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• What is the difference between Window.load and document.readyState

  - by prakash

  Hi All, I have one question , In my ASP.NET MVC web application i have to do certain validation once page and all controls got loaded. In javascript i was using belwow line of code for calling a method. window.load = JavascriptFunctionName ; Some one from my team asked me not used above line of code Instead use JQuery to do the same document.attachEvent("onreadystatechange", function() { if (document.readyState === "complete") { CheckThis(); } }); Please help me in understanding what is the difference between two. When i tested by keeping alert in both Jquery check is executing first and calling the CheckThis function where as window.load is taking some time and executing after it. Please suggest

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• Adding gwt project to existing java servlet 3 project

  - by Michael

  I have a standalone gwt project with RPC built with Maven. I also have java servlet 3.0 project. Both the servlet and gwt projects have war packaging but I want to have only one war file so I changed the packaging of the gwt project to jar and included it in my servlet project. Now I have a problem understanding how to wire everything together. Do I need to migrate gwt project's web.xml into the main project web.xml file ? How do I redirect to my gwt project entry index.html ? Thanks.

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• LAMP Stack with APC installed - WordPress Site - Is WP opcode being cached with APC?

  - by Christopher Altman

  I have a LAMP stack with APC installed. I have a WordPress site on this server. Is WP taking advantage of the opcode caching? I have done no WP configurations. My understanding is that simply having APC installed means that all PHP code is being cached. If that is untrue, please point me to the direction where I can configure WP to take advantage of APC. Note: I thought about this as a ServerFault question, but since the solution to is code related I posted on Stackoverflow.

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• Building a Monopoly Board with GridBagLayout

  - by Oetzi

  I have been building a Java version of Monopoly in my spare time and am having some trouble understanding layouts etc for Swing. Each one of my spaces on the board is a essentially a custom JButton and I have been trying to lay them around the edge of a frame (like on the monopoly board itself). I can't seem to find a useful explanation of how the layout system works and so am having trouble do so. Could someone please give me an example of how they would lay the buttons around the edge of the frame? Should I be using a different layout?

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• How do I plot more than one series using qplot?

  - by celenius

  I'm trying to understand how to have more than one series on a plot, using the following data. Year <- c('1950', '1960', '1970', '1980') Bus <- c(10,20,30,40) Bus.sd <- c(1.1, 2.2, 3.3, 4.4) Car <- c(20, 20, 40, 40) Car.sd <- c(1.1, 2.2, 3.3, 4.4) sample_data = data.frame(Year, Bus, Bus.sd, Car, Car.sd) qplot(Year, Bus, data=sample_data, geom="pointrange", ymin = Bus - Bus.sd/2, ymax = Bus + Bus.sd/2) For example, using the above data, how do I show both sample_data$Bus and sample_data$Car on the same plot in different colors? What I tried doing was: p <- qplot(...) then p <- p + qplot(...) where I replicated the previous line, but this gave me an error. I don't fully understand how AES works. I have studied the ggplot2 examples, but have difficulty understanding the relevant examples here.

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• Are Scala "continuations" just a funky syntax for defining and using Callback Functions?

  - by Alex R

  And I mean that in the same sense that a C/Java for is just a funky syntax for a while loop. I still remember when first learning about the for loop in C, the mental effort that had to go into understanding the execution sequence of the three control expressions relative to the loop statement. Seems to me the same sort of effort has to be applied to understand Continuations (in Scala and I guess probably other languages). And then there's the obvious follow-up question... if so, then what's the point? It seems like a lot of pain (language complexity, programmer errors, unreadable programs, etc) for no gain.

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• Magento layout override!

  - by Farid

  Hi, I'm kind of new to the Magento, so forgive me for my stupid question! As I understand the whole concept of Magento is base on overriding the basic components that's are available with in the Magento. So based on my understanding I've decided to update the layout of onepage checkout in Magento. I've created my own layout and in the config file set that my layout updates the checkout module layout. But the problem is it's actually does not update the base layout, it replaces it self with base layout! Should it be act like this or am I wrong?!

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• Preserving original StackTrace/LineNumbers in .NET Exceptions

  - by Sam

  Understanding the difference between throw ex and throw, why is the original StackTrace preserved in this example: static void Main(string[] args) { try { LongFaultyMethod(); } catch (System.Exception ex) { Console.WriteLine(ex.StackTrace); } } static void LongFaultyMethod() { try { int x = 20; SomethingThatThrowsException(x); } catch (Exception) { throw; } } static void SomethingThatThrowsException(int x) { int y = x / (x - x); } But not in this one: static void Main(string[] args) { try { LongFaultyMethod(); } catch (System.Exception ex) { Console.WriteLine(ex.StackTrace); } } static void LongFaultyMethod() { try { int x = 20; int y = x / (x - 20); } catch (Exception) { throw; } } The second scenario is producing the same output as throw ex would? In both cases, one expects to see the line number where y is initialized.

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• What software analogies have helped you?

  - by Galwegian

  I have often enjoyed the use of analogies in understanding a software scenario or problem. For example, to understand the concept of public key encryption, the 'locked mailbox' analogy or similar is often used as an aid: An analogy for public-key encryption is that of a locked mailbox with a mail slot. The mail slot is exposed and accessible to the public; its location (the street address) is in essence the public key. Anyone knowing the street address can go to the door and drop a written message through the slot; however, only the person who possesses the key can open the mailbox and read the message. My question is: What analogies have you used or heard of in your career that have given you that "Eureka" moment with a complex concept? EDIT: If you have a good one, don't just state the name, please share with the group!

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• ARC, worth it or not?

  - by MSK

  When I moved to Objective C (iOS) from C++ (and little Java) I had hard time understanding memory management in iOS. But now all this seems natural and I know retain, autorelease, copy and release stuff. After reading about ARC, I am wondering is there more benefits of using ARC or it is just that you dont have to worry about memory management. Before moving to ARC I wanted to know how worth is moving to ARC. XCode has "Convert to Objective C ARC" menu. Is the conversion is that simple (nothing to worry about)? Does it help me in reducing my apps memory foot-print, memory leaks etc (somehow ?) Does it has much testing impact on my apps ? What are non-obvious advantages? Any Disadvantage os moving to it?

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• Question about best practices and Macros from the book 'C++ Coding Standards'

  - by Victor T.

  From Herb Sutter and Andrei Alexandrescu's 'C++ Coding Standards', Item 16: Avoid Macros under Exceptions for this guideline they wrote: For conditional compilation (e.g., system-dependent parts), avoid littering your code with #ifdefs. Instead, prefer to organize code such that the use of macros drives alternative implementations of one common interface, and then use the interface throughout. I'm having trouble understanding exactly what they mean by this. How can you drive alternate implementations without the use of #ifdef conditional compile macro directives? Can someone provide an example to help illustrate what's being proposed by the above paragraph? Thanks

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• How does struts 1.X ActionForm handle pure html checkbox list?

  - by BlueDolphin

  I am dealing with an old application which uses struts 1.2. And for some reason, we are using pure html form to submit to struts action. For example: for the content output of testAction.do, I try to submit to itself. item 1 item 2 Then I associate an form bean TestForm with testAction. I am not sure how to specify the properties in the form so that it take the value from myitem1 after user click "submit" I tried to add getMyitem1(), setMyitem1(String[] items), getSelectedMyitem1(), setSelectedMyitem1(String[] items) Those set methods are only called when page are loaded. I guess my understanding of ActionForm in struts 1.x must be wrong. Please advise, thanks.

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• EXC_BAD_ACCESS when not using self.

  - by chris

  I got nabbed by the following bug again and would like some clarification to exactly why it is a bug. I have a simple UITableView that loads some data: // myclass.h @property (nonatomic, retain) NSArray *myData // myclass.m @synthesize myData; - (void) viewDidLoad { ... myData = someDataSource // note the lack of self } - (UITableViewCell *) cellForRowAtIndexPath ... { ... cell.textLabel.text = [self.myData objectAtIndex:indexPath.row]; // EXC_BAD_ACCESS } The table first loads fine, but when scrolling up enough that one of the cells is totally out of the view I then get the EXC_BAD_ACCESS error. Am I missing something in regards to @property retain. My understanding is that it releases anything that the pointer was previously pointing to before the reassignment. If I am correct then why would not using self. cause any problems? Thanks for the help.

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• Question about mysql indexes on low to medium cardinality columns

  - by Kevin J

  I have a general question about the way that database indexing works, particularly in mysql. Let's say I have a table with a million rows with a column "ClientID" that is distributed relatively equally among 30 values. Thus, this column is very low cardinality (30) relative to the primary key (1 million). Now, I understand that you shouldn't create indexes on low cardinality fields. However, in this case, queries are only ever done with one of the 30 clientIDs. Thus, wouldn't creating an index on ClientID be helpful, as the search space is automatically reduced to 1/30th what it normally would be? Or is my understanding of how the index works flawed? Thanks

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• Handling ID's with db4o and ASP.NET MVC2

  - by Craig McGuff

  So, i'm looking at the TekPub sample for ASP.NET MVC2 (http://mvcstarter.codeplex.com/) using DB4o and there are a bunch of templates to create controllers etc, the generated code looks like: public ActionResult Details(int id) { var item = _session.Single<Account>(x=>x.ID == id); return View(item); } Now, my understanding is that using DB4o or a simliar object database that ID's are not required, so how/what exactly do I pass to enable this kind of templated code to function? UPDATE: Both answers were useful, I have modifed the templates to use GUID as the ID. I will add any relevant code/notes here once I see how it works out.

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• gcc problem with explicit template instantiation?

  - by steve jaffe

  It is my understanding that either a declaration or typedef of a specialization ought to cause a template class to be instantiated, but this does not appear to be happening with gcc. E.g. I have a template class, template class Foo {}; I write class Foo<double>; or typedef Foo<double> DoubleFoo; but after compilation the symbol table of the resulting object file does not contain the members of Foo. If I create an instance: Foo<double> aFoo; then of course the symbols are all generated. Has anyone else experienced this and/or have an explanation?

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• MPI4Py Scatter sendbuf Argument Type?

  - by Noel

  I'm having trouble with the Scatter function in the MPI4Py Python module. My assumption is that I should be able to pass it a single list for the sendbuffer. However, I'm getting a consistent error message when I do that, or indeed add the other two arguments, recvbuf and root: File "code/step3.py", line 682, in subbox_grid i = mpi_communicator.Scatter(station_range, station_data) File "Comm.pyx", line 427, in mpi4py.MPI.Comm.Scatter (src/ mpi4py_MPI.c:44993) File "message.pxi", line 321, in mpi4py.MPI._p_msg_cco.for_scatter (src/mpi4py_MPI.c:14497) File "message.pxi", line 232, in mpi4py.MPI._p_msg_cco.for_cco_send (src/mpi4py_MPI.c:13630) File "message.pxi", line 36, in mpi4py.MPI.message_simple (src/ mpi4py_MPI.c:11904) ValueError: message: expecting 2 or 3 items Here is the relevant code snipped, starting a few lines above 682 mentioned above. for station in stations #snip--do some stuff with station station_data = [] station_range = range(1,len(station)) mpi_communicator = MPI.COMM_WORLD i = mpi_communicator.Scatter(station_range, nsm) #snip--do some stuff with station[i] nsm = combine(avg, wt, dnew, nf1, nl1, wti[i], wtm, station[i].id) station_data = mpi_communicator.Gather(station_range, nsm) I've tried a number of combinations initializing station_range, but I must not be understanding the Scatter argument types properly. Does a Python/MPI guru have a clarification this?

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• I need help translating this portion of the ECMAScript grammar?

  - by ChaosPandion

  I've been working on my own implementation of ECMAScript for quite some time now. I have basically done everything by hand to help gain a deep understanding of the process. Repeated attempts to analyze and understand this portion of the grammar have failed so I've been working on the run time instead. Now I am at a point were I will be working on object literals so I really need to polish my syntactic analyzer. Can anyone put this in terms a language parser novice could understand? My biggest source of confusion is the following: new MemberExpression Arguments This is supposed to be a member expression, but this seemingly conflicts with the following: NewExpression : MemberExpression new NewExpression Is a new expression a member expression or a left hand side expression? To be honest I am having trouble laying out the proper C# classes for the concrete grammar. MemberExpression : PrimaryExpression FunctionExpression MemberExpression [ Expression ] MemberExpression . IdentifierName new MemberExpression Arguments NewExpression : MemberExpression new NewExpression CallExpression : MemberExpression Arguments CallExpression Arguments CallExpression [ Expression ] CallExpression . IdentifierName LeftHandSideExpression : NewExpression CallExpression

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• abstract class MouseAdapter vs. interface

  - by Stefano Borini

  I noted this (it's a java.awt.event class). public abstract class MouseAdapter implements MouseListener, MouseWheelListener, MouseMotionListener { .... } Then you are clearly forced to extend from this adapter public class MouseAdapterImpl extends MouseAdapter {} the class is abstract and implements no methods. Is this a strategy to combine different interfaces into a single "basically interface" ? I assume in java it's not possible to combine different interfaces into a single one without using this approach. In other words, it's not possible to do something like this in java public interface MouseAdapterIface extends MouseListener, MouseWheelListener, MouseMotionListener { } and then eventually public class MouseAdapterImpl implements MouseAdapterIface {} Is my understanding of the point correct ? what about C# ?

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• Which Java modules get Spring Security

  - by HDave

  I have a classic Java SOA application, with a web UI module, web services module, a service module (Java API), a domain module and a persistence module. In a sense, each of these modules has their own public API. My understanding of Spring Security is that I can use web filters to handle the security of the web gui and web services, and method level security (via annotations) for the service module. My question is this: should I bother to add method level security to the domain module and the persistence module or is that considered overkill?

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• How do I get a right outer join in L2E?

  - by Dan

  I have two tables that I set up through the VS Entity Data Model Diagram tool. I'm trying to do a right outer join and it doesn't return results from the 2nd table. I have set up a 0..1 to MANY relationship from the diagram tool. When I run a Linq-To-Entities query, it still defaults to an INNER JOIN. From my understanding of entities, if I set up the relationship using VS, when I join the tables, it should automagically figure out the join syntax based on the relationship I supply. It doesn't seem to be doing that. I am using EF v1 (not Linq-to-Sql). Query I'm running: from s in SomeTable join t in SomeOtherTable on s.ID equals t.ID select new { s.MyFieldName, t.MyOtherFieldName }

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• Favouriting things in a database - most efficient method of keeping track?

  - by a2h

  I'm working on a forum-like webapp where I'd like to allow users to favourite an item so that they can keep track of it, and also so that others can see how many times an item's been favourited. The problem is, I'm unsure on the best practices for databases, which includes this situation. I have two ideas in my head on how to do this: Add an extra column to the user table and store things like so: "|2|5|73|" Add an extra table with at least two columns, one for referencing an item, the other for referencing a user. I feel uncomfortable about going for the second method as it involves an extra table, and potentially more queries would be required. Perhaps these beliefs aren't an issue, as I have little understanding of databases beyond simply working with table layouts and basic queries.

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• MDX: How To Aggregate Hierarchy Level Members With Same Name

  - by Dave Frautnick

  Greetings, I am new to MDX, and am having trouble understanding how to perform an aggregation on a hierarchy level with members that have the same names. This query is particular to Microsoft Analysis Services 2000 cubes. I have a given hierarchy dimension with levels defined as follows: [Segment].[Flow].[Segment Week] Within the [Segment Week] level, I have the following members: [Week- 1] [Week- 2] [Week- 3] ... [Week- 1] [Week- 2] [Week- 3] The members have the same names, but are aligned with a different [Flow] in the parent level. So, the first occurrence of the [Week- 1] member aligns with [Flow].[A] while the second occurrence of [Week- 1] aligns with [Flow].[B]. What I am trying to do is aggregate all the members within the [Segment Week] level that have the same name. In SQL terms, I want to GROUP BY the member names within the [Segment Week] level. I am unsure how to do this. Thank you. Dave

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• Haskell: Pattern Matching with Lists

  - by user1670032

  I'm trying to make a function that takes in a list, and if one of the elements is negative, then any elements in that list that are equal to its positive counterpart should be changed to 0. Eg, if there is a -2 in a list, then all 2's in that list should be changed to 0. Any ideas why it only works for some cases and not others? I'm not understanding why this is, I've looked it over several times. changeToZero [] = [] changeToZero [x] = [x] changeToZero (x:zs:y:ws) | (x < 0) && ((-1)*(x) == y) = x : zs : 0 : changeToZero ws changeToZero (x:xs) = x : changeToZero xs *Main changeToZero [-1,1,-2,2,-3,3] [-1,1,-2,2,-3,3] *Main changeToZero [-2,1,2,3] [-2,1,0,3] *Main changeToZero [-2,1,2,3,2] [-2,1,0,3,2] *Main changeToZero [1,-2,2,2,1] [1,-2,2,0,1]

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• Arrays & Pointers

  - by Thomas

  Hi, Looking for some help with arrays and pointers and explanation of what I am trying to do. I want to create a new array on the heap of type Foo* so that I may later assign objects that have been created else where to this array. I am having troubles understanding what I am creating exactly when I do something like the following. Foo *(*f) = new Foo*[10]; Also once I have created my array how do I access each element for example. (f + 9)->fooMember(); ?????? Thanks in advance.

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