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  1. #include <string>
  2. #include <map>
  3. #include <iostream>
  4.  
  5. class Whatever {
  6. public:
  7.     // контракт
  8.     virtual void foo() = 0;
  9. };
  10.  
  11. class WhateverFactory {
  12. public:
  13.     typedef Whatever* (*WhateverCtor)();
  14.  
  15.     static void registerClass(const std::string &name, WhateverCtor ctor) {
  16.         if ( m_plugins.find(name) == m_plugins.end() ) {
  17.             m_plugins[name] = ctor;
  18.         }
  19.     }
  20.  
  21.     static bool isRegistered(const std::string &cls) {
  22.         return m_plugins.find(cls) != m_plugins.end();
  23.     }
  24.  
  25.     static Whatever* createInstanceOf(const std::string &name) {
  26.         std::map<std::string, WhateverCtor>::iterator ctor;
  27.         if ( (ctor = m_plugins.find(name)) != m_plugins.end() ) {
  28.             return ctor->second();
  29.         } else {
  30.             return NULL;
  31.         }
  32.     }
  33.  
  34. private:
  35.     WhateverFactory() {}
  36.  
  37.     static std::map<std::string, WhateverCtor> m_plugins;
  38. };
  39.  
  40. std::map<std::string, WhateverFactory::WhateverCtor> WhateverFactory::m_plugins;
  41.  
  42. class HelloWorld : public Whatever {
  43. public:
  44.     HelloWorld() : m_message("Hello, World!") {}
  45.  
  46.     void foo() {
  47.         std::cout << m_message << std::endl;
  48.     }
  49.  
  50.     static HelloWorld* create() {
  51.         return new HelloWorld;
  52.     }
  53.  
  54. private:
  55.     std::string m_message;
  56. };
  57.  
  58. void load() {
  59.     WhateverFactory::registerClass("HelloWorld", reinterpret_cast<WhateverFactory::WhateverCtor>(HelloWorld::create));
  60. }
  61.  
  62. int main() {
  63.     load();
  64.     Whatever *w = WhateverFactory::createInstanceOf("HelloWorld");
  65.     if ( w ) {
  66.         w->foo();
  67.     }
  68.  
  69.     return 0;
  70. }
Success #stdin #stdout 0.02s 2860KB
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Standard input is empty
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Hello, World!
https://ideone.com/Y5jsQC
language:
C++ (gcc 8.3)
created:
12 years ago
visibility:
public

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