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• MYSQL not running on Ubuntu OS - Error 2002.

  - by mgj

  Hi, I am a novice to mysql DB. I am trying to run the MYSQL Server on Ubuntu 10.04. Through Synaptic Package Manager I am have installed the mysql version: mysql-client-5.1 I wonder that how was the database password set for the mysql-client software that I installed through the above way.It would be nice if you could enlighten me on this. When I tried running this database, I encountered the error given below: mohnish@mohnish-laptop:/var/lib$ mysql ERROR 2002 (HY000): Can't connect to local MySQL server through socket '/var/run/mysqld/mysqld.sock' (2) mohnish@mohnish-laptop:/var/lib$ I referred to a similar question posted by another user. I didn't find a solution through the proposed answers. For instance when I tried the solutions posted for the similar question I got the following: mohnish@mohnish-laptop:/var/lib$ service start mysqld start: unrecognized service mohnish@mohnish-laptop:/var/lib$ ps -u mysql ERROR: User name does not exist. ********* simple selection ********* ********* selection by list ********* -A all processes -C by command name -N negate selection -G by real group ID (supports names) -a all w/ tty except session leaders -U by real user ID (supports names) -d all except session leaders -g by session OR by effective group name -e all processes -p by process ID T all processes on this terminal -s processes in the sessions given a all w/ tty, including other users -t by tty g OBSOLETE -- DO NOT USE -u by effective user ID (supports names) r only running processes U processes for specified users x processes w/o controlling ttys t by tty *********** output format ********** *********** long options *********** -o,o user-defined -f full --Group --User --pid --cols --ppid -j,j job control s signal --group --user --sid --rows --info -O,O preloaded -o v virtual memory --cumulative --format --deselect -l,l long u user-oriented --sort --tty --forest --version -F extra full X registers --heading --no-heading --context ********* misc options ********* -V,V show version L list format codes f ASCII art forest -m,m,-L,-T,H threads S children in sum -y change -l format -M,Z security data c true command name -c scheduling class -w,w wide output n numeric WCHAN,UID -H process hierarchy mohnish@mohnish-laptop:/var/lib$ which mysql /usr/bin/mysql mohnish@mohnish-laptop:/var/lib$ mysql ERROR 2002 (HY000): Can't connect to local MySQL server through socket '/var/run/mysqld/mysqld.sock' (2) I even tried referring to http://forums.mysql.com/read.php?11,27769,84713#msg-84713 but couldn't find anything useful. Please let me know how I could tackle this error. Thank you very much..

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• Deep Zoom in Ajax - Possible? Any examples out there?

  - by Phil

  I have an idea to implement a deep zoom type interface hosted in a browser for sports training data (speed, distance, heart rate etc.) However, rather than images I actually want to zoom into a hierarchy of information. For example, the initial display would contain a grid of years - hover over 2008, for example, and spin the mouse wheel (or click) will zoom into that year but during the zoom I want 2008 to fade out and be replaced with a calendar of months. Again zoom into a month and the months are replaced with the months calendar, zoom into a day and you finally see a chart with the training data plotted on it. All the time only dates with actual data would be highlighted in some fashion. My question is whether this would even be possible and whether anyone has seen examples of this already. I'm imagining that most of the time the next level of information could be cached in the browser (in fact, because this is calendar-based, I can calculate most of that and cache the dates to be highlighted.) I could also zoom into an empty chart whilst an Ajax thread is fetching the data to display. I've never tried anything like this before and I'm especially interested in whether DHTML would be capable of this sort of zoom (I suspect not and I would have to resort to Silverlight) and whether the Ajax execution would be uninterrupted whilst the browser rendering thread is kept busy zooming.

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• Confused about UIView frame property

  - by slowfungus

  I'm building a prototype iPad app that draws diagrams. I have the following view hierarchy: UIView UIScrollView DiagramView : UIView TabBar NavigationBar And a UIViewController subclass holding all that together. Before drawing the diagram the first time I calculate the dimensions of the diagram, and set the DiagramView frame to that size, and the content size of the scrollview as well. -(void)recalculateBounds { [renderer diagram:diagram shouldDraw:NO]; SQXRect diagramRect = SQXMakeRect(0.0,0.0,[diagram bounds].size.width,[diagram bounds].size.height); self.frame = diagramRect; [(UIScrollView*)[self superview] setContentSize:diagramRect.size]; } I should disclose that the frame is being set to about 1500 x 3500 which i know is ridiculous. I just want to focus on some other parts of the app before I get into optimizing the render code. This works beautifully, except that the rect being passed to drawRect is not the size that I set, and my drawing is getting clipped at the bottom. Its close the size i set, but bigger in width, and shorter in height. Also of note, is the fact that if I force the frame to be much bigger than what I know the diagram needs, then the drawRect:rect is big enough, and no clipping occurs. Of course this has me wondering if the frame size needs to take into account some other screen real estate like the toolbars but my reading of the docs tells me the frame is in superview coordinates, which would be the scrollview so I reckon I need to worry about such things. Any idea what is causing this discrepancy?

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• Tools\addin's for formating or cleaning up xaml?

  - by cody

  I'm guessing these don't exist since I searched around for these but I'm looking for a few tools: 1) A tool that cleans up my xaml so that the properties of elements are consistent through a file. I think enforcing that consistence would make the xaml easier to read. Maybe there could be a hierarchy of what comes first but if not alphabetical might work. Example before: TextBox Name="myTextBox1" Grid.Row="3" Grid.Column="1" Margin="4" TextBox Grid.Column="1" Margin="4" Name="t2" Grid.Row="3" Example after: TextBox Name="myTextBox1" Grid.Row="3" Grid.Column="1" Margin="4" TextBox Name="t2" Grid.Row="3" Grid.Column="1" Margin="4" (note < / has been remove from the above since control seem to have issues parsing whe the after section was added) 2) Along the same lines as above, to increase readability, a tool to align properties, so from the above code example similar props would start in the same place. <TextBox Name="myTextBox1" Grid.Row="3" Grid.Column="1" Margin="4"/> <TextBox Name="t2" Grid.Row="3" Grid.Column="1" Margin="4"/> I know VS has default settings for XAML documents so props can be on one line or separate lines so maybe if there was a tool as described in (1) this would not be needed...but it would still be nice if you like your props all on one line. 3) A tool that adds X to the any of the Grid.Row values and Y to any of the Grid.Column values in the selected text. Every time I add a new row\column I have to go manually fix these. From my understanding Expression Blend can help with this but seem excessive to open Blend just to increment some numbers (and just don't grok Blend). Maybe vs2010 with the designer will help but right now I'm on VS08 and Silverlight. Any one know of any tools to help with this? Anyone planning to write something like this...I'm looking at you JetBrains and\or DevExpress. Thanks.

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• Rails: Getting rid of "X is invalid" validation errors

  - by DJTripleThreat

  I have a sign-up form that has nested associations/attributes whatever you want to call them. My Hierarchy is this: class User < ActiveRecord::Base acts_as_authentic belongs_to :user_role, :polymorphic => true end class Customer < ActiveRecord::Base has_one :user, :as => :user_role, :dependent => :destroy accepts_nested_attributes_for :user, :allow_destroy => true validates_associated :user end class Employee < ActiveRecord::Base has_one :user, :as => :user_role, :dependent => :destroy accepts_nested_attributes_for :user, :allow_destroy => true validates_associated :user end I have some validation stuff in these classes as well. My problem is that if I try to create and Customer (or Employee etc) with a blank form I get all of the validation errors I should get plus some Generic ones like "User is invalid" and "Customer is invalid" If I iterate through the errors I get something like: user.login can't be blank User is invalid customer.whatever is blah blah blah...etc customer.some_other_error etc etc Since there is at least one invalid field in the nested User model, an extra "X is invalid" message is added to the list of errors. This gets confusing to my client and so I'm wondering if there is a quick way to do this instead of having to filer through the errors myself.

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• Handles Comparison: empty classes vs. undefined classes vs. void*

  - by Nawaz

  Microsoft's GDI+ defines many empty classes to be treated as handles internally. For example, (source GdiPlusGpStubs.h) //Approach 1 class GpGraphics {}; class GpBrush {}; class GpTexture : public GpBrush {}; class GpSolidFill : public GpBrush {}; class GpLineGradient : public GpBrush {}; class GpPathGradient : public GpBrush {}; class GpHatch : public GpBrush {}; class GpPen {}; class GpCustomLineCap {}; There are other two ways to define handles. They're, //Approach 2 class BOOK; //no need to define it! typedef BOOK *PBOOK; typedef PBOOK HBOOK; //handle to be used internally //Approach 3 typedef void* PVOID; typedef PVOID HBOOK; //handle to be used internally I just want to know the advantages and disadvantages of each of these approaches. One advantage with Microsoft's approach is that, they can define type-safe hierarchy of handles using empty classes, which (I think) is not possible with the other two approaches. What else? EDIT: One advantage with the second approach (i.e using incomplete classes) is that we can prevent clients from dereferencing the handles (that means, this approach appears to support encapsulation strongly, I suppose). The code would not even compile if one attempts to dereference handles. What else?

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• Favourite Features of VS 2010

  - by Noldorin

  With the general public release of Visual Studio 2010 Beta 2 today, this latest version has created a lot of hype and interest. Indeed, the opinion I've gauged is that VS 2010 has resolved a great deal of the minor flaws left over from previous versions, as well as added some particularly useful new code editor and project development tools (in particular the Premium/Ultimate versions). My question here is: what are you favourite new features in VS 2010 that have really got you excited? Or similarly, what are the flaws of VS 2008 that you are most glad to have resolved? There is a wealth of changes in VS 2010, of course, but these are some of the ones that have interested me most (about which I know!). Integrated support for F# (with multi-targeting for .NET 2.0 - 4.0)/ Much improved WPF designer. The VS 2008 was more than a bit buggy at times. Great improvements to the code editor, such as call hierarchy viewing. A decent add-in framework. A greatly expanded testing framework (now capable of database testing, for example) in Premium/Ultimate. Project planning and modelling features in Premium/Ultimate. If I could request one point/feature per post, I think that would be best, so we could vote them individually.

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• Are document-oriented databases any more suitable than relational ones for persisting objects?

  - by Owen Fraser-Green

  In terms of database usage, the last decade was the age of the ORM with hundreds competing to persist our object graphs in plain old-fashioned RMDBS. Now we seem to be witnessing the coming of age of document-oriented databases. These databases are highly optimized for schema-free documents but are also very attractive for their ability to scale out and query a cluster in parallel. Document-oriented databases also hold a couple of advantages over RDBMS's for persisting data models in object-oriented designs. As the tables are schema-free, one can store objects belonging to different classes in an inheritance hierarchy side-by-side. Also, as the domain model changes, so long as the code can cope with getting back objects from an old version of the domain classes, one can avoid having to migrate the whole database at every change. On the other hand, the performance benefits of document-oriented databases mainly appear to come about when storing deeper documents. In object-oriented terms, classes which are composed of other classes, for example, a blog post and its comments. In most of the examples of this I can come up with though, such as the blog one, the gain in read access would appear to be offset by the penalty in having to write the whole blog post "document" every time a new comment is added. It looks to me as though document-oriented databases can bring significant benefits to object-oriented systems if one takes extreme care to organize the objects in deep graphs optimized for the way the data will be read and written but this means knowing the use cases up front. In the real world, we often don't know until we actually have a live implementation we can profile. So is the case of relational vs. document-oriented databases one of swings and roundabouts? I'm interested in people's opinions and advice, in particular if anyone has built any significant applications on a document-oriented database.

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• java.lang.ExceptionInInitializerError Exception when creating Application Context in Spring

  - by cyotee

  I am practicing with Spring, and am getting a java.lang.ExceptionInInitializerError exception when I try to instantiate the context. The Exception appears below, with my code following it. I have simplified my experiment from before. The Exception Oct 17, 2012 5:54:22 PM org.springframework.context.support.AbstractApplicationContext prepareRefresh INFO: Refreshing org.springframework.context.support.ClassPathXmlApplicationContext@570c16b7: startup date [Wed Oct 17 17:54:22 CDT 2012]; root of context hierarchy Exception in thread "main" java.lang.ExceptionInInitializerError at org.springframework.context.support.AbstractRefreshableApplicationContext.createBeanFactory(AbstractRefreshableApplicationContext.java:195) at org.springframework.context.support.AbstractRefreshableApplicationContext.refreshBeanFactory(AbstractRefreshableApplicationContext.java:128) at org.springframework.context.support.AbstractApplicationContext.obtainFreshBeanFactory(AbstractApplicationContext.java:535) at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:449) at org.springframework.context.support.ClassPathXmlApplicationContext.<init>(ClassPathXmlApplicationContext.java:139) at org.springframework.context.support.ClassPathXmlApplicationContext.<init>(ClassPathXmlApplicationContext.java:83) at helloworld.HelloWorldTest.main(HelloWorldTest.java:13) Caused by: java.lang.NullPointerException at org.springframework.beans.factory.support.DefaultListableBeanFactory.<clinit>(DefaultListableBeanFactory.java:105) ... 7 more My configuration XML <?xml version="1.0" encoding="UTF-8"?> <beans xmlns="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:c="http://www.springframework.org/schema/c" xmlns:p="http://www.springframework.org/schema/p" xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.1.xsd"> <bean id="messageContainer" class="helloworld.MessageContainer"> <property name="message" value="Hello World"> </property> </bean> <bean id="messageOutputService" class="helloworld.MessageOutputService"> </bean> My test class. package helloworld; import org.springframework.context.ApplicationContext; import org.springframework.context.support.ClassPathXmlApplicationContext; public class HelloWorldTest { /** * @param args */ public static void main(String[] args) { ApplicationContext context = new ClassPathXmlApplicationContext("HelloWorldTest-context.xml"); MessageContainer message = context.getBean(MessageContainer.class); MessageOutputService service = context.getBean(MessageOutputService.class); service.outputMessageToConsole(message); } }

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• Conditional column values in NSTableView?

  - by velocityb0y

  I have an NSTableView that binds via an NSArrayController to an NSMutableArray. What's in the array are derived classes; the first few columns of the table are bound to properties that exist on the base class. That all works fine. Where I'm running into problem is a column that should only be populated if the row maps to one specific subclass. The property that column is meant to display only exists in that subclass, since it makes no sense in terms of the base class. The user will know, from the first two columns, why the third column's cell is populated/editable or not. The binding on the third column's value is on arrangedObjects, with a model path of something like "foo.name" where foo is the property on the subclass. However, this doesn't work, as the other subclasses in the hierarchy are not key-value compliant for foo. It seems like my only choice is to have foo be a property on the base class so everybody responds to it, but this clutters up the interfaces of the model objects. Has anyone come up with a clean design for this situation? It can't be uncommon (I'm a relative newcomer to Cocoa and I'm just learning the ins and outs of bindings.)

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• Sorting by custom field and fetching whole tree from DB

  - by Niaxon

  Hello everyone, I am trying to do file browser in a tree form and have a problem to sort it somehow. I use PHP and MySQL for that. I've created mixed (nested set + adjacency) table 'element' with the following fields: element_id, left_key, right_key, level, parent_id, element_name, element_type (enum: 'folder','file'), element_size. Let's not discuss right now that it is better to move information about element (name, type, size) into other table. Function to scan specified directory and fill table work correctly. Noteworthy, i am adding elements to tree in specific order: folders first and then files. After that i can easily fetch and display whole table on the page using simple query: SELECT * FROM element WHERE 1=1 ORDER BY left_key With the result of that query and another function i can generate correct html code (<ul><li>... and so on). to display tree. Now back to the question (finally, huh?). I am struggling to add sorting functionality. For example i want to order my result by size. Here i need to keep in my mind whole hierarchy of tree and rule: folders first, files later. I believe i can do that by generating in PHP recursive query: SELECT * FROM element WHERE parent_id = {$parentId} ORDER BY element_type (so folders would be first), size (or name for example) asc/desc After that for each result which has type = 'folder' i will send another query to get it's content. Also it's possible to fetch whole tree by left_key and after that sort it in PHP as array but i guess that would be worse :) I wonder if there is better and more efficient way to do such a thing?

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• How can I render an in-memory UIViewController's view Landscape?

  - by Aaron

  I'm trying to render an in-memory (but not in hierarchy, yet) UIViewController's view into an in-memory image buffer so I can do some interesting transition animations. However, when I render the UIViewController's view into that buffer, it is always rendering as though the controller is in Portrait orientation, no matter the orientation of the rest of the app. How do I clue this controller in? My code in RootViewController looks like this: MyUIViewController* controller = [[MyUIViewController alloc] init]; int width = self.view.frame.size.width; int height = self.view.frame.size.height; int bitmapBytesPerRow = width * 4; unsigned char *offscreenData = calloc(bitmapBytesPerRow * height, sizeof(unsigned char)); CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB(); CGContextRef offscreenContext = CGBitmapContextCreate(offscreenData, width, height, 8, bitmapBytesPerRow, colorSpace, kCGImageAlphaPremultipliedLast); CGContextTranslateCTM(offscreenContext, 0.0f, height); CGContextScaleCTM(offscreenContext, 1.0f, -1.0f); [(CALayer*)[controller.view layer] renderInContext:offscreenContext]; At that point, the offscreen memory buffers contents are portrait-oriented, even when the window is in landscape orientation. Ideas?

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• Hashing the state of a complex object in .NET

  - by Jan

  Some background information: I am working on a C#/WPF application, which basically is about creating, editing, saving and loading some data model. The data model contains of a hierarchy of various objects. There is a "root" object of class A, which has a list of objects of class B, which each has a list of objects of class C, etc. Around 30 classes involved in total. Now my problem is that I want to prompt the user with the usual "you have unsaved changes, save?" dialog, if he tries to exit the program. But how do I know if the data in current loaded model is actually changed? There is of course ways to solve this, like e.g. reloading the model from file and compare against the one in memory value by value or make every UI control set a flag indicating the model has been changed. Now instead, I want to create a hash value based on the model state on load and generate a new value when the user tries to exit, and compare those two. Now the question: So inspired of that, I was wondering if there exist some way to generate a hash value from the (value)state of some arbitrary complex object? Preferably in a generic way, e.g. no need to apply attributes to each involved class/field. One idea could be to use some of .NET's serialization functionality (assuming it will work out-of-the-box in this case) and apply a hash function to the content of the resulting file. However, I guess there exist some more suitable approach. Thanks in advance.

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• SharePoint: Filtering a List that has Folders

  - by Gary McGill

  I have a SharePoint document library that has a folder structure used for organizing the documents (but also for controlling access, via permissions on the folders). The documents in the library are updated every month, and we store every month's version of the document in the same folder; there's a "month" column used for filtering that will contain values like Jan 09, Feb 09, etc. It looks like this: Title Month ----- ----- SubFolder 1 SubFolder 2 [] Interesting Facts Jan 09 [] Interesting Facts Feb 09 [] Interesting Facts Mar 09 [] Fascinating Numbers Jan 09 [] Fascinating Numbers Feb 09 ... Now, because users will generally be most interested in the 'current' month, I'd like them to be able to apply a filter, and select (say) Mar 09. However, if they do this using the built-in filtering, it also filters out the folders, and they can no longer navigate the folder hierarchy. This is no good - I want them to be able to move between folders with the filter intact, so that they don't need to keep switching it off and on again. I figured I might be able to use a custom view (selecting where type=folder or month=[month]), and to an extent that does work. However, I can only get it to work for a fixed month, whereas I need the user to be able to select the month - perhaps via a drop-down control on the page (and I don't want to create 60 views for 5 years' worth of months, nor do I want to have to create a new view every month). I thought it might be possible to create a view in code (rather than via the UI), but I've not been able to figure out how to get a dynamic value (a user-specific setting) into the CAML query. Any pointers gratefully appreciated! And by the way, I am aware of the dogma that folders are bad, and that everything should just be a list. However, having considered the alternatives, I still favour using folders - if I can solve this problem. Thanks in advance.

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• DRYing out implementation of ICloneable in several classes

  - by Sarah Vessels

  I have several different classes that I want to be cloneable: GenericRow, GenericRows, ParticularRow, and ParticularRows. There is the following class hierarchy: GenericRow is the parent of ParticularRow, and GenericRows is the parent of ParticularRows. Each class implements ICloneable because I want to be able to create deep copies of instances of each. I find myself writing the exact same code for Clone() in each class: object ICloneable.Clone() { object clone; using (var stream = new MemoryStream()) { var formatter = new BinaryFormatter(); // Serialize this object formatter.Serialize(stream, this); stream.Position = 0; // Deserialize to another object clone = formatter.Deserialize(stream); } return clone; } I then provide a convenience wrapper method, for example in GenericRows: public GenericRows Clone() { return (GenericRows)((ICloneable)this).Clone(); } I am fine with the convenience wrapper methods looking about the same in each class because it's very little code and it does differ from class to class by return type, cast, etc. However, ICloneable.Clone() is identical in all four classes. Can I abstract this somehow so it is only defined in one place? My concern was that if I made some utility class/object extension method, it would not correctly make a deep copy of the particular instance I want copied. Is this a good idea anyway?

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• Is there a good way to copy a Gtk widget?

  - by Jake

  Is there a way, using the Gtk library in C, to clone a Gtk button (for instance), and pack it somewhere else in the app. I know you can't pack the same widget twice. And that this code obviously wouldn't work, but shows what happens when I attempt a shallow copy of the button: GtkButton *a = g_object_new(GTK_TYPE_BUTTON, "label", "o_0", NULL); GtkButton *b = g_memdup(b, sizeof *b); gtk_box_pack_start_defaults(GTK_BOX(vbox), GTK_WIDGET(b)); There is surrounding code which creates a vbox and packs it in a window and runs gtk_main(). This will result in these hard to understand error messages: (main:6044): Gtk-CRITICAL **: gtk_widget_hide: assertion `GTK_IS_WIDGET (widget)' failed (main:6044): Gtk-CRITICAL **: gtk_widget_realize: assertion `GTK_WIDGET_ANCHORED (widget) || GTK_IS_INVISIBLE (widget)' failed ** Gtk:ERROR:/build/buildd/gtk+2.0-2.18.3/gtk/gtkwidget.c:8431:gtk_widget_real_map: assertion failed: (GTK_WIDGET_REALIZED (widget)) Along the same lines, if I were to write my own GObject (not necessarily a Gtk widget), is there a good way to write a copy constructor. Im thinking it should be an interface with optional hooks and based mostly on the properties, handling the class's hierarchy in some way. I'd want to do this: GtkButton *b = copyable_copy(COPYABLE(a)); If GtkButton could use a theoretical copyable interface.

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• Visual Studio hangs when deploying a cube

  - by Richie

  Hello All, I'm having an issue with an Analysis Services project in Visual Studio 2005. My project always builds but only occasionally deploys. No errors are reported and VS just hangs. This is my first Analysis Services project so I am hoping that there is something obvious that I am just missing. Here is the situation I have a cube that I have successfully deployed. I then make some change, e.g., adding a hierarchy to a dimension. When I try to deploy again VS hangs. I have to restart Analysis Services to regain control of VS so I can shut it down. I restart everything sometimes once, sometimes twice or more before the project will eventually deploy. This happens with any change I make there seems to be no pattern to this behaviour. Sometimes I have to delete the cube from Analysis Services before restarting everything to get a successful deploy. Also I have successfully deployed the cube, and then subsequently successfully reprocessed a dimension then when I open a query window in SQL Server Management Studio it says that it can find any cubes. As a test I have deployed a cube successfully. I have then deleted it in Analysis Services and attempted to redeploy it, without making any changes to the cube, only to have the same behaviour mentioned above. VS just hangs with no reason so I have no idea where to start hunting down the problem. It is taking 15-20 minutes to make a change as simple as setting the NameColumn of a dimension attribute. As you can imagine this is taking hours of my time so I would greatly appreciate any assistance anyone can give me.

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• How To Create a Flexible Plug-In Architecture?

  - by justkt

  A repeating theme in my development work has been the use of or creation of an in-house plug-in architecture. I've seen it approached many ways - configuration files (XML, .conf, and so on), inheritance frameworks, database information, libraries, and others. In my experience: A database isn't a great place to store your configuration information, especially co-mingled with data Attempting this with an inheritance hierarchy requires knowledge about the plug-ins to be coded in, meaning the plug-in architecture isn't all that dynamic Configuration files work well for providing simple information, but can't handle more complex behaviors Libraries seem to work well, but the one-way dependencies have to be carefully created. As I seek to learn from the various architectures I've worked with, I'm also looking to the community for suggestions. How have you implemented a solid plug-in architecture? What was your worst failure (or the worst failure you've seen)? What would you do if you were going to implement a new plug-in architecture? What SDK or open source project that you've worked with has the best example of a good architecture? A few examples I've been finding on my own: Perl's Module::Plugable An SO question with a list for Java (including Sever Provider Interfaces) An SO question for C++ pointing to a Dr. Dobbs article These examples seem to play to various language strengths. Is a good plugin architecture necessarily tied to the language? Is it best to use tools to create a plugin architecture, or to do it on one's own following models?

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• C/C++ Control Structure Limitations?

  - by STingRaySC

  I have heard of a limitation in VC++ (not sure which version) on the number of nested if statements (somewhere in the ballpark of 300). The code was of the form: if (a) ... else if (b) ... else if (c) ... ... I was surprised to find out there is a limit to this sort of thing, and that the limit is so small. I'm not looking for comments about coding practice and why to avoid this sort of thing altogether. Here's a list of things that I'd imagine could have some limitation: Number of functions in a scope (global, class, or namespace). Number of expressions in a single statement (e.g., compound conditionals). Number of cases in a switch. Number of parameters to a function. Number of classes in a single hierarchy (either inheritance or containment). What other control structures/language features have limits such as this? Do the language standards say anything about these limits (perhaps minimum requirements for an implementation)? Has anyone run into a particular language limitation like this with a particular compiler/implementation? EDIT: Please note that the above form of if statements is indeed "nested." It is equivalent to: if (a) { //... } else { if (b) { //... } else { if (c) { //... } else { //... } } }

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• SQL query recursion for a web-like structure

  - by MickeyD

  I have a table here, named "Foo". The data is set up something like this. ID TableReference DataId0 DataId1 DataId2 -- -------------- ------- ------- ------- 1 Prize 3 4 5 2 Prize 4 5 NULL 3 Cash 1 NULL NULL 4 Prize 8 NULL 12 5 Foo 2 3 NULL 6 Cash 8 1 10 7 Foo 5 1 2 Etc. The data is horribly set up, I know, but I didn't set it up that way. :) I'm only dealing with the after effect. I'm trying to come up with a way to essentially "flatten" the table; that is, to display all the data to a point where the table "Foo" does not reference itself. I'm trying to figure out a sql query that I can do to get there. Usually when I deal with recursion, I have (or can establish) parent IDs and set it up that way, but for this table there are seemingly multiple child and parent IDs creating a web-like structure instead of a hierarchy. So I'm at a loss where to even begin to write a sql query for something like this. Note: There is no infinite looping (where one Foo points to another Foo, which points back to the original Foo) from what I've found. Using t-sql. Thanks for any assistance, if at all possible.

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• Java object graph -> xml when direction of object association needs to be reversed.

  - by Sigmoidal

  An application I have been working on has objects with a relationship similar to below. In the real application both objects are JPA entities. class Underlying{} class Thing { private Underlying underlying; public Underlying getUnderlying() { return underlying; } public void setUnderlying(final Underlying underlying) { this.underlying = underlying; } } There is a requirement in the application to create xml of the form: <template> <underlying> <thing/> <thing/> <thing/> </underlying> </template> So we have a situation where the object graph expresses the relationship between Thing and Underlying in the opposite direction to how it's expressed in the xml. I expect to use JAXB to create the xml but ideally I don't want to have to create a new object hierarchy to reflect the associations in the xml. Is there any way to create xml of the form required from the entities in their current form (through the use of xml annotations or something)? I don't have any experience using JAXB but from the limited research I've done it doesn't seem like it's possible to reverse the direction of association in any straightforward way. Any help/advice would be greatly appreciated. One other option that has been suggested is to use XLST to transform the xml into the correct format. I have done no research on this topic as yet but I'll add to the question when I have some more info. Thanks, Matt.

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• Tagging in Subversion - how do I make the decision about continuing to work on my trunk vs. the new

  - by Howiecamp

  I'm running Tortoise SVN to manage a project. Obviously the principles around tagging apply to any implementation of SVN but in this question I'll be referring to some TortoiseSVN-specific dialog boxes and messages. My working directory and the subversion repository structure both have a Source root directory and the Trunk, Tags and Branches directories underneath. (I couldn't figure out how to do a multilevel indented hierarchy in markdown without using bullets, so if someone could edit and fix this I'd appreciate it.) I'm working out of the Trunk directory in my working copy and it's pointing at the Trunk directory in the repo. I want to apply a Tag "Release1" so I click the "Branch/tag..." menu option and set the repo path as my [repo_path/bla/Source/Tags/Release1" tag. This dialog box gives me the option to "Switch my working copy to new branch/tag". I understand that if this option is left unchecked, the new "Release1" branch under /Tags" will be created but my working copy will remain on the previous "Trunk" path. If I do check this option (or use the Switch command) I understand that my working copy will switch to the new "Release1" branch under "/Tags". Where I'm missing a concept is how to make this decision. It doesn't seem like I want to switch my working directory to the recently created tag since by definition (?) I want that tag to be a snapshot of my code as of a point in time. If I don't switch the working directory, I'll continue working off Trunk and when I'm ready to take another snapshot I'll make another tag. And so on... Am I understanding this right or am I stating something incorrectly in the previous paragraph (e.g. the statement about not wanting to switch to the tag since the tag should represent a point in time snapshot) or otherwise missing something regarding how to make this decision?

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• Rails: Getting rid of generic "X is invalid" validation errors

  - by DJTripleThreat

  I have a sign-up form that has nested associations/attributes whatever you want to call them. My Hierarchy is this: class User < ActiveRecord::Base acts_as_authentic belongs_to :user_role, :polymorphic => true end class Customer < ActiveRecord::Base has_one :user, :as => :user_role, :dependent => :destroy accepts_nested_attributes_for :user, :allow_destroy => true validates_associated :user end class Employee < ActiveRecord::Base has_one :user, :as => :user_role, :dependent => :destroy accepts_nested_attributes_for :user, :allow_destroy => true validates_associated :user end I have some validation stuff in these classes as well. My problem is that if I try to create and Customer (or Employee etc) with a blank form I get all of the validation errors I should get plus some Generic ones like "User is invalid" and "Customer is invalid" If I iterate through the errors I get something like: user.login can't be blank User is invalid customer.whatever is blah blah blah...etc customer.some_other_error etc etc Since there is at least one invalid field in the nested User model, an extra "X is invalid" message is added to the list of errors. This gets confusing to my client and so I'm wondering if there is a quick way to do this instead of having to filer through the errors myself.

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• Research and replace Word Rtf

  - by Perello

  I'm working on an application which has a workflow for postal mails. These postal mails are generated according to my application business rules. Models are in html or Rtf and it works perfectly as long the user do not create the rtf with word. This is not within the specs, but my hierarchy would welcome a Word compatibility if it don't involve too much work, and it would please and ease the life of our customer. The Rtf models have tags which are replaced by application values. In most RTF, tags are not splitted, so the search and replace works perfectly. I wish to be handle word with few modifications. Example data : [[FooBuzz]] in most rtf it's not splited. In word 2003 : {\rtlch\fcs1 \af0 \ltrch\fcs0 \insrsid5517131 [[}{\rtlch\fcs1 \af0 \ltrch\fcs0 \insrsid2708730 FooBuzz}{\rtlch\fcs1 \af0 \ltrch\fcs0 \insrsid5517131 ]]} And their word (word 2007) splitted also Foo{garbage inside} Buzz. So i wish to be able to handle common RTF perfectly, and detect tags even if they are splitted. I have 2 constraints. First no regression, second it has to stay simple. Performance is not an issue here. I'm using symfony 1.4. The actual relevant research code part : $regExpression = '/\[\[([^\[\]]*)\]\]/'; preg_match_all($regExpression, $sTemplate, $outKeys);

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• WCF: Exposed Object Model - stuck in a loop

  - by Mark

  Hi I'm working on a pretty big WSSF project. I have a normal object model in the business layer. Eg a customer has an orders collection property, when this is accessed then it loads from the data layer (lazy loading). An order has a productCollection property etc etc.. Now the bit I'm finding tricky is exposing this via WCF. I want to export a collection of orders. The client app will also need information about the customers. Using the WSSF data contract designer I have set it up so that customers have a property called "order collection". This is fine if you have a customer object and would like to look at the orders but if you have an order object there is no customer property so it doesn't work going up the hierarchy. I've tried adding a customer property to the orders object but then the code gets stuck in a loop when it loads the data contracts up. This is because it doesn't load on demand like in the business layer. I need to load all properties up before the objects can be sent out via WCF. It ends up loading an order, then the customer for that order, then the orders for that customer, then the customer for that order etc etc... I'm sure I've got all this wrong. Help!!

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