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  • Creating a dynamic proxy generator with c# – Part 4 – Calling the base method

    - by SeanMcAlinden
    Creating a dynamic proxy generator with c# – Part 1 – Creating the Assembly builder, Module builder and caching mechanism Creating a dynamic proxy generator with c# – Part 2 – Interceptor Design Creating a dynamic proxy generator with c# – Part 3 – Creating the constructors   The plan for calling the base methods from the proxy is to create a private method for each overridden proxy method, this will allow the proxy to use a delegate to simply invoke the private method when required. Quite a few helper classes have been created to make this possible so as usual I would suggest download or viewing the code at http://rapidioc.codeplex.com/. In this post I’m just going to cover the main points for when creating methods. Getting the methods to override The first two notable methods are for getting the methods. private static MethodInfo[] GetMethodsToOverride<TBase>() where TBase : class {     return typeof(TBase).GetMethods().Where(x =>         !methodsToIgnore.Contains(x.Name) &&                              (x.Attributes & MethodAttributes.Final) == 0)         .ToArray(); } private static StringCollection GetMethodsToIgnore() {     return new StringCollection()     {         "ToString",         "GetHashCode",         "Equals",         "GetType"     }; } The GetMethodsToIgnore method string collection contains an array of methods that I don’t want to override. In the GetMethodsToOverride method, you’ll notice a binary AND which is basically saying not to include any methods marked final i.e. not virtual. Creating the MethodInfo for calling the base method This method should hopefully be fairly easy to follow, it’s only function is to create a MethodInfo which points to the correct base method, and with the correct parameters. private static MethodInfo CreateCallBaseMethodInfo<TBase>(MethodInfo method) where TBase : class {     Type[] baseMethodParameterTypes = ParameterHelper.GetParameterTypes(method, method.GetParameters());       return typeof(TBase).GetMethod(        method.Name,        BindingFlags.Instance | BindingFlags.Public | BindingFlags.NonPublic,        null,        baseMethodParameterTypes,        null     ); }   /// <summary> /// Get the parameter types. /// </summary> /// <param name="method">The method.</param> /// <param name="parameters">The parameters.</param> public static Type[] GetParameterTypes(MethodInfo method, ParameterInfo[] parameters) {     Type[] parameterTypesList = Type.EmptyTypes;       if (parameters.Length > 0)     {         parameterTypesList = CreateParametersList(parameters);     }     return parameterTypesList; }   Creating the new private methods for calling the base method The following method outline how I’ve created the private methods for calling the base class method. private static MethodBuilder CreateCallBaseMethodBuilder(TypeBuilder typeBuilder, MethodInfo method) {     string callBaseSuffix = "GetBaseMethod";       if (method.IsGenericMethod || method.IsGenericMethodDefinition)     {                         return MethodHelper.SetUpGenericMethod             (                 typeBuilder,                 method,                 method.Name + callBaseSuffix,                 MethodAttributes.Private | MethodAttributes.HideBySig             );     }     else     {         return MethodHelper.SetupNonGenericMethod             (                 typeBuilder,                 method,                 method.Name + callBaseSuffix,                 MethodAttributes.Private | MethodAttributes.HideBySig             );     } } The CreateCallBaseMethodBuilder is the entry point method for creating the call base method. I’ve added a suffix to the base classes method name to keep it unique. Non Generic Methods Creating a non generic method is fairly simple public static MethodBuilder SetupNonGenericMethod(     TypeBuilder typeBuilder,     MethodInfo method,     string methodName,     MethodAttributes methodAttributes) {     ParameterInfo[] parameters = method.GetParameters();       Type[] parameterTypes = ParameterHelper.GetParameterTypes(method, parameters);       Type returnType = method.ReturnType;       MethodBuilder methodBuilder = CreateMethodBuilder         (             typeBuilder,             method,             methodName,             methodAttributes,             parameterTypes,             returnType         );       ParameterHelper.SetUpParameters(parameterTypes, parameters, methodBuilder);       return methodBuilder; }   private static MethodBuilder CreateMethodBuilder (     TypeBuilder typeBuilder,     MethodInfo method,     string methodName,     MethodAttributes methodAttributes,     Type[] parameterTypes,     Type returnType ) { MethodBuilder methodBuilder = typeBuilder.DefineMethod(methodName, methodAttributes, returnType, parameterTypes); return methodBuilder; } As you can see, you simply have to declare a method builder, get the parameter types, and set the method attributes you want.   Generic Methods Creating generic methods takes a little bit more work. /// <summary> /// Sets up generic method. /// </summary> /// <param name="typeBuilder">The type builder.</param> /// <param name="method">The method.</param> /// <param name="methodName">Name of the method.</param> /// <param name="methodAttributes">The method attributes.</param> public static MethodBuilder SetUpGenericMethod     (         TypeBuilder typeBuilder,         MethodInfo method,         string methodName,         MethodAttributes methodAttributes     ) {     ParameterInfo[] parameters = method.GetParameters();       Type[] parameterTypes = ParameterHelper.GetParameterTypes(method, parameters);       MethodBuilder methodBuilder = typeBuilder.DefineMethod(methodName,         methodAttributes);       Type[] genericArguments = method.GetGenericArguments();       GenericTypeParameterBuilder[] genericTypeParameters =         GetGenericTypeParameters(methodBuilder, genericArguments);       ParameterHelper.SetUpParameterConstraints(parameterTypes, genericTypeParameters);       SetUpReturnType(method, methodBuilder, genericTypeParameters);       if (method.IsGenericMethod)     {         methodBuilder.MakeGenericMethod(genericArguments);     }       ParameterHelper.SetUpParameters(parameterTypes, parameters, methodBuilder);       return methodBuilder; }   private static GenericTypeParameterBuilder[] GetGenericTypeParameters     (         MethodBuilder methodBuilder,         Type[] genericArguments     ) {     return methodBuilder.DefineGenericParameters(GenericsHelper.GetArgumentNames(genericArguments)); }   private static void SetUpReturnType(MethodInfo method, MethodBuilder methodBuilder, GenericTypeParameterBuilder[] genericTypeParameters) {     if (method.IsGenericMethodDefinition)     {         SetUpGenericDefinitionReturnType(method, methodBuilder, genericTypeParameters);     }     else     {         methodBuilder.SetReturnType(method.ReturnType);     } }   private static void SetUpGenericDefinitionReturnType(MethodInfo method, MethodBuilder methodBuilder, GenericTypeParameterBuilder[] genericTypeParameters) {     if (method.ReturnType == null)     {         methodBuilder.SetReturnType(typeof(void));     }     else if (method.ReturnType.IsGenericType)     {         methodBuilder.SetReturnType(genericTypeParameters.Where             (x => x.Name == method.ReturnType.Name).First());     }     else     {         methodBuilder.SetReturnType(method.ReturnType);     }             } Ok, there are a few helper methods missing, basically there is way to much code to put in this post, take a look at the code at http://rapidioc.codeplex.com/ to follow it through completely. Basically though, when dealing with generics there is extra work to do in terms of getting the generic argument types setting up any generic parameter constraints setting up the return type setting up the method as a generic All of the information is easy to get via reflection from the MethodInfo.   Emitting the new private method Emitting the new private method is relatively simple as it’s only function is calling the base method and returning a result if the return type is not void. ILGenerator il = privateMethodBuilder.GetILGenerator();   EmitCallBaseMethod(method, callBaseMethod, il);   private static void EmitCallBaseMethod(MethodInfo method, MethodInfo callBaseMethod, ILGenerator il) {     int privateParameterCount = method.GetParameters().Length;       il.Emit(OpCodes.Ldarg_0);       if (privateParameterCount > 0)     {         for (int arg = 0; arg < privateParameterCount; arg++)         {             il.Emit(OpCodes.Ldarg_S, arg + 1);         }     }       il.Emit(OpCodes.Call, callBaseMethod);       il.Emit(OpCodes.Ret); } So in the main method building method, an ILGenerator is created from the method builder. The ILGenerator performs the following actions: Load the class (this) onto the stack using the hidden argument Ldarg_0. Create an argument on the stack for each of the method parameters (starting at 1 because 0 is the hidden argument) Call the base method using the Opcodes.Call code and the MethodInfo we created earlier. Call return on the method   Conclusion Now we have the private methods prepared for calling the base method, we have reached the last of the relatively easy part of the proxy building. Hopefully, it hasn’t been too hard to follow so far, there is a lot of code so I haven’t been able to post it all so please check it out at http://rapidioc.codeplex.com/. The next section should be up fairly soon, it’s going to cover creating the delegates for calling the private methods created in this post.   Kind Regards, Sean.

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  • Guidelines for calling controller methods in helper modules?

    - by keruilin
    Few questions: Is it possible to call a controller method in a helper module (e.g., application helper)? If so, how does the helper handle the rendering of views? Ignore it? In what instances would you want to call a controller method from a helper? Is it bad practice? Do you have any sample code where you're calling controller methods in helper?

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  • what's the point of method overloading?

    - by David
    I am following a textbook in which I have just come across method overloading. It briefly described method overloading as: when the same method name is used with different parameters its called method overloading. From what I've learned so far in OOP is that if I want different behaviors from an object via methods, I should use different method names that best indicate the behavior, so why should I bother with method overloading in the first place?

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  • Calling helper function in Evaluate/Modify (Ctrl+F7) window

    - by m0f0
    Lets say i wrote helper for TStringList TslHelper = class helper for TStringList function DoSth: boolean; end; Then ive included this helper (unit in which helper is defined) in unit i want to use it. During debugging i hit Ctrl+F7 and i want to evaluate: someStringList.DoSth I cant get it to work. Is it possible? Regards

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  • How do I code a MVC3 Helper

    - by Mike Clarke
    I’ve just build my first Helper in MVC, it’s very basic and just displays a string where ever I use it. So it’s a .cshtml file in my App_Code folder, I think that is how it's supposed to be set up, with the following code in it, @helper DisplaySelect() { @:This text is coming from an helper class. } Now I am a wiz with helpers how do I make it do things. E.g.. say I want it to query the database and display something, I would normally do that work in my controller. How do I do that with helpers, do I create a helper controller and then treat the helper like a partial view??? Any help would be greatly appreciated. Cheers, Mike.

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  • Using a helper method in a mailer that is defined in a controller

    - by Horace Loeb
    The helper method current_user is defined and made available as a helper in ApplicationController like this: class ApplicationController < ActionController::Base helper_method :current_user def current_user return @current_user if defined?(@current_user) @current_user = current_user_session && current_user_session.record end end My question is how I can use the current_user helper method in a mailer template (obviously it will always return nil, but I'm trying to render a partial that depends on it). Normally when I want to use helpers in a mailer, I do something like add_template_helper(SongsHelper), but since the helper is defined in a class instead of a module I'm not sure what to do

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  • My helper methods in controller

    - by FancyDancy
    My app should render html, to answer when a user clicks ajax-link. My controller: def create_user @user = User.new(params) if @user.save status = 'success' link = link_to_profile(@user) #it's my custom helper in Application_Helper.rb else status = 'error' link = nil end render :json => {:status => status, :link => link} end My helper: def link_to_profile(user) link = link_to(user.login, {:controller => "users", :action => "profile", :id => user.login}, :class => "profile-link") return(image_tag("/images/users/profile.png") + " " + link) end I have tried such methods: ApplicationController.helpers.link_to_profile(@user) # It raises: NoMethodError (undefined method `url_for' for nil:NilClass) and: class Helper include Singleton include ApplicationHelper include ActionView::Helpers::TextHelper include ActionView::Helpers::UrlHelper include ApplicationHelper end def help Helper.instance end help.link_to_profile(@user) # It also raises: NoMethodError (undefined method `url_for' for nil:NilClass) In addition, yes, I KNOW about :helper_method, and it works, but i don't want to overload my ApplicationController with a plenty of that methods

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  • Another question about ASP.NET MVC and a separate project for helper classes

    - by rockinthesixstring
    I know this topic has been discussed to death, but there is one thing that I can't wrap my head around. I'm working on a Web Application using ASP.NET MVC and I come across a scenario where I need a helper class (this usually happens in the early stages of development. So I go ahead and create a helper project in my solution that I use to manage all of my Helper Classes. Now, do I have to build that project and dump the dll in the bin directory every time I make changes to is, or is there a way to have the main web application reference the classes contained within the separate project without the separate build process? I'm just looking for the easiest way to add helper classes without the hastel of building and moving the dll every time I make a change or addition. Also, sorry for the very newbie-esque question here. All of the web apps I've build in the past have all been in the same project (web forms, App_Code, etc).

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  • Zend Controller Action Helper Problem not able to add helper

    - by snakeyyy
    Trying to make a controller helper to have similar functionality in some controllers using the preDispatch method. Error: Fatal error: Class 'Helper_Action_Test' not found in /var/www/zend.dev/application/Bootstrap.php on line 9` Application layout /Application /Helpers **/Actions** this is where i will save the classes /Views /modules /configs /layouts /Bootstrap.php In the Bootstrap I have added: protected function _initActionHelpers(){ Zend_Controller_Action_HelperBroker::addHelper(new Helper_Action_Test()); } In the helper file I have: class Helper_Action_Test extends Zend_Controller_Action_Helper_Abstract{ public function preDispatch() { echo 'Test'; } } Any ideas?

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  • constructor function's object literal returns toString() method but no other method

    - by JohnMerlino
    I'm very confused with javascript methods defined in objects and the "this" keyword. In the below example, the toString() method is invoked when Mammal object instantiated: function Mammal(name){ this.name=name; this.toString = function(){ return '[Mammal "'+this.name+'"]'; } } var someAnimal = new Mammal('Mr. Biggles'); alert('someAnimal is '+someAnimal); Despite the fact that the toString() method is not invoked on the object someAnimal like this: alert('someAnimal is '+someAnimal.toString()); It still returns 'someAnimal is [Mammal "Mr. Biggles"]' . That doesn't make sense to me because the toString() function is not being called anywhere. Then to add even more confusion, if I change the toString() method to a method I make up such as random(): function Mammal(name){ this.name=name; this.random = function(){ return Math.floor(Math.random() * 15); } } var someAnimal = new Mammal('Mr. Biggles'); alert(someAnimal); It completely ignores the random method (despite the fact that it is defined the same way was the toString() method was) and returns: [object object] Another issue I'm having trouble understanding with inheritance is the value of "this". For example, in the below example function person(w,h){ width.width = w; width.height = h; } function man(w,h,s) { person.call(this, w, h); this.sex = s; } "this" keyword is being send to the person object clearly. However, does "this" refer to the subclass (man) or the super class (person) when the person object receives it? Thanks for clearing up any of the confusion I have with inheritance and object literals in javascript.

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  • Port a live system from App Engine Helper to App Engine Patch

    - by Alexander
    I am running a live system that is currently serving about 20K pages a day which is based on App Engine Helper (Python) with session support provided by AppEngine utilities. One problem that I have been having is that sessions are occasionally randomly logging out. I would like to try using the App Engine Patch, since it has "native" django session support, but I am worried that this is possibly going to be like doing a brain transplant. Specifically, current database models are all inhereted from BaseModel provided by the App Engine Helper. While, App Engine Patch does not have this inheritance. Does anyone know if it is possible to migrate a live system from App Engine Helper to App Engine Patch? If so, do you have any advice or warnings that I should heed, before attempting this transition? Thank you and kind regards Alex

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  • Method chaining and exceptions in C#

    - by devoured elysium
    If I have a method chain like the following: var abc = new ABC(); abc.method1() .method2() .methodThrowsException() .method3() ; assuming I've defined method1(), method2() and method3() as public ABC method1() { return this; } and methodThrowsException() as public ABC method3() { throw new ArgumentException(); } When running the code, is it possible to know which specific line of code has thrown the Exception, or will it just consider all the method chaining as just one line? I've done a simple test and it seems it considers them all as just one line but Method Chaining says Putting methods on separate lines also makes debugging easier as error messages and debugger control is usually on a line by line basis. Am I missing something, or does that just not apply to C#? Thanks

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  • alias_attribute and creating and method with the original attribute name causes a loop

    - by Tiago
    Im trying to dynamically create a method chain in one attribute in my model. By now I have this function: def create_filtered_attribute(attribute_name) alias_attribute "#{attribute_name}_without_filter", attribute_name define_method "#{attribute_name}" do filter_words(self.send("#{attribute_name}_without_filter")) end end so I receive a string with the attribute name, alias it for '*_without_filter*' (alias_method or alias_method_chain fails here, because the attribute isnt there when the class is created), and I create a new method with the attribute name, where I filter its contents. But somehow, when I call *"#{attribute_name}_without_filter"* it calls my new method (i think because the alias_attribute some how), and the program goes into a stack loop. Can someone please enlighten me on this.

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  • CodeIgniter helper inside controllers

    - by kapitanluffy
    can i call helper functions inside controller classes? let's say i have this controller with the _open_form method class User extends Controller { function _open_form($action){ print_r(form_open($action)); } } i tried echoing out the result of form_open() but it returns null. it seems that helper functions can't be called inside controllers if your wondering why i need to use it inside the controller instead in the view because we are required to use the given template parser xD

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  • WebGrid Helper and Complex Types

    - by imran_ku07
        Introduction:           WebGrid helper makes it very easy to show tabular data. It was originally designed for ASP.NET Web Pages(WebMatrix) to display, edit, page and sort tabular data but you can also use this helper in ASP.NET Web Forms and ASP.NET MVC. When using this helper, sometimes you may run into a problem if you use complex types in this helper. In this article, I will show you how you can use complex types in WebGrid helper.       Description:             Let's say you need to show the employee data and you have the following classes,   public class Employee { public string Name { get; set; } public Address Address { get; set; } public List<string> ContactNumbers { get; set; } } public class Address { public string City { get; set; } }               The Employee class contain a Name, an Address and list of ContactNumbers. You may think that you can easily show City in WebGrid using Address.City, but no. The WebGrid helper will throw an exception at runtime if any Address property is null in the Employee list. Also, you cannot directly show ContactNumbers property. The easiest way to show these properties is to add some additional properties,   public Address NotNullableAddress { get { return Address ?? new Address(); } } public string Contacts { get { return string.Join("; ",ContactNumbers); } }               Now you can easily use these properties in WebGrid. Here is the complete code of this example,  @functions{ public class Employee { public Employee(){ ContactNumbers = new List<string>(); } public string Name { get; set; } public Address Address { get; set; } public List<string> ContactNumbers { get; set; } public Address NotNullableAddress { get { return Address ?? new Address(); } } public string Contacts { get { return string.Join("; ",ContactNumbers); } } } public class Address { public string City { get; set; } } } @{ var myClasses = new List<Employee>{ new Employee { Name="A" , Address = new Address{ City="AA" }, ContactNumbers = new List<string>{"021-216452","9231425651"}}, new Employee { Name="C" , Address = new Address{ City="CC" }}, new Employee { Name="D" , ContactNumbers = new List<string>{"045-14512125","21531212121"}} }; var grid = new WebGrid(source: myClasses); } @grid.GetHtml(columns: grid.Columns( grid.Column("NotNullableAddress.City", header: "City"), grid.Column("Name"), grid.Column("Contacts")))                    Summary:           You can use WebGrid helper to show tabular data in ASP.NET MVC, ASP.NET Web Forms and  ASP.NET Web Pages. Using this helper, you can also show complex types in the grid. In this article, I showed you how you use complex types with WebGrid helper. Hopefully you will enjoy this article too.  

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  • Call asp.net mvc Html Helper within custom html helper with expression parameter

    - by Frank Michael Kraft
    I am trying to write an html helper extension within the asp.net mvc framework. public static MvcHtmlString PlatformNumericTextBoxFor<TModel>(this HtmlHelper instance, TModel model, Expression<Func<TModel,double>> selector) where TModel : TableServiceEntity { var viewModel = new PlatformNumericTextBox(); var func = selector.Compile(); MemberExpression memExpession = (MemberExpression)selector.Body; string name = memExpession.Member.Name; var message = instance.ValidationMessageFor<TModel, double>(selector); viewModel.name = name; viewModel.value = func(model); viewModel.validationMessage = String.Empty; var result = instance.Partial(typeof(PlatformNumericTextBox).Name, viewModel); return result; } The line var message = instance.ValidationMessageFor<TModel, double>(selector); has a syntax error. But I do not understand it. The error is: Fehler 2 "System.Web.Mvc.HtmlHelper" enthält keine Definition für "ValidationMessageFor", und die Überladung der optimalen Erweiterungsmethode "System.Web.Mvc.Html.ValidationExtensions.ValidationMessageFor(System.Web.Mvc.HtmlHelper, System.Linq.Expressions.Expression)" weist einige ungültige Argumente auf. C:\Projects\WorkstreamPlatform\WorkstreamPlatform_WebRole\Extensions\PlatformHtmlHelpersExtensions.cs 97 27 WorkstreamPlatform_WebRole So according to the message, the parameter is invalid. But the method is actually declared like this: public static MvcHtmlString ValidationMessageFor<TModel, TProperty>(this HtmlHelper<TModel> htmlHelper, Expression<Func<TModel, TProperty>> expression); So actually it should work.

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  • What's the convention for extending Linq with set based helper operations

    - by Luke Rohde
    Hi All I might be vaguing out here but I'm looking for a nice place to put set based helper operations in linq so I can do things like; db.Selections.ClearTemporary() which does something like db.DeleteAllOnSubmit(db.Selections.Where(s => s.Temporary)) Since I can figure out how to extend Table<Selection> the best I can do is create a static method in partial class of Selection (similar to Ruby) but I have to pass in the datacontext like; Selection.ClearTemporary(MyDataContext) This kind of sucks because I have two conventions for doing set based operations and I have to pass the data context to the static class. I've seen other people recommending piling helper methods into a partial of the datacontext like; myDataContext.ClearTemporarySelections(); But I feel this makes the dc a dumping ground for in-cohesive operations. Surely I'm missing something. I hope so. What's the convention? TIA

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  • What's the convention for extending Linq datacontext with set based helper operations specific to on

    - by Luke Rohde
    Hi All I might be vaguing out here but I'm looking for a nice place to put set based helper operations in linq so I can do things like; db.Selections.ClearTemporary() which does something like db.DeleteAllOnSubmit(db.Selections.Where(s => s.Temporary)) Since I can figure out how to extend Table<Selection> the best I can do is create a static method in partial class of Selection (similar to Ruby) but I have to pass in the datacontext like; Selection.ClearTemporary(MyDataContext) This kind of sucks because I have two conventions for doing set based operations and I have to pass the data context to the static class. I've seen other people recommending piling helper methods into a partial of the datacontext like; myDataContext.ClearTemporarySelections(); But I feel this makes the dc a dumping ground for in-cohesive operations. Surely I'm missing something. I hope so. What's the convention? TIA

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  • Not see my view helper

    - by Alexandr
    I create my view helper it located in /library/My/View/helpers/SpecialPurpose.php the class name is My_View_Helper_SpecialPurpose it have public function specialPurpose() it return some HTML i register this path in bootstrap.php $view = Zend_Layout::getMvcInstance()-getView(); $view-addBasePath('/my/view/helpers',"My_View_Helper"); when i tring specialPurpose();? in any view .phtml it trow exeption Message: Plugin by name 'SpecialPurpose' was not found in the registry; used paths: My_View_Helper_Helper_: /my/view/helpers\helpers/ Zend_View_Helper_: Zend/View/Helper/;D:/WWW/zends/application/modules/default/views\helpers/ P.S I read many post in stackoverflow but not one solutions not helped If it possible weácan how do this task with bootstrap and application.ini zf version 1.10.3

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  • Can Eclipse generate method-chaining setters

    - by Chris R
    I'd like to generate method-chaining setters (setters that return the object being set), like so: public MyObject setField (Object value) { this.field = value; return this; } This makes it easier to do one-liner instantiations, which I find easier to read: myMethod (new MyObject ().setField (someValue).setOtherField (someOtherValue)); Can Eclipse's templates be modified to do this? I've changed the content to include return this; but the signature is not changed.

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  • Override ActiveRecord#save, Method Alias? Trying to mixin functionality into save method...

    - by viatropos
    Here's the situation: I have a User model, and two modules for authentication: Oauth and Openid. Both of them override ActiveRecord#save, and have a fair share of implementation logic. Given that I can tell when the user is trying to login via Oauth vs. Openid, but that both of them have overridden save, how do "finally" override save such that I can conditionally call one of the modules' implementations of it? Here is the base structure of what I'm describing: module UsesOauth def self.included(base) base.class_eval do def save puts "Saving with Oauth!" end def save_with_oauth save end end end end module UsesOpenid def self.included(base) base.class_eval do def save puts "Saving with OpenID!" end def save_with_openid save end end end end module Sequencer def save if using_oauth? save_with_oauth elsif using_openid? save_with_openid else super end end end class User < ActiveRecord::Base include UsesOauth include UsesOpenid include Sequencer end I was thinking about using alias_method like so, but that got too complicated, because I might have 1 or 2 more similar modules. I also tried using those save_with_oauth methods (shown above), which almost works. The only thing that's missing is that I also need to call ActiveRecord::Base#save (the super method), so something like this: def save_with_oauth # do this and that super.save # the rest end But I'm not allowed to do that in ruby. Any ideas for a clever solution to this?

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  • Why does Java's invokevirtual need to resolve the called method's compile-time class?

    - by Chris
    Consider this simple Java class: class MyClass { public void bar(MyClass c) { c.foo(); } } I want to discuss what happens on the line c.foo(). At the bytecode level, the meat of c.foo() will be the invokevirtual opcode, and, according to the documentation for invokevirtual, more or less the following will happen: Look up the foo method defined in compile-time class MyClass. (This involves first resolving MyClass.) Do some checks, including: Verify that c is not an initialization method, and verify that calling MyClass.foo wouldn't violate any protected modifiers. Figure out which method to actually call. In particular, look up c's runtime type. If that type has foo(), call that method and return. If not, look up c's runtime type's superclass; if that type has foo, call that method and return. If not, look up c's runtime type's superclass's superclass; if that type has foo, call that method and return. Etc.. If no suitable method can be found, then error. Step #3 alone seems adequate for figuring out which method to call and verifying that said method has the correct argument/return types. So my question is why step #1 gets performed in the first place. Possible answers seem to be: You don't have enough information to perform step #3 until step #1 is complete. (This seems implausible at first glance, so please explain.) The linking or access modifier checks done in #1 and #2 are essential to prevent certain bad things from happening, and those checks must be performed based on the compile-time type, rather than the run-time type hierarchy. (Please explain.)

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  • Are there any drawbacks to using helper :all in Rails

    - by Rob Jones
    In Rails 'helper :all' makes all your helpers 'available' to all your controllers. This is concise and convenient, but does it have any memory and/or performance implications compared to explicitly calling the helpers that each controller actually needs? It's unclear form the docs whether using it involves 'require'ing all those files, or whether autoload is being used. I can't tell from the source in the Rails framework docs. thanks

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