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  • Replacement Text Syntax for JavaScript’s String.replace()

    - by Jan Goyvaerts
    A RegexBuddy user told me that he couldn’t easily find a detailed explanation of the replacement text syntax supported by the String.replace() function in JavaScript. I had to admin that my own web page about JavaScript’s regular expression support was also lacking. I’ve now added a new Replacement Syntax section that has all the details. I’ll summarize it here: $1: Text matched by the first capturing group or the literal text $1 if the regex has no capturing groups. $99: Text matched by the 99th capturing group if the regex has 99 or more groups. Text matched by the 9th capturing group followed by a literal 9 if the regex has 9 or more but less than 99 groups. The literal text $99 if the regex has fewer than 9 groups. $+: Text matched by the highest-numbered capturing group. Replaced with nothing if the highest-numbered group didn’t participate in the match. $&: Text matched by the entire regex. You cannot use $0 for this. $` (backtick): Text to the left of the regex match. $' (single quote): Text to the right of the regex match. $_: The entire subject string.

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  • Creating a Dynamic DataRow for easier DataRow Syntax

    - by Rick Strahl
    I've been thrown back into an older project that uses DataSets and DataRows as their entity storage model. I have several applications internally that I still maintain that run just fine (and I sometimes wonder if this wasn't easier than all this ORM crap we deal with with 'newer' improved technology today - but I disgress) but use this older code. For the most part DataSets/DataTables/DataRows are abstracted away in a pseudo entity model, but in some situations like queries DataTables and DataRows are still surfaced to the business layer. Here's an example. Here's a business object method that runs dynamic query and the code ends up looping over the result set using the ugly DataRow Array syntax:public int UpdateAllSafeTitles() { int result = this.Execute("select pk, title, safetitle from " + Tablename + " where EntryType=1", "TPks"); if (result < 0) return result; result = 0; foreach (DataRow row in this.DataSet.Tables["TPks"].Rows) { string title = row["title"] as string; string safeTitle = row["safeTitle"] as string; int pk = (int)row["pk"]; string newSafeTitle = this.GetSafeTitle(title); if (newSafeTitle != safeTitle) { this.ExecuteNonQuery("update " + this.Tablename + " set safeTitle=@safeTitle where pk=@pk", this.CreateParameter("@safeTitle",newSafeTitle), this.CreateParameter("@pk",pk) ); result++; } } return result; } The problem with looping over DataRow objecs is two fold: The array syntax is tedious to type and not real clear to look at, and explicit casting is required in order to do anything useful with the values. I've highlighted the place where this matters. Using the DynamicDataRow class I'll show in a minute this code can be changed to look like this:public int UpdateAllSafeTitles() { int result = this.Execute("select pk, title, safetitle from " + Tablename + " where EntryType=1", "TPks"); if (result < 0) return result; result = 0; foreach (DataRow row in this.DataSet.Tables["TPks"].Rows) { dynamic entry = new DynamicDataRow(row); string newSafeTitle = this.GetSafeTitle(entry.title); if (newSafeTitle != entry.safeTitle) { this.ExecuteNonQuery("update " + this.Tablename + " set safeTitle=@safeTitle where pk=@pk", this.CreateParameter("@safeTitle",newSafeTitle), this.CreateParameter("@pk",entry.pk) ); result++; } } return result; } The code looks much a bit more natural and describes what's happening a little nicer as well. Well, using the new dynamic features in .NET it's actually quite easy to implement the DynamicDataRow class. Creating your own custom Dynamic Objects .NET 4.0 introduced the Dynamic Language Runtime (DLR) and opened up a whole bunch of new capabilities for .NET applications. The dynamic type is an easy way to avoid Reflection and directly access members of 'dynamic' or 'late bound' objects at runtime. There's a lot of very subtle but extremely useful stuff that dynamic does (especially for COM Interop scenearios) but in its simplest form it often allows you to do away with manual Reflection at runtime. In addition you can create DynamicObject implementations that can perform  custom interception of member accesses and so allow you to provide more natural access to more complex or awkward data structures like the DataRow that I use as an example here. Bascially you can subclass DynamicObject and then implement a few methods (TryGetMember, TrySetMember, TryInvokeMember) to provide the ability to return dynamic results from just about any data structure using simple property/method access. In the code above, I created a custom DynamicDataRow class which inherits from DynamicObject and implements only TryGetMember and TrySetMember. Here's what simple class looks like:/// <summary> /// This class provides an easy way to turn a DataRow /// into a Dynamic object that supports direct property /// access to the DataRow fields. /// /// The class also automatically fixes up DbNull values /// (null into .NET and DbNUll to DataRow) /// </summary> public class DynamicDataRow : DynamicObject { /// <summary> /// Instance of object passed in /// </summary> DataRow DataRow; /// <summary> /// Pass in a DataRow to work off /// </summary> /// <param name="instance"></param> public DynamicDataRow(DataRow dataRow) { DataRow = dataRow; } /// <summary> /// Returns a value from a DataRow items array. /// If the field doesn't exist null is returned. /// DbNull values are turned into .NET nulls. /// /// </summary> /// <param name="binder"></param> /// <param name="result"></param> /// <returns></returns> public override bool TryGetMember(GetMemberBinder binder, out object result) { result = null; try { result = DataRow[binder.Name]; if (result == DBNull.Value) result = null; return true; } catch { } result = null; return false; } /// <summary> /// Property setter implementation tries to retrieve value from instance /// first then into this object /// </summary> /// <param name="binder"></param> /// <param name="value"></param> /// <returns></returns> public override bool TrySetMember(SetMemberBinder binder, object value) { try { if (value == null) value = DBNull.Value; DataRow[binder.Name] = value; return true; } catch {} return false; } } To demonstrate the basic features here's a short test: [TestMethod] [ExpectedException(typeof(RuntimeBinderException))] public void BasicDataRowTests() { DataTable table = new DataTable("table"); table.Columns.Add( new DataColumn() { ColumnName = "Name", DataType=typeof(string) }); table.Columns.Add( new DataColumn() { ColumnName = "Entered", DataType=typeof(DateTime) }); table.Columns.Add(new DataColumn() { ColumnName = "NullValue", DataType = typeof(string) }); DataRow row = table.NewRow(); DateTime now = DateTime.Now; row["Name"] = "Rick"; row["Entered"] = now; row["NullValue"] = null; // converted in DbNull dynamic drow = new DynamicDataRow(row); string name = drow.Name; DateTime entered = drow.Entered; string nulled = drow.NullValue; Assert.AreEqual(name, "Rick"); Assert.AreEqual(entered,now); Assert.IsNull(nulled); // this should throw a RuntimeBinderException Assert.AreEqual(entered,drow.enteredd); } The DynamicDataRow requires a custom constructor that accepts a single parameter that sets the DataRow. Once that's done you can access property values that match the field names. Note that types are automatically converted - no type casting is needed in the code you write. The class also automatically converts DbNulls to regular nulls and vice versa which is something that makes it much easier to deal with data returned from a database. What's cool here isn't so much the functionality - even if I'd prefer to leave DataRow behind ASAP -  but the fact that we can create a dynamic type that uses a DataRow as it's 'DataSource' to serve member values. It's pretty useful feature if you think about it, especially given how little code it takes to implement. By implementing these two simple methods we get to provide two features I was complaining about at the beginning that are missing from the DataRow: Direct Property Syntax Automatic Type Casting so no explicit casts are required Caveats As cool and easy as this functionality is, it's important to understand that it doesn't come for free. The dynamic features in .NET are - well - dynamic. Which means they are essentially evaluated at runtime (late bound). Rather than static typing where everything is compiled and linked by the compiler/linker, member invokations are looked up at runtime and essentially call into your custom code. There's some overhead in this. Direct invocations - the original code I showed - is going to be faster than the equivalent dynamic code. However, in the above code the difference of running the dynamic code and the original data access code was very minor. The loop running over 1500 result records took on average 13ms with the original code and 14ms with the dynamic code. Not exactly a serious performance bottleneck. One thing to remember is that Microsoft optimized the DLR code significantly so that repeated calls to the same operations are routed very efficiently which actually makes for very fast evaluation. The bottom line for performance with dynamic code is: Make sure you test and profile your code if you think that there might be a performance issue. However, in my experience with dynamic types so far performance is pretty good for repeated operations (ie. in loops). While usually a little slower the perf hit is a lot less typically than equivalent Reflection work. Although the code in the second example looks like standard object syntax, dynamic is not static code. It's evaluated at runtime and so there's no type recognition until runtime. This means no Intellisense at development time, and any invalid references that call into 'properties' (ie. fields in the DataRow) that don't exist still cause runtime errors. So in the case of the data row you still get a runtime error if you mistype a column name:// this should throw a RuntimeBinderException Assert.AreEqual(entered,drow.enteredd); Dynamic - Lots of uses The arrival of Dynamic types in .NET has been met with mixed emotions. Die hard .NET developers decry dynamic types as an abomination to the language. After all what dynamic accomplishes goes against all that a static language is supposed to provide. On the other hand there are clearly scenarios when dynamic can make life much easier (COM Interop being one place). Think of the possibilities. What other data structures would you like to expose to a simple property interface rather than some sort of collection or dictionary? And beyond what I showed here you can also implement 'Method missing' behavior on objects with InvokeMember which essentially allows you to create dynamic methods. It's all very flexible and maybe just as important: It's easy to do. There's a lot of power hidden in this seemingly simple interface. Your move…© Rick Strahl, West Wind Technologies, 2005-2011Posted in CSharp  .NET   Tweet (function() { var po = document.createElement('script'); po.type = 'text/javascript'; po.async = true; po.src = 'https://apis.google.com/js/plusone.js'; var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(po, s); })();

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  • MDX needs a function or macro syntax

    - by Darren Gosbell
    I was having an interesting discussion with a few people about the impact of named sets on performance (the same discussion noted by Chris Webb here: http://cwebbbi.wordpress.com/2011/03/16/referencing-named-sets-in-calculations). And apparently the core of the performance issue comes down to the way named sets are materialized within the SSAS engine. Which lead me to the thought that what we really need is a syntax for declaring a non-materialized set or to take this even further a way of declaring an MDX expression as function or macro so that it can be re-used in multiple places. Because sometimes you do want the set materialised, such as when you use an ordered set for calculating rankings. But a lot of the time we just want to make our MDX modular and want to avoid having to repeat the same code over and over. I did some searches on connect and could not find any similar suggestions so I posted one here: https://connect.microsoft.com/SQLServer/feedback/details/651646/mdx-macro-or-function-syntax Although apparently I did not search quite hard enough as Chris Webb made a similar suggestion some time ago, although he also included a request for true MDX stored procedures (not the .Net style stored procs that we have at the moment): https://connect.microsoft.com/SQLServer/feedback/details/473694/create-parameterised-queries-and-functions-on-the-server Chris also pointed out this post that he did last year http://cwebbbi.wordpress.com/2010/09/13/iccube/ where he pointed out that the icCube product already has this sort of functionality. So if you think either or both of these suggestions is a good idea then I would encourage you to click on the links and vote for them.

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  • Programming languages with a Lisp-like syntax extension mechanism

    - by Giorgio
    I have only a limited knowledge of Lisp (trying to learn a bit in my free time) but as far as I understand Lisp macros allow to introduce new language constructs and syntax by describing them in Lisp itself. This means that a new construct can be added as a library, without changing the Lisp compiler / interpreter. This approach is very different from that of other programming languages. E.g., if I wanted to extend Pascal with a new kind of loop or some particular idiom I would have to extend the syntax and semantics of the language and then implement that new feature in the compiler. Are there other programming languages outside the Lisp family (i.e. apart from Common Lisp, Scheme, Clojure (?), Racket (?), etc) that offer a similar possibility to extend the language within the language itself? EDIT Please, avoid extended discussion and be specific in your answers. Instead of a long list of programming languages that can be extended in some way or another, I would like to understand from a conceptual point of view what is specific to Lisp macros as an extension mechanism, and which non-Lisp programming languages offer some concept that is close to them.

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  • C++: calling non-member functions with the same syntax of member ones

    - by peoro
    One thing I'd like to do in C++ is to call non-member functions with the same syntax you call member functions: class A { }; void f( A & this ) { /* ... */ } // ... A a; a.f(); // this is the same as f(a); Of course this could only work as long as f is not virtual (since it cannot appear in A's virtual table. f doesn't need to access A's non-public members. f doesn't conflict with a function declared in A (A::f). I'd like such a syntax because in my opinion it would be quite comfortable and would push good habits: calling str.strip() on a std::string (where strip is a function defined by the user) would sound a lot better than calling strip( str );. most of the times (always?) classes provide some member functions which don't require to be member (ie: are not virtual and don't use non-public members). This breaks encapsulation, but is the most practical thing to do (due to point 1). My question here is: what do you think of such feature? Do you think it would be something nice, or something that would introduce more issues than the ones it aims to solve? Could it make sense to propose such a feature to the next standard (the one after C++0x)? Of course this is just a brief description of this idea; it is not complete; we'd probably need to explicitly mark a function with a special keyword to let it work like this and many other stuff.

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  • What's the "revised syntax" in OCaml?

    - by aneccodeal
    When people refer to the "revised syntax" in OCaml, do they mean that this will become a new syntax for the language, or is it just an alternative syntax created in CamlP4? If it's the former, then when does the "revised syntax" become the "official syntax" of OCaml?

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  • Grails - Link checking as part of a continuous integration.

    - by Reverend Gonzo
    So, we have a grails app set up with a Hudson CI build process. We're running unit tests, integration tests, and about to set up Selenium for some functional tests as well. However, are there any good ways of fully testing a sites links to make sure nothing has broken in a release. I know there's link checkers in general, but I'd like to have it be a part of the build process, so a build outright fails if something isn't right.

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  • Best IDE macro tools to combat the verbosity of Java syntax for someone with carpal tunnel?

    - by Carlsberg
    I have a bad case of carpal tunnel so I'm looking for an editor that would make my Java programming less painful (literally!). Does anyone have any recommendations for tools that you can add to Eclipse, Netbeans or other IDEs to produce some of the repetitive code that's common in Java syntax? Overall what would be the best code editor for this purpose? (I'm coding on Ubuntu, in case it matters).

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  • Is there a command line C++ to PDF converter with syntax highlighting?

    - by NoMoreZealots
    I need to supply "Source code documents w/ Line numbers" which is essentially just a PDF of the source code with syntax highlighting and Line numbers. Is there any existing command line tools for windows that I could call from a script as a "build release version" script? Right now I'm doing it manually using VC++, which isn't even the dev enviroment the code is for a TI processor, and a PDF printer driver, which has a pop up for each file I print.

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  • Installing MySQL-Ruby on Linux and Ruby 1.9.2

    - by Klam
    I am having an absurdly difficult time getting MySQL-Ruby to install on RedHat 4 using Ruby 1.9.2. I am behind a company proxy that prevents pretty much any package tool from connecting to external repositories so "gem install mysql" isn't going to cut it. I have tried installing the mysql-ruby gem locally but it fails with a mysterious: $gem install mysql-2.8.1.gem Building native extensions. This could take a while... ERROR: Error installing mysql-2.8.1.gem: ERROR: Failed to build gem native extension. /ns/local/apps/internal/SWS/MetricsPublisher/ruby/bin/ruby extconf.rb checking for mysql_query() in -lmysqlclient... no checking for main() in -lm... yes checking for mysql_query() in -lmysqlclient... no checking for main() in -lz... yes checking for mysql_query() in -lmysqlclient... no checking for main() in -lsocket... no checking for mysql_query() in -lmysqlclient... no checking for main() in -lnsl... yes checking for mysql_query() in -lmysqlclient... no checking for main() in -lmygcc... no checking for mysql_query() in -lmysqlclient... no *** extconf.rb failed *** Could not create Makefile due to some reason, probably lack of necessary libraries and/or headers. Check the mkmf.log file for more details. You may need configuration options. I have also tried building the module myself by following the included readme. The results: $ruby extconf.rb --with-mysql-include=/path_to_my_sql_headers/mysql/include/ --with-mysql-lib=/path_to_my_sql_lib/mysql/lib/ checking for mysql_query() in -lmysqlclient... no checking for main() in -lm... yes checking for mysql_query() in -lmysqlclient... no checking for main() in -lz... yes checking for mysql_query() in -lmysqlclient... no checking for main() in -lsocket... no checking for mysql_query() in -lmysqlclient... no checking for main() in -lnsl... yes checking for mysql_query() in -lmysqlclient... no checking for main() in -lmygcc... no checking for mysql_query() in -lmysqlclient... no *** extconf.rb failed *** Could not create Makefile due to some reason, probably lack of necessary libraries and/or headers. Check the mkmf.log file for more details. You may need configuration options. Does anybody have any ideas? Quite frankly, I don't even care if MySQL-Ruby specifically works, I just want ANY means of connecting to a MySQL DB through a ruby call in ruby 1.9. Thanks.

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  • ASP.NET MVC 4: Short syntax for script and style bundling

    - by DigiMortal
    ASP.NET MVC 4 introduces new methods for style and scripts bundling. I found something brilliant there I want to introduce you. In this posting I will show you how easy it is to include whole folder with stylesheets or JavaScripts to your page. I’m using ASP.NET MVC 4 Internet Site template for this example. When we open layout pages located in shared views folder we can see something like this in layout file header: <link href="@System.Web.Optimization.BundleTable.Bundles.ResolveBundleUrl("~/Content/css")" rel="stylesheet" type="text/css" />    <link href="@System.Web.Optimization.BundleTable.Bundles.ResolveBundleUrl("~/Content/themes/base/css")" rel="stylesheet" type="text/css" />    <script src="@System.Web.Optimization.BundleTable.Bundles.ResolveBundleUrl("~/Scripts/js")"></script> Let’s take the last line and modify it so it looks like this: <script src="/Scripts/js"></script> After saving the layout page let’s run browser and see what is coming in over network. As you can see the request to folder ended up with result code 200 which means that request was successful. 327.2KB was received and it is not mark-up size for error page or directory index. Here is the body of response: I scrolled down to point where one script ends and another one starts when I made the screenshot above. All scripts delivered with ASP.NET MVC project templates start with this green note. So now we can be sure that the request to scripts folder ended up with bundled script and not with something else. Conclusion Script and styles bundling uses currently by default long syntax where bundling is done through Bundling class. We can still avoid those long lines and use extremely short syntax for script and styles bundling – we just write usual script or link tag and give folder URL as source. ASP.NET MVC 4 is smart enough to combine styles or scripts when request like this comes in.

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  • Deprecate UPDATE FROM? Not if I can help it!

    - by AaronBertrand
    Fellow MVP Hugo Kornelis ( blog ) has suggested that the proprietary UPDATE FROM and DELETE FROM syntax, which has worked for several SQL Server versions, should be deprecated in favor of MERGE. Here is the Connect item he raised: #332437 : Deprecate UPDATE FROM and DELETE FROM As you can see, the response is quite divided (more so than any other item that I can recall) - at the time of writing, it was 11 up-votes and 12 down-votes. I have no shame in admitting that I am one of the people who down-voted...(read more)

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  • Does relying on intellisense and documentation a lot while coding makes you a bad programmer? [duplicate]

    - by sharp12345
    This question already has an answer here: Forgetting basic language functions due to use of IDE, over reliance? [duplicate] 4 answers Is a programmer required to learn and memorize all syntax, or is it ok to keep handy some documentation? Would it affect the way that managers look at coders? What are the downside of depending on intellisense and auto-complete technologies and pdf documentation?

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  • "Pointers" with $ Syntax in /etc/environment

    - by Tyson Trautmann
    Is it valid to have "pointers" in /etc/environment using $FOO syntax? Right now my /etc/environment looks like this: JAVA_HOME=/usr/lib/jvm/java-6-openjdk MAVEN_HOME=/usr/bin/apache-maven/apache-maven-3.0.4 M2_HOME=$MAVEN_HOME M2=$MAVEN_HOME/bin PATH=/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:$JAVA_HOME/bin:$MAVEN_HOME/bin I'm not getting the results that I'm expecting though: ~$ echo $JAVA_HOME /usr/lib/jvm/java-6-openjdk ~$ echo $MAVEN_HOME /usr/bin/apache-maven/apache-maven-3.0.4 ~$ echo $PATH /usr/lib/lightdm/lightdm:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin/bin:/usr/games:$JAVA_HOME/bin:$MAVEN_HOME/bin

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  • Are there any technical obstacles for implementing `function* ()` syntax

    - by shabunc
    In Python we have yield which is very similar to that one which is proposed in ES6 (in fact, pythonic co-routines were the main source of inspiration for implementing co-routines in I wonder what are the reasons for choosing a separate function* () syntax for generators compared to just defining "regular" functions with yeilds - just like in python by the way? I'm talking strictly of technical issues and peculiarities. Why it had been decided that a separate form will be more appropriate?

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  • Watch syntax help

    - by Jason
    In my Systems Programming class, there are weekly programming experiments, and I'm having trouble with the current one. The objective is to write a C program that slowly writes a string of text to a file, metered by usleep() in a 100 count for loop. The goal of the experiment is to observe the file size buffer in action via the watch command. However, I can't get it to work using watch -d ./output What syntax do I need for the watch command to see the changes made to the file size?

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  • System.Data.Sqlclient.Sqlexception: Line1 incorrect syntax ...

    - by marocanu2001
    Given a SqlConnection, a SqlCommand if you need to execute a stored procedure it is enough to specify the stored procedure name as the CommandText and it will work. Now the surprise is that if you also add parametres, you get this creepy error: SqlException: Line 1 incorrect syntax near [storedProcedureName]. The quick fix is to specify the CommandType to be StoredProcedure.

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  • Keep Getting Syntax Error C2199?

    - by DARK3ZOOZ
    Here's my problem I'm trying to define something, but keep getting a syntax error Code: #define R_RegisterShader 0x50C8A0 int (*trap_R_RegisterShader)( const char *name, int Arg_1 ) = (int (_cdecl *)(const char *, int ))R_RegisterShader; ^^^^^^^ This last part is where I keep getting the error if you need more lines of codes, just let me know. thanks http://gyazo.com/1a47ebc12cfbd6ea72feb72c686ae84d screenshot of error

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