Re: [Cppcms-users] Plugins and templates

[Artyom <art...@ya...>]

> class IPlugin  {
>     public:
>     virtual content::master  handleRequest() const = 0;
> };
> class  HelloPlugin: public IPlugin {
>      public:
>     virtual content::master handleRequest()  {
>         content::hello_plugin  hp;
>         hp.title =  "Hello";
>         hp.message =  "World";
>         return  hp;
>     }
> }

----------------------------------------------------
In C++, objects are not references! They are values.
----------------------------------------------------

What happens there
that content::master is copties from content::hello_plugin
and this forgets all about hello_plugin. For handling polymorphic
classes you need to use pointers or references.

> 
> // This is the function that dispatches to plugin
> void  myapp::dispatcher(std::string module) {
>     IPlugin p =  plugcontainer.getPluginByModule(module);
>     content::master m  = p.handleRequest();
>      render("hello_plugin",m);
> }

And in this point m is type of content::master  so when in plugin it tryes to 
cast
to the content::hello_pluging it fails for very good reason :-)

What you need is something like this with smart pointers:

 class IPlugin  {
     public:
     virtual booster::shared_ptr<content::master> handleRequest() const = 0;
 };
 class  HelloPlugin: public IPlugin {
      public:
     virtual booster::shared_ptr<content::master> handleRequest()  {
         booster::shared_ptr<content::hello_plugin>  hp(new 
content::hello_plugin);
         hp->title =  "Hello";
         hp->message =  "World";
         return  hp;
     }
 }

 void  myapp::dispatcher(std::string module) {
     IPlugin p =  plugcontainer.getPluginByModule(module);
     booster::shared_ptr<content::master> m  = p.handleRequest();
      render("hello_plugin",*m);
 }

This should work
Best,
  Artyom