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  • Jboss 5.1.0: java.lang.LinkageError: loader constraint violation for class javax.sql.DataSource

    - by lawrencexu
    have read quite a lot about this error, the reason is 1) more than one jar containing this class have been include into the classpath, 2)include the jar twice or more, but in my case, this class is jdk class, and I have search no this class have been found under my application. any clue would be very helpful. exception stack: 2012-10-31 14:09:58,319 WARN [org.jboss.detailed.classloader.ClassLoaderManager] (http-0.0.0.0-8080-1:) Unexpected error during load of:javax.sql.DataSource java.lang.LinkageError: loader constraint violation: loader (instance of org/jboss/classloader/spi/base/BaseClassLoader) previously initiated loading for a different type with name "javax/sql/DataSource" at java.lang.ClassLoader.defineClass1(Native Method) at java.lang.ClassLoader.defineClassCond(ClassLoader.java:631) at java.lang.ClassLoader.defineClass(ClassLoader.java:615) at org.jboss.classloader.spi.base.BaseClassLoader.access$200(BaseClassLoader.java:67) at org.jboss.classloader.spi.base.BaseClassLoader$2.run(BaseClassLoader.java:633) at org.jboss.classloader.spi.base.BaseClassLoader$2.run(BaseClassLoader.java:592) at java.security.AccessController.doPrivileged(Native Method) at org.jboss.classloader.spi.base.BaseClassLoader.loadClassLocally(BaseClassLoader.java:591) at org.jboss.classloader.spi.base.BaseClassLoader.loadClassLocally(BaseClassLoader.java:568) at org.jboss.classloader.spi.base.BaseDelegateLoader.loadClass(BaseDelegateLoader.java:135) at org.jboss.classloader.spi.filter.FilteredDelegateLoader.loadClass(FilteredDelegateLoader.java:131) at org.jboss.classloader.spi.base.ClassLoadingTask$ThreadTask.run(ClassLoadingTask.java:455) at org.jboss.classloader.spi.base.ClassLoaderManager.nextTask(ClassLoaderManager.java:267) at org.jboss.classloader.spi.base.ClassLoaderManager.process(ClassLoaderManager.java:166) at org.jboss.classloader.spi.base.BaseClassLoaderDomain.loadClass(BaseClassLoaderDomain.java:287) at org.jboss.classloader.spi.base.BaseClassLoaderDomain.loadClass(BaseClassLoaderDomain.java:1163) at org.jboss.classloader.spi.base.BaseClassLoader.loadClassFromDomain(BaseClassLoader.java:862) at org.jboss.classloader.spi.base.BaseClassLoader.doLoadClass(BaseClassLoader.java:502) at org.jboss.classloader.spi.base.BaseClassLoader.loadClass(BaseClassLoader.java:447) at java.lang.ClassLoader.loadClass(ClassLoader.java:247) at com.lombardrisk.webgui.dwr.ajax_search.UmbrellaNettingFundsSearch.getBranchesByAgreementId(UmbrellaNettingFundsSearch.java:199) at com.lombardrisk.webgui.dwr.ajax_search.UmbrellaNettingFundsSearch.buildConditionOfPrinAndCpty(UmbrellaNettingFundsSearch.java:177) at com.lombardrisk.webgui.dwr.ajax_search.UmbrellaNettingFundsSearch.getFunds(UmbrellaNettingFundsSearch.java:58) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25) at java.lang.reflect.Method.invoke(Method.java:597) at org.directwebremoting.impl.ExecuteAjaxFilter.doFilter(ExecuteAjaxFilter.java:34) at org.directwebremoting.impl.DefaultRemoter$1.doFilter(DefaultRemoter.java:428) at org.directwebremoting.impl.DefaultRemoter.execute(DefaultRemoter.java:431) at org.directwebremoting.impl.DefaultRemoter.execute(DefaultRemoter.java:283) at org.directwebremoting.servlet.PlainCallHandler.handle(PlainCallHandler.java:52) at org.directwebremoting.servlet.UrlProcessor.handle(UrlProcessor.java:101) at org.directwebremoting.servlet.DwrServlet.doPost(DwrServlet.java:146) at javax.servlet.http.HttpServlet.service(HttpServlet.java:637) at javax.servlet.http.HttpServlet.service(HttpServlet.java:717) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206) at com.lombardrisk.webgui.filter.ValidRequestFilter.doFilter(ValidRequestFilter.java:41) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206) at org.jboss.web.tomcat.filters.ReplyHeaderFilter.doFilter(ReplyHeaderFilter.java:96) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206) at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:235) at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191) at org.jboss.web.tomcat.security.SecurityAssociationValve.invoke(SecurityAssociationValve.java:183) at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:525) at org.jboss.web.tomcat.security.JaccContextValve.invoke(JaccContextValve.java:95) at org.jboss.web.tomcat.security.SecurityContextEstablishmentValve.process(SecurityContextEstablishmentValve.java:126) at org.jboss.web.tomcat.security.SecurityContextEstablishmentValve.invoke(SecurityContextEstablishmentValve.java:70) at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127) at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102) at org.jboss.web.tomcat.service.jca.CachedConnectionValve.invoke(CachedConnectionValve.java:158) at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109) at org.jboss.web.tomcat.service.request.ActiveRequestResponseCacheValve.internalProcess(ActiveRequestResponseCacheValve.java:74) at org.jboss.web.tomcat.service.request.ActiveRequestResponseCacheValve.invoke(ActiveRequestResponseCacheValve.java:47) at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:330) at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:829) at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:599) at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:451) at java.lang.Thread.run(Thread.java:662)

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  • All network devices freezing when Airport Extreme Base Station is connected. Any ideas?

    - by Jon
    I've been troubleshooting this issue for a while, and through a series of events have it narrowed down to my airport extreme base station. I like this router, since I'm able to connect to IPV6 sites without any insane configuration (my alternate router is too old and doesn't support v6). My question is: Has anyone else had this issue, if so how is it resolved? If not, can you recommend a good IPv6 router? Here is how I came to the conclusion that it is the router: Devices: XBOX 360, HTC Incredible, Home-Built machine running FreeBSD, Home-Built machine running Ubuntu 10.04. 1.) Noticed freezing on Ubuntu Box. 2.) Noticed freezing on XBOX360 3.) Noticed freezing on HTC Incredible (only when connected to my network wirelessly). The above all happened at random times throughout the past few weeks. Over the last few days, I was playing XBOX and noticed that the XBOX and Ubuntu machines both froze. I picked up my phone, and it was also frozen. I reset all devices, power-cycled my router, and all was fine again. About two hours later, it happened again (I was playing Forza III, the XBOX froze; I went to the Ubuntu box and it was frozen; unfortunately, the HTC phone was not connected wirelessly, and the FreeBSD box was turned off). I can't even begin to imaging what a router could be doing to freeze devices with such differing hardware/software/OS, and I feel absurd for coming to this conclusion, but I have nothing else. I hooked up my archaic Netgear router, and have had no problems since. :(

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  • Problem with videos on heroku

    - by mnml
    Hi, I have recently moved my RoR app on the Heroku platform, and almost everything works fine apart from the videos. It works fine when my app runs in local but not on heroku. This is the error log I'm getting, if anyone knows where it can be coming from: Processing VideosController#new (for IP at 2010-03-20 04:32:09) [GET] Session ID: 6abecf60c3369d7c7029e366bb801e08 Parameters: {"artist_id"=>"10", "action"=>"new", "controller"=>"admin/videos"} Rendering within layouts/admin Rendering admin/videos/new ActionView::TemplateError (undefined method `video_file_relative_path' for #<Video:0x2adc9839fe28>) on line #21 of app/views/admin/videos/ _form.rhtml: 18: 19: <p><label for="videos_image_file">Fichier Vidéo SWF</label><br/> 20: <% if @video.video_file %> 21: <%= link_to image_tag(url_for_file_column("video", "video_file", :name => "thumbnail"))+"<br>", {:controller => url_for_file_column("video", "video_file")}, :popup => ['new_window', 'height=200,width=200'] %> 22: <% end %> 23: <%= file_column_field 'video', 'video_file' %> 24: &nbsp;&nbsp;&nbsp; #{RAILS_ROOT}/vendor/rails/activerecord/lib/active_record/base.rb: 1792:in `method_missing' #{RAILS_ROOT}/vendor/plugins/file_column/lib/file_column_helper.rb: 75:in `send' #{RAILS_ROOT}/vendor/plugins/file_column/lib/file_column_helper.rb: 75:in `url_for_file_column' #{RAILS_ROOT}/app/views/admin/videos/_form.rhtml:21:in `_run_rhtml_admin_videos__form' #{RAILS_ROOT}/vendor/rails/actionpack/lib/action_view/base.rb: 314:in `send' #{RAILS_ROOT}/vendor/rails/actionpack/lib/action_view/base.rb: 314:in `compile_and_render_template' #{RAILS_ROOT}/vendor/rails/actionpack/lib/action_view/base.rb: 290:in `render_template' #{RAILS_ROOT}/vendor/rails/actionpack/lib/action_view/base.rb: 249:in `render_file' #{RAILS_ROOT}/vendor/rails/actionpack/lib/action_view/base.rb: 264:in `render' #{RAILS_ROOT}/vendor/rails/actionpack/lib/action_view/partials.rb: 59:in `render_partial' #{RAILS_ROOT}/vendor/rails/actionpack/lib/action_controller/ benchmarking.rb:33:in `benchmark' #{RAILS_ROOT}/vendor/rails/actionpack/lib/action_view/partials.rb: 58:in `render_partial' #{RAILS_ROOT}/vendor/rails/actionpack/lib/action_view/base.rb: 276:in `render' #{RAILS_ROOT}/app/views/admin/videos/new.rhtml:4:in `_run_rhtml_admin_videos_new' #{RAILS_ROOT}/vendor/rails/actionpack/lib/action_view/base.rb: 314:in `send' #{RAILS_ROOT}/vendor/rails/actionpack/lib/action_view/base.rb: 314:in `compile_and_render_template' #{RAILS_ROOT}/vendor/rails/actionpack/lib/action_view/base.rb: 290:in `render_template' #{RAILS_ROOT}/vendor/rails/actionpack/lib/action_view/base.rb: 249:in `render_file' #{RAILS_ROOT}/vendor/rails/actionpack/lib/action_controller/ base.rb:699:in `render_file' #{RAILS_ROOT}/vendor/rails/actionpack/lib/action_controller/ base.rb:621:in `render_with_no_layout' #{RAILS_ROOT}/vendor/rails/actionpack/lib/action_controller/ layout.rb:243:in `render_without_benchmark' #{RAILS_ROOT}/vendor/rails/actionpack/lib/action_controller/ benchmarking.rb:53:in `render' /usr/local/lib/ruby/1.8/benchmark.rb:293:in `measure' #{RAILS_ROOT}/vendor/rails/actionpack/lib/action_controller/ benchmarking.rb:53:in `render' #{RAILS_ROOT}/vendor/rails/actionpack/lib/action_controller/ base.rb:911:in `perform_action_without_filters' #{RAILS_ROOT}/vendor/rails/actionpack/lib/action_controller/ filters.rb:368:in `perform_action_without_benchmark' #{RAILS_ROOT}/vendor/rails/actionpack/lib/action_controller/ benchmarking.rb:69:in `perform_action_without_rescue' /usr/local/lib/ruby/1.8/benchmark.rb:293:in `measure' #{RAILS_ROOT}/vendor/rails/actionpack/lib/action_controller/ benchmarking.rb:69:in `perform_action_without_rescue' #{RAILS_ROOT}/vendor/rails/actionpack/lib/action_controller/ rescue.rb:82:in `perform_action' #{RAILS_ROOT}/vendor/rails/actionpack/lib/action_controller/ base.rb:381:in `send' #{RAILS_ROOT}/vendor/rails/actionpack/lib/action_controller/ base.rb:381:in `process_without_filters' #{RAILS_ROOT}/vendor/rails/actionpack/lib/action_controller/ filters.rb:377:in `process_without_session_management_support' #{RAILS_ROOT}/vendor/rails/actionpack/lib/action_controller/ session_management.rb:117:in `process' #{RAILS_ROOT}/vendor/rails/railties/lib/dispatcher.rb:38:in `dispatch' /usr/local/lib/ruby/gems/1.8/gems/thin-1.0.1/lib/rack/adapter/ rails.rb:60:in `serve_rails' /usr/local/lib/ruby/gems/1.8/gems/thin-1.0.1/lib/rack/adapter/ rails.rb:80:in `call' /home/heroku_rack/lib/static_assets.rb:9:in `call' /home/heroku_rack/lib/last_access.rb:25:in `call' /usr/local/lib/ruby/gems/1.8/gems/rack-1.0.1/lib/rack/urlmap.rb: 46:in `call' /usr/local/lib/ruby/gems/1.8/gems/rack-1.0.1/lib/rack/urlmap.rb: 40:in `each' /usr/local/lib/ruby/gems/1.8/gems/rack-1.0.1/lib/rack/urlmap.rb: 40:in `call' /home/heroku_rack/lib/date_header.rb:14:in `call' /usr/local/lib/ruby/gems/1.8/gems/rack-1.0.1/lib/rack/builder.rb: 60:in `call' /usr/local/lib/ruby/gems/1.8/gems/thin-1.0.1/lib/thin/ connection.rb:80:in `pre_process' /usr/local/lib/ruby/gems/1.8/gems/thin-1.0.1/lib/thin/ connection.rb:78:in `catch' /usr/local/lib/ruby/gems/1.8/gems/thin-1.0.1/lib/thin/ connection.rb:78:in `pre_process' /usr/local/lib/ruby/gems/1.8/gems/thin-1.0.1/lib/thin/ connection.rb:57:in `process' /usr/local/lib/ruby/gems/1.8/gems/thin-1.0.1/lib/thin/ connection.rb:42:in `receive_data' /usr/local/lib/ruby/gems/1.8/gems/eventmachine-0.12.6/lib/ eventmachine.rb:240:in `run_machine' /usr/local/lib/ruby/gems/1.8/gems/eventmachine-0.12.6/lib/ eventmachine.rb:240:in `run' /usr/local/lib/ruby/gems/1.8/gems/thin-1.0.1/lib/thin/backends/ base.rb:57:in `start' /usr/local/lib/ruby/gems/1.8/gems/thin-1.0.1/lib/thin/server.rb: 150:in `start' /usr/local/lib/ruby/gems/1.8/gems/thin-1.0.1/lib/thin/controllers/ controller.rb:80:in `start' /usr/local/lib/ruby/gems/1.8/gems/thin-1.0.1/lib/thin/runner.rb: 173:in `send' /usr/local/lib/ruby/gems/1.8/gems/thin-1.0.1/lib/thin/runner.rb: 173:in `run_command' /usr/local/lib/ruby/gems/1.8/gems/thin-1.0.1/lib/thin/runner.rb: 139:in `run!' /usr/local/lib/ruby/gems/1.8/gems/thin-1.0.1/bin/thin:6 /usr/local/bin/thin:20:in `load' /usr/local/bin/thin:20 Thanks

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  • Why does JAXB not create a member variable in its generated code when an XML schema base type and subtype have the same element declared in them?

    - by belltower
    I have a question regarding with regard to JAXB generated classes. As you can I see, I have a complex type, DG_PaymentIdentification1, declared in my schema. Its a restriction of PaymentIdentification1. DG_PaymentIdentification1 is also identical to PaymentIdentification1. I also have a type called DG_CreditTransferTransactionInformation10 which has a base type of CreditTransferTransactionInformation10 and is identical to it. I have included the relevant XML schema snippets below. <xs:complexType name="DG_PaymentIdentification1"> <xs:complexContent> <xs:restriction base="PaymentIdentification1"> <xs:sequence> <xs:element name="InstrId" type="DG_Max35Text_REF" minOccurs="0"/> <xs:element name="EndToEndId" type="DG_Max35Text_REF" id="DG-41"/> </xs:sequence> </xs:restriction> </xs:complexContent> </xs:complexType> <xs:complexType name="PaymentIdentification1"> <xs:sequence> <xs:element name="InstrId" type="Max35Text" minOccurs="0"/> <xs:element name="EndToEndId" type="Max35Text"/> </xs:sequence> </xs:complexType> <xs:complexType name="DG_CreditTransferTransactionInformation10"> <xs:complexContent> <xs:restriction base="CreditTransferTransactionInformation10"> <xs:sequence> <xs:element name="PmtId" type="DG_PaymentIdentification1"/> <xs:simpleType name="DG_Max35Text_REF"> <xs:restriction base="DG_NotEmpty35"> <xs:pattern value="[\-A-Za-z0-9\+/\?:\(\)\.,'&#x20;]*"/> </xs:restriction> </xs:simpleType> <xs:simpleType name="Max35Text"> <xs:restriction base="xs:string"> <xs:minLength value="1"/> <xs:maxLength value="35"/> </xs:restriction> </xs:simpleType> JAXB generates the following java class for DG_PaymentIdentification1: @XmlAccessorType(XmlAccessType.FIELD) @XmlType(name = "DG_CreditTransferTransactionInformDGion10") public class DGCreditTransferTransactionInformation10 extends CreditTransferTransactionInformation10 { } My question is why doesnt the DGCreditTransferTransactionInformation10 generated class have a variable of type DG_PaymentIdentification1 in the generated code? The base class CreditTransferTransactionInformation10 does have a type PaymentIdentification1 declared in it. Is there any way of ensuring that DGCreditTransferTransactionInformation10 will have a DG_PaymentIdentification1 in it?

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  • Hosting the Razor Engine for Templating in Non-Web Applications

    - by Rick Strahl
    Microsoft’s new Razor HTML Rendering Engine that is currently shipping with ASP.NET MVC previews can be used outside of ASP.NET. Razor is an alternative view engine that can be used instead of the ASP.NET Page engine that currently works with ASP.NET WebForms and MVC. It provides a simpler and more readable markup syntax and is much more light weight in terms of functionality than the full blown WebForms Page engine, focusing only on features that are more along the lines of a pure view engine (or classic ASP!) with focus on expression and code rendering rather than a complex control/object model. Like the Page engine though, the parser understands .NET code syntax which can be embedded into templates, and behind the scenes the engine compiles markup and script code into an executing piece of .NET code in an assembly. Although it ships as part of the ASP.NET MVC and WebMatrix the Razor Engine itself is not directly dependent on ASP.NET or IIS or HTTP in any way. And although there are some markup and rendering features that are optimized for HTML based output generation, Razor is essentially a free standing template engine. And what’s really nice is that unlike the ASP.NET Runtime, Razor is fairly easy to host inside of your own non-Web applications to provide templating functionality. Templating in non-Web Applications? Yes please! So why might you host a template engine in your non-Web application? Template rendering is useful in many places and I have a number of applications that make heavy use of it. One of my applications – West Wind Html Help Builder - exclusively uses template based rendering to merge user supplied help text content into customizable and executable HTML markup templates that provide HTML output for CHM style HTML Help. This is an older product and it’s not actually using .NET at the moment – and this is one reason I’m looking at Razor for script hosting at the moment. For a few .NET applications though I’ve actually used the ASP.NET Runtime hosting to provide templating and mail merge style functionality and while that works reasonably well it’s a very heavy handed approach. It’s very resource intensive and has potential issues with versioning in various different versions of .NET. The generic implementation I created in the article above requires a lot of fix up to mimic an HTTP request in a non-HTTP environment and there are a lot of little things that have to happen to ensure that the ASP.NET runtime works properly most of it having nothing to do with the templating aspect but just satisfying ASP.NET’s requirements. The Razor Engine on the other hand is fairly light weight and completely decoupled from the ASP.NET runtime and the HTTP processing. Rather it’s a pure template engine whose sole purpose is to render text templates. Hosting this engine in your own applications can be accomplished with a reasonable amount of code (actually just a few lines with the tools I’m about to describe) and without having to fake HTTP requests. It’s also much lighter on resource usage and you can easily attach custom properties to your base template implementation to easily pass context from the parent application into templates all of which was rather complicated with ASP.NET runtime hosting. Installing the Razor Template Engine You can get Razor as part of the MVC 3 (RC and later) or Web Matrix. Both are available as downloadable components from the Web Platform Installer Version 3.0 (!important – V2 doesn’t show these components). If you already have that version of the WPI installed just fire it up. You can get the latest version of the Web Platform Installer from here: http://www.microsoft.com/web/gallery/install.aspx Once the platform Installer 3.0 is installed install either MVC 3 or ASP.NET Web Pages. Once installed you’ll find a System.Web.Razor assembly in C:\Program Files\Microsoft ASP.NET\ASP.NET Web Pages\v1.0\Assemblies\System.Web.Razor.dll which you can add as a reference to your project. Creating a Wrapper The basic Razor Hosting API is pretty simple and you can host Razor with a (large-ish) handful of lines of code. I’ll show the basics of it later in this article. However, if you want to customize the rendering and handle assembly and namespace includes for the markup as well as deal with text and file inputs as well as forcing Razor to run in a separate AppDomain so you can unload the code-generated assemblies and deal with assembly caching for re-used templates little more work is required to create something that is more easily reusable. For this reason I created a Razor Hosting wrapper project that combines a bunch of this functionality into an easy to use hosting class, a hosting factory that can load the engine in a separate AppDomain and a couple of hosting containers that provided folder based and string based caching for templates for an easily embeddable and reusable engine with easy to use syntax. If you just want the code and play with the samples and source go grab the latest code from the Subversion Repository at: http://www.west-wind.com:8080/svn/articles/trunk/RazorHosting/ or a snapshot from: http://www.west-wind.com/files/tools/RazorHosting.zip Getting Started Before I get into how hosting with Razor works, let’s take a look at how you can get up and running quickly with the wrapper classes provided. It only takes a few lines of code. The easiest way to use these Razor Hosting Wrappers is to use one of the two HostContainers provided. One is for hosting Razor scripts in a directory and rendering them as relative paths from these script files on disk. The other HostContainer serves razor scripts from string templates… Let’s start with a very simple template that displays some simple expressions, some code blocks and demonstrates rendering some data from contextual data that you pass to the template in the form of a ‘context’. Here’s a simple Razor template: @using System.Reflection Hello @Context.FirstName! Your entry was entered on: @Context.Entered @{ // Code block: Update the host Windows Form passed in through the context Context.WinForm.Text = "Hello World from Razor at " + DateTime.Now.ToString(); } AppDomain Id: @AppDomain.CurrentDomain.FriendlyName Assembly: @Assembly.GetExecutingAssembly().FullName Code based output: @{ // Write output with Response object from code string output = string.Empty; for (int i = 0; i < 10; i++) { output += i.ToString() + " "; } Response.Write(output); } Pretty easy to see what’s going on here. The only unusual thing in this code is the Context object which is an arbitrary object I’m passing from the host to the template by way of the template base class. I’m also displaying the current AppDomain and the executing Assembly name so you can see how compiling and running a template actually loads up new assemblies. Also note that as part of my context I’m passing a reference to the current Windows Form down to the template and changing the title from within the script. It’s a silly example, but it demonstrates two-way communication between host and template and back which can be very powerful. The easiest way to quickly render this template is to use the RazorEngine<TTemplateBase> class. The generic parameter specifies a template base class type that is used by Razor internally to generate the class it generates from a template. The default implementation provided in my RazorHosting wrapper is RazorTemplateBase. Here’s a simple one that renders from a string and outputs a string: var engine = new RazorEngine<RazorTemplateBase>(); // we can pass any object as context - here create a custom context var context = new CustomContext() { WinForm = this, FirstName = "Rick", Entered = DateTime.Now.AddDays(-10) }; string output = engine.RenderTemplate(this.txtSource.Text new string[] { "System.Windows.Forms.dll" }, context); if (output == null) this.txtResult.Text = "*** ERROR:\r\n" + engine.ErrorMessage; else this.txtResult.Text = output; Simple enough. This code renders a template from a string input and returns a result back as a string. It  creates a custom context and passes that to the template which can then access the Context’s properties. Note that anything passed as ‘context’ must be serializable (or MarshalByRefObject) – otherwise you get an exception when passing the reference over AppDomain boundaries (discussed later). Passing a context is optional, but is a key feature in being able to share data between the host application and the template. Note that we use the Context object to access FirstName, Entered and even the host Windows Form object which is used in the template to change the Window caption from within the script! In the code above all the work happens in the RenderTemplate method which provide a variety of overloads to read and write to and from strings, files and TextReaders/Writers. Here’s another example that renders from a file input using a TextReader: using (reader = new StreamReader("templates\\simple.csHtml", true)) { result = host.RenderTemplate(reader, new string[] { "System.Windows.Forms.dll" }, this.CustomContext); } RenderTemplate() is fairly high level and it handles loading of the runtime, compiling into an assembly and rendering of the template. If you want more control you can use the lower level methods to control each step of the way which is important for the HostContainers I’ll discuss later. Basically for those scenarios you want to separate out loading of the engine, compiling into an assembly and then rendering the template from the assembly. Why? So we can keep assemblies cached. In the code above a new assembly is created for each template rendered which is inefficient and uses up resources. Depending on the size of your templates and how often you fire them you can chew through memory very quickly. This slighter lower level approach is only a couple of extra steps: // we can pass any object as context - here create a custom context var context = new CustomContext() { WinForm = this, FirstName = "Rick", Entered = DateTime.Now.AddDays(-10) }; var engine = new RazorEngine<RazorTemplateBase>(); string assId = null; using (StringReader reader = new StringReader(this.txtSource.Text)) { assId = engine.ParseAndCompileTemplate(new string[] { "System.Windows.Forms.dll" }, reader); } string output = engine.RenderTemplateFromAssembly(assId, context); if (output == null) this.txtResult.Text = "*** ERROR:\r\n" + engine.ErrorMessage; else this.txtResult.Text = output; The difference here is that you can capture the assembly – or rather an Id to it – and potentially hold on to it to render again later assuming the template hasn’t changed. The HostContainers take advantage of this feature to cache the assemblies based on certain criteria like a filename and file time step or a string hash that if not change indicate that an assembly can be reused. Note that ParseAndCompileTemplate returns an assembly Id rather than the assembly itself. This is done so that that the assembly always stays in the host’s AppDomain and is not passed across AppDomain boundaries which would cause load failures. We’ll talk more about this in a minute but for now just realize that assemblies references are stored in a list and are accessible by this ID to allow locating and re-executing of the assembly based on that id. Reuse of the assembly avoids recompilation overhead and creation of yet another assembly that loads into the current AppDomain. You can play around with several different versions of the above code in the main sample form:   Using Hosting Containers for more Control and Caching The above examples simply render templates into assemblies each and every time they are executed. While this works and is even reasonably fast, it’s not terribly efficient. If you render templates more than once it would be nice if you could cache the generated assemblies for example to avoid re-compiling and creating of a new assembly each time. Additionally it would be nice to load template assemblies into a separate AppDomain optionally to be able to be able to unload assembli es and also to protect your host application from scripting attacks with malicious template code. Hosting containers provide also provide a wrapper around the RazorEngine<T> instance, a factory (which allows creation in separate AppDomains) and an easy way to start and stop the container ‘runtime’. The Razor Hosting samples provide two hosting containers: RazorFolderHostContainer and StringHostContainer. The folder host provides a simple runtime environment for a folder structure similar in the way that the ASP.NET runtime handles a virtual directory as it’s ‘application' root. Templates are loaded from disk in relative paths and the resulting assemblies are cached unless the template on disk is changed. The string host also caches templates based on string hashes – if the same string is passed a second time a cached version of the assembly is used. Here’s how HostContainers work. I’ll use the FolderHostContainer because it’s likely the most common way you’d use templates – from disk based templates that can be easily edited and maintained on disk. The first step is to create an instance of it and keep it around somewhere (in the example it’s attached as a property to the Form): RazorFolderHostContainer Host = new RazorFolderHostContainer(); public RazorFolderHostForm() { InitializeComponent(); // The base path for templates - templates are rendered with relative paths // based on this path. Host.TemplatePath = Path.Combine(Environment.CurrentDirectory, TemplateBaseFolder); // Add any assemblies you want reference in your templates Host.ReferencedAssemblies.Add("System.Windows.Forms.dll"); // Start up the host container Host.Start(); } Next anytime you want to render a template you can use simple code like this: private void RenderTemplate(string fileName) { // Pass the template path via the Context var relativePath = Utilities.GetRelativePath(fileName, Host.TemplatePath); if (!Host.RenderTemplate(relativePath, this.Context, Host.RenderingOutputFile)) { MessageBox.Show("Error: " + Host.ErrorMessage); return; } this.webBrowser1.Navigate("file://" + Host.RenderingOutputFile); } You can also render the output to a string instead of to a file: string result = Host.RenderTemplateToString(relativePath,context); Finally if you want to release the engine and shut down the hosting AppDomain you can simply do: Host.Stop(); Stopping the AppDomain and restarting it (ie. calling Stop(); followed by Start()) is also a nice way to release all resources in the AppDomain. The FolderBased domain also supports partial Rendering based on root path based relative paths with the same caching characteristics as the main templates. From within a template you can call out to a partial like this: @RenderPartial(@"partials\PartialRendering.cshtml", Context) where partials\PartialRendering.cshtml is a relative to the template root folder. The folder host example lets you load up templates from disk and display the result in a Web Browser control which demonstrates using Razor HTML output from templates that contain HTML syntax which happens to me my target scenario for Html Help Builder.   The Razor Engine Wrapper Project The project I created to wrap Razor hosting has a fair bit of code and a number of classes associated with it. Most of the components are internally used and as you can see using the final RazorEngine<T> and HostContainer classes is pretty easy. The classes are extensible and I suspect developers will want to build more customized host containers for their applications. Host containers are the key to wrapping up all functionality – Engine, BaseTemplate, AppDomain Hosting, Caching etc in a logical piece that is ready to be plugged into an application. When looking at the code there are a couple of core features provided: Core Razor Engine Hosting This is the core Razor hosting which provides the basics of loading a template, compiling it into an assembly and executing it. This is fairly straightforward, but without a host container that can cache assemblies based on some criteria templates are recompiled and re-created each time which is inefficient (although pretty fast). The base engine wrapper implementation also supports hosting the Razor runtime in a separate AppDomain for security and the ability to unload it on demand. Host Containers The engine hosting itself doesn’t provide any sort of ‘runtime’ service like picking up files from disk, caching assemblies and so forth. So my implementation provides two HostContainers: RazorFolderHostContainer and RazorStringHostContainer. The FolderHost works off a base directory and loads templates based on relative paths (sort of like the ASP.NET runtime does off a virtual). The HostContainers also deal with caching of template assemblies – for the folder host the file date is tracked and checked for updates and unless the template is changed a cached assembly is reused. The StringHostContainer similiarily checks string hashes to figure out whether a particular string template was previously compiled and executed. The HostContainers also act as a simple startup environment and a single reference to easily store and reuse in an application. TemplateBase Classes The template base classes are the base classes that from which the Razor engine generates .NET code. A template is parsed into a class with an Execute() method and the class is based on this template type you can specify. RazorEngine<TBaseTemplate> can receive this type and the HostContainers default to specific templates in their base implementations. Template classes are customizable to allow you to create templates that provide application specific features and interaction from the template to your host application. How does the RazorEngine wrapper work? You can browse the source code in the links above or in the repository or download the source, but I’ll highlight some key features here. Here’s part of the RazorEngine implementation that can be used to host the runtime and that demonstrates the key code required to host the Razor runtime. The RazorEngine class is implemented as a generic class to reflect the Template base class type: public class RazorEngine<TBaseTemplateType> : MarshalByRefObject where TBaseTemplateType : RazorTemplateBase The generic type is used to internally provide easier access to the template type and assignments on it as part of the template processing. The class also inherits MarshalByRefObject to allow execution over AppDomain boundaries – something that all the classes discussed here need to do since there is much interaction between the host and the template. The first two key methods deal with creating a template assembly: /// <summary> /// Creates an instance of the RazorHost with various options applied. /// Applies basic namespace imports and the name of the class to generate /// </summary> /// <param name="generatedNamespace"></param> /// <param name="generatedClass"></param> /// <returns></returns> protected RazorTemplateEngine CreateHost(string generatedNamespace, string generatedClass) { Type baseClassType = typeof(TBaseTemplateType); RazorEngineHost host = new RazorEngineHost(new CSharpRazorCodeLanguage()); host.DefaultBaseClass = baseClassType.FullName; host.DefaultClassName = generatedClass; host.DefaultNamespace = generatedNamespace; host.NamespaceImports.Add("System"); host.NamespaceImports.Add("System.Text"); host.NamespaceImports.Add("System.Collections.Generic"); host.NamespaceImports.Add("System.Linq"); host.NamespaceImports.Add("System.IO"); return new RazorTemplateEngine(host); } /// <summary> /// Parses and compiles a markup template into an assembly and returns /// an assembly name. The name is an ID that can be passed to /// ExecuteTemplateByAssembly which picks up a cached instance of the /// loaded assembly. /// /// </summary> /// <param name="namespaceOfGeneratedClass">The namespace of the class to generate from the template</param> /// <param name="generatedClassName">The name of the class to generate from the template</param> /// <param name="ReferencedAssemblies">Any referenced assemblies by dll name only. Assemblies must be in execution path of host or in GAC.</param> /// <param name="templateSourceReader">Textreader that loads the template</param> /// <remarks> /// The actual assembly isn't returned here to allow for cross-AppDomain /// operation. If the assembly was returned it would fail for cross-AppDomain /// calls. /// </remarks> /// <returns>An assembly Id. The Assembly is cached in memory and can be used with RenderFromAssembly.</returns> public string ParseAndCompileTemplate( string namespaceOfGeneratedClass, string generatedClassName, string[] ReferencedAssemblies, TextReader templateSourceReader) { RazorTemplateEngine engine = CreateHost(namespaceOfGeneratedClass, generatedClassName); // Generate the template class as CodeDom GeneratorResults razorResults = engine.GenerateCode(templateSourceReader); // Create code from the codeDom and compile CSharpCodeProvider codeProvider = new CSharpCodeProvider(); CodeGeneratorOptions options = new CodeGeneratorOptions(); // Capture Code Generated as a string for error info // and debugging LastGeneratedCode = null; using (StringWriter writer = new StringWriter()) { codeProvider.GenerateCodeFromCompileUnit(razorResults.GeneratedCode, writer, options); LastGeneratedCode = writer.ToString(); } CompilerParameters compilerParameters = new CompilerParameters(ReferencedAssemblies); // Standard Assembly References compilerParameters.ReferencedAssemblies.Add("System.dll"); compilerParameters.ReferencedAssemblies.Add("System.Core.dll"); compilerParameters.ReferencedAssemblies.Add("Microsoft.CSharp.dll"); // dynamic support! // Also add the current assembly so RazorTemplateBase is available compilerParameters.ReferencedAssemblies.Add(Assembly.GetExecutingAssembly().CodeBase.Substring(8)); compilerParameters.GenerateInMemory = Configuration.CompileToMemory; if (!Configuration.CompileToMemory) compilerParameters.OutputAssembly = Path.Combine(Configuration.TempAssemblyPath, "_" + Guid.NewGuid().ToString("n") + ".dll"); CompilerResults compilerResults = codeProvider.CompileAssemblyFromDom(compilerParameters, razorResults.GeneratedCode); if (compilerResults.Errors.Count > 0) { var compileErrors = new StringBuilder(); foreach (System.CodeDom.Compiler.CompilerError compileError in compilerResults.Errors) compileErrors.Append(String.Format(Resources.LineX0TColX1TErrorX2RN, compileError.Line, compileError.Column, compileError.ErrorText)); this.SetError(compileErrors.ToString() + "\r\n" + LastGeneratedCode); return null; } AssemblyCache.Add(compilerResults.CompiledAssembly.FullName, compilerResults.CompiledAssembly); return compilerResults.CompiledAssembly.FullName; } Think of the internal CreateHost() method as setting up the assembly generated from each template. Each template compiles into a separate assembly. It sets up namespaces, and assembly references, the base class used and the name and namespace for the generated class. ParseAndCompileTemplate() then calls the CreateHost() method to receive the template engine generator which effectively generates a CodeDom from the template – the template is turned into .NET code. The code generated from our earlier example looks something like this: //------------------------------------------------------------------------------ // <auto-generated> // This code was generated by a tool. // Runtime Version:4.0.30319.1 // // Changes to this file may cause incorrect behavior and will be lost if // the code is regenerated. // </auto-generated> //------------------------------------------------------------------------------ namespace RazorTest { using System; using System.Text; using System.Collections.Generic; using System.Linq; using System.IO; using System.Reflection; public class RazorTemplate : RazorHosting.RazorTemplateBase { #line hidden public RazorTemplate() { } public override void Execute() { WriteLiteral("Hello "); Write(Context.FirstName); WriteLiteral("! Your entry was entered on: "); Write(Context.Entered); WriteLiteral("\r\n\r\n"); // Code block: Update the host Windows Form passed in through the context Context.WinForm.Text = "Hello World from Razor at " + DateTime.Now.ToString(); WriteLiteral("\r\nAppDomain Id:\r\n "); Write(AppDomain.CurrentDomain.FriendlyName); WriteLiteral("\r\n \r\nAssembly:\r\n "); Write(Assembly.GetExecutingAssembly().FullName); WriteLiteral("\r\n\r\nCode based output: \r\n"); // Write output with Response object from code string output = string.Empty; for (int i = 0; i < 10; i++) { output += i.ToString() + " "; } } } } Basically the template’s body is turned into code in an Execute method that is called. Internally the template’s Write method is fired to actually generate the output. Note that the class inherits from RazorTemplateBase which is the generic parameter I used to specify the base class when creating an instance in my RazorEngine host: var engine = new RazorEngine<RazorTemplateBase>(); This template class must be provided and it must implement an Execute() and Write() method. Beyond that you can create any class you chose and attach your own properties. My RazorTemplateBase class implementation is very simple: public class RazorTemplateBase : MarshalByRefObject, IDisposable { /// <summary> /// You can pass in a generic context object /// to use in your template code /// </summary> public dynamic Context { get; set; } /// <summary> /// Class that generates output. Currently ultra simple /// with only Response.Write() implementation. /// </summary> public RazorResponse Response { get; set; } public object HostContainer {get; set; } public object Engine { get; set; } public RazorTemplateBase() { Response = new RazorResponse(); } public virtual void Write(object value) { Response.Write(value); } public virtual void WriteLiteral(object value) { Response.Write(value); } /// <summary> /// Razor Parser implements this method /// </summary> public virtual void Execute() {} public virtual void Dispose() { if (Response != null) { Response.Dispose(); Response = null; } } } Razor fills in the Execute method when it generates its subclass and uses the Write() method to output content. As you can see I use a RazorResponse() class here to generate output. This isn’t necessary really, as you could use a StringBuilder or StringWriter() directly, but I prefer using Response object so I can extend the Response behavior as needed. The RazorResponse class is also very simple and merely acts as a wrapper around a TextWriter: public class RazorResponse : IDisposable { /// <summary> /// Internal text writer - default to StringWriter() /// </summary> public TextWriter Writer = new StringWriter(); public virtual void Write(object value) { Writer.Write(value); } public virtual void WriteLine(object value) { Write(value); Write("\r\n"); } public virtual void WriteFormat(string format, params object[] args) { Write(string.Format(format, args)); } public override string ToString() { return Writer.ToString(); } public virtual void Dispose() { Writer.Close(); } public virtual void SetTextWriter(TextWriter writer) { // Close original writer if (Writer != null) Writer.Close(); Writer = writer; } } The Rendering Methods of RazorEngine At this point I’ve talked about the assembly generation logic and the template implementation itself. What’s left is that once you’ve generated the assembly is to execute it. The code to do this is handled in the various RenderXXX methods of the RazorEngine class. Let’s look at the lowest level one of these which is RenderTemplateFromAssembly() and a couple of internal support methods that handle instantiating and invoking of the generated template method: public string RenderTemplateFromAssembly( string assemblyId, string generatedNamespace, string generatedClass, object context, TextWriter outputWriter) { this.SetError(); Assembly generatedAssembly = AssemblyCache[assemblyId]; if (generatedAssembly == null) { this.SetError(Resources.PreviouslyCompiledAssemblyNotFound); return null; } string className = generatedNamespace + "." + generatedClass; Type type; try { type = generatedAssembly.GetType(className); } catch (Exception ex) { this.SetError(Resources.UnableToCreateType + className + ": " + ex.Message); return null; } // Start with empty non-error response (if we use a writer) string result = string.Empty; using(TBaseTemplateType instance = InstantiateTemplateClass(type)) { if (instance == null) return null; if (outputWriter != null) instance.Response.SetTextWriter(outputWriter); if (!InvokeTemplateInstance(instance, context)) return null; // Capture string output if implemented and return // otherwise null is returned if (outputWriter == null) result = instance.Response.ToString(); } return result; } protected virtual TBaseTemplateType InstantiateTemplateClass(Type type) { TBaseTemplateType instance = Activator.CreateInstance(type) as TBaseTemplateType; if (instance == null) { SetError(Resources.CouldnTActivateTypeInstance + type.FullName); return null; } instance.Engine = this; // If a HostContainer was set pass that to the template too instance.HostContainer = this.HostContainer; return instance; } /// <summary> /// Internally executes an instance of the template, /// captures errors on execution and returns true or false /// </summary> /// <param name="instance">An instance of the generated template</param> /// <returns>true or false - check ErrorMessage for errors</returns> protected virtual bool InvokeTemplateInstance(TBaseTemplateType instance, object context) { try { instance.Context = context; instance.Execute(); } catch (Exception ex) { this.SetError(Resources.TemplateExecutionError + ex.Message); return false; } finally { // Must make sure Response is closed instance.Response.Dispose(); } return true; } The RenderTemplateFromAssembly method basically requires the namespace and class to instantate and creates an instance of the class using InstantiateTemplateClass(). It then invokes the method with InvokeTemplateInstance(). These two methods are broken out because they are re-used by various other rendering methods and also to allow subclassing and providing additional configuration tasks to set properties and pass values to templates at execution time. In the default mode instantiation sets the Engine and HostContainer (discussed later) so the template can call back into the template engine, and the context is set when the template method is invoked. The various RenderXXX methods use similar code although they create the assemblies first. If you’re after potentially cashing assemblies the method is the one to call and that’s exactly what the two HostContainer classes do. More on that in a minute, but before we get into HostContainers let’s talk about AppDomain hosting and the like. Running Templates in their own AppDomain With the RazorEngine class above, when a template is parsed into an assembly and executed the assembly is created (in memory or on disk – you can configure that) and cached in the current AppDomain. In .NET once an assembly has been loaded it can never be unloaded so if you’re loading lots of templates and at some time you want to release them there’s no way to do so. If however you load the assemblies in a separate AppDomain that new AppDomain can be unloaded and the assemblies loaded in it with it. In order to host the templates in a separate AppDomain the easiest thing to do is to run the entire RazorEngine in a separate AppDomain. Then all interaction occurs in the other AppDomain and no further changes have to be made. To facilitate this there is a RazorEngineFactory which has methods that can instantiate the RazorHost in a separate AppDomain as well as in the local AppDomain. The host creates the remote instance and then hangs on to it to keep it alive as well as providing methods to shut down the AppDomain and reload the engine. Sounds complicated but cross-AppDomain invocation is actually fairly easy to implement. Here’s some of the relevant code from the RazorEngineFactory class. Like the RazorEngine this class is generic and requires a template base type in the generic class name: public class RazorEngineFactory<TBaseTemplateType> where TBaseTemplateType : RazorTemplateBase Here are the key methods of interest: /// <summary> /// Creates an instance of the RazorHost in a new AppDomain. This /// version creates a static singleton that that is cached and you /// can call UnloadRazorHostInAppDomain to unload it. /// </summary> /// <returns></returns> public static RazorEngine<TBaseTemplateType> CreateRazorHostInAppDomain() { if (Current == null) Current = new RazorEngineFactory<TBaseTemplateType>(); return Current.GetRazorHostInAppDomain(); } public static void UnloadRazorHostInAppDomain() { if (Current != null) Current.UnloadHost(); Current = null; } /// <summary> /// Instance method that creates a RazorHost in a new AppDomain. /// This method requires that you keep the Factory around in /// order to keep the AppDomain alive and be able to unload it. /// </summary> /// <returns></returns> public RazorEngine<TBaseTemplateType> GetRazorHostInAppDomain() { LocalAppDomain = CreateAppDomain(null); if (LocalAppDomain == null) return null; /// Create the instance inside of the new AppDomain /// Note: remote domain uses local EXE's AppBasePath!!! RazorEngine<TBaseTemplateType> host = null; try { Assembly ass = Assembly.GetExecutingAssembly(); string AssemblyPath = ass.Location; host = (RazorEngine<TBaseTemplateType>) LocalAppDomain.CreateInstanceFrom(AssemblyPath, typeof(RazorEngine<TBaseTemplateType>).FullName).Unwrap(); } catch (Exception ex) { ErrorMessage = ex.Message; return null; } return host; } /// <summary> /// Internally creates a new AppDomain in which Razor templates can /// be run. /// </summary> /// <param name="appDomainName"></param> /// <returns></returns> private AppDomain CreateAppDomain(string appDomainName) { if (appDomainName == null) appDomainName = "RazorHost_" + Guid.NewGuid().ToString("n"); AppDomainSetup setup = new AppDomainSetup(); // *** Point at current directory setup.ApplicationBase = AppDomain.CurrentDomain.BaseDirectory; AppDomain localDomain = AppDomain.CreateDomain(appDomainName, null, setup); return localDomain; } /// <summary> /// Allow unloading of the created AppDomain to release resources /// All internal resources in the AppDomain are released including /// in memory compiled Razor assemblies. /// </summary> public void UnloadHost() { if (this.LocalAppDomain != null) { AppDomain.Unload(this.LocalAppDomain); this.LocalAppDomain = null; } } The static CreateRazorHostInAppDomain() is the key method that startup code usually calls. It uses a Current singleton instance to an instance of itself that is created cross AppDomain and is kept alive because it’s static. GetRazorHostInAppDomain actually creates a cross-AppDomain instance which first creates a new AppDomain and then loads the RazorEngine into it. The remote Proxy instance is returned as a result to the method and can be used the same as a local instance. The code to run with a remote AppDomain is simple: private RazorEngine<RazorTemplateBase> CreateHost() { if (this.Host != null) return this.Host; // Use Static Methods - no error message if host doesn't load this.Host = RazorEngineFactory<RazorTemplateBase>.CreateRazorHostInAppDomain(); if (this.Host == null) { MessageBox.Show("Unable to load Razor Template Host", "Razor Hosting", MessageBoxButtons.OK, MessageBoxIcon.Exclamation); } return this.Host; } This code relies on a local reference of the Host which is kept around for the duration of the app (in this case a form reference). To use this you’d simply do: this.Host = CreateHost(); if (host == null) return; string result = host.RenderTemplate( this.txtSource.Text, new string[] { "System.Windows.Forms.dll", "Westwind.Utilities.dll" }, this.CustomContext); if (result == null) { MessageBox.Show(host.ErrorMessage, "Template Execution Error", MessageBoxButtons.OK, MessageBoxIcon.Exclamation); return; } this.txtResult.Text = result; Now all templates run in a remote AppDomain and can be unloaded with simple code like this: RazorEngineFactory<RazorTemplateBase>.UnloadRazorHostInAppDomain(); this.Host = null; One Step further – Providing a caching ‘Runtime’ Once we can load templates in a remote AppDomain we can add some additional functionality like assembly caching based on application specific features. One of my typical scenarios is to render templates out of a scripts folder. So all templates live in a folder and they change infrequently. So a Folder based host that can compile these templates once and then only recompile them if something changes would be ideal. Enter host containers which are basically wrappers around the RazorEngine<t> and RazorEngineFactory<t>. They provide additional logic for things like file caching based on changes on disk or string hashes for string based template inputs. The folder host also provides for partial rendering logic through a custom template base implementation. There’s a base implementation in RazorBaseHostContainer, which provides the basics for hosting a RazorEngine, which includes the ability to start and stop the engine, cache assemblies and add references: public abstract class RazorBaseHostContainer<TBaseTemplateType> : MarshalByRefObject where TBaseTemplateType : RazorTemplateBase, new() { public RazorBaseHostContainer() { UseAppDomain = true; GeneratedNamespace = "__RazorHost"; } /// <summary> /// Determines whether the Container hosts Razor /// in a separate AppDomain. Seperate AppDomain /// hosting allows unloading and releasing of /// resources. /// </summary> public bool UseAppDomain { get; set; } /// <summary> /// Base folder location where the AppDomain /// is hosted. By default uses the same folder /// as the host application. /// /// Determines where binary dependencies are /// found for assembly references. /// </summary> public string BaseBinaryFolder { get; set; } /// <summary> /// List of referenced assemblies as string values. /// Must be in GAC or in the current folder of the host app/ /// base BinaryFolder /// </summary> public List<string> ReferencedAssemblies = new List<string>(); /// <summary> /// Name of the generated namespace for template classes /// </summary> public string GeneratedNamespace {get; set; } /// <summary> /// Any error messages /// </summary> public string ErrorMessage { get; set; } /// <summary> /// Cached instance of the Host. Required to keep the /// reference to the host alive for multiple uses. /// </summary> public RazorEngine<TBaseTemplateType> Engine; /// <summary> /// Cached instance of the Host Factory - so we can unload /// the host and its associated AppDomain. /// </summary> protected RazorEngineFactory<TBaseTemplateType> EngineFactory; /// <summary> /// Keep track of each compiled assembly /// and when it was compiled. /// /// Use a hash of the string to identify string /// changes. /// </summary> protected Dictionary<int, CompiledAssemblyItem> LoadedAssemblies = new Dictionary<int, CompiledAssemblyItem>(); /// <summary> /// Call to start the Host running. Follow by a calls to RenderTemplate to /// render individual templates. Call Stop when done. /// </summary> /// <returns>true or false - check ErrorMessage on false </returns> public virtual bool Start() { if (Engine == null) { if (UseAppDomain) Engine = RazorEngineFactory<TBaseTemplateType>.CreateRazorHostInAppDomain(); else Engine = RazorEngineFactory<TBaseTemplateType>.CreateRazorHost(); Engine.Configuration.CompileToMemory = true; Engine.HostContainer = this; if (Engine == null) { this.ErrorMessage = EngineFactory.ErrorMessage; return false; } } return true; } /// <summary> /// Stops the Host and releases the host AppDomain and cached /// assemblies. /// </summary> /// <returns>true or false</returns> public bool Stop() { this.LoadedAssemblies.Clear(); RazorEngineFactory<RazorTemplateBase>.UnloadRazorHostInAppDomain(); this.Engine = null; return true; } … } This base class provides most of the mechanics to host the runtime, but no application specific implementation for rendering. There are rendering functions but they just call the engine directly and provide no caching – there’s no context to decide how to cache and reuse templates. The key methods are Start and Stop and their main purpose is to start a new AppDomain (optionally) and shut it down when requested. The RazorFolderHostContainer – Folder Based Runtime Hosting Let’s look at the more application specific RazorFolderHostContainer implementation which is defined like this: public class RazorFolderHostContainer : RazorBaseHostContainer<RazorTemplateFolderHost> Note that a customized RazorTemplateFolderHost class template is used for this implementation that supports partial rendering in form of a RenderPartial() method that’s available to templates. The folder host’s features are: Render templates based on a Template Base Path (a ‘virtual’ if you will) Cache compiled assemblies based on the relative path and file time stamp File changes on templates cause templates to be recompiled into new assemblies Support for partial rendering using base folder relative pathing As shown in the startup examples earlier host containers require some startup code with a HostContainer tied to a persistent property (like a Form property): // The base path for templates - templates are rendered with relative paths // based on this path. HostContainer.TemplatePath = Path.Combine(Environment.CurrentDirectory, TemplateBaseFolder); // Default output rendering disk location HostContainer.RenderingOutputFile = Path.Combine(HostContainer.TemplatePath, "__Preview.htm"); // Add any assemblies you want reference in your templates HostContainer.ReferencedAssemblies.Add("System.Windows.Forms.dll"); // Start up the host container HostContainer.Start(); Once that’s done, you can render templates with the host container: // Pass the template path for full filename seleted with OpenFile Dialog // relativepath is: subdir\file.cshtml or file.cshtml or ..\file.cshtml var relativePath = Utilities.GetRelativePath(fileName, HostContainer.TemplatePath); if (!HostContainer.RenderTemplate(relativePath, Context, HostContainer.RenderingOutputFile)) { MessageBox.Show("Error: " + HostContainer.ErrorMessage); return; } webBrowser1.Navigate("file://" + HostContainer.RenderingOutputFile); The most critical task of the RazorFolderHostContainer implementation is to retrieve a template from disk, compile and cache it and then deal with deciding whether subsequent requests need to re-compile the template or simply use a cached version. Internally the GetAssemblyFromFileAndCache() handles this task: /// <summary> /// Internally checks if a cached assembly exists and if it does uses it /// else creates and compiles one. Returns an assembly Id to be /// used with the LoadedAssembly list. /// </summary> /// <param name="relativePath"></param> /// <param name="context"></param> /// <returns></returns> protected virtual CompiledAssemblyItem GetAssemblyFromFileAndCache(string relativePath) { string fileName = Path.Combine(TemplatePath, relativePath).ToLower(); int fileNameHash = fileName.GetHashCode(); if (!File.Exists(fileName)) { this.SetError(Resources.TemplateFileDoesnTExist + fileName); return null; } CompiledAssemblyItem item = null; this.LoadedAssemblies.TryGetValue(fileNameHash, out item); string assemblyId = null; // Check for cached instance if (item != null) { var fileTime = File.GetLastWriteTimeUtc(fileName); if (fileTime <= item.CompileTimeUtc) assemblyId = item.AssemblyId; } else item = new CompiledAssemblyItem(); // No cached instance - create assembly and cache if (assemblyId == null) { string safeClassName = GetSafeClassName(fileName); StreamReader reader = null; try { reader = new StreamReader(fileName, true); } catch (Exception ex) { this.SetError(Resources.ErrorReadingTemplateFile + fileName); return null; } assemblyId = Engine.ParseAndCompileTemplate(this.ReferencedAssemblies.ToArray(), reader); // need to ensure reader is closed if (reader != null) reader.Close(); if (assemblyId == null) { this.SetError(Engine.ErrorMessage); return null; } item.AssemblyId = assemblyId; item.CompileTimeUtc = DateTime.UtcNow; item.FileName = fileName; item.SafeClassName = safeClassName; this.LoadedAssemblies[fileNameHash] = item; } return item; } This code uses a LoadedAssembly dictionary which is comprised of a structure that holds a reference to a compiled assembly, a full filename and file timestamp and an assembly id. LoadedAssemblies (defined on the base class shown earlier) is essentially a cache for compiled assemblies and they are identified by a hash id. In the case of files the hash is a GetHashCode() from the full filename of the template. The template is checked for in the cache and if not found the file stamp is checked. If that’s newer than the cache’s compilation date the template is recompiled otherwise the version in the cache is used. All the core work defers to a RazorEngine<T> instance to ParseAndCompileTemplate(). The three rendering specific methods then are rather simple implementations with just a few lines of code dealing with parameter and return value parsing: /// <summary> /// Renders a template to a TextWriter. Useful to write output into a stream or /// the Response object. Used for partial rendering. /// </summary> /// <param name="relativePath">Relative path to the file in the folder structure</param> /// <param name="context">Optional context object or null</param> /// <param name="writer">The textwriter to write output into</param> /// <returns></returns> public bool RenderTemplate(string relativePath, object context, TextWriter writer) { // Set configuration data that is to be passed to the template (any object) Engine.TemplatePerRequestConfigurationData = new RazorFolderHostTemplateConfiguration() { TemplatePath = Path.Combine(this.TemplatePath, relativePath), TemplateRelativePath = relativePath, }; CompiledAssemblyItem item = GetAssemblyFromFileAndCache(relativePath); if (item == null) { writer.Close(); return false; } try { // String result will be empty as output will be rendered into the // Response object's stream output. However a null result denotes // an error string result = Engine.RenderTemplateFromAssembly(item.AssemblyId, context, writer); if (result == null) { this.SetError(Engine.ErrorMessage); return false; } } catch (Exception ex) { this.SetError(ex.Message); return false; } finally { writer.Close(); } return true; } /// <summary> /// Render a template from a source file on disk to a specified outputfile. /// </summary> /// <param name="relativePath">Relative path off the template root folder. Format: path/filename.cshtml</param> /// <param name="context">Any object that will be available in the template as a dynamic of this.Context</param> /// <param name="outputFile">Optional - output file where output is written to. If not specified the /// RenderingOutputFile property is used instead /// </param> /// <returns>true if rendering succeeds, false on failure - check ErrorMessage</returns> public bool RenderTemplate(string relativePath, object context, string outputFile) { if (outputFile == null) outputFile = RenderingOutputFile; try { using (StreamWriter writer = new StreamWriter(outputFile, false, Engine.Configuration.OutputEncoding, Engine.Configuration.StreamBufferSize)) { return RenderTemplate(relativePath, context, writer); } } catch (Exception ex) { this.SetError(ex.Message); return false; } return true; } /// <summary> /// Renders a template to string. Useful for RenderTemplate /// </summary> /// <param name="relativePath"></param> /// <param name="context"></param> /// <returns></returns> public string RenderTemplateToString(string relativePath, object context) { string result = string.Empty; try { using (StringWriter writer = new StringWriter()) { // String result will be empty as output will be rendered into the // Response object's stream output. However a null result denotes // an error if (!RenderTemplate(relativePath, context, writer)) { this.SetError(Engine.ErrorMessage); return null; } result = writer.ToString(); } } catch (Exception ex) { this.SetError(ex.Message); return null; } return result; } The idea is that you can create custom host container implementations that do exactly what you want fairly easily. Take a look at both the RazorFolderHostContainer and RazorStringHostContainer classes for the basic concepts you can use to create custom implementations. Notice also that you can set the engine’s PerRequestConfigurationData() from the host container: // Set configuration data that is to be passed to the template (any object) Engine.TemplatePerRequestConfigurationData = new RazorFolderHostTemplateConfiguration() { TemplatePath = Path.Combine(this.TemplatePath, relativePath), TemplateRelativePath = relativePath, }; which when set to a non-null value is passed to the Template’s InitializeTemplate() method. This method receives an object parameter which you can cast as needed: public override void InitializeTemplate(object configurationData) { // Pick up configuration data and stuff into Request object RazorFolderHostTemplateConfiguration config = configurationData as RazorFolderHostTemplateConfiguration; this.Request.TemplatePath = config.TemplatePath; this.Request.TemplateRelativePath = config.TemplateRelativePath; } With this data you can then configure any custom properties or objects on your main template class. It’s an easy way to pass data from the HostContainer all the way down into the template. The type you use is of type object so you have to cast it yourself, and it must be serializable since it will likely run in a separate AppDomain. This might seem like an ugly way to pass data around – normally I’d use an event delegate to call back from the engine to the host, but since this is running over AppDomain boundaries events get really tricky and passing a template instance back up into the host over AppDomain boundaries doesn’t work due to serialization issues. So it’s easier to pass the data from the host down into the template using this rather clumsy approach of set and forward. It’s ugly, but it’s something that can be hidden in the host container implementation as I’ve done here. It’s also not something you have to do in every implementation so this is kind of an edge case, but I know I’ll need to pass a bunch of data in some of my applications and this will be the easiest way to do so. Summing Up Hosting the Razor runtime is something I got jazzed up about quite a bit because I have an immediate need for this type of templating/merging/scripting capability in an application I’m working on. I’ve also been using templating in many apps and it’s always been a pain to deal with. The Razor engine makes this whole experience a lot cleaner and more light weight and with these wrappers I can now plug .NET based templating into my code literally with a few lines of code. That’s something to cheer about… I hope some of you will find this useful as well… Resources The examples and code require that you download the Razor runtimes. Projects are for Visual Studio 2010 running on .NET 4.0 Platform Installer 3.0 (install WebMatrix or MVC 3 for Razor Runtimes) Latest Code in Subversion Repository Download Snapshot of the Code Documentation (CHM Help File) © Rick Strahl, West Wind Technologies, 2005-2010Posted in ASP.NET  .NET  

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  • HttpServerUtility.UrlTokenDecode fails "sometimes" (Invalid length for a Base-64 char array.)

    - by Josef
    We have an IHttpHandler for stylesheets and add a <link/> tag to the page like this: HtmlGenericControl link = new HtmlGenericControl("link"); link.Attributes.Add("rel", "stylesheet"); link.Attributes.Add("href", "stylesheet.axd?d=" + HttpServerUtility.UrlTokenEncode(token)); head.Controls.Add(link); In the stylesheet.axd handler, we UrlTokenDecode the d query string parameter like this: var token = HttpServerUtility.UrlTokenDecode(Request.QueryString["d"]); This works most of the time but every now and then we find one of the following two exceptions in our log: [FormatException: Invalid character in a Base-64 string.] System.Convert.FromBase64CharArray(Char[] inArray, Int32 offset, Int32 length) System.Web.HttpServerUtility.UrlTokenDecode(String input) ... [FormatException: Invalid length for a Base-64 char array.] System.Convert.FromBase64CharArray(Char[] inArray, Int32 offset, Int32 length) System.Web.HttpServerUtility.UrlTokenDecode(String input) System.Web.HttpServerUtilityWrapper.UrlTokenDecode(String input) ... Any ideas what would cause this phenomenon? Remarks: the resulting URL is < 1500, so below any known URL limits (e.g. IE: 2083) seems to be independent of user agent (we have these exceptions for IE6,7,8, FF & Chrome) our (unconfirmed) suspicions include AntiVirus products, HTTP proxies, browser addons found this remotely related question, but it's about a viewstate issue

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  • Using abstract base to implement private parts of a template class?

    - by StackedCrooked
    When using templates to implement mix-ins (as an alternative to multiple inheritance) there is the problem that all code must be in the header file. I'm thinking of using an abstract base class to get around that problem. Here's a code sample: class Widget { public: virtual ~Widget() {} }; // Abstract base class allows to put code in .cpp file. class AbstractDrawable { public: virtual ~AbstractDrawable() = 0; virtual void draw(); virtual int getMinimumSize() const; }; // Drawable mix-in template<class T> class Drawable : public T, public AbstractDrawable { public: virtual ~Drawable() {} virtual void draw() { AbstractDrawable::draw(); } virtual int getMinimumSize() const { return AbstractDrawable::getMinimumSize(); } }; class Image : public Drawable< Widget > { }; int main() { Image i; i.draw(); return 0; } Has anyone walked that road before? Are there any pitfalls that I should be aware of?

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  • How to code Microsoft Excel "Shift Cells Up" feature in SQL

    - by user293249
    Take a simple table like below: Column Headings: || Agent's Name || Time Logged In || Center || Row 1: Andrew || 12:30 PM || Home Base Row 2: Jeff || 7:00 AM || Virtual Base Row 3: Ryan || 6:30 PM || Test Base Now lets say that a single cell is deleted so the table now looks like this: Column Headings: || Agent's Name || Time Logged In || Center || Row 1: Andrew || 12:30 PM || Row 2: Jeff || 7:00 AM || Virtual Base Row 3: Ryan || 6:30 PM || Test Base Notice that "Home Base" is missing. Now in excel you can delete the cell and shift the rest so the finished product looks like below: Column Headings: || Agent's Name || Time Logged In || Center || Row 1: Andrew || 12:30 PM || Virtual Base Row 2: Jeff || 7:00 AM || Test Base Row 3: Ryan || 6:30 PM || And you can see we are left with a blank cell last row. How do I code this procedure of shifting the cells up in SQL? I've been struggling on this problem for weeks! Thank you!

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  • Where to download Fabrikam Fiber Call center code base?

    - by PraveenLearnsEveryday
    I am trying to download for Asp.Net application for Fabrikam Fiber Call center. It was used by Larry guger in his presentation on http://channel9.msdn.com/Events/TechEd/NorthAmerica/2012/DEV365 about "Advanced IntelliTrace in Production with Visual Studio 2012". It would be a great help as it is perfect code base to try out all new VS 2012 features at one go. If this is not the right forum to ask this question please suggest. Thanks for the help.

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  • Importing owl files

    - by Mikae Combarado
    Hello, I have a problem with importing owl files using owl api in Java. I successfully can import 2 owl files. However, a problem occurs, when I try to import 3 or more owl files that are integrated to each other. E.g. Base.owl -- base ontology Electronics.owl -- electronics ontology which imports Base.owl Telephone.owl -- telephone ontology which imports Base.owl and Electronics.owl When, I just import Base.owl and run Electronics.owl, it works smoothly. The code is given below: File fileBase = new File("filepath/Base.owl"); File fileElectronic = new File("filePath/Electronic.owl"); SimpleIRIMapper iriMapper = new SimpleIRIMapper(IRI.create("url/Base.owl"), IRI.create(fileBase)); OWLOntologyManager manager = OWLManager.createOWLOntologyManager(); manager.addIRIMapper(iriMapper); OWLOntology ont = manager.loadOntologyFromOntologyDocument(fileElectronic); However, when I want to load Telephone.owl, I just create an additional iriMapper and add it to the manager. The additional code is shown with ** : File fileBase = new File("filepath/Base.owl"); File fileElectronic = new File("filePath/Electronic.owl"); **File fileTelephone = new File("filePath/Telephone.owl");** SimpleIRIMapper iriMapper = new SimpleIRIMapper(IRI.create("url/Base.owl"), IRI.create(fileBase)); **SimpleIRIMapper iriMapper2 = new SimpleIRIMapper(IRI.create("url/Electronic.owl"), IRI.create(fileElectronic));** OWLOntologyManager manager = OWLManager.createOWLOntologyManager(); manager.addIRIMapper(iriMapper); **manager.addIRIMapper(iriMapper2);** OWLOntology ont = manager.loadOntologyFromOntologyDocument(**fileTelephone**); The code shown above gives this error : Could not load import: Import(url/Electronic.owl>) Reason: Could not loaded imported ontology: <url/Base.owl> Cause: null It would be really appreciated, if someone gives me a hand... Thanks in advance...

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  • Rewrite arrays using collections

    - by owca
    I have a task, which I was able to do with the use of simplest methods - arrays. Now I'd like to go further and redo it using some more complicated java features like collections, but I've never used anything more complicated than 2d matrix. What should I look at and how to start with it. Should Tower become a Collection ? And here's the task : We have two classes - Tower and Block. Towers are built from Blocks. Ande here's sample code for testing: Block k1=new Block("yellow",1,5,4); Block k2=new Block("blue",2,2,6); Block k3=new Block("green",3,4,2); Block k4=new Block("yellow",1,5,4); Tower tower=new Tower(); tower.add(k1,k2,k3); "Added 3 blocks." System.out.println(tower); "block: green, base: 4cm x 3cm, thicknes: 2 cm block: blue, base: 6cm x 2cm, thicknes: 2 cm block: yellow, base: 5cm x 4cm, thicknes: 1 cm" tower.add(k2); "Tower already contains this block." tower.add(k4); "Added 1 block." System.out.println(tower); "block: green, base: 4cm x 3cm, thicknes: 2 cm block: blue, base: 6cm x 2cm, thicknes: 2 cm block: yellow, base: 5cm x 4cm, thicknes: 1 cm block: yellow, base: 5cm x 4cm, thicknes: 1 cm" tower.delete(k1); "Deleted 1 block" tower.delete(k1); "Block not in tower" System.out.println(tower); "block: blue, base: 6cm x 2cm, thicknes: 2 cm block: yellow, base: 5cm x 4cm, thicknes: 1 cm block: yellow, base: 5cm x 4cm, thicknes: 1 cm" Let's say I will treat Tower as a collection of blocks. How to perform search for specific block among whole collection ? Or should I use other interface ?

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  • How to call base abstract or interface from DAL into BLL?

    - by programmerist
    How can i access abstract class in BLL ? i shouldn't see GenAccessor in BLL it must be private class GenAccessor . i should access Save method over _AccessorForSQL. ok? MY BLL cs: public class AccessorForSQL: GenoTip.DAL._AccessorForSQL { public bool Save(string Name, string SurName, string Adress) { ListDictionary ld = new ListDictionary(); ld.Add("@Name", Name); ld.Add("@SurName", SurName); ld.Add("@Adress", Adress); return **base.Save("sp_InsertCustomers", ld, CommandType.StoredProcedure);** } } i can not access base.Save....???????? it is my DAL Layer: namespace GenoTip.DAL { public abstract class _AccessorForSQL { public abstract bool Save(string sp, ListDictionary ld, CommandType cmdType); public abstract bool Update(); public abstract bool Delete(); public abstract DataSet Select(); } private class GenAccessor : _AccessorForSQL { DataSet ds; DataTable dt; public override bool Save(string sp, ListDictionary ld, CommandType cmdType) { SqlConnection con = null; SqlCommand cmd = null; SqlDataReader dr = null; try { con = GetConnection(); cmd = new SqlCommand(sp, con); con.Open(); cmd.CommandType = cmdType; foreach (string ky in ld.Keys) { cmd.Parameters.AddWithValue(ky, ld[ky]); } dr = cmd.ExecuteReader(); ds = new DataSet(); dt = new DataTable(); ds.Tables.Add(dt); ds.Load(dr, LoadOption.OverwriteChanges, dt); } catch (Exception exp) { HttpContext.Current.Trace.Warn("Error in GetCustomerByID()", exp.Message, exp); } finally { if (dr != null) dr.Close(); if (con != null) con.Close(); } return (ds.Tables[0].Rows.Count 0) ? true : false; } public override bool Update() { return true; } public override bool Delete() { return true; } public override DataSet Select() { DataSet dst = new DataSet(); return dst; } private static SqlConnection GetConnection() { string connStr = WebConfigurationManager.ConnectionStrings["ConnectionString"].ConnectionString; SqlConnection conn = new SqlConnection(connStr); return conn; }

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  • Png image processing in .NET.

    - by Oybek
    I have the following task. Take a base image and overlay on it another one. The base image is 8b png as well as overlay. Here are the base (left) and overlay (right) images. Here is a result and how it must look. The picture in the left is a screenshot when one picture is on top of another (html and positioning) and the second is the result of programmatic merging. As you can see in the screenshot the borders of the text is darker. Also here are the sizes of the images Base image 14.9 KB Overlay image 6.87 KB Result image 34.8 KB The size of the resulting image is also huge Here is my code that I use to merge those pictures /*...*/ public Stream Concatinate(Stream baseStream, params Stream[] overlayStreams) { var @base = Image.FromStream(baseStream); var canvas = new Bitmap(@base.Width, @base.Height); using (var g = canvas.ToGraphics()) { g.DrawImage(@base, 0, 0); foreach (var item in overlayStreams) { using (var overlayImage = Image.FromStream(item)) { try { Overlay(@base, overlayImage, g); } catch { } } } } var ms = new MemoryStream(); canvas.Save(ms, ImageFormat.Png); canvas.Dispose(); @base.Dispose(); return ms; } /*...*/ /*Tograpics extension*/ public static Graphics ToGraphics(this Image image, CompositingQuality compositingQuality = CompositingQuality.HighQuality, SmoothingMode smoothingMode = SmoothingMode.HighQuality, InterpolationMode interpolationMode = InterpolationMode.HighQualityBicubic) { var g = Graphics.FromImage(image); g.CompositingQuality = compositingQuality; g.SmoothingMode = smoothingMode; g.InterpolationMode = interpolationMode; return g; } My questions are What should I do in order to merge images to achieve the result as in the screenshot? How can I lower the size of the result image? Is the System.Drawing a suitable tool for this or is there any better tool for working with png for .NET?

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  • C++ non-member functions for nested template classes

    - by beldaz
    I have been writing several class templates that contain nested iterator classes, for which an equality comparison is required. As I believe is fairly typical, the comparison is performed with a non-member (and non-friend) operator== function. In doing so, my compiler (I'm using Mingw32 GCC 4.4 with flags -O3 -g -Wall) fails to find the function and I have run out of possible reasons. In the rather large block of code below there are three classes: a Base class, a Composed class that holds a Base object, and a Nested class identical to the Composed class except that it is nested within an Outer class. Non-member operator== functions are supplied for each. These classes are in templated and untemplated forms (in their own respective namespaces), with the latter equivalent to the former specialised for unsigned integers. In main, two identical objects for each class are compared. For the untemplated case there is no problem, but for the templated case the compiler fails to find operator==. What's going on? #include <iostream> namespace templated { template<typename T> class Base { T t_; public: explicit Base(const T& t) : t_(t) {} bool equal(const Base& x) const { return x.t_==t_; } }; template<typename T> bool operator==(const Base<T> &x, const Base<T> &y) { return x.equal(y); } template<typename T> class Composed { typedef Base<T> Base_; Base_ base_; public: explicit Composed(const T& t) : base_(t) {} bool equal(const Composed& x) const {return x.base_==base_;} }; template<typename T> bool operator==(const Composed<T> &x, const Composed<T> &y) { return x.equal(y); } template<typename T> class Outer { public: class Nested { typedef Base<T> Base_; Base_ base_; public: explicit Nested(const T& t) : base_(t) {} bool equal(const Nested& x) const {return x.base_==base_;} }; }; template<typename T> bool operator==(const typename Outer<T>::Nested &x, const typename Outer<T>::Nested &y) { return x.equal(y); } } // namespace templated namespace untemplated { class Base { unsigned int t_; public: explicit Base(const unsigned int& t) : t_(t) {} bool equal(const Base& x) const { return x.t_==t_; } }; bool operator==(const Base &x, const Base &y) { return x.equal(y); } class Composed { typedef Base Base_; Base_ base_; public: explicit Composed(const unsigned int& t) : base_(t) {} bool equal(const Composed& x) const {return x.base_==base_;} }; bool operator==(const Composed &x, const Composed &y) { return x.equal(y); } class Outer { public: class Nested { typedef Base Base_; Base_ base_; public: explicit Nested(const unsigned int& t) : base_(t) {} bool equal(const Nested& x) const {return x.base_==base_;} }; }; bool operator==(const Outer::Nested &x, const Outer::Nested &y) { return x.equal(y); } } // namespace untemplated int main() { using std::cout; unsigned int testVal=3; { // No templates first typedef untemplated::Base Base_t; Base_t a(testVal); Base_t b(testVal); cout << "a=b=" << testVal << "\n"; cout << "a==b ? " << (a==b ? "TRUE" : "FALSE") << "\n"; typedef untemplated::Composed Composed_t; Composed_t c(testVal); Composed_t d(testVal); cout << "c=d=" << testVal << "\n"; cout << "c==d ? " << (c==d ? "TRUE" : "FALSE") << "\n"; typedef untemplated::Outer::Nested Nested_t; Nested_t e(testVal); Nested_t f(testVal); cout << "e=f=" << testVal << "\n"; cout << "e==f ? " << (e==f ? "TRUE" : "FALSE") << "\n"; } { // Now with templates typedef templated::Base<unsigned int> Base_t; Base_t a(testVal); Base_t b(testVal); cout << "a=b=" << testVal << "\n"; cout << "a==b ? " << (a==b ? "TRUE" : "FALSE") << "\n"; typedef templated::Composed<unsigned int> Composed_t; Composed_t c(testVal); Composed_t d(testVal); cout << "c=d=" << testVal << "\n"; cout << "d==c ? " << (c==d ? "TRUE" : "FALSE") << "\n"; typedef templated::Outer<unsigned int>::Nested Nested_t; Nested_t e(testVal); Nested_t f(testVal); cout << "e=f=" << testVal << "\n"; cout << "e==f ? " << (e==f ? "TRUE" : "FALSE") << "\n"; // Above line causes compiler error: // error: no match for 'operator==' in 'e == f' } cout << std::endl; return 0; }

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  • Operator== in derived class never gets called.

    - by Robin Welch
    Can someone please put me out of my misery with this? I'm trying to figure out why a derived operator== never gets called in a loop. To simplify the example, here's my Base and Derived class: class Base { // ... snipped bool operator==( const Base& other ) const { return name_ == other.name_; } }; class Derived : public Base { // ... snipped bool operator==( const Derived& other ) const { return ( static_cast<const Base&>( *this ) == static_cast<const Base&>( other ) ? age_ == other.age_ : false ); }; Now when I instantiate and compare like this ... Derived p1("Sarah", 42); Derived p2("Sarah", 42); bool z = ( p1 == p2 ); ... all is fine. Here the operator== from Derived gets called, but when I loop over a list, comparing items in a list of pointers to Base objects ... list<Base*> coll; coll.push_back( new Base("fred") ); coll.push_back( new Derived("sarah", 42) ); // ... snipped // Get two items from the list. Base& obj1 = **itr; Base& obj2 = **itr2; cout << obj1.asString() << " " << ( ( obj1 == obj2 ) ? "==" : "!=" ) << " " << obj2.asString() << endl; Here asString() (which is virtual and not shown here for brevity) works fine, but obj1 == obj2 always calls the Base operator== even if the two objects are Derived. I know I'm going to kick myself when I find out what's wrong, but if someone could let me down gently it would be much appreciated.

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  • Who calls the Destructor of the class when operator delete is used in multiple inheritance.

    - by dicaprio-leonard
    This question may sound too silly, however , I don't find concrete answer any where else. With little knowledge on how late binding works and virtual keyword used in inheritance. As in the code sample, when in case of inheritance where a base class pointer pointing to a derived class object created on heap and delete operator is used to deallocate the memory , the destructor of the of the derived and base will be called in order only when the base destructor is declared virtual function. Now my question is : 1) When the destructor of base is not virtual, why the problem of not calling derived dtor occur only when in case of using "delete" operator , why not in the case given below: derived drvd; base *bPtr; bPtr = &drvd; //DTOR called in proper order when goes out of scope. 2) When "delete" operator is used, who is reponsible to call the destructor of the class? The operator delete will have an implementation to call the DTOR ? or complier writes some extra stuff ? If the operator has the implementation then how does it looks like , [I need sample code how this would have been implemented]. 3) If virtual keyword is used in this example, how does operator delete now know which DTOR to call? Fundamentaly i want to know who calls the dtor of the class when delete is used. Sample Code class base { public: base() { cout<<"Base CTOR called"<<endl; } virtual ~base() { cout<<"Base DTOR called"<<endl; } }; class derived:public base { public: derived() { cout<<"Derived CTOR called"<<endl; } ~derived() { cout<<"Derived DTOR called"<<endl; } }; I'm not sure if this is a duplicate, I couldn't find in search. int main() { base *bPtr = new derived(); delete bPtr;// only when you explicitly try to delete an object return 0; }

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  • Generating custom-form documents from base-form plus XML?

    - by KlaymenDK
    Hi all, this is my first stack overflow, and it's a complex one. Sorry. My task is to generate custom documents from a basic template plus some XML without having a custom form design element for each case. Here's the whole picture: We are building a Lotus Notes (client, not web) application for world-wide application access control; the scope is something like 400.000 users being able to request access to any of 1000+ applications. Each application needs its own request form -- different number of approvers, various info required, that sort of thing. We simply can't have a thousand forms in a database (one per application), and anyway their maintenance really needs to be pushed from the developers to the application owners. So instead of custom forms, we'd like to create a generic "template" form that stores a block of basic fields, but then allows application owners to define another block of fields dynamically -- "I want a mandatory plain-text field named 'Name' here, and then a date field named 'Due' here that must be later than today's date, and then ...". I hope this makes sense (if not, think of it as a generic questionnaire application). I pretty much have the structure in place for designing the dynamic fields (form builder GUI - XML-encoded data - pre-rendered DXL for injecting into a form), including mark-up for field types, value options, and rudimentary field validation instructions. My problem is generating a document with this dynamic content injected at the proper location (without needing a custom form design element for each case). Doing the dynamic content via HTML is out. The Notes client web rendering is simply way too poor, and it would be quite a challenge to implement things like field validation instructions, date selectors, and name look-ups. DXL, on the other hand, would allow us to use native Notes fields and code. As a tech demo, I've managed to implement a custom form generator that injects the pre-rendered DXL for the dynamic content into a base form; but as I said, we don't want a ton of custom form design elements. I've tried to implement a way to create a document with the "store form in document" flag set, but once I've created the document from the base form, I can't get DXL access to the stored form design, and so I can't inject my dynamic content. I know this is not something Notes was ever intended to do. Has anyone ever tried something like it (and gotten away with it)? Thanks for reading this far. With a boatload of thanks in advance, Jan Gundtofte-Bruun

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  • Why is the this-pointer needed to access inherited attributes?

    - by Shadow
    Hi, assume the following class is given: class Base{ public: Base() {} Base( const Base& b) : base_attr(b.base_attr) {} void someBaseFunction() { .... } protected: SomeType base_attr; }; When I want a class to inherit from this one and include a new attribute for the derived class, I would write: class Derived: public Base { public: Derived() {} Derived( const Derived& d ) : derived_attr(d.derived_attr) { this->base_attr = d.base_attr; } void SomeDerivedFunction() { .... } private: SomeOtherType derived_attr; }; This works for me (let's ignore eventually missing semicolons or such please). However, when I remove the "this-" in the copy constructor of the derived class, the compiler complains that "'base_attr' was not declared in this scope". I thought that, when inheriting from a class, the protected attributes would then also be accessible directly. I did not know that the "this-" pointer was needed. I am now confused if it is actually correct what I am doing there, especially the copy-constructor of the Derived-class. Because each Derived object is supposed to have a base_attr and a derived_attr and they obviously need to be initialized/set correctly. And because Derived is inheriting from Base, I don't want to explicitly include an attribute named "base_attr" in the Derived-class. IMHO doing so would generally destroy the idea behind inheritance, as everything would have to be defined again. EDIT Thank you all for the quick answers. I completely forgot the fact that the classes actually are templates. Please, see the new examples below, which are actually compiling when including "this-" and are failing when omiting "this-" in the copy-constructor of the Derived-class: Base-class: #include <iostream> template<class T> class Base{ public: Base() : base_attr(0) {} Base( const Base& b) : base_attr(b.base_attr) {} void baseIncrement() { ++base_attr; } void printAttr() { std::cout << "Base Attribute: " << base_attr << std::endl; } protected: T base_attr; }; Derived-class: #include "base.hpp" template< class T > class Derived: public Base<T>{ public: Derived() : derived_attr(1) {} Derived( const Derived& d) : derived_attr(d.derived_attr) { this->base_attr = d.base_attr; } void derivedIncrement() { ++derived_attr; } protected: T derived_attr; }; and for completeness also the main function: #include "derived.hpp" int main() { Derived<int> d; d.printAttr(); d.baseIncrement(); d.printAttr(); Derived<int> d2(d); d2.printAttr(); return 0; }; I am using g++-4.3.4. Although I understood now that it seems to come from the fact that I use template-class definitions, I did not quite understand what is causing the problem when using templates and why it works when not using templates. Could someone please further clarify this?

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  • How to Implement Overlay blend method using opengles 1.1

    - by Cylon
    Blow is the algorithm of overlay. and i want using it on iphone, but iphone 3g only support opengles 1.1, can not using glsl. can i using blend function or texture combine to implement it. thank you /////////Reference from OpenGL Shading® Language Third Edition /////////// 19.6.12 Overlay OVERLAY first computes the luminance of the base value. If the luminance value is less than 0.5, the blend and base values are multiplied together. If the luminance value is greater than 0.5, a screen operation is performed. The effect is that the base value is mixed with the blend value, rather than being replaced. This allows patterns and colors to overlay the base image, but shadows and highlights in the base image are preserved. A discontinuity occurs where luminance = 0.5. To provide a smooth transition, we actually do a linear blend of the two equations for luminance in the range [0.45,0.55]. float luminance = dot(base, lumCoeff); if (luminance < 0.45) result = 2.0 * blend * base; else if (luminance 0.55) result = white - 2.0 * (white - blend) * (white - base); else { vec4 result1 = 2.0 * blend * base; vec4 result2 = white - 2.0 * (white - blend) * (white - base); result = mix(result1, result2, (luminance - 0.45) * 10.0); }

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  • Copying a Polymorphic object in C++

    - by doron
    I have base-class Base from which is derived Derived1, Derived2 and Derived3. I have constructed an instance for one of the the derived classes which I store as Base* a. I now need to make a deep copy of the object which I will store as Base* b. As far as I know, the normal way of copying a class is to use copy constructors and to overload operator=. However since I don't know whether a is of type Derived1, Derived2 or Derived3, I cannot think of a way of using either the copy constructor or operator=. The only way I can think of to cleanly make this work is to implement something like: class Base { public: virtual Base* Clone() = 0; }; and the implement Clone in in the derived class as in: class Derivedn : public Base { public: Base* Clone() { Derived1* ret = new Derived1; copy all the data members } }; Java tends to use Clone quite a bit is there more of a C++ way of doing this?

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  • A c# Generics question involving Controllers and Repositories

    - by UpTheCreek
    I have a base repository class which contains all the common repository methods (as generic): public abstract class BaseRepository<T, IdType> : IBaseRepository<T, IdType> My repositories from this base e.g.: public class UserRepository : BaseRepository<User, int>, IUserRepository I also have a base controller class containing common actions, and inherit from this in controllers. The repository is injected into this by DI. E.g. public class UserController : BaseController<User> { private readonly IUserRepository userRepository; public UserController (IUserRepository userRepository) { this.userRepository= userRepository; } My question is this: The base controller needs to be able to access the repository methods that are defined in the base repository. However I'm passing in via DI a different repository type for each controller (even though they all inherrit from the base repository). How can the base controller somehow access the repository that is passed in (regardless of what type it is), so that it can access the common base methods?

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  • Base SDK Missing? No, I fixed that. Still?!

    - by Moshe
    XCode 3.2.3 Beta does not allow building for below 3.2. I opened a project that was made in an earlier XCode. For some reason, the base SDK is reported as missing even after changing it to 4.0. Other projects from earlier XCode do not have this issue. What can I do?

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