be recalculated (this should be done with a delayed job, because it is not important to have the changes instantly). Possible problems in Scaling: Database to large (n² items for n events), too much calculation to be done. For example we should see if this is okay for 10.000 users. If each has created just one event, then this would be 100 million integers... Do you think this would be a good way to do it efficiently? How could one realize such a distance table with an rails model? Is it possible with a SQL databse? Would you start other approaches?

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• Modify columns in a data frame in R more cleanly - maybe using with() or apply()?

  - by Mittenchops

  I understand the answer in R to repetitive things is usually "apply()" rather than loop. Is there a better R-design pattern for a nasty bit of code I create frequently? So, pulling tabular data from HTML, I usually need to change the data type, and end up running something like this, to convert the first column to date format (from decimal), and columns 2-4 from character strings with comma thousand separators like "2,400,000" to numeric "2400000." X[,1] <- decYY2YY(as.numeric(X[,1])) X[,2] <- as.numeric(gsub(",", "", X[,2])) X[,3] <- as.numeric(gsub(",", "", X[,3])) X[,4] <- as.numeric(gsub(",", "", X[,4])) I don't like that I have X[,number] repeated on both the left and ride sides here, or that I have basically the same statement repeated for 2-4. Is there a very R-style way of making X[,2] less repetitive but still loop-free? Something that sort of says "apply this to columns 2,3,4---a function that reassigns the current column to a modified version in place?" I don't want to create a whole, repeatable cleaning function, really, just a quick anonymous function that does this with less repetition.

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• Code Contracts: Do we have to specify Contract.Requires(...) statements redundantly in delegating me

  - by herzmeister der welten

  I'm intending to use the new .NET 4 Code Contracts feature for future development. This made me wonder if we have to specify equivalent Contract.Requires(...) statements redundantly in a chain of methods. I think a code example is worth a thousand words: public bool CrushGodzilla(string weapon, int velocity) { Contract.Requires(weapon != null); // long code return false; } public bool CrushGodzilla(string weapon) { Contract.Requires(weapon != null); // specify contract requirement here // as well??? return this.CrushGodzilla(weapon, int.MaxValue); } For runtime checking it doesn't matter much, as we will eventually always hit the requirement check, and we will get an error if it fails. However, is it considered bad practice when we don't specify the contract requirement here in the second overload again? Also, there will be the feature of compile time checking, and possibly also design time checking of code contracts. It seems it's not yet available for C# in Visual Studio 2010, but I think there are some languages like Spec# that already do. These engines will probably give us hints when we write code to call such a method and our argument currently can or will be null. So I wonder if these engines will always analyze a call stack until they find a method with a contract that is currently not satisfied? Furthermore, here I learned about the difference between Contract.Requires(...) and Contract.Assume(...). I suppose that difference is also to consider in the context of this question then?

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• Books for Computer Networking

  - by Altimet Gaandu

  Hi, I am a student of computer engineering from Vasula University, Somalia. We have a subject called Advanced Computer Networks and the following is the list of recommended books: Text Books: 1. B. A. Forouzan, "TCP/IP Protocol Suite", Tata McGraw Hill edition, Third Edition. 2. N. Olifer, V. Olifer, "Computer Networks: Principles, Technologies and Protocols for Network design", Wiley India Edition, First edition. References: 1. W.Richard Stevens, "TCP/IP Volume1, 2, 3", Addison Wesley. 2. D.E.Comer,"TCP/IPVolumeI and II", PearsonEducation. . 3.W.R. Stevens, "Unix Network Programming", Vol. 1, Pearson Education. 4. J.Walrand, P. Var~fya, "High Performance Communication Networks", Morgan Kaufmann. . 5. A.S.Tanenbaum,"Computer Networks", Pearson Education, Fourth Edition. But we have been unable to find these either in the market or on the internet (read: torrents). Please provide download links to any of these books and oblige. Thanks.

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• Please help with IFrame callback

  - by Code Sherpa

  Hi - thanks for clicking. I am trying to get status feedback using an IFrame for file uploads. I am not trying to get progress or percentages - just when a file is done uploading and if it was a success or failure. THE PROBLEM is that I can't seem to get the server response to appear on the client. I have to following design: I have an iframe on my page: <iframe id="target_frame" src="" style="border:0px; width:0px; height:0px"></iframe> The form tag points to it: <form enctype="multipart/form-data" id="fileUploadForm" name="fileUploadForm" action="picupload.aspx" method="post" target="target_frame"> And the submit button starts a file upload via the iframe: <input id="submit" type="submit" value="upload" /> In the picupload.aspx.cs file, I have a method that returns dynamic data. I then send it to the client: message = data; Response.Write(String.Format("<script language='javascript' type='text/javascript'>window.parent.handleResponse('{0}');</script>", message)); On the client, I have a response handler: function handleResponse(msg) { document.getElementById('statusDiv').innerHTML = msg; } My intent is to see the msg value change for each uploaded file but I never see anything appear in statusDiv, let alone dynamically changing messages. Can somebody please help??

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• MVC for a desktop application, connection a view/controller pair with another one

  - by lcf

  Hello. I've had mostly experience with "server-side" mvc frameworks very popular in different languages like ASP.NET MVC or Zend Framework for php, Spring for Java etc. Some of them are also possible to use for desktop applications development but I never tried that. I fully understand that design patterns should not limit implementation, they should generally provide ideas and common rules that can be differently implemented. Now I'm playing with one of those mvc frameworks for usual Desktop Applications development (it does not have many tutorials or a decent quickstart) and I have some questions regarding to the mvc paradigm. Here is one of them: What are common ways to link different views / controllers? If I click a button, special controller for that button dispatches the event that is generated, does something with the model, changes view state. But what if I need to interact with another view? Like, when I click on a button, it changes a model, but also I need to open another window or change state of another window (hiding a button on another window let's say...), without changing actually the model. What are common ways here to address this? Should my first controller generate an event for the second controller (or second view)? Or should the second controller be handling events from first view? Some links or examples for any languages/frameworks would be really helpful, thanks!

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