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  • How do i pass null into stdin like this perl code?

    - by acidzombie24
    This is my question and apparently this is the answer. I found you can stdout to null by writing NUL in command prompt so i tried writing < NUL at the end of my argument. No luck. How do i pass in null or do something with the IO locks like that perl code does so i can get my ffmpeg script not locking up after 15 or so seconds?

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  • ActiveRecord validates... custom field name.

    - by Dmitriy Likhten
    I would like to fix up some error messages my site generates. Here is the problem: class Brand < ActiveRecord::Base validates_presence_of :foo ... end My goal is to make a message "Ticket description is required" instead of "Foo is required" or may not be blank, or whatever. The reason this is so important is because lets say previously the field was ticket_summary. That was great and the server was coded to use that, but now due to crazy-insane business analysts it has been determined that ticket_summary is a poor name, and should be ticket_description. Now I don't necessarily want to have my db be driven by the user requirements for field names, especially since they can change frequently without functionality changes. Is there a mechanism for providing this already?

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  • How do I set the dimensions of a custom component defined in an ActionScript class?

    - by user339681
    I'm trying to set the height of a vertical bar (activityBar) but it does not appear to do anything. i have tried something similar with the whole component, but setting the dimensions does nothing (even in the mxml used to instantiate the class). Indeed, I've added transparent graphics just to give the component some dimensions I'm not sure what I'm doing wrong. It's something bad though; my approach seems dire. FYI: I'm trying to create a mic activity bar that will respond to the mic by simply setting the height of the activityBar child (which seems to me to be more efficient than redrawing the graphics each time). Thanks for your help! package components { import mx.core.UIComponent; public class MicActivityBar extends UIComponent { public var activityBar:UIComponent; // Constructor public function MicActivityBar() { super(); this.opaqueBackground = 0xcc4444; graphics.beginFill(0xcccccc, 0); graphics.drawRect(0,-15,5,30); graphics.endFill();// background for bar activityBar = new UIComponent(); activityBar.graphics.beginFill(0xcccccc, 0.8); activityBar.graphics.drawRect(0,-15,5,20); activityBar.graphics.endFill(); activityBar.height=10; addChild(activityBar); } } }

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  • Any point in subclassing UIButton to create a custom looking button?

    - by glitch
    I want to create a set of buttons that would work and feel very much like the Metro-style tiles that are available on Windows Phones. I would like to allow the user to tap them to access their underlying functionality (open a modal or something or that sort). I'm concerned that subclassing UIButton will not get me there. I need square corners and dynamic content inside the tiles themselves. The posts I've found around SO seem to suggest that subclassing a UIButton would not be a good idea for several reasons and that I should instead use UIView. That reply is from 2010, and I have no idea if in the 2+ years since then there have been considerable changes to how one would achieve that effect. Most users these days will have iOS 5.1+ if not 6.0 soon. Let's say I do go the UIView route. Should I implement UIResponder's touch events or should I instead go the UITapGestureRecognizer route? What's the better practice in 2012? Thank you!

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  • How do I add a custom table to a form in another module in Drupal?

    - by Kareed
    I am trying to make a module to add a table to a form in another module. I found I can add the new data in a module_form_alter hook but how to I get it to run through a theme hook? The module I am trying to modify has a theme hook for the page I want to modify. I don't want to change the original form I just want to add a table with new data below it. Thanks

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  • How do I group my package imports into a single custom package?

    - by pavun_cool
    Hi All.. Normally when I am writing the perl program . I used to include following package . use strict ; use warnings ; use Data::Dumper ; Now , I want like this, I will not include all this package for every program . for that I will have these all package in my own package. like following. my_packages.pm package my_packages ; { use strict ; use warnings ; use Data::Dumper; } 1; So, that if I add my_packages.pm in perl program , it needs have all above packages . Actually I have done this experimentation . But I am not able get this things . which means when I am using my_packages . I am not able get the functionality of "use strict, use warnings , use Data::Dumper ". Someone help me out of this problem.....

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  • Do we still need backup code for people who have javascript disabled?

    - by SLC
    I hear about it a bit in tutorials that I watch, that certain things won't work if javascript is disabled. Occasionally I see workarounds. The question is, are these relevent? I can't imagine anyone not having a javascript enabled browser nowadays, except the most ancient of phones, and chances are your page won't render on them properly anyway. Do people still bother to write backup code for javascript being disabled?

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  • Any pitfalls using char* instead of void* when writing cross platform code?

    - by UberMongoose
    Is there any pitfalls when using char*'s to write cross platform code that does memory access? I'm working on a play memory allocator to better understand how to debug memmory issues. I have come to believe char*'s are preferable because of the ability to do pointer arithmetic and derefernce them over void*'s, is that true? Do the following assumptions always hold true on different common platforms? sizeof(char) == 1 sizeof(char*) == sizeof(void*) sizeof(char*) == sizeof(size_t)

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  • How can I view the source code for a particular `predict` function?

    - by merlin2011
    Based on the documentation, predict is a polymorphic function in R and a different function is actually called depending on what is passed as the first argument. However, the documentation does not give any information about the names of the functions that predict actually invokes for any particular class. Normally, one could type the name of a function to get its source, but this does not work with predict. If I want to view the source code for the predict function when invoked on objects of the type glmnet, what is the easiest way?

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  • Download Microsoft MSDN Magazine PDF Issues For Offline Reading

    - by Kavitha
    MSDN Magazine is a must read for every Microsoft developer. It provides in-depth analysis and excellent guides on all the latest Microsoft development tools and technologies. Every month one can grab this magazine on the stands or read it online for free. What if you want to read the magazine offline on your PC or mobile devices? Just grab a PDF version of the magazine and read it whenever you want. The PDF version of MSDN magazines are very handy for travellers who don’t get access to internet always. In this post we are going to provide you links to download PDF version, source code and online version of every month MSDN Magazine issue starting from 2010. Bookmark this post and keep checking it monthly to get access to MSDN Magazine links. December 2010 Issue    Download PDF(not yet available)    Download Source Code    Read Magazine Online        November 2010 Issue    Download PDF (not yet available)    Read Magazine Online    Download Source Code       October 2010 Issue    Download PDF    Download Source Code    Read Magazine Online        September 2010 Issue    Download PDF    Download Source Code    Read Magazine Online       August 2010 Issue    Download PDF    Download Source Code    Read Magazine Online       July 2010 Issue    Download PDF    Download Source Code    Read Magazine Online       June 2010 Issue    Download PDF    Download Source Code    Read Magazine Online       May 2010 Issue      Download PDF    Download Source Code    Read Magazine Online       April 2010 Issue    Download PDF    Read Magazine Online    Download Source Code       March 2010 Issue    Download PDF    Download Source Code    Read Magazine Online       February 2010 Issue    Download PDF    Download Source Code    Read Magazine Online       January 2010 Issue    Download PDF    Download Source Code    Read Magazine Online This article titled,Download Microsoft MSDN Magazine PDF Issues For Offline Reading, was originally published at Tech Dreams. Grab our rss feed or fan us on Facebook to get updates from us.

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  • A ToDynamic() Extension Method For Fluent Reflection

    - by Dixin
    Recently I needed to demonstrate some code with reflection, but I felt it inconvenient and tedious. To simplify the reflection coding, I created a ToDynamic() extension method. The source code can be downloaded from here. Problem One example for complex reflection is in LINQ to SQL. The DataContext class has a property Privider, and this Provider has an Execute() method, which executes the query expression and returns the result. Assume this Execute() needs to be invoked to query SQL Server database, then the following code will be expected: using (NorthwindDataContext database = new NorthwindDataContext()) { // Constructs the query. IQueryable<Product> query = database.Products.Where(product => product.ProductID > 0) .OrderBy(product => product.ProductName) .Take(2); // Executes the query. Here reflection is required, // because Provider, Execute(), and ReturnValue are not public members. IEnumerable<Product> results = database.Provider.Execute(query.Expression).ReturnValue; // Processes the results. foreach (Product product in results) { Console.WriteLine("{0}, {1}", product.ProductID, product.ProductName); } } Of course, this code cannot compile. And, no one wants to write code like this. Again, this is just an example of complex reflection. using (NorthwindDataContext database = new NorthwindDataContext()) { // Constructs the query. IQueryable<Product> query = database.Products.Where(product => product.ProductID > 0) .OrderBy(product => product.ProductName) .Take(2); // database.Provider PropertyInfo providerProperty = database.GetType().GetProperty( "Provider", BindingFlags.NonPublic | BindingFlags.GetProperty | BindingFlags.Instance); object provider = providerProperty.GetValue(database, null); // database.Provider.Execute(query.Expression) // Here GetMethod() cannot be directly used, // because Execute() is a explicitly implemented interface method. Assembly assembly = Assembly.Load("System.Data.Linq"); Type providerType = assembly.GetTypes().SingleOrDefault( type => type.FullName == "System.Data.Linq.Provider.IProvider"); InterfaceMapping mapping = provider.GetType().GetInterfaceMap(providerType); MethodInfo executeMethod = mapping.InterfaceMethods.Single(method => method.Name == "Execute"); IExecuteResult executeResult = executeMethod.Invoke(provider, new object[] { query.Expression }) as IExecuteResult; // database.Provider.Execute(query.Expression).ReturnValue IEnumerable<Product> results = executeResult.ReturnValue as IEnumerable<Product>; // Processes the results. foreach (Product product in results) { Console.WriteLine("{0}, {1}", product.ProductID, product.ProductName); } } This may be not straight forward enough. So here a solution will implement fluent reflection with a ToDynamic() extension method: IEnumerable<Product> results = database.ToDynamic() // Starts fluent reflection. .Provider.Execute(query.Expression).ReturnValue; C# 4.0 dynamic In this kind of scenarios, it is easy to have dynamic in mind, which enables developer to write whatever code after a dot: using (NorthwindDataContext database = new NorthwindDataContext()) { // Constructs the query. IQueryable<Product> query = database.Products.Where(product => product.ProductID > 0) .OrderBy(product => product.ProductName) .Take(2); // database.Provider dynamic dynamicDatabase = database; dynamic results = dynamicDatabase.Provider.Execute(query).ReturnValue; } This throws a RuntimeBinderException at runtime: 'System.Data.Linq.DataContext.Provider' is inaccessible due to its protection level. Here dynamic is able find the specified member. So the next thing is just writing some custom code to access the found member. .NET 4.0 DynamicObject, and DynamicWrapper<T> Where to put the custom code for dynamic? The answer is DynamicObject’s derived class. I first heard of DynamicObject from Anders Hejlsberg's video in PDC2008. It is very powerful, providing useful virtual methods to be overridden, like: TryGetMember() TrySetMember() TryInvokeMember() etc.  (In 2008 they are called GetMember, SetMember, etc., with different signature.) For example, if dynamicDatabase is a DynamicObject, then the following code: dynamicDatabase.Provider will invoke dynamicDatabase.TryGetMember() to do the actual work, where custom code can be put into. Now create a type to inherit DynamicObject: public class DynamicWrapper<T> : DynamicObject { private readonly bool _isValueType; private readonly Type _type; private T _value; // Not readonly, for value type scenarios. public DynamicWrapper(ref T value) // Uses ref in case of value type. { if (value == null) { throw new ArgumentNullException("value"); } this._value = value; this._type = value.GetType(); this._isValueType = this._type.IsValueType; } public override bool TryGetMember(GetMemberBinder binder, out object result) { // Searches in current type's public and non-public properties. PropertyInfo property = this._type.GetTypeProperty(binder.Name); if (property != null) { result = property.GetValue(this._value, null).ToDynamic(); return true; } // Searches in explicitly implemented properties for interface. MethodInfo method = this._type.GetInterfaceMethod(string.Concat("get_", binder.Name), null); if (method != null) { result = method.Invoke(this._value, null).ToDynamic(); return true; } // Searches in current type's public and non-public fields. FieldInfo field = this._type.GetTypeField(binder.Name); if (field != null) { result = field.GetValue(this._value).ToDynamic(); return true; } // Searches in base type's public and non-public properties. property = this._type.GetBaseProperty(binder.Name); if (property != null) { result = property.GetValue(this._value, null).ToDynamic(); return true; } // Searches in base type's public and non-public fields. field = this._type.GetBaseField(binder.Name); if (field != null) { result = field.GetValue(this._value).ToDynamic(); return true; } // The specified member is not found. result = null; return false; } // Other overridden methods are not listed. } In the above code, GetTypeProperty(), GetInterfaceMethod(), GetTypeField(), GetBaseProperty(), and GetBaseField() are extension methods for Type class. For example: internal static class TypeExtensions { internal static FieldInfo GetBaseField(this Type type, string name) { Type @base = type.BaseType; if (@base == null) { return null; } return @base.GetTypeField(name) ?? @base.GetBaseField(name); } internal static PropertyInfo GetBaseProperty(this Type type, string name) { Type @base = type.BaseType; if (@base == null) { return null; } return @base.GetTypeProperty(name) ?? @base.GetBaseProperty(name); } internal static MethodInfo GetInterfaceMethod(this Type type, string name, params object[] args) { return type.GetInterfaces().Select(type.GetInterfaceMap).SelectMany(mapping => mapping.TargetMethods) .FirstOrDefault( method => method.Name.Split('.').Last().Equals(name, StringComparison.Ordinal) && method.GetParameters().Count() == args.Length && method.GetParameters().Select( (parameter, index) => parameter.ParameterType.IsAssignableFrom(args[index].GetType())).Aggregate( true, (a, b) => a && b)); } internal static FieldInfo GetTypeField(this Type type, string name) { return type.GetFields( BindingFlags.GetField | BindingFlags.Instance | BindingFlags.Static | BindingFlags.Public | BindingFlags.NonPublic).FirstOrDefault( field => field.Name.Equals(name, StringComparison.Ordinal)); } internal static PropertyInfo GetTypeProperty(this Type type, string name) { return type.GetProperties( BindingFlags.GetProperty | BindingFlags.Instance | BindingFlags.Static | BindingFlags.Public | BindingFlags.NonPublic).FirstOrDefault( property => property.Name.Equals(name, StringComparison.Ordinal)); } // Other extension methods are not listed. } So now, when invoked, TryGetMember() searches the specified member and invoke it. The code can be written like this: dynamic dynamicDatabase = new DynamicWrapper<NorthwindDataContext>(ref database); dynamic dynamicReturnValue = dynamicDatabase.Provider.Execute(query.Expression).ReturnValue; This greatly simplified reflection. ToDynamic() and fluent reflection To make it even more straight forward, A ToDynamic() method is provided: public static class DynamicWrapperExtensions { public static dynamic ToDynamic<T>(this T value) { return new DynamicWrapper<T>(ref value); } } and a ToStatic() method is provided to unwrap the value: public class DynamicWrapper<T> : DynamicObject { public T ToStatic() { return this._value; } } In the above TryGetMember() method, please notice it does not output the member’s value, but output a wrapped member value (that is, memberValue.ToDynamic()). This is very important to make the reflection fluent. Now the code becomes: IEnumerable<Product> results = database.ToDynamic() // Here starts fluent reflection. .Provider.Execute(query.Expression).ReturnValue .ToStatic(); // Unwraps to get the static value. With the help of TryConvert(): public class DynamicWrapper<T> : DynamicObject { public override bool TryConvert(ConvertBinder binder, out object result) { result = this._value; return true; } } ToStatic() can be omitted: IEnumerable<Product> results = database.ToDynamic() .Provider.Execute(query.Expression).ReturnValue; // Automatically converts to expected static value. Take a look at the reflection code at the beginning of this post again. Now it is much much simplified! Special scenarios In 90% of the scenarios ToDynamic() is enough. But there are some special scenarios. Access static members Using extension method ToDynamic() for accessing static members does not make sense. Instead, DynamicWrapper<T> has a parameterless constructor to handle these scenarios: public class DynamicWrapper<T> : DynamicObject { public DynamicWrapper() // For static. { this._type = typeof(T); this._isValueType = this._type.IsValueType; } } The reflection code should be like this: dynamic wrapper = new DynamicWrapper<StaticClass>(); int value = wrapper._value; int result = wrapper.PrivateMethod(); So accessing static member is also simple, and fluent of course. Change instances of value types Value type is much more complex. The main problem is, value type is copied when passing to a method as a parameter. This is why ref keyword is used for the constructor. That is, if a value type instance is passed to DynamicWrapper<T>, the instance itself will be stored in this._value of DynamicWrapper<T>. Without the ref keyword, when this._value is changed, the value type instance itself does not change. Consider FieldInfo.SetValue(). In the value type scenarios, invoking FieldInfo.SetValue(this._value, value) does not change this._value, because it changes the copy of this._value. I searched the Web and found a solution for setting the value of field: internal static class FieldInfoExtensions { internal static void SetValue<T>(this FieldInfo field, ref T obj, object value) { if (typeof(T).IsValueType) { field.SetValueDirect(__makeref(obj), value); // For value type. } else { field.SetValue(obj, value); // For reference type. } } } Here __makeref is a undocumented keyword of C#. But method invocation has problem. This is the source code of TryInvokeMember(): public override bool TryInvokeMember(InvokeMemberBinder binder, object[] args, out object result) { if (binder == null) { throw new ArgumentNullException("binder"); } MethodInfo method = this._type.GetTypeMethod(binder.Name, args) ?? this._type.GetInterfaceMethod(binder.Name, args) ?? this._type.GetBaseMethod(binder.Name, args); if (method != null) { // Oops! // If the returnValue is a struct, it is copied to heap. object resultValue = method.Invoke(this._value, args); // And result is a wrapper of that copied struct. result = new DynamicWrapper<object>(ref resultValue); return true; } result = null; return false; } If the returned value is of value type, it will definitely copied, because MethodInfo.Invoke() does return object. If changing the value of the result, the copied struct is changed instead of the original struct. And so is the property and index accessing. They are both actually method invocation. For less confusion, setting property and index are not allowed on struct. Conclusions The DynamicWrapper<T> provides a simplified solution for reflection programming. It works for normal classes (reference types), accessing both instance and static members. In most of the scenarios, just remember to invoke ToDynamic() method, and access whatever you want: StaticType result = someValue.ToDynamic()._field.Method().Property[index]; In some special scenarios which requires changing the value of a struct (value type), this DynamicWrapper<T> does not work perfectly. Only changing struct’s field value is supported. The source code can be downloaded from here, including a few unit test code.

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