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  1. #include <iostream>
  2. #include <vector>
  3. using namespace std;
  4.  
  5. /// singleton class
  6. class ConfigurationManager {
  7. private:
  8.     string configuration_path;
  9.     vector<string> servers_ips;
  10.     string aws_service_url;
  11.     bool is_loaded = false;
  12.     static ConfigurationManager* obj;
  13.  
  14.     ConfigurationManager() {} 
  15.  
  16.     void load() {
  17.         if (is_loaded) return;
  18.         cout << "Lazy Loading\n";
  19.         servers_ips.push_back("10.20.30.40");
  20.         servers_ips.push_back("10.20.30.41");
  21.         servers_ips.push_back("10.20.30.42");
  22.         aws_service_url = "https://d...content-available-to-author-only...s.com";
  23.         is_loaded = true;
  24.     }
  25.  
  26. public:
  27.     ConfigurationManager(const ConfigurationManager& other) = delete;
  28.     ConfigurationManager& operator=(const ConfigurationManager& other) = delete;
  29.  
  30.     static ConfigurationManager* GetInstance() {
  31.         if (!obj) {
  32.             obj = new ConfigurationManager();
  33.         }
  34.         return obj;
  35.     }
  36.  
  37.     string GetAwsServiceUrl() {
  38.         load();
  39.         return aws_service_url;
  40.     }
  41. };
  42.  
  43. // Initialize static member
  44. ConfigurationManager* ConfigurationManager::obj = nullptr;
  45.  
  46. void f1() {
  47.     ConfigurationManager* mgr = ConfigurationManager::GetInstance();
  48.     cout << "Instance address in f1: " << mgr << '\n';
  49.     cout << mgr->GetAwsServiceUrl() << '\n';
  50.     cout <<"-------------------------------------------\n";
  51. }
  52.  
  53. void f2() {
  54.     ConfigurationManager* mgr = ConfigurationManager::GetInstance();
  55.     cout << "Instance address in f1: " << mgr << '\n';
  56.     cout << mgr->GetAwsServiceUrl() << '\n';
  57.     cout <<"-------------------------------------------\n";
  58. }
  59.  
  60. int main() {
  61.     f1();
  62.     f2();
  63.     return 0;
  64. }
  65.  
Success #stdin #stdout 0.01s 5288KB
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stdin
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Standard input is empty
stdout
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Instance address in f1: 0x55cd91f42e70
Lazy Loading
https://d...content-available-to-author-only...s.com
-------------------------------------------
Instance address in f1: 0x55cd91f42e70
https://d...content-available-to-author-only...s.com
-------------------------------------------
https://ideone.com/Jjb6QT
language:
C++ (gcc 8.3)
created:
6 days ago
visibility:
public

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