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  • Visual Basic Book Excerpt: Useful Namespaces

    This chapter provides an overview of some of the most important system namespaces and gives more detailed examples that demonstrate regular expressions, XML, cryptography, reflection, threading, parallel programming, and Direct3D....Did you know that DotNetSlackers also publishes .net articles written by top known .net Authors? We already have over 80 articles in several categories including Silverlight. Take a look: here.

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  • How would you rank these programming skills in order of learning them? [closed]

    - by mumtaz
    As a general purpose programmer, what should you learn first and what should you learn later on? Here are some skills I wonder about... SQL Regular Expressions Multi-threading / Concurrency Functional Programming Graphics The mastery of your mother programming language's syntax/semantics/featureset The mastery of your base class framework libraries Version Control System Unit Testing XML Do you know other important ones? Please specify them... On which skills should I focus first?

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  • Prevent hotlinking of attachments

    - by reggie
    People are able to embed my forum's attachments (vbulletin). I tried to create an htaccess rule for the hotlinking, but it did not work. RewriteCond %{HTTP_REFERER} !^$ RewriteCond %{HTTP_REFERER} !^http://(www\.)?mydomain\.com.*$ [NC] RewriteRule attachmentid=\d+(\&d=\d*)?|\.([Gg][Ii][Ff]|[Jj][Pp][Gg])$ http://mydomain.com/antihotlink.jpeg [R] Is it not possible to check for numbers in regular expressions in htaccess files?

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  • What is a good replacement for MS Frontpage?

    - by Clay Nichols
    I've been using MS Frontpage 2003 to maintain our company website for years. Looking for a replacement that can: Import/convert a MS FrontPage website and "modernize it" (clean up the HTML to make it standards compliant, etc.) Supports (or converts) the substitutions (Include Page and Text substitutions that are done when the page is published (so they become static HTML). Leverages my knowledge of FrontPage Looks like the likely contender is Web Expressions but I'm open to objective suggestions.

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  • T-SQL User-Defined Functions: the good, the bad, and the ugly (part 2)

    - by Hugo Kornelis
    In a previous blog post , I demonstrated just how much you can hurt your performance by encapsulating expressions and computations in a user-defined function (UDF). I focused on scalar functions that didn’t include any data access. In this post, I will complete the discussion on scalar UDFs by covering the effect of data access in a scalar UDF. Note that, like the previous post, this all applies to T-SQL user-defined functions only. SQL Server also supports CLR user-defined functions (written in...(read more)

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  • Analyzing a programming language

    - by Matt Fenwick
    In SICP, the authors state (Section 1.1) that there are three basic "mechanisms" of programming languages: primitive expressions, which represent the simplest entities the language is concerned with means of combination, by which compound elements are built from simpler ones means of abstraction, by which compound elements can be named and manipulated as units How can I analyze a mainstream programming language (Java, for example) in terms of these elements or mechanisms?

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  • T-SQL User-Defined Functions: the good, the bad, and the ugly (part 2)

    - by Hugo Kornelis
    In a previous blog post , I demonstrated just how much you can hurt your performance by encapsulating expressions and computations in a user-defined function (UDF). I focused on scalar functions that didn’t include any data access. In this post, I will complete the discussion on scalar UDFs by covering the effect of data access in a scalar UDF. Note that, like the previous post, this all applies to T-SQL user-defined functions only. SQL Server also supports CLR user-defined functions (written in...(read more)

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  • Lambda&rsquo;s for .NET made easy&hellip;

    - by mbcrump
    The purpose of my blog is to explain things for a beginner to intermediate c# programmer. I’ve seen several blog post that use lambda expressions always assuming the audience is familiar with them. The purpose of this post is to make them simple and easily understood. Let’s begin with a definition. A lambda expression is an anonymous function that can contain expressions and statements, and can be used to create delegates or expression tree types. So anonymous function… delegates or expression tree types? I don’t get it??? Confused yet?   Lets break this into a few definitions and jump right into the code. anonymous function – is an "inline" statement or expression that can be used wherever a delegate type is expected. delegate - is a type that references a method. Once a delegate is assigned a method, it behaves exactly like that method. The delegate method can be used like any other method, with parameters and a return value. Expression trees - represent code in a tree-like data structure, where each node is an expression, for example, a method call or a binary operation such as x < y.   Don’t worry if this still sounds confusing, lets jump right into the code with a simple 3 line program. We are going to use a Function Delegate (all you need to remember is that this delegate returns a value.) Lambda expressions are used most commonly with the Func and Action delegates, so you will see an example of both of these. Lambda Expression 3 lines. using System; using System.Collections.Generic; using System.Linq; using System.Text;   namespace ConsoleApplication7 {     class Program     {          static void Main(string[] args)         {             Func<int, int> myfunc = x => x *x;             Console.WriteLine(myfunc(6).ToString());             Console.ReadLine();         }       } } Is equivalent to Old way of doing it. using System; using System.Collections.Generic; using System.Linq; using System.Text;   namespace ConsoleApplication7 {     class Program     {          static void Main(string[] args)         {               Console.WriteLine(myFunc(6).ToString());             Console.ReadLine();         }            static int myFunc(int x)          {              return x * x;            }       } } In the example, there is a single parameter, x, and the expression is x*x. I’m going to stop here to make sure you are still with me. A lambda expression is an unnamed method written in place of a delegate instance. In other words, the compiler converts the lambda expression to either a : A delegate instance An expression tree All lambda have the following form: (parameters) => expression or statement block Now look back to the ones we have created. It should start to sink in. Don’t get stuck on the => form, use it as an identifier of a lambda. A Lamba expression can also be written in the following form: Lambda Expression. using System; using System.Collections.Generic; using System.Linq; using System.Text;   namespace ConsoleApplication7 {     class Program     {          static void Main(string[] args)         {             Func<int, int> myFunc = x =>             {                 return x * x;             };               Console.WriteLine(myFunc(6).ToString());             Console.ReadLine();         }       } } This form may be easier to read but consumes more space. Lets try an Action delegate – this delegate does not return a value. Action Delegate example. using System; using System.Collections.Generic; using System.Linq; using System.Text;   namespace ConsoleApplication7 {     class Program     {          static void Main(string[] args)         {             Action<string> myAction = (string x) => { Console.WriteLine(x); };             myAction("michael has made this so easy");                                   Console.ReadLine();         }       } } Lambdas can also capture outer variables (such as the example below) A lambda expression can reference the local variables and parameters of the method in which it’s defined. Outer variables referenced by a lambda expression are called captured variables. Capturing Outer Variables using System; using System.Collections.Generic; using System.Linq; using System.Text;   namespace ConsoleApplication7 {     class Program     {          static void Main(string[] args)         {             string mike = "Michael";             Action<string> myAction = (string x) => {                 Console.WriteLine("{0}{1}", mike, x);          };             myAction(" has made this so easy");                                   Console.ReadLine();         }       } } Lamba’s can also with a strongly typed list to loop through a collection.   Used w a strongly typed list. using System; using System.Collections.Generic; using System.Linq; using System.Text;   namespace ConsoleApplication7 {     class Program     {          static void Main(string[] args)         {             List<string> list = new List<string>() { "1", "2", "3", "4" };             list.ForEach(s => Console.WriteLine(s));             Console.ReadLine();         }       } } Outputs: 1 2 3 4 I think this will get you started with Lambda’s, as always consult the MSDN documentation for more information. Still confused? Hopefully you are not.

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  • Architecture for a template-building, WYSIWIG application

    - by Sam Selikoff
    I'm building a WYSIWYG designer in Ember.js. The designer will allow users to create campaigns - think MailChimp. To build a campaign, users will choose an existing template. The template will have a defined layout. The user will then be taken to the designer, where he will be able to edit the text and style, and additionally change some layout options. I've been thinking about how best to go about structuring this app, and there are a few hurdles. Specifically, the output of the campaign will be dynamic: eventually, it will be published somewhere, and when the consumers (not my users, but the people clicking on the campaign that my user created) visit the campaign, certain pieces of data will change, depending on the type of consumer viewing the campaign. That means the ultimate output of the designer will be a dynamic site. The data that is dynamic for this site - the end product - will not be manipulated by the user in the designer. However, the data that will be manipulated by the user in the designer are things like copy, styles, layout options, etc. I'll call the first set of variables server-side data, and the second client-side data. It seems, then, that the process will go something like this: I'll need to create templates for this designer that have two dynamic segments. For instance, the server-side data could be Liquid expressions, and the client-side data Handlebars expressions. When the user creates a campaign, I would compile the template on the back end using some dummy data for the server-side variables, and serve up a handlebars template to the Ember app. The user would then edit the template, and the Ember app would save all his edits to the JS variables that were powering the template. This way he'd be able to preview the template. When he saves, he'll send back the selected template, along with all the data and options he's made. When it comes time to publish, the back-end system will have to do two things: compile the template with Handlebars using the campaign data, and then compile the template with Liquid using the server-side data Is my thinking roughly accurate about this, or is there a simpler way?

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  • Why don't languages include implication as a logical operator?

    - by Maciej Piechotka
    It might be a strange question, but why there is no implication as a logical operator in many languages (Java, C, C++, Python Haskell - although as last one have user defined operators its trivial to add it)? I find logical implication much clearer to write (particularly in asserts or assert-like expressions) then negation with or: encrypt(buf, key, mode, iv = null) { assert (mode != ECB --> iv != null); assert (mode == ECB || iv != null); assert (implies(mode != ECB, iv != null)); // User-defined function }

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  • How to get better at solving Dynamic programming problems

    - by newbie
    I recently came across this question: "You are given a boolean expression consisting of a string of the symbols 'true', 'false', 'and', 'or', and 'xor'. Count the number of ways to parenthesize the expression such that it will evaluate to true. For example, there is only 1 way to parenthesize 'true and false xor true' such that it evaluates to true." I knew it is a dynamic programming problem so i tried to come up with a solution on my own which is as follows. Suppose we have a expression as A.B.C.....D where '.' represents any of the operations and, or, xor and the capital letters represent true or false. Lets say the number of ways for this expression of size K to produce a true is N. when a new boolean value E is added to this expression there are 2 ways to parenthesize this new expression 1. ((A.B.C.....D).E) ie. with all possible parenthesizations of A.B.C.....D we add E at the end. 2. (A.B.C.(D.E)) ie. evaluate D.E first and then find the number of ways this expression of size K can produce true. suppose T[K] is the number of ways the expression with size K produces true then T[k]=val1+val2+val3 where val1,val2,val3 are calculated as follows. 1)when E is grouped with D. i)It does not change the value of D ii)it inverses the value of D in the first case val1=T[K]=N.( As this reduces to the initial A.B.C....D expression ). In the second case re-evaluate dp[K] with value of D reversed and that is val1. 2)when E is grouped with the whole expression. //val2 contains the number of 'true' E will produce with expressions which gave 'true' among all parenthesized instances of A.B.C.......D i) if true.E = true then val2 = N ii) if true.E = false then val2 = 0 //val3 contains the number of 'true' E will produce with expressions which gave 'false' among all parenthesized instances of A.B.C.......D iii) if false.E=true then val3=( 2^(K-2) - N ) = M ie. number of ways the expression with size K produces a false [ 2^(K-2) is the number of ways to parenthesize an expression of size K ]. iv) if false.E=false then val3 = 0 This is the basic idea i had in mind but when i checked for its solution http://people.csail.mit.edu/bdean/6.046/dp/dp_9.swf the approach there was completely different. Can someone tell me what am I doing wrong and how can i get better at solving DP so that I can come up with solutions like the one given above myself. Thanks in advance.

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  • Looking for terminology for the relation of a subject and a predicate

    - by kostja
    While writing some predicates for collection filtering I have stumbled over the choice of the right words for the relation of the subject and the predicate (English is a foreign language for me). What I ended up writing was "Subjects matching this predicate..." This seems to be incorrect, since predicates are functions and not regular expressions. But saying "Subjects for which this predicate returns true..." sounds awkward to me as well.. So what would be the correct term?

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  • Perl like regular expression in Oracle DB

    - by user13136722
    There's regular expression support in Oracle DB Using Regular Expressions in Database Applications Oracle SQL PERL-Influenced Extensions to POSIX Standard But '\b' is not supported which I believe is quite wideliy used in perl and/or other tools perlre - perldoc.perl.org \b Match a word boundary So, I experimented with '\W' which is non-"word" character When combined with beginning-of-line and end-of-line like below, I think it works exactly the same as '\b' SELECT * FROM TAB1 WHERE regexp_like(TEXTCOL1, '(^|\W)a_word($|\W)', 'i')

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  • JSR Updates

    - by heathervc
    JSR 349, Bean Validation 1.1, has published a Public Review. The review closes on 12 November. JSR 331, Constraint Programming API, has published a Maintenance Release. JSR 335, Lambda Expressions for the Java Programming Language, has moved to JCP 2.8!  Check out their java.net project. JSR 107, JCACHE - Java Temporary Caching API, has posted their Early Draft Release.  The review closes on 22 November.

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  • Are there any good Java/JVM libraries for my Expression Tree architecture?

    - by Snuggy
    My team and I are developing an enterprise-level application and I have devised an architecture for it that's best described as an "Expression Tree". The basic idea is that the leaf nodes of the tree are very simple expressions (perhaps simple values or strings). Nodes closer to the trunk will get more and more complex, taking the simpler nodes as their inputs and returning more complex results for their parents. Looking at it the other way, the application performs some task, and for this it creates a root expression. The root expression divides its input into smaller units and creates child expressions, which when evaluated it can use to build it's own result. The subdividing process continues until the simplest leaf nodes. There are two very important aspects of this architecture: It must be possible to manipulate nodes of the tree after it is built. The nodes may be given new input values to work with and any change in result for that node needs to be propagated back up the tree to the root node. The application must make best use of available processors and ultimately be scalable to other computers in a grid or in the cloud. Nodes in the tree will often be updating concurrently and notifying other interested nodes in the tree when they get a new value. Unfortunately, I'm not at liberty to discuss my actual application, but to aid understanding a little bit, you might imagine a kind of spreadsheet application being implemented with a similar architecture, where changes to cells in the table are propagated all over the place to other cells that need the result. The spreadsheet could get so massive that applying multi-core multi-computer distributed system to solve it would be of benefit. I've got my prototype "Expression Engine" working nicely on a single multi-core PC but I've started to run into a few concurrency issues (as expected because I haven't been taking too much care so far) so it's now time to start thinking about migrating the Engine to a more robust library, and that leads to a number of related questions: Is there any precedent for my "Expression Tree" architecture that I could research? What programming concepts should I consider. I realise this approach has many similarities to a functional programming style, and I'm already aware of the concepts of using futures and actors. Are there any others? Are there any languages or libraries that I should study? This question is inspired by my accidental discovery of Scala and the Akka library (which has good support for Actors, Futures, Distributed workloads etc.) and I'm wondering if there is anything else I should be looking at as well?

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  • DAX Statistical Functions

    Following on from his first four articles on using Data Analysis Expressions (DAX) with tabular databases, Robert Sheldon dives into some of the DAX statistical functions available, demonstrating which are the most useful and examples of how they work. The seven tools in the SQL DBA Bundle support your core SQL Server database administration tasks.Make backups a breeze! Enjoy trouble-free troubleshooting! Make the most of monitoring! Download a free trial now.

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  • Overused or abused programming techniques

    - by Anto
    Are there any techniques in programming that you find to be overused (IE used way more excessively than what they should be) or abused, or used a bit for everything, while not being a really good solution to many of the problems which people attempt to solve with it. It could be regular expressions, some kind of design pattern or maybe an algorithm, or something completely different. Maybe you think people abuse multiple inheritance etc.

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  • XPath execution utility

    - by TATWORTH
    I have written an XPath test utility at http://commonxpath.codeplex.com/releases/view/96687This is a WPF application that allows you to enter some test XML and and an XPath expression. When writing such expressions it is important to get the XPath expression correct before embedding it into a program.The program is available as source under LGPL so you can run it both on your office and home PCs. There is a link to help on XPATH syntax.

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  • Customizable Method Bodies in NetBeans IDE 7.3

    - by Geertjan
    In NetBeans IDE 7.3, bodies of newly created methods can now be customized in Tools/Templates/Java/Code Snippets, see below: The content of the first of the two above, "Generated Method Body", is like this: <#-- A built-in Freemarker template (see http://freemarker.sourceforge.net) used for filling the body of methods generated by the IDE. When editing the template, the following predefined variables, that will be then expanded into the corresponding values, could be used together with Java expressions and comments: ${method_return_type}       a return type of a created method ${default_return_value}     a value returned by the method by default ${method_name}              name of the created method ${class_name}               qualified name of the enclosing class ${simple_class_name}        simple name of the enclosing class --> throw new java.lang.UnsupportedOperationException("Not supported yet."); //To change body of generated methods, choose Tools | Templates. The second one, "Overriden Methody Body", is as follows: <#-- A built-in Freemarker template (see http://freemarker.sourceforge.net) used for filling the body of overridden methods generated by the IDE. When editing the template, the following predefined variables, that will be then expanded into the corresponding values, could be used together with Java expressions and comments: ${super_method_call}        a super method call ${method_return_type}       a return type of a created method ${default_return_value}     a value returned by the method by default ${method_name}              name of the created method ${class_name}               qualified name of the enclosing class ${simple_class_name}        simple name of the enclosing class --> <#if method_return_type?? && method_return_type != "void"> return ${super_method_call}; //To change body of generated methods, choose Tools | Templates. <#else> ${super_method_call}; //To change body of generated methods, choose Tools | Templates. </#if>

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