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• On REST: WADL or not IDL, is the following approach right ?

  - by redben

  This question is a bit long, please bear with me. In REST, i think we should not need WADL or any IDL. But rather something that would implicitly cover its concept. The way I think about it is when we (humans) surf the Web, when we go to a web site for the first time, we don't know what services it provides. You discover those on the html home page (or a sitemap page in a help section) or maybe just the main menu on the home page. If you make an analogy, the homepage or site map to us humans is what WSDL is to WS-* or what WADL could be to a REST service. Only that its just like any other html content. I think that in REST the following is a good way to do things, respecting the HATEOS paradigm. Have a top level (or default) resource that lists links to your other resources. For a library example, say RestLibrary.com/ it could be something like: <root xmlns:lib="http://librarystandards.com/libraryml"> <resource class="lib:book"> <link type="application/vnd.libraryml+xml" template="mylib.com/book/{isbn}" /> <link type="application/vnd.libraryml+xml" rel="add" href="mylib.com/book" method="POST" /> <link type="application/vnd.libraryml+xml" rel="update" template="mylib.com/book/{isbn}" method="PUT" /> </resource> <resource class="lib:bookList"> <link template="mylib.com/book?keywords={keywords}" type="application/vnd.openlibrary+xml" rel="search" /> </resource> </root> Note that it is assumed that the media type "application/vnd.libraryml+xml" is a defined standard or (may be just proprietary vocabulary) named libraryml. Also, the client should be able to understand this "homepage" resource (elements root, resource and link). This is the part that could be used instead of WADL : an Abstract vocabulary that should be understandable by any client. You could use an existing standard like Atom for example. But the main idea is to have an abstract vocabulary understandable by any client. Why not WADL then ? well wadl is only for service discovery. The idea here is to have an light abstract vocabulary that would serve as a base for hypermedia. A "root" vocabulary. Like in owl we have owl:thing...etc Now if the client knows the "libraryml" standard it can follow the links to the things it understands (after parsing the media type properties and xmlns). If not, it just won't. When i can't understand how to deal with something in REST architecture i tend to see how we Humans do it in the Web. In the Web, we have the Generic language that is HTML that enables site builders to deliver any specific content, regardless of its meaning to the client (the user), Browsers understand HTML but not the "meaning" of its content. It is the user that understands the (domain specific) content. If i go to say QuantumPhysics.org, my browser can render the home page (it is just html after all) and i can read the home page. If i understand quantum then fine i can continue browsing. If i don't i just get out (unless i want to learn the hardway :) ) In the RetsLibrary.com example the client app is just like me+my browser on QuantumPhysics.org. the media type "application/vnd.libraryml+xml" is quantum physics (knowledge). http is http in both examples. Now HTML of QuantumPhysics.org is in RestLibrary.com is XML + that tiny little abstract vocabulary (root resource and link, that you could replace with something like Atom). So does this approach have any value ? don't we need a root tiny hyper-vocabulary so we can succeed with hypermedia and the "initial URI" concept ? edit Yeah why not RDF as the root vocabulary !

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• Add Silverlight Bing Maps Control to Windows Mobile 7 application

  - by Jacob

  I know the bits just came out today, but one of the first things I want to do with the newly released Windows Mobile 7 SDK is put a map up on the screen and mess around. I've downloaded the latest version of the Silverlight Maps Control and added the references to my application. As a matter of fact, the VS 2010 design view of the MainPage.xaml shows the map control after adding the namespace and placing the control. I'm using the provided VS 2010 Express version that comes with the Win Mobile 7 SDK and have just used the New Project - Windows Phone Application template. When I try to build I get two warnings related to the Microsoft.Maps.MapControl dll's. Warning 1 The primary reference "Microsoft.Maps.MapControl, Version=1.0.1.0, Culture=neutral, PublicKeyToken=498d0d22d7936b73, processorArchitecture=MSIL" could not be resolved because it has an indirect dependency on the framework assembly "System.Windows.Browser, Version=2.0.5.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e" which could not be resolved in the currently targeted framework. "Silverlight,Version=v4.0,Profile=WindowsPhone". To resolve this problem, either remove the reference "Microsoft.Maps.MapControl, Version=1.0.1.0, Culture=neutral, PublicKeyToken=498d0d22d7936b73, processorArchitecture=MSIL" or retarget your application to a framework version which contains "System.Windows.Browser, Version=2.0.5.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e". Warning 2 The primary reference "Microsoft.Maps.MapControl.Common, Version=1.0.1.0, Culture=neutral, PublicKeyToken=498d0d22d7936b73, processorArchitecture=MSIL" could not be resolved because it has an indirect dependency on the framework assembly "System.Windows.Browser, Version=2.0.5.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e" which could not be resolved in the currently targeted framework. "Silverlight,Version=v4.0,Profile=WindowsPhone". To resolve this problem, either remove the reference "Microsoft.Maps.MapControl.Common, Version=1.0.1.0, Culture=neutral, PublicKeyToken=498d0d22d7936b73, processorArchitecture=MSIL" or retarget your application to a framework version which contains "System.Windows.Browser, Version=2.0.5.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e". I'm leaning towards some way of adding the System.Windows.Browser to the targeted framework version. But I'm not even sure if that is possible. To be more specific; I'm looking for a way to get the Silverlight Maps Control up on a Windows Phone 7 series application. If possible. Thanks.

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• android: two issues using Tablerow+TextView in Tablelayout

  - by Yang

  I am using Tablerow+TextView to make a simple view for blog posts and their replies. In each TableRow I put a TextView in. Now I have two issues: The text which is longer than the screen won't automatically wrap up to be multi-line. Is it by design of TableRow? I've already set tr_content.setSingleLine(false); [update] This has been addressed, I think I should change Fill_parent to be Wrap_content in textView.tr_author_time.setLayoutParams(new LayoutParams( LayoutParams.**WRAP_CONTENT**, LayoutParams.WRAP_CONTENT)); The Table won't scroll like ListView. My rows are more than the screen size. I expect the table could be scrolled down for viewing just like ListView. Is that possible? Here is my code: TableLayout tl = (TableLayout) findViewById(R.id.article_content_table); TextView tr_title = new TextView(this); TextView tr_author_time = new TextView(this); TextView tr_content = new TextView(this); TableRow tr = new TableRow(this); for(int i = 0; i < BlogPost.size(); i++){ try{ // add the author, time tr = new TableRow(this); /////////////////add author+time row BlogPost article = mBlogPost.get(i); tr_author_time = new TextView(this); tr_author_time.setText(article.author+"("+ article.post_time+")"); tr_author_time.setTextColor(getResources().getColor(R.color.black)); tr_author_time.setGravity(0x03); tr_author_time.setLayoutParams(new LayoutParams( LayoutParams.FILL_PARENT, LayoutParams.WRAP_CONTENT)); tr.addView(tr_author_time); tl.addView(tr,new TableLayout.LayoutParams( LayoutParams.FILL_PARENT, LayoutParams.WRAP_CONTENT)); ////////////////////// then add content row tr = new TableRow(this); tr_content = new TextView(this); tr_content.setText(article.content); tr_content.setSingleLine(false); tr_content.setGravity(0x03); tr_content.setLayoutParams(new LayoutParams( LayoutParams.FILL_PARENT, LayoutParams.WRAP_CONTENT)); tr.addView(tr_content); tr.setBackgroundResource(R.color.white); tl.addView(tr,new TableLayout.LayoutParams( LayoutParams.FILL_PARENT, LayoutParams.WRAP_CONTENT)); }

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• Server side Xforms form validation and integration into ASP.NET

  - by Nigel

  I have recently been investigating methods of creating web-based forms for an ASP.NET web application that can be edited and managed at runtime. For example an administrator might wish to add a new validation rule or a new set of fields. The holy grail would provide a means of specifying a form along with (potentially very complex) arbitrary validation rules, and allocation of data sources for each field. The specification would then be used to update the deployed form in the web application which would then validate submissions both on the client side and on the server side. My investigations led me to Xforms and a number of technologies that support it. One solution appears to be IBM Lotus Forms, but this requires a very large investment in terms of infrastructure, which makes it infeasible, although the forms designer may be useful as a stand-alone tool for creating the forms. I have also discounted browser plug-ins as the form must be publicly visible and cross-browser compliant. I have noticed that there are numerous javascript libraries that provide client side implementations given an Xforms schema. These would provide a partial solution but server side validation is still a requirement. Another option seems to involve the use of server side solutions such as the Java application Orbeon. Orbeon provides a tool for specifying the forms (although not as rich as Lotus Forms Designer), but the most interesting point is that it can translate an XForms schema into an XHTML form complete with validation. The fact that it is written in Java is not a big problem if it is possible to integrate with the existing ASP.NET application. So my question is whether anyone has done this before. It sounds like a problem that should have been solved but is inherently very complex. It seems possible to use an off-the-shelf tool to design the form and export it to an Xforms schema and xhtml form, and it seems possible to take that xforms schema and form and publish it using a client side library. What seems to be difficult is providing a means of validating the form submission on the server side and integrating the process nicely with .NET (although it seems the .NET community doesn't involve themselves with XForms; please correct me if I'm wrong on this count). I would be more than happy if a product provided something simple like a web service that could validate a submission against a schema. Maybe Orbeon does this but I'd be grateful if somebody in the know could point me in the right direction before I research it further. Many thanks.

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• Shawn Wildermuth violating MVVM in MSDN article?

  - by rasx

  This may be old news but back in March 2009, Shawn Wildermuth, his article, “Model-View-ViewModel In Silverlight 2 Apps,” has a code sample that includes DataServiceEntityBase: // COPIED FROM SILVERLIGHTCONTRIB Project for simplicity /// <summary> /// Base class for DataService Data Contract classes to implement /// base functionality that is needed like INotifyPropertyChanged. /// Add the base class in the partial class to add the implementation. /// </summary> public abstract class DataServiceEntityBase : INotifyPropertyChanged { /// <summary> /// The handler for the registrants of the interface's event /// </summary> PropertyChangedEventHandler _propertyChangedHandler; /// <summary> /// Allow inheritors to fire the event more simply. /// </summary> /// <param name="propertyName"></param> protected void FirePropertyChanged(string propertyName) { if (_propertyChangedHandler != null) { _propertyChangedHandler(this, new PropertyChangedEventArgs(propertyName)); } } #region INotifyPropertyChanged Members /// <summary> /// The interface used to notify changes on the entity. /// </summary> event PropertyChangedEventHandler INotifyPropertyChanged.PropertyChanged { add { _propertyChangedHandler += value; } remove { _propertyChangedHandler -= value; } } #endregion What this class implies is that the developer intends to bind visuals directly to data (yes, a ViewModel is used but it defines an ObservableCollection of data objects). Is this design diverging too far from the guidance of MVVM? Now I can see some of the reasons why Shawn would go this way: what Shawn can do with DataServiceEntityBase is this sort of thing (which is intimate with the Entity Framework): // Partial Method to support the INotifyPropertyChanged interface public partial class Game : DataServiceEntityBase { #region Partial Method INotifyPropertyChanged Implementation // Override the Changed partial methods to implement the // INotifyPropertyChanged interface // This helps with the Model implementation to be a mostly // DataBound implementation partial void OnDeveloperChanged() { base.FirePropertyChanged("Developer"); } partial void OnGenreChanged() { base.FirePropertyChanged("Genre"); } partial void OnListPriceChanged() { base.FirePropertyChanged("ListPrice"); } partial void OnListPriceCurrencyChanged() { base.FirePropertyChanged("ListPriceCurrency"); } partial void OnPlayerInfoChanged() { base.FirePropertyChanged("PlayerInfo"); } partial void OnProductDescriptionChanged() { base.FirePropertyChanged("ProductDescription"); } partial void OnProductIDChanged() { base.FirePropertyChanged("ProductID"); } partial void OnProductImageUrlChanged() { base.FirePropertyChanged("ProductImageUrl"); } partial void OnProductNameChanged() { base.FirePropertyChanged("ProductName"); } partial void OnProductTypeIDChanged() { base.FirePropertyChanged("ProductTypeID"); } partial void OnPublisherChanged() { base.FirePropertyChanged("Publisher"); } partial void OnRatingChanged() { base.FirePropertyChanged("Rating"); } partial void OnRatingUrlChanged() { base.FirePropertyChanged("RatingUrl"); } partial void OnReleaseDateChanged() { base.FirePropertyChanged("ReleaseDate"); } partial void OnSystemNameChanged() { base.FirePropertyChanged("SystemName"); } #endregion } Of course MSDN code can seen as “toy code” for educational purposes but is anyone doing anything like this in the real world of Silverlight development?

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• Which functions in the C standard library commonly encourage bad practice?

  - by Ninefingers

  Hello all, This is inspired by this question and the comments on one particular answer in that I learnt that strncpy is not a very safe string handling function in C and that it pads zeros, until it reaches n, something I was unaware of. Specifically, to quote R.. strncpy does not null-terminate, and does null-pad the whole remainder of the destination buffer, which is a huge waste of time. You can work around the former by adding your own null padding, but not the latter. It was never intended for use as a "safe string handling" function, but for working with fixed-size fields in Unix directory tables and database files. snprintf(dest, n, "%s", src) is the only correct "safe strcpy" in standard C, but it's likely to be a lot slower. By the way, truncation in itself can be a major bug and in some cases might lead to privilege elevation or DoS, so throwing "safe" string functions that truncate their output at a problem is not a way to make it "safe" or "secure". Instead, you should ensure that the destination buffer is the right size and simply use strcpy (or better yet, memcpy if you already know the source string length). And from Jonathan Leffler Note that strncat() is even more confusing in its interface than strncpy() - what exactly is that length argument, again? It isn't what you'd expect based on what you supply strncpy() etc - so it is more error prone even than strncpy(). For copying strings around, I'm increasingly of the opinion that there is a strong argument that you only need memmove() because you always know all the sizes ahead of time and make sure there's enough space ahead of time. Use memmove() in preference to any of strcpy(), strcat(), strncpy(), strncat(), memcpy(). So, I'm clearly a little rusty on the C standard library. Therefore, I'd like to pose the question: What C standard library functions are used inappropriately/in ways that may cause/lead to security problems/code defects/inefficiencies? In the interests of objectivity, I have a number of criteria for an answer: Please, if you can, cite design reasons behind the function in question i.e. its intended purpose. Please highlight the misuse to which the code is currently put. Please state why that misuse may lead towards a problem. I know that should be obvious but it prevents soft answers. Please avoid: Debates over naming conventions of functions (except where this unequivocably causes confusion). "I prefer x over y" - preference is ok, we all have them but I'm interested in actual unexpected side effects and how to guard against them. As this is likely to be considered subjective and has no definite answer I'm flagging for community wiki straight away. I am also working as per C99.

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• How to Solve N-Queens Problem in Scheme?

  - by Philip

  Hi, I'm stuck on the extended exercise 28.2 of How to Design Programs. Here is the link to the question: http://www.htdp.org/2003-09-26/Book/curriculum-Z-H-35.html#node_chap_28 I used a vector of true or false values to represent the board instead of using a list. This is what I've got which doesn't work: #lang Scheme (define-struct posn (i j)) ;takes in a position in i, j form and a board and returns a natural number that represents the position in index form ;example for board xxx ; xxx ; xxx ;(0, 1) - 1 ;(2, 1) - 7 (define (board-ref a-posn a-board) (+ (* (sqrt (vector-length a-board)) (posn-i a-posn)) (posn-j a-posn))) ;reverse of the above function ;1 - (0, 1) ;7 - (2, 1) (define (get-posn n a-board) (local ((define board-length (sqrt (vector-length a-board)))) (make-posn (floor (/ n board-length)) (remainder n board-length)))) ;determines if posn1 threatens posn2 ;true if they are on the same row/column/diagonal (define (threatened? posn1 posn2) (cond ((= (posn-i posn1) (posn-i posn2)) #t) ((= (posn-j posn1) (posn-j posn2)) #t) ((= (abs (- (posn-i posn1) (posn-i posn2))) (abs (- (posn-j posn1) (posn-j posn2)))) #t) (else #f))) ;returns a list of positions that are not threatened or occupied by queens ;basically any position with the value true (define (get-available-posn a-board) (local ((define (get-ava index) (cond ((= index (vector-length a-board)) '()) ((vector-ref a-board index) (cons index (get-ava (add1 index)))) (else (get-ava (add1 index)))))) (get-ava 0))) ;consume a position in the form of a natural number and a board ;returns a board after placing a queen on the position of the board (define (place n a-board) (local ((define (foo x) (cond ((not (board-ref (get-posn x a-board) a-board)) #f) ((threatened? (get-posn x a-board) (get-posn n a-board)) #f) (else #t)))) (build-vector (vector-length a-board) foo))) ;consume a list of positions in the form of natural number and consumes a board ;returns a list of boards after placing queens on each of the positions on the board (define (place/list alop a-board) (cond ((empty? alop) '()) (else (cons (place (first alop) a-board) (place/list (rest alop) a-board))))) ;returns a possible board after placing n queens on a-board ;returns false if impossible (define (placement n a-board) (cond ((zero? n) a-board) (else (local ((define available-posn (get-available-posn a-board))) (cond ((empty? available-posn) #f) (else (or (placement (sub1 n) (place (first available-posn) a-board)) (placement/list (sub1 n) (place/list (rest available-posn) a-board))))))))) ;returns a possible board after placing n queens on a list of boards ;returns false if all the boards are not valid (define (placement/list n boards) (cond ((empty? boards) #f) ((zero? n) (first boards)) ((not (boolean? (placement n (first boards)))) (first boards)) (else (placement/list n (rest boards)))))

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• WPF Beginner - A simple XAML layout not working as expected

  - by OrWhen

  Hi, I've just started learning WPF, and followed a book to make this sample calculator application in XAML. The XAML code is attached below. I don't have any UI specific code in the xaml.cs file. However, I'm seeing a difference between design time and runtime. As you can see in the attached screenshot, the upper left button of the calculator is bigger than the rest. Even more confusingly, the designer when I edit the XAML shows the button correctly. I've tried to determine why is that, and I'm stumped. Can anyone help? I'm using VS2008, targeting framework 3.5, if it's any help. Here's the XAML: <TextBlock Grid.Row="0" Grid.Column="0" Grid.ColumnSpan="4" FontSize="24" Name="Header" VerticalAlignment="Center" HorizontalAlignment="Center">Calculator</TextBlock> <TextBox Grid.ColumnSpan="4" Grid.Column="0" Grid.Row="1" Name="Display" HorizontalContentAlignment="Left" Margin="5" /> <Button Grid.Row="2" Grid.Column="0" Click="Button_Click">7</Button> <Button Grid.Row="2" Grid.Column="1" Click="Button_Click">8</Button> <Button Grid.Row="2" Grid.Column="2" Click="Button_Click">9</Button> <Button Grid.Row="3" Grid.Column="0" Click="Button_Click">4</Button> <Button Grid.Row="3" Grid.Column="1" Click="Button_Click">5</Button> <Button Grid.Column="2" Grid.Row="3" Click="Button_Click">6</Button> <Button Grid.Row="4" Grid.Column="0" Click="Button_Click">1</Button> <Button Grid.Row="4" Grid.Column="1" Click="Button_Click">2</Button> <Button Grid.Row="4" Grid.Column="2" Click="Button_Click">3</Button> <Button Grid.Row="5" Grid.Column="0" Click="Button_Click">0</Button> <Button Grid.Row="5" Grid.Column="3" Tag="{x:Static local:Operation.PLUS}" Click="Op_Click">+</Button> <Button Grid.Row="4" Grid.Column="3" Tag="{x:Static local:Operation.MINUS}" Click="Op_Click">-</Button> <Button Grid.Row="3" Grid.Column="3" Tag="{x:Static local:Operation.TIMES}" Click="Op_Click">*</Button> <Button Grid.Row="2" Grid.Column="3" Tag="{x:Static local:Operation.DIVIDE}" Click="Op_Click">/</Button> <Button Grid.Row="5" Grid.Column="1" >.</Button> <Button Grid.Row="5" Grid.Column="2" Tag="{x:Static local:Operation.EQUALS}" Click="Op_Click">=</Button> </Grid>

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• Defining InputBindings within a Style

  - by Brent

  I'm creating a WPF app using the MVVM design pattern, and I'm trying to extend the TabItem control so that it closes the tab when the user clicks the middle mouse button. I'm trying to achieve this using InputBindings, and it works very well until I try to define it within a style. I've learned that you cannot add InputBindings to a style unless you attach it using a DependencyProperty. So I followed this similar post here... and it works... almost. I can close one tab using the middle mouse button, but it won't work on any of the other tabs (all of the tabs are added at runtime and inherit the same style). So I need some help. Why would this only be working the first time, and not after? Obviously I could create a custom control that inherits from a TabItem and make it work, but I'd like to figure this out as I can see this being expanded in my projects. I'm no expert on DependencyProperties, so please help me out. Thanks! Style: <Style TargetType="{x:Type TabItem}"> <Setter Property="w:Attach.InputBindings"> <Setter.Value> <InputBindingCollection> <MouseBinding MouseAction="MiddleClick" Command="{Binding CloseCommand}"/> </InputBindingCollection> </Setter.Value> </Setter> ... </Style> Class public class Attach { public static readonly DependencyProperty InputBindingsProperty = DependencyProperty.RegisterAttached("InputBindings", typeof(InputBindingCollection), typeof(Attach), new FrameworkPropertyMetadata(new InputBindingCollection(), (sender, e) => { var element = sender as UIElement; if (element == null) return; element.InputBindings.Clear(); element.InputBindings.AddRange((InputBindingCollection)e.NewValue); })); public static InputBindingCollection GetInputBindings(UIElement element) { return (InputBindingCollection)element.GetValue(InputBindingsProperty); } public static void SetInputBindings(UIElement element, InputBindingCollection inputBindings) { element.SetValue(InputBindingsProperty, inputBindings); } }

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• Loading, listing, and using R Modules and Functions in PL/R

  - by Dave Jarvis

  I am having difficulty with: Listing the R packages and functions available to PostgreSQL. Installing a package (such as Kendall) for use with PL/R Calling an R function within PostgreSQL Listing Available R Packages Q.1. How do you find out what R modules have been loaded? SELECT * FROM r_typenames(); That shows the types that are available, but what about checking if Kendall( X, Y ) is loaded? For example, the documentation shows: CREATE TABLE plr_modules ( modseq int4, modsrc text ); That seems to allow inserting records to dictate that Kendall is to be loaded, but the following code doesn't explain, syntactically, how to ensure that it gets loaded: INSERT INTO plr_modules VALUES (0, 'pg.test.module.load <-function(msg) {print(msg)}'); Q.2. What would the above line look like if you were trying to load Kendall? Q.3. Is it applicable? Installing R Packages Using the "synaptic" package manager the following packages have been installed: r-base r-base-core r-base-dev r-base-html r-base-latex r-cran-acepack r-cran-boot r-cran-car r-cran-chron r-cran-cluster r-cran-codetools r-cran-design r-cran-foreign r-cran-hmisc r-cran-kernsmooth r-cran-lattice r-cran-matrix r-cran-mgcv r-cran-nlme r-cran-quadprog r-cran-robustbase r-cran-rpart r-cran-survival r-cran-vr r-recommended Q.4. How do I know if Kendall is in there? Q.5. If it isn't, how do I find out what package it is in? Q.6. If it isn't in a package suitable for installing with apt-get (aptitude, synaptic, dpkg, what have you), how do I go about installing it on Ubuntu? Q.7. Where are the installation steps documented? Calling R Functions I have the following code: EXECUTE 'SELECT ' 'regr_slope( amount, year_taken ),' 'regr_intercept( amount, year_taken ),' 'corr( amount, year_taken ),' 'sum( measurements ) AS total_measurements ' 'FROM temp_regression' INTO STRICT slope, intercept, correlation, total_measurements; This code calls the PostgreSQL function corr to calculate Pearson's correlation over the data. Ideally, I'd like to do the following (by switching corr for plr_kendall): EXECUTE 'SELECT ' 'regr_slope( amount, year_taken ),' 'regr_intercept( amount, year_taken ),' 'plr_kendall( amount, year_taken ),' 'sum( measurements ) AS total_measurements ' 'FROM temp_regression' INTO STRICT slope, intercept, correlation, total_measurements; Q.8. Do I have to write plr_kendall myself? Q.9. Where can I find a simple example that walks through: Loading an R module into PG. Writing a PG wrapper for the desired R function. Calling the PG wrapper from a SELECT. For example, would the last two steps look like: create or replace function plr_kendall( _float8, _float8 ) returns float as ' agg_kendall(arg1, arg2) ' language 'plr'; CREATE AGGREGATE agg_kendall ( sfunc = plr_array_accum, basetype = float8, -- ??? stype = _float8, -- ??? finalfunc = plr_kendall ); And then the SELECT as above? Thank you!

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• The Skyline Problem.

  - by zeroDivisible

  I just came across this little problem on UVA's Online Judge and thought, that it may be a good candidate for a little code-golf. The problem: You are to design a program to assist an architect in drawing the skyline of a city given the locations of the buildings in the city. To make the problem tractable, all buildings are rectangular in shape and they share a common bottom (the city they are built in is very flat). The city is also viewed as two-dimensional. A building is specified by an ordered triple (Li, Hi, Ri) where Li and Ri are left and right coordinates, respectively, of building i and Hi is the height of the building. In the diagram below buildings are shown on the left with triples (1,11,5), (2,6,7), (3,13,9), (12,7,16), (14,3,25), (19,18,22), (23,13,29), (24,4,28) and the skyline, shown on the right, is represented by the sequence: 1, 11, 3, 13, 9, 0, 12, 7, 16, 3, 19, 18, 22, 3, 23, 13, 29, 0 The output should consist of the vector that describes the skyline as shown in the example above. In the skyline vector (v1, v2, v3, ... vn) , the vi such that i is an even number represent a horizontal line (height). The vi such that i is an odd number represent a vertical line (x-coordinate). The skyline vector should represent the "path" taken, for example, by a bug starting at the minimum x-coordinate and traveling horizontally and vertically over all the lines that define the skyline. Thus the last entry in the skyline vector will be a 0. The coordinates must be separated by a blank space. If I will not count declaration of provided (test) buildings and including all spaces and tab characters, my solution, in Python, is 223 characters long. Here is the condensed version: B=[[1,11,5],[2,6,7],[3,13,9],[12,7,16],[14,3,25],[19,18,22],[23,13,29],[24,4,28]] # Solution. R=range v=[0 for e in R(max([y[2] for y in B])+1)] for b in B: for x in R(b[0], b[2]): if b[1]>v[x]: v[x]=b[1] p=1 k=0 for x in R(len(v)): V=v[x] if p and V==0: continue elif V!=k: p=0 print "%s %s" % (str(x), str(V)), k=V I think that I didn't made any mistake but if so - feel free to criticize me. EDIT I don't have much reputation, so I will pay only 100 for a bounty - I am curious, if anyone could try to solve this in less than .. lets say, 80 characters. Solution posted by cobbal is 101 characters long and currently it is the best one. ANOTHER EDIT I thought, that 80 characters is a sick limit for this kind of problem. cobbal, with his 46 character solution totaly amazed me - though I must admit, that I spent some time reading his explanation before I partially understood what he had written.

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• C#.NET Socket Programming: Connecting to remote computers.

  - by Gio Borje

  I have a typical server in my end and a friend using a client to connect to my IP/Port and he consistently receives the exception: "A connection attempt failed because the connected party did not properly respond after a period of time, or established connection failed because connected host has failed to respond {MY_IP}:{MY_PORT}"—You don't need to know my IP. The client and server, however, work fine on the loopback address (127.0.0.1). I also do not have any firewall nor is windows firewall active. Server: static void Main(string[] args) { Console.Title = "Socket Server"; Console.WriteLine("Listening for messages..."); Socket serverSock = new Socket( AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp); IPAddress serverIP = IPAddress.Any; IPEndPoint serverEP = new IPEndPoint(serverIP, 33367); SocketPermission perm = new SocketPermission(NetworkAccess.Accept, TransportType.Tcp, "98.112.235.18", 33367); serverSock.Bind(serverEP); serverSock.Listen(10); while (true) { Socket connection = serverSock.Accept(); Byte[] serverBuffer = new Byte[8]; String message = String.Empty; while (connection.Available > 0) { int bytes = connection.Receive( serverBuffer, serverBuffer.Length, 0); message += Encoding.UTF8.GetString( serverBuffer, 0, bytes); } Console.WriteLine(message); connection.Close(); } } Client: static void Main(string[] args) { // Design the client a bit Console.Title = "Socket Client"; Console.Write("Enter the IP of the server: "); IPAddress clientIP = IPAddress.Parse(Console.ReadLine()); String message = String.Empty; while (true) { Console.Write("Enter the message to send: "); // The messsage to send message = Console.ReadLine(); IPEndPoint clientEP = new IPEndPoint(clientIP, 33367); // Setup the socket Socket clientSock = new Socket( AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp); // Attempt to establish a connection to the server Console.Write("Establishing connection to the server... "); try { clientSock.Connect(clientEP); // Send the message clientSock.Send(Encoding.UTF8.GetBytes(message)); clientSock.Shutdown(SocketShutdown.Both); clientSock.Close(); Console.Write("Message sent successfully.\n\n"); } catch (Exception ex) { Console.WriteLine(ex.Message); } } }

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• jQueryMobile: how to work with slider events?

  - by balexandre

  I'm testing the slider events in jQueryMobile and I must been missing something. page code is: <div data-role="fieldcontain"> <label for="slider">Input slider:</label> <input type="range" name="slider" id="slider" value="0" min="0" max="100" /> </div> and if I do: $("#slider").data("events"); I get blur, focus, keyup, remove What I want to do is to get the value once user release the slider handle and having a hook to the keyup event as $("#slider").bind("keyup", function() { alert('here'); } ); does absolutely nothing :( I must say that I wrongly assumed that jQueryMobile used jQueryUI controls as it was my first thought, but now working deep in the events I can see this is not the case, only in terms of CSS Design. What can I do? jQuery Mobile Slider source code can be found on Git if it helps anyone as well a test page can be found at JSBin As I understand, the #slider is the textbox with the value, so I would need to hook into the slider handle as the generated code for this slider is: <div data-role="fieldcontain" class="ui-field-contain ui-body ui-br"> <label for="slider" class="ui-input-text ui-slider" id="slider-label">Input slider:</label> <input data-type="range" max="100" min="0" value="0" id="slider" name="slider" class="ui-input-text ui-body-null ui-corner-all ui-shadow-inset ui-body-c ui-slider-input" /> <div role="application" class="ui-slider ui-btn-down-c ui-btn-corner-all"> <a class="ui-slider-handle ui-btn ui-btn-corner-all ui-shadow ui-btn-up-c" href="#" data-theme="c" role="slider" aria-valuemin="0" aria-valuemax="100" aria-valuenow="54" aria-valuetext="54" title="54" aria-labelledby="slider-label" style="left: 54%;"> <span class="ui-btn-inner ui-btn-corner-all"> <span class="ui-btn-text"></span> </span> </a> </div> </div> and checking the events in the handler anchor I get only the click event $("#slider").next().find("a").data("events");

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• .htaccess blocking images on some internal pages

  - by jethomas

  I'm doing some web design for a friend and I noticed that everywhere else on her site images will load fine except for the subdirectory I'm working in. I looked in her .htaccess file and sure enough it is setup to deny people from stealing her images. Fair Enough, except the pages i'm working on are in her domain and yet I still get the 403 error. I'm pasting the .htaccess contents below but I replaced the domain names with xyz, 123 and abc. So specifically the page I'm on (xyz.com/DesignGallery.asp) pulls images from (xyz.com/machform/data/form_1/files) and it results in a forbidden error. RewriteEngine on <Files 403.shtml> order allow,deny allow from all </Files> RewriteCond %{HTTP_REFERER} !^http://xyz.com/.*$ [NC] RewriteCond %{HTTP_REFERER} !^http://xyz.com/machform/.*$ [NC] RewriteCond %{HTTP_REFERER} !^http://xyz.com/machform/data/form_1/files/.*$ [NC] RewriteCond %{HTTP_REFERER} !^http://xyz.com$ [NC] RewriteCond %{HTTP_REFERER} !^http://abc.com/.*$ [NC] RewriteCond %{HTTP_REFERER} !^http://abc.com$ [NC] RewriteCond %{HTTP_REFERER} !^http://abc.xyz.com/.*$ [NC] RewriteCond %{HTTP_REFERER} !^http://abc.xyz.com$ [NC] RewriteCond %{HTTP_REFERER} !^http://123.com/.*$ [NC] RewriteCond %{HTTP_REFERER} !^http://123.com$ [NC] RewriteCond %{HTTP_REFERER} !^http://123.xyz.com/.*$ [NC] RewriteCond %{HTTP_REFERER} !^http://123.xyz.com$ [NC] RewriteCond %{HTTP_REFERER} !^http://www.xyz.com/.*$ [NC] RewriteCond %{HTTP_REFERER} !^http://www.xyz.com/machform/.*$ [NC] RewriteCond %{HTTP_REFERER} !^http://www.xyz.com/machform/$ [NC] RewriteCond %{HTTP_REFERER} !^http://www.xyz.com/machform/data/form_1/files/.*$ [NC] RewriteCond %{HTTP_REFERER} !^http://www.xyz.com$ [NC] RewriteCond %{HTTP_REFERER} !^http://www.abc.com/.*$ [NC] RewriteCond %{HTTP_REFERER} !^http://www.abc.com$ [NC] RewriteCond %{HTTP_REFERER} !^http://www.abc.xyz.com/.*$ [NC] RewriteCond %{HTTP_REFERER} !^http://www.abc.xyz.com$ [NC] RewriteCond %{HTTP_REFERER} !^http://www.123.com/.*$ [NC] RewriteCond %{HTTP_REFERER} !^http://www.123.com$ [NC] RewriteCond %{HTTP_REFERER} !^http://www.123.xyz.com/.*$ [NC] RewriteCond %{HTTP_REFERER} !^http://www.123.xyz.com$ [NC] RewriteRule .*\.(jpg|jpeg|gif|png|bmp)$ - [F,NC] deny from 69.49.149.17 RewriteCond %{HTTP_HOST} ^.*$ RewriteRule ^vendors\.html$ "http\:\/\/www\.xyz\.com\/Design_Gallery_1\.htm" [R=301,L] RewriteCond %{HTTP_HOST} ^.*$ RewriteRule ^vendors\.asp$ "http\:\/\/www\.xyz\.com\/Design_Gallery_1\.htm" [R=301,L] RewriteCond %{HTTP_HOST} ^.*$ RewriteRule ^ArtGraphics\.html$ "http\:\/\/www\.xyz\.com\/Art_Gallery_1\.htm" [R=301,L] RewriteCond %{HTTP_HOST} ^.*$ RewriteRule ^ArtGraphics\.asp$ "http\:\/\/www\.xyz\.com\/Art_Gallery_1\.htm" [R=301,L] RewriteCond %{HTTP_HOST} ^.*$ RewriteRule ^Gear\.asp$ "http\:\/\/www\.xyz\.com\/Gear_Gallery_1\.htm" [R=301,L] RewriteCond %{HTTP_HOST} ^.*$ RewriteRule ^Gear\.html$ "http\:\/\/www\.xyz\.com\/Gear_Gallery_1\.htm" [R=301,L] RewriteCond %{HTTP_HOST} ^.*$ RewriteRule ^NewsletterSign\-Up\.html$ "http\:\/\/www\.xyz\.com\/Newsletter\.htm" [R=301,L] RewriteCond %{HTTP_HOST} ^.*$ RewriteRule ^NewsletterSign\-Up\.asp$ "http\:\/\/www\.xyz\.com\/Newsletter\.htm" [R=301,L] RewriteCond %{HTTP_HOST} ^.*$ RewriteRule ^KidzStuff\.html$ "http\:\/\/www\.xyz\.com\/KidzStuff1\.htm" [R=301,L] RewriteCond %{HTTP_HOST} ^.*$ RewriteRule ^KidzStuff\.asp$ "http\:\/\/www\.xyz\.com\/KidzStuff1\.htm" [R=301,L] RewriteCond %{HTTP_HOST} ^.*$ RewriteRule ^Vendors\.html$ "http\:\/\/www\.xyz\.com\/Design_Gallery_1\.htm" [R=301,L] RewriteCond %{HTTP_HOST} ^.*$ RewriteRule ^Vendors\.asp$ "http\:\/\/www\.xyz\.com\/Design_Gallery_1\.htm" [R=301,L]

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• Table header to stay fixed at the top when user scrolls it out of view with jQuery

  - by PeterBZ

  I am trying to design an HTML table where the header will stay at the top of the page when AND ONLY when the user scrolls it out of view. For example, the table may be 500 pixels down from the page, how do I make it so that if the user scrolls the header out of view (browser detects its no longer in the windows view somehow), it will stay put at the top? Anyone can give me a Javascript solution to this? <table> <thead> <tr> <th>Col1</th> <th>Col2</th> <th>Col3</th> </tr> </thead> <tbody> <tr> <td>info</td> <td>info</td> <td>info</td> </tr> <tr> <td>info</td> <td>info</td> <td>info</td> </tr> <tr> <td>info</td> <td>info</td> <td>info</td> </tr> </tbody> </table> So in the above example, I want the <thead> to scroll with the page if it goes out of view. IMPORTANT: I am NOT looking for a solution where the <tbody> will have a scrollbar (overflow:auto).

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• Controls not aligning properly.

  - by RPK

  I am using following code to design my home page. The output (as shown below) is not appearing properly. You can see the banner going to far left and the navigation links have a huge gap in between. How to set this? Can it be done using only the DIV tag instead of TABLE? <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> <html> <head> <title> First Website </title> </head> <body> <table id="main" align="center" width="600 px"> <tr id="trBanner"> <td id="tdBanner"> <img src="../../../My Pictures/banner copy.bmp.jpg" </td> </tr> <tr id="trNavLinks"> <td id="lnkHome"> <a href="" id="lnkHome" name="lnkHome">Home</a> </td> <td id="lnkLife"> <a href="" id="lnkLife" name="lnkLife">Life</a> </td> <td id="lnkTeachings"> <a href="" id="lnkTeachings" name="lnkTeachings">Teachings</a> </td> <td id="lnkExperiences"> <a href="" id="lnkExperiences" name="lnkExperiences">Experiences</a> </td> <td id="lnkPhotoGallery"> <a href="" id="lnkPhotoGallery" name="lnkPhotoGallery">Photo Gallery</a> </td> <td id="lnkReach"> <a href="" id="lnkReach" name="lnkReach">How to Reach</a> </td> <td id="lnkContact"> <a href="" id="lnkContact" name="lnkContact">Contact Us</a> </td> </tr> </table> </body> </html>

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• Custom Control Not Playing Nice With PropertyGrid

  - by lumberjack4

  I have a class that is implementing a custom ToolStripItem. Everything seems to work great until I try to add the item to a ContextMenuStrip at design time. If I try to add my custom control straight from the ContextMenuStrip the PropertyGrid freezes up and will not let me modify my Checked or Text properties. But if I go into the ContextMenuStrip PropertyGrid and add my custom control through the Items(...) property, I can modify the custom control just fine within that dialog. I'm not sure if I'm missing an attribute somewhere of if its a problem with the underlying code. Here is a copy of the CustomToolStripItem class. As you can see, its a very simple class. [ToolStripItemDesignerAvailability(ToolStripItemDesignerAvailability.ContextMenuStrip)] public class CustomToolStripItem : ToolStripControlHost { #region Public Properties [Description("Gets or sets a value indicating whether the object is in the checked state")] [ReadOnly(false)] public bool Checked { get { return checkBox.Checked; } set { checkBox.Checked = value; } } [Description("Gets or sets the object's text")] [ReadOnly(false)] public override string Text { get { return checkBox.Text; } set { checkBox.Text = value; } } #endregion Public Properties #region Public Events public event EventHandler CheckedChanged; #endregion Public Events #region Constructors public CustomToolStripItem() : base(new FlowLayoutPanel()) { // Setup the FlowLayoutPanel. controlPanel = (FlowLayoutPanel)base.Control; controlPanel.BackColor = Color.Transparent; // Add the child controls. checkBox.AutoSize = true; controlPanel.Controls.Add(checkBox); ContextMenuStrip strip = new ContextMenuStrip(); } #endregion Constructors #region Protected Methods protected override void OnSubscribeControlEvents(Control control) { base.OnSubscribeControlEvents(control); checkBox.CheckedChanged += new EventHandler(CheckChanged); } protected override void OnUnsubscribeControlEvents(Control control) { base.OnUnsubscribeControlEvents(control); checkBox.CheckedChanged -= new EventHandler(CheckChanged); } #endregion Protected Methods #region Private Methods private void CheckChanged(object sender, EventArgs e) { // Throw the CustomToolStripItem's CheckedChanged event EventHandler handler = CheckedChanged; if (handler != null) { handler(sender, e); } } #endregion Private Methods #region Private Fields private FlowLayoutPanel controlPanel; private CheckBox checkBox = new CheckBox(); #endregion Private Fields }

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• Keeping the DI-container usage in the composition root in Silverlight and MVVM

  - by adrian hara

  It's not quite clear to me how I can design so I keep the reference to the DI-container in the composition root for a Silverlight + MVVM application. I have the following simple usage scenario: there's a main view (perhaps a list of items) and an action to open an edit view for one single item. So the main view has to create and show the edit view when the user takes the action (e.g. clicks some button). For this I have the following code: public interface IView { IViewModel ViewModel {get; set;} } Then, for each view that I need to be able to create I have an abstract factory, like so public interface ISomeViewFactory { IView CreateView(); } This factory is then declared a dependency of the "parent" view model, like so: public class SomeParentViewModel { public SomeParentViewModel(ISomeViewFactory viewFactory) { // store it } private void OnSomeUserAction() { IView view = viewFactory.CreateView(); dialogService.ShowDialog(view); } } So all is well until here, no DI-container in sight :). Now comes the implementation of ISomeViewFactory: public class SomeViewFactory : ISomeViewFactory { public IView CreateView() { IView view = new SomeView(); view.ViewModel = ???? } } The "????" part is my problem, because the view model for the view needs to be resolved from the DI-container so it gets its dependencies injected. What I don't know is how I can do this without having a dependency to the DI-container anywhere except the composition root. One possible solution would be to have either a dependency on the view model that gets injected into the factory, like so: public class SomeViewFactory : ISomeViewFactory { public SomeViewFactory(ISomeViewModel viewModel) { // store it } public IView CreateView() { IView view = new SomeView(); view.ViewModel = viewModel; } } While this works, it has the problem that since the whole object graph is wired up "statically" (i.e. the "parent" view model will get an instance of SomeViewFactory, which will get an instance of SomeViewModel, and these will live as long as the "parent" view model lives), the injected view model implementation is stateful and if the user opens the child view twice, the second time the view model will be the same instance and have the state from before. I guess I could work around this with an "Initialize" method or something similar, but it doesn't smell quite right. Another solution might be to wrap the DI-container and have the factories depend on the wrapper, but it'd still be a DI-container "in disguise" there :) Any thoughts on this are greatly appreciated. Also, please forgive any mistakes or rule-breaking, since this is my first post on stackoverflow :) Thanks! ps: my current solution is that the factories know about the DI-container, and it's only them and the composition root that have this dependency.

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• Installed Perl DBI Module Can't Be Found

  - by Russell C.

  I'm trying to setup a Perl development environment on my Mac laptop and have been having a really hard time getting it working. I thought I had everything configured correctly but when I try to run a sample script it is reporting errors with the DBI module and can't access the DB. Here is what is reported in the Apache error logs: [Fri Apr 30 23:11:33 2010] [error] [client 127.0.0.1] Can't locate DBI.pm in @INC (@INC contains: /Library/Perl/Updates/5.10.0/darwin-thread-multi-2level /Library/Perl/Updates/5.10.0 /System/Library/Perl/5.10.0/darwin-thread-multi-2level /System/Library/Perl/5.10.0 /Library/Perl/5.10.0/darwin-thread-multi-2level /Library/Perl/5.10.0 /Network/Library/Perl/5.10.0/darwin-thread-multi-2level /Network/Library/Perl/5.10.0 /Network/Library/Perl /System/Library/Perl/Extras/5.10.0/darwin-thread-multi-2level /System/Library/Perl/Extras/5.10.0 .) at main.pm line 5. I downloaded and installed both modules manually to work with MAMP using the following commands as specified in this forum post: For DBI 1. cd /Library/Perl/DBI-1.611 2. sudo Perl Makefile.PL 3. sudo make 4. sudo make install For DBD 1. cd /Library/Perl/DBD-mysql-4.014 2. sudo Perl Makefile.PL --mysql_config=/Applications/MAMP/Library/bin/mysql_config 3. sudo make 4. sudo make install What I noticed while running the above commands is that the files seems to be getting installed in the '/opt/local/lib/perl5/site_perl/5.8.9/darwin-2level/' directory which doesn't seem to be one of the search directories that Apache mentions in the error at the beginning of this post. Here is what I'm seeing during the install: $ sudo make install Files found in blib/arch: installing files in blib/lib into architecture dependent library tree Installing /opt/local/lib/perl5/site_perl/5.8.9/darwin-2level/auto/DBI/DBI.bundle Installing /opt/local/lib/perl5/site_perl/5.8.9/darwin-2level/auto/DBI/dbipport.h Installing /opt/local/lib/perl5/site_perl/5.8.9/darwin-2level/auto/DBI/DBIXS.h Installing /opt/local/lib/perl5/site_perl/5.8.9/darwin-2level/auto/DBI/dbixs_rev.h Installing /opt/local/lib/perl5/site_perl/5.8.9/darwin-2level/auto/DBI/Driver.xst Installing /opt/local/lib/perl5/site_perl/5.8.9/darwin-2level/auto/DBI/Driver_xst.h Installing /opt/local/lib/perl5/site_perl/5.8.9/darwin-2level/DBI.pm Installing /opt/local/lib/perl5/site_perl/5.8.9/darwin-2level/TASKS.pod Installing /opt/local/lib/perl5/site_perl/5.8.9/darwin-2level/DBD/DBM.pm Installing /opt/local/lib/perl5/site_perl/5.8.9/darwin-2level/DBD/File.pm Installing /opt/local/lib/perl5/site_perl/5.8.9/darwin-2level/DBD/Gofer.pm Installing /opt/local/lib/perl5/site_perl/5.8.9/darwin-2level/DBI/Changes.pm Installing /opt/local/lib/perl5/site_perl/5.8.9/darwin-2level/DBI/DBD.pm Installing /opt/local/lib/perl5/site_perl/5.8.9/darwin-2level/DBI/Profile.pm Installing /opt/local/lib/perl5/site_perl/5.8.9/darwin-2level/DBI/ProxyServer.pm Installing /opt/local/lib/perl5/site_perl/5.8.9/darwin-2level/DBI/PurePerl.pm Installing /opt/local/share/man/man3/DBD::DBM.3pm Installing /opt/local/share/man/man3/DBD::File.3pm Installing /opt/local/share/man/man3/DBD::Gofer.3pm Installing /opt/local/share/man/man3/DBI.3pm Installing /opt/local/share/man/man3/DBI::DBD.3pm Installing /opt/local/share/man/man3/DBI::Profile.3pm Installing /opt/local/share/man/man3/DBI::ProxyServer.3pm Installing /opt/local/share/man/man3/DBI::PurePerl.3pm Installing /opt/local/share/man/man3/TASKS.3pm Installing /opt/local/bin/dbiprof Installing /opt/local/bin/dbiproxy Writing /opt/local/lib/perl5/site_perl/5.8.9/darwin-2level/auto/DBI/.packlist Appending installation info to /opt/local/lib/perl5/5.8.9/darwin-2level/perllocal.pod My question is, what am I doing wrong and how can I either 1) Get Apache to look in the right directory where the DBD & DBI modules are installed or 2) Update the way I'm installing the module to install them into one of the search directories. I honestly don't know what option makes more sense and could use guidance on that as well. As you can probably tell I'm pretty lost at the moment. Please help!!!

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• Is this question too hard for a seasoned C++ architect?

  - by Monomer

  Background Information We're looking to hire a seasoned C++ architect (10+years dev, of which at least 6years must be C++ ) for a high frequency trading platform. Job advert says STL, Boost proficiency is a must with preferences to modern uses of C++. The company I work for is a Fortune 500 IB (aka finance industry), it requires passes in all the standard SHL tests (numeric, vocab, spatial etc) before interviews can commence. Everyone on the team was given the task of coming up with one question to ask the candidates during a written/typed test, please note this is the second test provided to the candidates, the first being Advanced IKM C++ test, done in the offices supervised and without internet access. People passing that do the second test. After roughly 70 candidates, my question has been determined to be statistically the worst performing - aka least number of people attempted it, furthermore even less people were able to give meaningful answers. Please note, the second test is not timed, the candidate can literally take as long as they like (we've had one person take roughly 10.5hrs) My question to SO is this, after SHL and IKM adv c++ tests, backed up with at least 6+ years C++ development experience, is it still ok not to be able to even comment about let alone come up with some loose strategy for solving the following question. The Question There is a class C with methods foo, boo, boo_and_foo and foo_and_boo. Each method takes i,j,k and l clock cycles respectively, where i < j, k < i+j and l < i+j. class C { public: int foo() {...} int boo() {...} int boo_and_foo() {...} int foo_and_boo() {...} }; In code one might write: C c; . . int i = c.foo() + c.boo(); But it would be better to have: int i = c.foo_and_boo(); What changes or techniques could one make to the definition of C, that would allow similar syntax of the original usage, but instead have the compiler generate the latter. Note that foo and boo are not commutative. Possible Solution We were basically looking for an expression templates based approach, and were willing to give marks to anyone who had even hinted or used the phrase or related terminology. We got only two people that used the wording, but weren't able to properly describe how they accomplish the task in detail. We use such techniques all over the place, due to the use of various mathematical operators for matrix and vector based calculations, for example to decide when to use IPP or hand woven implementations at compile time for a particular architecture and many other things. The particular area of software development requires microsecond response times. I believe could/should be able to teach a junior such techniques, but given the assumed caliber of candidates I expected a little more. Is this really a difficult question? Should it be removed? Or are we just not seeing the right candidates?

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• How can I install Perl's DBI on Mac OS X so Apache can find it?

  - by Russell C.

  I'm trying to setup a Perl development environment on my Mac laptop and have been having a really hard time getting it working. I thought I had everything configured correctly but when I try to run a sample script it is reporting errors with the DBI module and can't access the DB. Here is what is reported in the Apache error logs: [Fri Apr 30 23:11:33 2010] [error] [client 127.0.0.1] Can't locate DBI.pm in @INC (@INC contains: /Library/Perl/Updates/5.10.0/darwin-thread-multi-2level /Library/Perl/Updates/5.10.0 /System/Library/Perl/5.10.0/darwin-thread-multi-2level /System/Library/Perl/5.10.0 /Library/Perl/5.10.0/darwin-thread-multi-2level /Library/Perl/5.10.0 /Network/Library/Perl/5.10.0/darwin-thread-multi-2level /Network/Library/Perl/5.10.0 /Network/Library/Perl /System/Library/Perl/Extras/5.10.0/darwin-thread-multi-2level /System/Library/Perl/Extras/5.10.0 .) at main.pm line 5. I downloaded and installed both modules manually to work with MAMP using the following commands as specified in this forum post: For DBI 1. cd /Library/Perl/DBI-1.611 2. sudo Perl Makefile.PL 3. sudo make 4. sudo make install For DBD 1. cd /Library/Perl/DBD-mysql-4.014 2. sudo Perl Makefile.PL --mysql_config=/Applications/MAMP/Library/bin/mysql_config 3. sudo make 4. sudo make install What I noticed while running the above commands is that the files seems to be getting installed in the '/opt/local/lib/perl5/site_perl/5.8.9/darwin-2level/' directory which doesn't seem to be one of the search directories that Apache mentions in the error at the beginning of this post. Here is what I'm seeing during the install: $ sudo make install Files found in blib/arch: installing files in blib/lib into architecture dependent library tree Installing /opt/local/lib/perl5/site_perl/5.8.9/darwin-2level/auto/DBI/DBI.bundle Installing /opt/local/lib/perl5/site_perl/5.8.9/darwin-2level/auto/DBI/dbipport.h Installing /opt/local/lib/perl5/site_perl/5.8.9/darwin-2level/auto/DBI/DBIXS.h Installing /opt/local/lib/perl5/site_perl/5.8.9/darwin-2level/auto/DBI/dbixs_rev.h Installing /opt/local/lib/perl5/site_perl/5.8.9/darwin-2level/auto/DBI/Driver.xst Installing /opt/local/lib/perl5/site_perl/5.8.9/darwin-2level/auto/DBI/Driver_xst.h Installing /opt/local/lib/perl5/site_perl/5.8.9/darwin-2level/DBI.pm Installing /opt/local/lib/perl5/site_perl/5.8.9/darwin-2level/TASKS.pod Installing /opt/local/lib/perl5/site_perl/5.8.9/darwin-2level/DBD/DBM.pm Installing /opt/local/lib/perl5/site_perl/5.8.9/darwin-2level/DBD/File.pm Installing /opt/local/lib/perl5/site_perl/5.8.9/darwin-2level/DBD/Gofer.pm Installing /opt/local/lib/perl5/site_perl/5.8.9/darwin-2level/DBI/Changes.pm Installing /opt/local/lib/perl5/site_perl/5.8.9/darwin-2level/DBI/DBD.pm Installing /opt/local/lib/perl5/site_perl/5.8.9/darwin-2level/DBI/Profile.pm Installing /opt/local/lib/perl5/site_perl/5.8.9/darwin-2level/DBI/ProxyServer.pm Installing /opt/local/lib/perl5/site_perl/5.8.9/darwin-2level/DBI/PurePerl.pm Installing /opt/local/share/man/man3/DBD::DBM.3pm Installing /opt/local/share/man/man3/DBD::File.3pm Installing /opt/local/share/man/man3/DBD::Gofer.3pm Installing /opt/local/share/man/man3/DBI.3pm Installing /opt/local/share/man/man3/DBI::DBD.3pm Installing /opt/local/share/man/man3/DBI::Profile.3pm Installing /opt/local/share/man/man3/DBI::ProxyServer.3pm Installing /opt/local/share/man/man3/DBI::PurePerl.3pm Installing /opt/local/share/man/man3/TASKS.3pm Installing /opt/local/bin/dbiprof Installing /opt/local/bin/dbiproxy Writing /opt/local/lib/perl5/site_perl/5.8.9/darwin-2level/auto/DBI/.packlist Appending installation info to /opt/local/lib/perl5/5.8.9/darwin-2level/perllocal.pod My question is, what am I doing wrong and how can I either 1) Get Apache to look in the right directory where the DBD & DBI modules are installed or 2) Update the way I'm installing the module to install them into one of the search directories. I honestly don't know what option makes more sense and could use guidance on that as well. As you can probably tell I'm pretty lost at the moment. Please help!!! Thanks in advance.

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• Visual Web Developer 2008 Express and XHTML 1.1 (not applying)

  - by Mike Valeriano

  Hello. I may be missing something since I'm not used to work with IDEs for web development, so please understand if I'm doing something stupid. I've picked a copy of Beginning ASP.NET 3.5 in C# and VB to try and learn this thing quickly. I'm no HTML guru, but I know something about the DTDs and I want to either use XHTML 1.0 Strict or XHTML 1.1 while learning the ins and outs of ASP.NET. Following the book (just started actually), I'm not having any trouble understanding the concepts, since I have a C# background, but what I don't understand is how VWD goes about applying the schema you select for validation. The book explains that the drop-down list on the toolbar is enough to set this, so that's what I did: I've selected XHTML 1.1 (since there is no 1.0 strict option, what I find really odd) and then started the project. The thing is that the code generated automatically for the Default page had the XHTML 1.0 transitional DTD. Every other page added had the same DTD, even though XHTML 1.1 is still the selected schema in the drop-down list. I decided to test it out and there it was: inserting some text in the design view and then applying a bold formatting just inserted < b tags on the code. Changing color does add a span tag with added CSS though. What I want to know is: if I want strict XHTML (or 1.1) should I just code it manually? Or is there a "fix" for this problem (having a schema selected but not applied by the IDE)? Am I missing something really easy and dumb? I have no problem with coding it manually - I actually prefer doing that. The thing is that I really wanna try this WYSIWYG approach for once, since some developers swear by it. Plus I don't know yet if I'll need special tags for ASP.NET, so I think having them inserted automatically should be the best practice. I couldn't find any similar problems around (MSDN, Google, here), and as far as the book goes (up to the point I've read), this is the expected VWD behavior, which I find suspect at least. Sorry for the long text (and poor English - not my primary language). Thanks in advance for any help/tips.

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• Implement looped movement animation with tap to cancel

  - by Nader

  Hi All; My app is based around a grid and an image that moves within a grid that is contained within a scrollview. I have an imageview that I am animating from one cell to another in time with a slow finger movement and recentering the scrollview. That is rather straight forward. I have also implement the ability to detect a swipe and therefore move the image all the way to the end of the grid and the uiscrollview recentering. I have even implemented the ability to detect a subsequent tap and freeze the swiped movement. The issue with the swipe movement is that the UIScrollView will scroll all the way to the end before the Image reaches the end and so I have to wait for the image to arrive. Also, when I freeze the movement of the image, I have to re-align the image to a cell (which I can do). I have come to the realization that I have to animate the image one cell at a time for swipes and recentering the uiscrollview before moving the image to the next cell. I have attempted to implement this but I cannot come up with a solution that works or works properly. Can anyone suggest how I go about implementing this? Even if you are able to put up code from a different example or sudo code, it would help a lot as I cannot workout how this should be done, should I be using selectors, a listener in delegates, I just simply lack the experience to solve this design pattern. Here is some code: Note that the sprite is an UIImageView - (void)animateViewToPosition:(SpriteView *)sprite Position:(CGPoint)pos Duration:(CFTimeInterval)duration{ CGMutablePathRef traversePath = CGPathCreateMutable(); CGPathMoveToPoint(traversePath, NULL, sprite.center.x, sprite.center.y); CGPathAddLineToPoint(traversePath, NULL, pos.x, pos.y); CAKeyframeAnimation *traverseAnimation = [CAKeyframeAnimation animationWithKeyPath:kAnimatePosition]; traverseAnimation.duration = duration; traverseAnimation.removedOnCompletion = YES; traverseAnimation.timingFunction = [CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionLinear]; traverseAnimation.delegate = sprite; traverseAnimation.path = traversePath; CGPathRelease(traversePath); [sprite.layer addAnimation:traverseAnimation forKey:kAnimatePosition]; sprite.center = pos; }

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• Implement looped movement animation with tap to cancel

  - by Nader

  Hi All; My app is based around a grid and an image that moves within a grid that is contained within a scrollview. I have an imageview that I am animating from one cell to another in time with a slow finger movement and recentering the scrollview. That is rather straight forward. I have also implement the ability to detect a swipe and therefore move the image all the way to the end of the grid and the uiscrollview recentering. I have even implemented the ability to detect a subsequent tap and freeze the swiped movement. The issue with the swipe movement is that the UIScrollView will scroll all the way to the end before the Image reaches the end and so I have to wait for the image to arrive. Also, when I freeze the movement of the image, I have to re-align the image to a cell (which I can do). I have come to the realization that I have to animate the image one cell at a time for swipes and recentering the uiscrollview before moving the image to the next cell. I have attempted to implement this but I cannot come up with a solution that works or works properly. Can anyone suggest how I go about implementing this? Even if you are able to put up code from a different example or sudo code, it would help a lot as I cannot workout how this should be done, should I be using selectors, a listener in delegates, I just simply lack the experience to solve this design pattern. Here is some code: Note that the sprite is an UIImageView - (void)animateViewToPosition:(SpriteView *)sprite Position:(CGPoint)pos Duration:(CFTimeInterval)duration{ CGMutablePathRef traversePath = CGPathCreateMutable(); CGPathMoveToPoint(traversePath, NULL, sprite.center.x, sprite.center.y); CGPathAddLineToPoint(traversePath, NULL, pos.x, pos.y); CAKeyframeAnimation *traverseAnimation = [CAKeyframeAnimation animationWithKeyPath:kAnimatePosition]; traverseAnimation.duration = duration; traverseAnimation.removedOnCompletion = YES; traverseAnimation.timingFunction = [CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionLinear]; traverseAnimation.delegate = sprite; traverseAnimation.path = traversePath; CGPathRelease(traversePath); [sprite.layer addAnimation:traverseAnimation forKey:kAnimatePosition]; sprite.center = pos;

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• Problem in JSF2 with client-side state saving and serialization

  - by marcel

  I have a problem in JSF2 with client side state saving and serialization. I have created a page with a full description and a small class diagram: http://tinyurl.com/jsf2serial. For the client-side state saving I have to implement Serializable at the classes Search, BackingBean and Connection. The exception that was thrown is: java.io.NotSerializableException: org.apache.commons.httpclient.HttpClient at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1156) at java.io.ObjectOutputStream.defaultWriteFields(ObjectOutputStream.java:1509) at java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1474) at java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1392) at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1150) at java.io.ObjectOutputStream.defaultWriteFields(ObjectOutputStream.java:1509) at java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1474) at java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1392) at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1150) at java.io.ObjectOutputStream.defaultWriteFields(ObjectOutputStream.java:1509) at java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1474) at java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1392) at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1150) at java.io.ObjectOutputStream.writeObject(ObjectOutputStream.java:326) at java.util.HashMap.writeObject(HashMap.java:1001) at sun.reflect.GeneratedMethodAccessor80.invoke(Unknown Source) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25) at java.lang.reflect.Method.invoke(Method.java:597) at java.io.ObjectStreamClass.invokeWriteObject(ObjectStreamClass.java:945) at java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1461) at java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1392) at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1150) at java.io.ObjectOutputStream.defaultWriteFields(ObjectOutputStream.java:1509) at java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1474) at java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1392) at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1150) at java.io.ObjectOutputStream.writeArray(ObjectOutputStream.java:1338) at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1146) at java.io.ObjectOutputStream.writeObject(ObjectOutputStream.java:326) at java.util.HashMap.writeObject(HashMap.java:1001) at sun.reflect.GeneratedMethodAccessor80.invoke(Unknown Source) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25) at java.lang.reflect.Method.invoke(Method.java:597) at java.io.ObjectStreamClass.invokeWriteObject(ObjectStreamClass.java:945) at java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1461) at java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1392) at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1150) at java.io.ObjectOutputStream.writeObject(ObjectOutputStream.java:326) at com.sun.faces.renderkit.ClientSideStateHelper.doWriteState(ClientSideStateHelper.java:293) at com.sun.faces.renderkit.ClientSideStateHelper.writeState(ClientSideStateHelper.java:167) at com.sun.faces.renderkit.ResponseStateManagerImpl.writeState(ResponseStateManagerImpl.java:123) at com.sun.faces.application.StateManagerImpl.writeState(StateManagerImpl.java:155) at com.sun.faces.application.view.WriteBehindStateWriter.flushToWriter(WriteBehindStateWriter.java:221) at com.sun.faces.application.view.FaceletViewHandlingStrategy.renderView(FaceletViewHandlingStrategy.java:397) at com.sun.faces.application.view.MultiViewHandler.renderView(MultiViewHandler.java:126) at com.sun.faces.lifecycle.RenderResponsePhase.execute(RenderResponsePhase.java:127) at com.sun.faces.lifecycle.Phase.doPhase(Phase.java:101) at com.sun.faces.lifecycle.LifecycleImpl.render(LifecycleImpl.java:139) at javax.faces.webapp.FacesServlet.service(FacesServlet.java:313) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206) at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:233) at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191) at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127) at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102) at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109) at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:298) at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:852) at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:588) at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:489) at java.lang.Thread.run(Thread.java:637) Maybe this is a problem of my design, because I am new in developing Java webapps.

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