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• Are .NET's regular expressions Turing complete?

  - by Robert

  Regular expressions are often pointed to as the classical example of a language that is not Turning complete. For example "regular expressions" is given in as the answer to this SO question looking for languages that are not Turing complete. In my, perhaps somewhat basic, understanding of the notion of Turning completeness, this means that regular expressions cannot be used check for patterns that are "balanced". Balanced meaning have an equal number of opening characters as closing characters. This is because to do this would require you to have some kind of state, to allow you to match the opening and closing characters. However the .NET implementation of regular expressions introduces the notion of a balanced group. This construct is designed to let you backtrack and see if a previous group was matched. This means that a .NET regular expressions: ^(?<p>a)*(?<-p>b)*(?(p)(?!))$ Could match a pattern that: ab aabb aaabbb aaaabbbb ... etc. ... Does this means .NET's regular expressions are Turing complete? Or are there other things that are missing that would be required for the language to be Turing complete?

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• Groovy as a substitute for Java when using BigDecimal?

  - by geejay

  I have just completed an evaluation of Java, Groovy and Scala. The factors I considered were: readability, precision The factors I would like to know: performance, ease of integration I needed a BigDecimal level of precision. Here are my results: Java void someOp() { BigDecimal del_theta_1 = toDec(6); BigDecimal del_theta_2 = toDec(2); BigDecimal del_theta_m = toDec(0); del_theta_m = abs(del_theta_1.subtract(del_theta_2)) .divide(log(del_theta_1.divide(del_theta_2))); } Groovy void someOp() { def del_theta_1 = 6.0 def del_theta_2 = 2.0 def del_theta_m = 0.0 del_theta_m = Math.abs(del_theta_1 - del_theta_2) / Math.log(del_theta_1 / del_theta_2); } Scala def other(){ var del_theta_1 = toDec(6); var del_theta_2 = toDec(2); var del_theta_m = toDec(0); del_theta_m = ( abs(del_theta_1 - del_theta_2) / log(del_theta_1 / del_theta_2) ) } Note that in Java and Scala I used static imports. Java: Pros: it is Java Cons: no operator overloading (lots o methods), barely readable/codeable Groovy: Pros: default BigDecimal means no visible typing, least surprising BigDecimal support for all operations (division included) Cons: another language to learn Scala: Pros: has operator overloading for BigDecimal Cons: some surprising behaviour with division (fixed with Decimal128), another language to learn

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• Is learning C++ a good idea?

  - by chang

  The more I hear and read about C++ (e.g. this: http://lwn.net/Articles/249460/), I get the impression, that I'd waste my time learning C++. I some wrote network routing algorithm in C++ for a simulator, and it was a pain (as expected, especially coming from a perl/python/Java background ...). I'm never happy about giving up on some technology, but I would be happy, if I could limit my knowledge of C-family languages to just C, C# and Objective-C (even OS Xs Cocoa, which is huge and takes a lot of time to learn looks like joy compared to C++ ...). Do I need to consider myself dumb or unwilling, just because I'm not partial to the pain involved learning this stuff? Technologies advance and there will be options other than C++, when deciding on implementation languages, or not? And for speed: If speed were that critical, I'd go for a plain C implementation instead, or write C extensions for much more productive languages like ruby or python ... The one-line version of the above: Will C++ stay such a relevant language that every committed programmer should be familiar with it? [ edit / thank you very much for your interesting and useful answers so far .. ] [ edit / .. i am accepting the top-rated answer; thanks again for all answers! ]

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• Why is my user control not instanciated on a postback?

  - by Antoine

  Hi, I'd like to set the trigger of an UpdatePanel to a user control outside the UpdatePanel on the same page . The user control is added at design time, not at runtime. If I statically declare the trigger, I get an error "A control with ID 'xx' cannot be found for the trigger in UpdatePanel". I tried to add the trigger at runtime in Page_Init or Page_Load, but it fails with the user control being null, although it has ViewState enabled. Has someone an idea on how to solve this? Here is the code of the user control: <%@ Control Language="C#" AutoEventWireup="true" CodeFile="ComponentDropDownControl.ascx.cs" Inherits="ComponentDropDownControl" EnableViewState="true" %> <asp:DropDownList ID="ComponentDropDown" runat="server" DataSourceID="ComponentFile" DataTextField="name" DataValueField="name" OnSelectedIndexChanged="ComponentDropDown_SelectedIndexChanged" AutoPostBack="True" EnableTheming="True"> </asp:DropDownList><asp:XmlDataSource ID="ComponentFile" runat="server" DataFile="~/App_Data/Components.xml" XPath="//component"></asp:XmlDataSource> And here it is in the aspx page: <%@ Page Language="C#" MasterPageFile="~/MasterPage.master" AutoEventWireup="true" CodeFile="create.aspx.cs" Inherits="create" Title="Create task" %> <%@ Register Src="ComponentDropDownControl.ascx" TagName="ComponentDropDownControl" TagPrefix="uc1" %> ... <uc1:ComponentDropDownControl ID="CustomComponentDropDown" runat="server" EnableViewState="true" /> In the Page_Load function of the aspx page, the following lines work at first time, but fail on the first PostBack (line 2, CustomComponentDropDown is null). AsyncPostBackTrigger trigger = new AsyncPostBackTrigger(); trigger.ControlID = CustomComponentDropDown.UniqueID.ToString(); UpdatePanel1.Triggers.Add(trigger);

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• Algorithm for generating an array of non-equal costs for a transport problem optimization

  - by Carlos

  I have an optimizer that solves a transportation problem, using a cost matrix of all the possible paths. The optimiser works fine, but if two of the costs are equal, the solution contains one more path that the minimum number of paths. (Think of it as load balancing routers; if two routes are same cost, you'll use them both.) I would like the minimum number of routes, and to do that I need a cost matrix that doesn't have two costs that are equal within a certain tolerance. At the moment, I'm passing the cost matrix through a baking function which tests every entry for equality to each of the other entries, and moves it a fixed percentage if it matches. However, this approach seems to require N^2 comparisons, and if the starting values are all the same, the last cost will be r^N bigger. (r is the arbitrary fixed percentage). Also there is the problem that by multiplying by the percentage, you end up on top of another value. So the problem seems to have an element of recursion, or at least repeated checking, which bloats the code. The current implementation is basically not very good (I won't paste my GOTO-using code here for you all to mock), and I'd like to improve it. Is there a name for what I'm after, and is there a standard implementation? Example: {1,1,2,3,4,5} (tol = 0.05) becomes {1,1.05,2,3,4,5}

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• Please help with C++ syntax for const accessor by reference.

  - by Hamish Grubijan

  Right not my implementation returns the thing by value. The member m_MyObj itself is not const - it's value changes depending on what the user selects with a Combo Box. I am no C++ guru, but I want to do this right. If I simply stick a & in front of GetChosenSourceSystem in both decl. and impl., I get one sort of compiler error. If I do one but not another - another error. If I do return &m_MyObj;. I will not list the errors here for now, unless there is a strong demand for it. I assume that an experienced C++ coder can tell what is going on here. I could omit constness or reference, but I want to make it tight and learn in the process as well. Thanks! // In header file MyObj GetChosenThingy() const; // In Implementation file. MyObj MyDlg::GetChosenThingy() const { return m_MyObj; }

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• Creating a RESTful API - HELP!

  - by Martin Cox

  Hi Chaps Over the last few weeks I've been learning about iOS development, which has naturally led me into the world of APIs. Now, searching around on the Internet, I've come to the conclusion that using the REST architecture is very much recommended - due to it's supposed simplicity and ease of implementation. However, I'm really struggling with the implementation side of REST. I understand the concept; using HTTP methods as verbs to describe the action of a request and responding with suitable response codes, and so on. It's just, I don't understand how to code it. I don't get how I map a URI to an object. I understand that a GET request for domain.com/api/user/address?user_id=999 would return the address of user 999 - but I don't understand where or how that mapping from /user/address to some method that queries a database has taken place. Is this all coded in one php script? Would I just have a method that grabs the URI like so: $array = explode("/", ltrim(rtrim($_SERVER['REQUEST_URI'], "/"), "/")) And then cycle through that array, first I would have a request for a "user", so the PHP script would direct my request to the user object and then invoke the address method. Is that what actually happens? I've probably not explained my thought process very well there. The main thing I'm not getting is how that URI /user/address?id=999 somehow is broken down and executed - does it actually resolve to code? class user(id) { address() { //get user address } } I doubt I'm making sense now, so I'll call it a day trying to explain further. I hope someone out there can understand what I'm trying to say! Thanks Chaps, look forward to your responses. Martin p.s - I'm not a developer yet, I'm learning :)

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• Quality of TFS 2008 merged code

  - by paologios

  Does the quality of code merged by TFS 2008 depend on the used programming language? I know merging in Java / Subversion, and merging a branch to its trunk usually does not create much conflicts. Now in my company, we use VB.NET. When I merge two files TFS does not always get code blocks right, e.g. does not find the right If..then / end if lines. To give you an example, I mean: File 2 is created as a branch of File 1. Both files were changed later, now I'm going to merge those files and am recieving conficts: The marked end-if lines (1) are detected as corresponding, meaning the added event handler Button1_Click is being deleted. Now I wonder if this behavior is by language (C# vs. VB.NET) or are other source control solutions just better than TFS? (And I really liked TFS up to now :) ) File 1: Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load If Not Page.IsPostBack Then Label1.Text = "Hello" Label2.Text = "World" End If End Sub Protected Sub Button2_Click(ByVal sender, ByVal e as System.EventArgs) Handles Button2.Click // .... If Page.IsValid Then Label3.Text = "Hello Button 2" End If // .... End Sub File 2 (Branch of File 1): Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load If Not Page.IsPostBack Then fillTableFromDatabase() End If // (1) End Sub Protected Sub Button1_Click(ByVal sender, ByVal e as System.EventArgs) Handles Button1.Click // do something here End Sub Protected Sub Button2_Click(ByVal sender, ByVal e as System.EventArgs) Handles Button2.Click // .... If Page.IsValid Then End If // (1) // .... End Sub

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• Does it ever make sense to make a fundamental (non-pointer) parameter const?

  - by Scott Smith

  I recently had an exchange with another C++ developer about the following use of const: void Foo(const int bar); He felt that using const in this way was good practice. I argued that it does nothing for the caller of the function (since a copy of the argument was going to be passed, there is no additional guarantee of safety with regard to overwrite). In addition, doing this prevents the implementer of Foo from modifying their private copy of the argument. So, it both mandates and advertises an implementation detail. Not the end of the world, but certainly not something to be recommended as good practice. I'm curious as to what others think on this issue. Edit: OK, I didn't realize that const-ness of the arguments didn't factor into the signature of the function. So, it is possible to mark the arguments as const in the implementation (.cpp), and not in the header (.h) - and the compiler is fine with that. That being the case, I guess the policy should be the same for making local variables const. One could make the argument that having different looking signatures in the header and source file would confuse others (as it would have confused me). While I try to follow the Principle of Least Astonishment with whatever I write, I guess it's reasonable to expect developers to recognize this as legal and useful.

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• iOS: click counter for row in tableview

  - by roger.arliner21

  I am developing and tableView in which in each row I have to display the click counter and row number.Each cell must have an initial click counter value of 0 when application is initialized. Then increment the click counter value within a cell whenever a user clicks on the cell. I have take 26 fixed rows. I have taken tableData.plist file as in the attached image. I am initializing the self.dataArray with the plist . Now I want to do implementation in the didSelectRowAtIndexPath delegate method,if any row is tapped that row's click counter should increment. - (void)viewDidLoad { [super viewDidLoad]; NSString *path = [[NSBundle mainBundle] pathForResource:@"tableData" ofType:@"plist"]; self.dataArray = [NSMutableArray arrayWithContentsOfFile:path];//array initialized with plist } - (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section { return [self.dataArray count]; } - (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath { static NSString *kCustomCellID = @"MyCellID"; UILabel *label1 = [[UILabel alloc] initWithFrame:CGRectMake(160.0f, 2.0f, 30.0f, 20.0f)]; UILabel *label2 = [[UILabel alloc] initWithFrame:CGRectMake(160.0f, 24.0f, 30.0f, 30.0f)]; label2.textColor = [UIColor grayColor]; UITableViewCell *cell = (UITableViewCell *)[tableView dequeueReusableCellWithIdentifier:kCustomCellID]; if (cell == nil) { cell = [[[UITableViewCell alloc] initWithStyle:UITableViewCellStyleSubtitle reuseIdentifier:kCustomCellID] autorelease]; cell.selectionStyle = UITableViewCellSelectionStyleNone; } if([self.dataArray count]>indexPath.row) { label1.text = [[self.dataArray objectAtIndex:indexPath.row] objectForKey:@"Lable1"]; label2.text =[[self.dataArray objectAtIndex:indexPath.row] objectForKey:@"Lable2"]; } else { label1.text = @""; label2.text =@""; } [cell.contentView addSubview:label1]; [cell.contentView addSubview:label2]; [label1 release]; [label2 release]; return cell; } #pragma mark - #pragma mark Table view delegate - (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath { //implementation for row counter incrementer. }

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• Is there a definitive reference document for Ruby syntax?

  - by JSW

  I'm searching for a definitive document on Ruby syntax. I know about the definitive documents for the core API and standard library, but what about the syntax itself? For instance, such a document should cover: reserved words, string literals syntax, naming rules for variables/classes/modules, all the conditional statements and their permutations, and so forth. I know there are many books and tutorials, yes, but every one of them is essentially a tutorial, each one having a range of different depth and focus. They will all, by necessity of brevity and narrative flow, omit certain details of the language that the author deems insignificant. For instance, did you know that you can use a case statement without an initial case value, and it will then execute the first true when clause? Any given Ruby book or tutorial may or may not cover that particular lesser-known functionality of the case syntax. It's not discussed in the section in "Programming Ruby" about case statements. But that is just one small example. So far the best documentation I've found is the rubyspec project, which appears to be an attempt to write a complete test suite for the language. That's not bad, but it's a bit hard to use from a practical standpoint as a developer working on my own projects. Am I just missing something or is there really no definitive readable document defining the whole of Ruby syntax?

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• Display all feeds using simplexml_load() using PHP

  - by Jean

  Hello, I want to loop to get all feeds, but displaying only one $url = "http://localhost/feeds/feeds.rss"; $xml = simplexml_load_file($url); foreach($xml->item as $result){ echo $result->description."<br>"; } RSS Feed is - <channel> <title>/</title> <link>/</link> <atom:link type="application/rss+xml" href="/" rel="self"/> <description>/</description> <language>/</language> <ttl>/</ttl> <item> <title>/</title> <description>/</description> <pubDate>/</pubDate> <guid>/</guid> <link>/</link> </item> <item> <title>/</title> <description>/</description> <pubDate>/</pubDate> <guid>/</guid> <link>/</link> </item> </channel> Thanks Jean

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• Memory management of objects returned by methods (iOS / Objective-C)

  - by iOSNewb

  I am learning Objective-C and iOS programming through the terrific iTunesU course posted by Stanford (http://www.stanford.edu/class/cs193p/cgi-bin/drupal/) Assignment 2 is to create a calculator with variable buttons. The chain of commands (e.g. 3+x-y) is stored in a NSMutableArray as "anExpression", and then we sub in random values for x and y based on an NSDictionary to get a solution. This part of the assignment is tripping me up: The final two [methods] “convert” anExpression to/from a property list: + (id)propertyListForExpression:(id)anExpression; + (id)expressionForPropertyList:(id)propertyList; You’ll remember from lecture that a property list is just any combination of NSArray, NSDictionary, NSString, NSNumber, etc., so why do we even need this method since anExpression is already a property list? (Since the expressions we build are NSMutableArrays that contain only NSString and NSNumber objects, they are, indeed, already property lists.) Well, because the caller of our API has no idea that anExpression is a property list. That’s an internal implementation detail we have chosen not to expose to callers. Even so, you may think, the implementation of these two methods is easy because anExpression is already a property list so we can just return the argument right back, right? Well, yes and no. The memory management on this one is a bit tricky. We’ll leave it up to you to figure out. Give it your best shot. Obviously, I am missing something with respect to memory management because I don't see why I can't just return the passed arguments right back. Thanks in advance for any answers!

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• Get Browser to send both If-None-Match and If-Modified-Since

  - by Glen

  My Browser isn't sending back an If-Modified-Since Header for PHP generated Content on the first request my script sends: (Status-Line) HTTP/1.1 200 OK Date Thu, 21 Jan 2010 08:55:25 GMT Server Apache/2.2.11 (Win32) PHP/5.2.9-1 X-Powered-By PHP/5.2.9-1 Pragma no-cache x-ua-compatible IE=8;FF=3;OtherUA=4 Last-Modfied Sat, 02 Jan 2010 02:02:20 GMT Content-Length 28453 Etag b98e0795b509be20146f58e06fbb624f Keep-Alive timeout=5, max=90 Connection Keep-Alive Content-Type image/png it on the second request it sends: (Request-Line) GET /kincumberunitingchurch/banner_image.php?id=1 HTTP/1.1 Host localhost User-Agent Mozilla/5.0 (Windows; U; Windows NT 6.1; en-US; rv:1.9.0.17) Gecko/2009122116 Firefox/3.0.17 Accept image/png,image/*;q=0.8,*/*;q=0.5 Accept-Language en-us,en;q=0.5 Accept-Encoding gzip,deflate Accept-Charset ISO-8859-1,utf-8;q=0.7,*;q=0.7 Keep-Alive 300 Connection keep-alive Referer http://localhost/kincumberunitingchurch/index.php?sid=tgl9jq3f71nau3cj9vps6pna03 Cookie sid=tgl9jq3f71nau3cj9vps6pna03; PHPSESSID=m0jvven6d7l65pl6odm9ecfnt4 If-None-Match b98e0795b509be20146f58e06fbb624f Cache-Control max-age=0 for other files the sever sends first: (Status-Line) HTTP/1.1 200 OK Date Thu, 21 Jan 2010 08:55:25 GMT Server Apache/2.2.11 (Win32) PHP/5.2.9-1 Last-Modified Wed, 30 Dec 2009 02:40:58 GMT Etag "1000000013d35-40d9-47be9117f6280" Accept-Ranges bytes Content-Length 16601 Keep-Alive timeout=5, max=84 Connection Keep-Alive Content-Type image/png and my browser send the following on the next request: (Request-Line) GET /kincumberunitingchurch/img/cbuttons.png HTTP/1.1 Host localhost User-Agent Mozilla/5.0 (Windows; U; Windows NT 6.1; en-US; rv:1.9.0.17) Gecko/2009122116 Firefox/3.0.17 Accept image/png,image/*;q=0.8,*/*;q=0.5 Accept-Language en-us,en;q=0.5 Accept-Encoding gzip,deflate Accept-Charset ISO-8859-1,utf-8;q=0.7,*;q=0.7 Keep-Alive 300 Connection keep-alive Referer http://localhost/kincumberunitingchurch/mystyle.css Cookie sid=tgl9jq3f71nau3cj9vps6pna03; PHPSESSID=m0jvven6d7l65pl6odm9ecfnt4 If-Modified-Since Wed, 30 Dec 2009 02:40:58 GMT If-None-Match "1000000013d35-40d9-47be9117f6280" Cache-Control max-age=0 why would it send the If-Modified-Since header

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• are C functions declared in <c____> headers gauranteed to be in the global namespace as well as std?

  - by Evan Teran

  So this is something that I've always wondered but was never quite sure about. So it is strictly a matter of curiosity, not a real problem. As far as I understand, what you do something like #include <cstdlib> everything (except macros of course) are declared in the std:: namespace. Every implementation that I've ever seen does this by doing something like the following: #include <stdlib.h> namespace std { using ::abort; // etc.... } Which of course has the effect of things being in both the global namespace and std. Is this behavior guaranteed? Or is it possible that an implementation could put these things in std but not in the global namespace? The only way I can think of to do that would be to have your libstdc++ implement every c function itself placing them in std directly instead of just including the existing libc headers (because there is no mechanism to remove something from a namespace). Which is of course a lot of effort with little to no benefit. The essence of my question is, is the following program strictly conforming and guaranteed to work? #include <cstdio> int main() { ::printf("hello world\n"); }

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• Is there an equivalent for ActiveRecord#find_by equivalent for C#?

  - by Benjamin Manns

  I'm originally a C# developer (as a hobby), but as of late I have been digging into Ruby on Rails and I am really enjoying it. Right now I am building an application in C# and I was wondering if there is any collection implementation for C# that could match (or "semi-match") the find_by method of ActiveRecord. What I am essentially looking for is a list that would hold Rectangles: class Rectangle { public int Width { get; set; } public int Height { get; set; } public String Name { get; set; } } Where I could query this list and find all entries with Height = 10, Width = 20, or name = "Block". This was done with ActiveRecord by doing a call similar to Rectangle.find_by_name('Block'). The only way I can think of doing this in C# is to create my own list implementation and iterate through each item manually checking each item against the criteria. I fear I would be reinventing the wheel (and one of poorer quality). Any input or suggestions is much appreciated.

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• Diff/Merge functionality for objects (not files!)

  - by gehho

  I have a collection of objects of the same type, let's call it DataItem. The user can view and edit these items in an editor. It should also be possible to compare and merge different items, i.e. some sort of diff/merge for DataItem instances. The DIFF functionality should compare all (relevant) properties/fields of the items and detect possible differences. The MERGE functionality should then be able to merge two instances by applying selected differences to one of the items. For example (pseudo objects): DataItem1 { DataItem2 { Prop1 = 10 Prop1 = 10 Prop2 = 25 Prop2 = 13 Prop3 = 0 Prop3 = 5 Coll = { 7, 4, 8 } Coll = { 7, 4, 8, 12 } } } Now, the user should be provided with a list of differences (i.e. Prop2, Prop3, and Coll) and he should be able to select which differences he wants to eliminate by assigning the value from one item to the other. He should also be able to choose if he wants to assign the value from DataItem1 to DataItem2 or vice versa. Are there common practices which should be used to implement this functionality? Since the same editor should also provide undo/redo functionality (using the Command pattern), I was thinking about reusing the ICommand implementations because both scenarios basically handle with property assignments, collection changes, and so on... My idea was to create Difference objects with ICommand properties which can be used to perform a merge operation for this specific Difference. Btw: The programming language will be C# with .NET 3.5SP1/4.0. However, I think this is more of a language-independent question. Any design pattern/idea/whatsoever is welcome!

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• C++ Matrix class hierachy

  - by bpw1621

  Should a matrix software library have a root class (e.g., MatrixBase) from which more specialized (or more constrained) matrix classes (e.g., SparseMatrix, UpperTriangluarMatrix, etc.) derive? If so, should the derived classes be derived publicly/protectively/privately? If not, should they be composed with a implementation class encapsulating common functionality and be otherwise unrelated? Something else? I was having a conversation about this with a software developer colleague (I am not per se) who mentioned that it is a common programming design mistake to derive a more restricted class from a more general one (e.g., he used the example of how it was not a good idea to derive a Circle class from an Ellipse class as similar to the matrix design issue) even when it is true that a SparseMatrix "IS A" MatrixBase. The interface presented by both the base and derived classes should be the same for basic operations; for specialized operations, a derived class would have additional functionality that might not be possible to implement for an arbitrary MatrixBase object. For example, we can compute the cholesky decomposition only for a PositiveDefiniteMatrix class object; however, multiplication by a scalar should work the same way for both the base and derived classes. Also, even if the underlying data storage implementation differs the operator()(int,int) should work as expected for any type of matrix class. I have started looking at a few open-source matrix libraries and it appears like this is kind of a mixed bag (or maybe I'm looking at a mixed bag of libraries). I am planning on helping out with a refactoring of a math library where this has been a point of contention and I'd like to have opinions (that is unless there really is an objective right answer to this question) as to what design philosophy would be best and what are the pros and cons to any reasonable approach.

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• Beginner SQL section: avoiding repeated expression

  - by polygenelubricants

  I'm entirely new at SQL, but let's say that on the StackExchange Data Explorer, I just want to list the top 15 users by reputation, and I wrote something like this: SELECT TOP 15 DisplayName, Id, Reputation, Reputation/1000 As RepInK FROM Users WHERE RepInK > 10 ORDER BY Reputation DESC Currently this gives an Error: Invalid column name 'RepInK', which makes sense, I think, because RepInK is not a column in Users. I can easily fix this by saying WHERE Reputation/1000 > 10, essentially repeating the formula. So the questions are: Can I actually use the RepInK "column" in the WHERE clause? Do I perhaps need to create a virtual table/view with this column, and then do a SELECT/WHERE query on it? Can I name an expression, e.g. Reputation/1000, so I only have to repeat the names in a few places instead of the formula? What do you call this? A substitution macro? A function? A stored procedure? Is there an SQL quicksheet, glossary of terms, language specification, anything I can use to quickly pick up the syntax and semantics of the language? I understand that there are different "flavors"?

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• How to load a type in parent-child website

  - by salvationishere

  I am developing a C# VS 2008 / SQL Server 2008 website. Although this same code compiles in the Project version, the website version does not compile. Many of their files are the same so I do not understand even where to look. The only compile error I get is: Could not load type 'DataMatch' in my DataMatch.aspx file. Is the problem in my web.config file? How do websites differ from projects in VS? All four of these files reside in same directory. Default.aspx file: <%@ Page Language="C#" MasterPageFile="~/Site.master" AutoEventWireup="true" CodeFile="Default.aspx.cs" Inherits="AddFileToSQL" Title="Untitled Page" % ... Default.aspx.cs file: ... using System.Data.SqlClient; using System.Security.Principal; namespace AddFileToSQL { public partial class AddFileToSQL : System.Web.UI.Page { ... DataMatch.aspx file: <%@ Page Language="C#" AutoEventWireup="true" CodeBehind="DataMatch.aspx.cs" Inherits="DataMatch" % ... DataMatch.aspx.cs file: ... using System.Web.UI.WebControls; using AddFileToSQL; public partial class DataMatch : AddFileToSQL { ...

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• What *is* an IPM.DistList?

  - by Jeremy

  I'm trying to get the recipient addresses within an IPM.DistList that is stored in a public folder (of type contacts) in Exchange 2003. The typeName of the object (once I get hold of it) is a Message (with a parent object being a Messages collection) and the messageType is "IPM.DistList". I can find all sorts of things about IPM.DistListItems, which you would think an IPM.DistList would contain, but there apparently isn't any documentation on the DistList (that I can find) and DistListItems documentation lists no parent possibilities in MSDN. I'll state it another way in case I've left you confused: We have an Exchange 2003 info store with Public Folders. Within those Public Folders is a [sub]folder (that holds items of type "Contact") that has a bunch of distribution lists (IPM.DistList's) that have contact entries, members of the list essentially. I need to get the addresses of the members of the lists in the Public Folder sub-folder using any VB language, because the company I work for hired me as a VB guy and expects me to write VB solutions, even though I could do it in C++... alas, I digress. VB is the language I'm supposed to figure this out in. (.net, script, vba, vb6, it doesn't matter which one. Yes, I know vb.net is not really related to those that came before, but they don't know that.) Anyone ran into anything like this? Am I just not finding the IPM.DistList documentation but it does actually exist somewhere? This isn't a Message.MAPIOBJECT (iUnknown) problem is it? Thanks.... Jeremy

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• cross-platform development for mobile devices

  - by user924

  What language/framework is best worth learning for mobile application development? My specific situation is that I'm very familiar with Java and C++ (I especially love Qt), but have limited experience with other languages. Some options I'm considering: 1) Learn Objective-C and all the iPhone-specific tools I do have access to a mac. The downside here is I'm restricted to the iPhone, so I'd have to rewrite almost everything if I wanted to branch off into another mobile device (or move later to a cross-platform framework). Even after knowing Objective-C, it seems like other frameworks might be more efficient/faster to code in? 2) Use some existing cross-platform framework for development I've looked at rhomobile, but I only have limited experience with Ruby (and at first glance, it might be a little pricey comapred to other options). Appcelerator also looks popular and nice, but it uses html/css/javascript. Airplaysdk looks good, but it's new and I haven't been able to see much written about it (is it worth going for?). 3) Wait for something better to come along How far away is Qt for the iPhone? That would be ideal, but it isn't available now. So what do you recommend? Productivity/efficiency is my top priority, although learning a useful language for the long term would also be okay. Thanks

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• How to parse time stamps with Unicode characters in Java or Perl?

  - by ram

  I'm trying to make my code as generic as possible. I'm trying to parse install time of a product installation. I will have two files in the product, one that has time stamp I need to parse and other file tells the language of the installation. This is how I'm parsing the timestamp public class ts { public static void main (String[] args){ String installTime = "2009/11/26 \u4e0b\u5348 04:40:54"; //This timestamp I got from the first file. Those unicode charecters are some Chinese charecters...AM/PM I guess //Locale = new Locale();//don't set the language yet SimpleDateFormat df = (SimpleDateFormat)DateFormat.getDateTimeInstance(DateFormat.DEFAULT,DateFormat.DEFAULT); Date instTime = null; try { instTime = df.parse(installTime); } catch (ParseException e) { // TODO Auto-generated catch block e.printStackTrace(); } System.out.println(instTime.toString()); } } The output I get is Parsing Failed java.text.ParseException: Unparseable date: "2009/11/26 \u4e0b\u5348 04:40:54" at java.text.DateFormat.parse(Unknown Source) at ts.main(ts.java:39) Exception in thread "main" java.lang.NullPointerException at ts.main(ts.java:45) It throws exception and at the end when I print it, it shows some proper date... wrong though. I would really appreciate if you could clarify me on these doubts How to parse timestamps that have unicode characters if this is not the proper way? If parsing is failed, how could instTime able to hold some date, wrong though? I know its some chinese,Korean time stamps so I set the locale to zh and ko as follows.. even then same error comes again Locale = new Locale("ko"); Locale = new Locale("ja"); Locale = new Locale("zh"); How can I do the same thing in Perl? I can't use Date::Manip package; Is there any other way?

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• Learn Prolog Now! DCG Practice Example

  - by Timothy

  I have been progressing through Learn Prolog Now! as self-study and am now learning about Definite Clause Grammars. I am having some difficulty with one of the Practical Session's tasks. The task reads: The formal language anb2mc2mdn consists of all strings of the following form: an unbroken block of as followed by an unbroken block of bs followed by an unbroken block of cs followed by an unbroken block of ds, such that the a and d blocks are exactly the same length, and the c and d blocks are also exactly the same length and furthermore consist of an even number of cs and ds respectively. For example, ε, abbccd, and aaabbbbccccddd all belong to anb2mc2mdn. Write a DCG that generates this language. I am able to write rules that generate andn, b2mc2m, and even anb2m and c2mndn... but I can't seem to join all these rules into anb2mc2mdn. The following are my rules that can generate andn and b2mc2m. s1 --> []. s1 --> a,s1,d. a --> [a]. d --> [d]. s2 --> []. s2 --> c,c,s2,d,d. c --> [c]. d --> [d]. Is anb2mc2mdn really a CFG, and is it possible to write a DCG using only what was taught in the lesson (no additional arguments or code, etc)? If so, can anyone offer me some guidance how I can join these so that I can solve the given task?

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• How do I implement a collection in Scala 2.8?

  - by Simon Reinhardt

  In trying to write an API I'm struggling with Scala's collections in 2.8(.0-beta1). Basically what I need is to write something that: adds functionality to immutable sets of a certain type where all methods like filter and map return a collection of the same type without having to override everything (which is why I went for 2.8 in the first place) where all collections you gain through those methods are constructed with the same parameters the original collection had (similar to how SortedSet hands through an ordering via implicits) which is still a trait in itself, independent of any set implementations. Additionally I want to define a default implementation, for example based on a HashSet. The companion object of the trait might use this default implementation. I'm not sure yet if I need the full power of builder factories to map my collection type to other collection types. I read the paper on the redesign of the collections API but it seems like things have changed a bit since then and I'm missing some details in there. I've also digged through the collections source code but I'm not sure it's very consistent yet. Ideally what I'd like to see is either a hands-on tutorial that tells me step-by-step just the bits that I need or an extensive description of all the details so I can judge myself which bits I need. I liked the chapter on object equality in "Programming in Scala". :-) But I appreciate any pointers to documentation or examples that help me understand the new collections design better.

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