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  • What should I learn from Scheme?

    - by bunglestink
    I was wondering what unique features I can learn from Scheme that would help me become a better programmer? I have a lot experience in mainstream languages, and I am looking to expand my horizons and learn about functional aspects that are missing from other languages. I am familiar with closures from javascript, lambda expressions from C#, and I was wondering what I can focus on that is lacking in other languages? Aside from the Lisp syntax, I feel like what I have seen so far I've already encountered in other languages. What is unique to Scheme/Lisp that will teach me something new?

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  • Crawling for geotagged data

    - by abe3
    I have no experience with web crawlers -- but I know that Apache maintains an open source web crawler called "Lucene." How would I go about writing such a crawler to search the web for geo tagged data close to a particular location? What would a general road map look like? How do I pick which slice of the web to crawl? Do I use regular expressions to find things that look like longitudes and latitudes? What does a general sketch of that solution look like?

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  • Am I getting Scheme wrong?

    - by nischayn22
    Inspired by the numerous posts about the importance of learning Lisp/Scheme I started to learn Scheme two days back, I am using the book "The little Schemer" and have completed half of it. But I still haven't learned anything new, the book teaches about recursion which I already understand and uses lambda (which I can think of a way to define a function in C). I still haven't got the concept of functional programming (please point to some example of functional compared to normal programming methods in C/C++ so I can get it). Am I learning in the wrong way? or is "The little Schemer" for a newbie in programming and I should look for some other books?

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  • KDE fonts not rendering bold in Ubuntu 12.04

    - by Doran
    I'm using Ubuntu 12.04 with some KDE programs: kate and yakuake. Neither of these programs will render bold font. Instead, the font appears as "Regular". How can I fix this? The image below shows an example of Kate rendering python with the stock python highlighting (the colors are inverted using CompizConfig Settings Manager's Negative option). The following words should have appeared bold: class def __init__ lambda + print Similarly Yakuake (or perhaps, the underlying Konsole) is not rendering bold. My LS_COLORS includes: di=01;34 (bold blue) Below is my gnome-terminal rendering bold fonts just fine.

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  • Automatic language transformation in editor or IDE [on hold]

    - by Rumca
    Are there any tools that are capable of editing code but in different language? To be more concrete, I want to parse java source file in editor, compile it to my language X, edit in X and compile back to java on save. Or edit pom.xml file using non-XML syntax. Which editor or IDE would be easiest to use for implementing such prototype? Option to transform only a snippet would be ideal to limit effort on parsing. For one example, Intellij IDEA can display anonymous class so it looks like lambda expression hiding some of boilerplate.

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  • AdWords : Google s'attaque aux publicités douteuses avec une politique de contrôle et de modération contre les annonces frauduleuses

    AdWords : Google s'attaque aux publicités douteuses Et met en place une politique de contrôle et de modération pour traquer les annonces frauduleuses Via un post publié sur son blog officiel, Google a révélé avoir amélioré sa politique de contrôle et de modération pour lutter contre toutes les annonces AdWords douteuses (vente de produits illicites et nocifs, annonces trompeuses,...). Google AdWords permet aux entreprises de créer leurs annonces publicitaires et de les diffuser sur Google. L'entreprise doit créer une annonce et choisir des mots ou des expressions clés en rapport avec son activité. L'internaute, lorsqu'il effectue une recherche à l'aide de l'un de ces mots clés, voit s'af...

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  • BIT of a Problem

    The BIT data type is an awkward fit for a SQL database. It doesn't have just two values, and it can do unexpected things in expressions. What is worse, it is a flag rather than a predicate, and so its overuse, along with bit masks, is a prime candidate for being listed as a 'SQL Code Smell'. Joe Celko makes the case. Free trial of SQL Backup™“SQL Backup was able to cut down my backup time significantly AND achieved a 90% compression at the same time!” Joe Cheng. Download a free trial now.

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  • If there's no problem treating a statement as an expression, why was there a distinction in the first place in some programming languages?

    - by cdmckay
    Why do we have the distinction between statements and expressions in most programming languages? For example, in Java, assuming f and g return ints, this still won't compile because it's a statement and statements don't return values. // won't compile int i = if (pred) { f(x); } else { g(x); } but in Scala, it's very happy with treating if as an expression. // compiles fine val i: Int = if (pred) f(x) else g(x) So if there's no problem treating an if statement as an expression, why was there a distinction in the first place?

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  • Data Conversion in SQL Server

    Most of the time, you do not have to worry about implicit conversion in SQL expressions, or when assigning a value to a column. Just occasionally, though, you'll find that data gets truncated, queries run slowly, or comparisons just seem plain wrong. Robert Sheldon explains why you sometimes need to be very careful if you mix data types when manipulating values. Free trial of SQL Backup™“SQL Backup was able to cut down my backup time significantly AND achieved a 90% compression at the same time!” Joe Cheng. Download a free trial now.

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  • JavaOne India Technical Sessions

    - by Tori Wieldt
    If you’re working with Java technology, it pays to go straight to the source for your information. At JavaOne and Oracle Develop India, you’ll be able to choose from more than 90 sessions, hands-on labs, keynotes, and demos delivered by today’s most knowledgeable Java experts. You'll also hear the most up-to-date information on current releases and future directions of Java standards and technologies, and see the latest Java developer tools and solutions. Register now! Technical sessions include: Project Lambda: To Multicore and Beyond Introduction to JavaFX 2.0 GlassFish REST Administration Back End: An Insider Look at a Real REST Application Java-Powered Home Gateway: Basis of the Next-Generation Smart Home Mobile Java Evolution Cloud-Enabled Java Persistence Visit the JavaOne India web pages for a complete list of conference sessions. See you there!

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  • How would you tackle a pattern-finding program?

    - by Neil
    Just to be clear, I don't think this should be question better suited for stackoverflow.com simply because there's not a single answer but a wide range of possible solutions, making this question far more subjective in nature. I was curious how you guys would tackle a pattern-finding program, which is to say I'd do the following operations: I enter in some input. Program predicts my next input based on all previous inputs. Rinse. Repeat. Since the amount of input I could provide is so varied, including empty strings, conventional means such as switches or regular expressions are out, since it would require you to have an inkling of information about what to expect. I was thinking about some form of genetic algorithm, yet even then I don't have a clue as to how to approach a problem of this caliber. I think some feedback mechanism would be necessary as well as to let the program know how close it was. Anyone had to do a similar type program before?

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  • Simple mod_rewrite Question

    - by user5358
    Hello, I want to have everything that looks like this: /1/2/3/4/5/[...] to redirect to this: /index.php?u=/1/2/3/4/5/[...] unless the requested string is a specific file. So anything that doesn't have a ".", I want to redirect to "index.php?u=[...]". I'll then parse the URI segments in PHP to determine what the user is requesting. I've been looking around for how to do this, but have only a very rough understanding of regular expressions and have been unable to find an example of how to do it. Thanks!

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  • Why creating a new MDX language instead of extending SQL?

    - by DReispt
    I have a long experience with SQL, but recently began working with datawarehouse and OLAP technologies: building fact and dimension tables, that then are queried using MDX (MultiDimensional eXpressions). The problem is that MDX works with a completely different logic compared to SQL, and it's a whole new learning curve even for someone with a strong SQL background. Yes, MDX allows you to do things that would be hard or almost impossible with plain SQL. But sometimes it's frustrating to be hours around an MDX to do something you know you could achieve in minutes using SQL (ok, you can tell me to RTFM ...). But why go on to the trouble of creating a new completely different language when you could build on SQL, extend it to add the features needed by OLAP applications?

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  • JavaOne 2012 : Oracle dévoile ses plans pour Java, les préversions du JDK 8 et JavaFX Scene Builder 1.1 disponibles

    JavaOne 2012 : Oracle renouvelle son engagement à faire évoluer Java et dévoile ses plans les préversions de JDK 8 et JavaFX Scene Builder 1.1 disponibles JavaOne 2012, la plus grande conférence annuelle autour de la plateforme Java se déroule actuellement à San Francisco. Oracle a profité de l'occasion pour dévoiler sa feuille de route pour Java et renouveler son engagement à faire évoluer le langage afin de rassurer les utilisateurs sceptiques face aux récentes découvertes de failles dans la plateforme. Pendant ces prochains mois, Oracle travaillera essentiellement sur Java SE 8. Au menu : l'éditeur prévoit l'intégration des expressions lambda, du moteur JavaScript Nash...

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  • Architecture driven by users, or by actions/content?

    - by hugerth
    I have a question about designing MVC app architecture. Let's say our application has three main categories of views (items of type 1, items of type 2...). And we have three (or more in future) types of users - Admins, let's say Moderators and typical Users. And in the future there might be more of them. Admins have full access to app, Moderators can visit only 2/3 type of items, and Users can visit only basic type of items. Should I divide my controllers/views/whatever like this: Items "A", Items "B", Items "C", then make them 100% finished and at the end add access privileges? Pros: DRY option Cons Conditional expressions in views Or another options: Items "A" / Admin, Items "A" / Moderator / Items "B" Admin ...? Pros: Divided parts of application for specific user (is that pros?) Cons: A lot of repeated code I don't have great experience in planning such things so it would nice if you can give me some tips or links to learn something about it.

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  • Java Magazine????7???

    - by sasa
    11?20??Java Magazine????7?????????? ?7???????????????? ?????Java DUKE’S CHOICE AWARDS BlueJ?????????????????????? Web??????????????????????????? Project Lambda??? Java HotSpot VM??????(2):????????????????? NIO.2??????·????API??? Java EE Connector Architecture 1.6 Payment API—JSR 229?? Oracle Berkeley DB Java Edition?Java API(???2) ???????JavaFX????????? Graal??? JavaFX Media API????????? ?????????????????????????????????????????? Java Magazone?????????Java??????????????Java Developer Newsletter???????????????????????????12?31?????????????1,000???Java??????Duke?????????????????????

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  • How to pass an enum to Html.RadioButtonFor to get a list of radio buttons in MVC 2 RC 2, C#

    - by Matt W
    Hi, I'm trying to render a radio button list in MVC 2 RC 2 (C#) using the following line: <%= Html.RadioButtonFor(model => Enum.GetNames(typeof(DataCarry.ProtocolEnum)), null) %> but it's just giving me the following exception at runtime: Templates can be used only with field access, property access, single-dimension array index, or single-parameter custom indexer expressions. Is this possible and if so, how, please? Thanks, Matt.

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  • Reg Ex parsing error - too many )'s

    - by Chris Herring
    Using regular expressions in .NET with the pattern ^%[^%]+%\Z and the string "few)few%" I get the error - System.ArgumentException: parsing "few)few%" - Too many )'s. Dim match As System.Text.RegularExpressions.Match = System.Text.RegularExpressions.Regex.Match("^%[^%]+%\Z", "few)few%") What would the issue be? Do I need to escape brackets in any input expression to reg ex? (I'm trying the determine if string has the wildcard % at the beginning and end of the string but not elsewhere in the string)

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  • OWASP Regex Repository: Is this regex correct?

    - by Jacco
    I was looking at the regular expression for validating various data types from the (OWASP Regex Repository). One of the regular expressions in there is called safetext and looks like: ^[a-zA-Z0-9\s.\-]+$ My first question is: Is this regular expression correct? complementary question If this Regex Repository any good at all?

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  • InternalsVisibleTo attribute and security vulnerability

    - by Sergey Litvinov
    I found one issue with InternalsVisibleTo attribute usage. The idea of InternalsVisibleTo attribute to allow some other assemblies to use internal classes\methods of this assembly. To make it work you need sign your assemblies. So, if other assemblies isn't specified in main assembly and if they have incorrect public key, then they can't use Internal members. But the issue in Reflection Emit type generation. For example, we have CorpLibrary1 assembly and it has such class: public class TestApi { internal virtual void DoSomething() { Console.WriteLine("Base DoSomething"); } public void DoApiTest() { // some internal logic // ... // call internal method DoSomething(); } } This assembly is marked with such attribute to allow another CorpLibrary2 to make inheritor for that TestAPI and override behaviour of DoSomething method. [assembly: InternalsVisibleTo("CorpLibrary2, PublicKey=0024000004800000940000000602000000240000525341310004000001000100434D9C5E1F9055BF7970B0C106AAA447271ECE0F8FC56F6AF3A906353F0B848A8346DC13C42A6530B4ED2E6CB8A1E56278E664E61C0D633A6F58643A7B8448CB0B15E31218FB8FE17F63906D3BF7E20B9D1A9F7B1C8CD11877C0AF079D454C21F24D5A85A8765395E5CC5252F0BE85CFEB65896EC69FCC75201E09795AAA07D0")] The issue is that I'm able to override this internal DoSomething method and break class logic. My steps to do it: Generate new assembly in runtime via AssemblyBuilder Get AssemblyName from CorpLibrary1 and copy PublikKey to new assembly Generate new assembly that will inherit TestApi class As PublicKey and name of generated assembly is the same as in InternalsVisibleTo, then we can generate new DoSomething method that will override internal method in TestAPI assembly Then we have another assembly that isn't related to this CorpLibrary1 and can't use internal members. We have such test code in it: class Program { static void Main(string[] args) { var builder = new FakeBuilder(InjectBadCode, "DoSomething", true); TestApi fakeType = builder.CreateFake(); fakeType.DoApiTest(); // it will display: // Inject bad code // Base DoSomething Console.ReadLine(); } public static void InjectBadCode() { Console.WriteLine("Inject bad code"); } } And this FakeBuilder class has such code: /// /// Builder that will generate inheritor for specified assembly and will overload specified internal virtual method /// /// Target type public class FakeBuilder { private readonly Action _callback; private readonly Type _targetType; private readonly string _targetMethodName; private readonly string _slotName; private readonly bool _callBaseMethod; public FakeBuilder(Action callback, string targetMethodName, bool callBaseMethod) { int randomId = new Random((int)DateTime.Now.Ticks).Next(); _slotName = string.Format("FakeSlot_{0}", randomId); _callback = callback; _targetType = typeof(TFakeType); _targetMethodName = targetMethodName; _callBaseMethod = callBaseMethod; } public TFakeType CreateFake() { // as CorpLibrary1 can't use code from unreferences assemblies, we need to store this Action somewhere. // And Thread is not bad place for that. It's not the best place as it won't work in multithread application, but it's just a sample LocalDataStoreSlot slot = Thread.AllocateNamedDataSlot(_slotName); Thread.SetData(slot, _callback); // then we generate new assembly with the same nameand public key as target assembly trusts by InternalsVisibleTo attribute var newTypeName = _targetType.Name + "Fake"; var targetAssembly = Assembly.GetAssembly(_targetType); AssemblyName an = new AssemblyName(); an.Name = GetFakeAssemblyName(targetAssembly); // copying public key to new generated assembly var assemblyName = targetAssembly.GetName(); an.SetPublicKey(assemblyName.GetPublicKey()); an.SetPublicKeyToken(assemblyName.GetPublicKeyToken()); AssemblyBuilder assemblyBuilder = Thread.GetDomain().DefineDynamicAssembly(an, AssemblyBuilderAccess.RunAndSave); ModuleBuilder moduleBuilder = assemblyBuilder.DefineDynamicModule(assemblyBuilder.GetName().Name, true); // create inheritor for specified type TypeBuilder typeBuilder = moduleBuilder.DefineType(newTypeName, TypeAttributes.Public | TypeAttributes.Class, _targetType); // LambdaExpression.CompileToMethod can be used only with static methods, so we need to create another method that will call our Inject method // we can do the same via ILGenerator, but expression trees are more easy to use MethodInfo methodInfo = CreateMethodInfo(moduleBuilder); MethodBuilder methodBuilder = typeBuilder.DefineMethod(_targetMethodName, MethodAttributes.Public | MethodAttributes.Virtual); ILGenerator ilGenerator = methodBuilder.GetILGenerator(); // call our static method that will call inject method ilGenerator.EmitCall(OpCodes.Call, methodInfo, null); // in case if we need, then we put call to base method if (_callBaseMethod) { var baseMethodInfo = _targetType.GetMethod(_targetMethodName, BindingFlags.NonPublic | BindingFlags.Instance); // place this to stack ilGenerator.Emit(OpCodes.Ldarg_0); // call the base method ilGenerator.EmitCall(OpCodes.Call, baseMethodInfo, new Type[0]); // return ilGenerator.Emit(OpCodes.Ret); } // generate type, create it and return to caller Type cheatType = typeBuilder.CreateType(); object type = Activator.CreateInstance(cheatType); return (TFakeType)type; } /// /// Get name of assembly from InternalsVisibleTo AssemblyName /// private static string GetFakeAssemblyName(Assembly assembly) { var internalsVisibleAttr = assembly.GetCustomAttributes(typeof(InternalsVisibleToAttribute), true).FirstOrDefault() as InternalsVisibleToAttribute; if (internalsVisibleAttr == null) { throw new InvalidOperationException("Assembly hasn't InternalVisibleTo attribute"); } var ind = internalsVisibleAttr.AssemblyName.IndexOf(","); var name = internalsVisibleAttr.AssemblyName.Substring(0, ind); return name; } /// /// Generate such code: /// ((Action)Thread.GetData(Thread.GetNamedDataSlot(_slotName))).Invoke(); /// private LambdaExpression MakeStaticExpressionMethod() { var allocateMethod = typeof(Thread).GetMethod("GetNamedDataSlot", BindingFlags.Static | BindingFlags.Public); var getDataMethod = typeof(Thread).GetMethod("GetData", BindingFlags.Static | BindingFlags.Public); var call = Expression.Call(allocateMethod, Expression.Constant(_slotName)); var getCall = Expression.Call(getDataMethod, call); var convCall = Expression.Convert(getCall, typeof(Action)); var invokExpr = Expression.Invoke(convCall); var lambda = Expression.Lambda(invokExpr); return lambda; } /// /// Generate static class with one static function that will execute Action from Thread NamedDataSlot /// private MethodInfo CreateMethodInfo(ModuleBuilder moduleBuilder) { var methodName = "_StaticTestMethod_" + _slotName; var className = "_StaticClass_" + _slotName; TypeBuilder typeBuilder = moduleBuilder.DefineType(className, TypeAttributes.Public | TypeAttributes.Class); MethodBuilder methodBuilder = typeBuilder.DefineMethod(methodName, MethodAttributes.Static | MethodAttributes.Public); LambdaExpression expression = MakeStaticExpressionMethod(); expression.CompileToMethod(methodBuilder); var type = typeBuilder.CreateType(); return type.GetMethod(methodName, BindingFlags.Static | BindingFlags.Public); } } remarks about sample: as we need to execute code from another assembly, CorpLibrary1 hasn't access to it, so we need to store this delegate somewhere. Just for testing I stored it in Thread NamedDataSlot. It won't work in multithreaded applications, but it's just a sample. I know that we use Reflection to get private\internal members of any class, but within reflection we can't override them. But this issue is allows anyone to override internal class\method if that assembly has InternalsVisibleTo attribute. I tested it on .Net 3.5\4 and it works for both of them. How does it possible to just copy PublicKey without private key and use it in runtime? The whole sample can be found there - https://github.com/sergey-litvinov/Tests_InternalsVisibleTo UPDATE1: That test code in Program and FakeBuilder classes hasn't access to key.sn file and that library isn't signed, so it hasn't public key at all. It just copying it from CorpLibrary1 by using Reflection.Emit

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  • Installing Fabric On Windows (Error No Module Called Readline)

    - by Jon
    I'm trying to use the Fabric 0.1.1 deploy tool (http://docs.fabfile.org/) on Windows and we're running into an issue with the readline module. I've been through various threads but can't seem to solve the issue. It's important because we can't deploy applications from Windows based machines. C:\Documents and Settings\dev\Desktop\deploy>fab Traceback (most recent call last): File "C:\python\Scripts\fab-script.py", line 8, in <module> load_entry_point('fabric==0.1.1', 'console_scripts', 'fab')() File "c:\python\lib\site-packages\setuptools-0.6c9-py2.6.egg\pkg_resources.py" , line 277, in load_entry_point File "c:\python\lib\site-packages\setuptools-0.6c9-py2.6.egg\pkg_resources.py" , line 2180, in load_entry_point File "c:\python\lib\site-packages\setuptools-0.6c9-py2.6.egg\pkg_resources.py" , line 1913, in load File "build\bdist.win32\egg\fabric.py", line 25, in <module> **ImportError: No module named readline** Installing the module results in: **easy_install readline** Searching for readline Reading http://pypi.python.org/simple/readline/ Reading http://www.python.org/ Best match: readline 2.6.4 Downloading http://pypi.python.org/packages/source/r/readline/readline-2.6.4.tar .gz#md5=7568e8b78f383443ba57c9afec6f4285 Processing readline-2.6.4.tar.gz Running readline-2.6.4\setup.py -q bdist_egg --dist-dir c:\docume~1\ji81b9~1.che \locals~1\temp\easy_install-pzkz1a\readline-2.6.4\egg-dist-tmp-szs2ps Traceback (most recent call last): File "C:\python\Scripts\easy_install-script.py", line 8, in <module> load_entry_point('setuptools==0.6c9', 'console_scripts', 'easy_install')() File "c:\python\lib\site-packages\setuptools-0.6c9-py2.6.egg\setuptools\comman d\easy_install.py", line 1671, in main File "c:\python\lib\site-packages\setuptools-0.6c9-py2.6.egg\setuptools\comman d\easy_install.py", line 1659, in with_ei_usage File "c:\python\lib\site-packages\setuptools-0.6c9-py2.6.egg\setuptools\comman d\easy_install.py", line 1675, in <lambda> File "c:\python\lib\distutils\core.py", line 152, in setup dist.run_commands() File "c:\python\lib\distutils\dist.py", line 975, in run_commands self.run_command(cmd) File "c:\python\lib\distutils\dist.py", line 995, in run_command cmd_obj.run() File "c:\python\lib\site-packages\setuptools-0.6c9-py2.6.egg\setuptools\comman d\easy_install.py", line 211, in run File "c:\python\lib\site-packages\setuptools-0.6c9-py2.6.egg\setuptools\comman d\easy_install.py", line 446, in easy_install File "c:\python\lib\site-packages\setuptools-0.6c9-py2.6.egg\setuptools\comman d\easy_install.py", line 476, in install_item File "c:\python\lib\site-packages\setuptools-0.6c9-py2.6.egg\setuptools\comman d\easy_install.py", line 655, in install_eggs File "c:\python\lib\site-packages\setuptools-0.6c9-py2.6.egg\setuptools\comman d\easy_install.py", line 930, in build_and_install File "c:\python\lib\site-packages\setuptools-0.6c9-py2.6.egg\setuptools\comman d\easy_install.py", line 919, in run_setup File "c:\python\lib\site-packages\setuptools-0.6c9-py2.6.egg\setuptools\sandbo x.py", line 27, in run_setup File "c:\python\lib\site-packages\setuptools-0.6c9-py2.6.egg\setuptools\sandbo x.py", line 63, in run File "c:\python\lib\site-packages\setuptools-0.6c9-py2.6.egg\setuptools\sandbo x.py", line 29, in <lambda> File "setup.py", line 93, in <module> AttributeError: 'module' object has no attribute 'symlink' Has anybody solved this issue or can anybody suggest a workaround?

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  • JSLint -Tolerate inefficient subscripting?

    - by James Wiseman
    I'm reading the JSlint Options Documentation to understand each of the available options, and have come across one that I don't quite understand, and can't find any useful information regarding it elsewhere. sub - Tolerate inefficient subscripting true if subscript notation may be used for expressions better expressed in dot notation. Can anyone shed more light as to what this means? Thanks

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  • Shouldn’t Bind() pass child control’s values to GridView before Page.PreRender?

    - by SourceC
    hello, For controls such as the GridView, DetailsView, and FormView controls, data-binding expressions are resolved automatically during the control's PreRender event But doesn’t data source control perform updates prior to Page.PreRender event? Meaning, shouldn’t Bind() pass child control’s values to GridView ( so they can be passed to data source control as parameters ) before data source control updates the data source, thus before Page.PreRender event? thanx

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