scoped_env_var.hpp

 
#pragma once
 
#include <cstdlib>
#include <string>
 
namespace rapidsmpf::rrun {
 
class ScopedEnvVar {
  public:
    ScopedEnvVar(char const* name, char const* value) : name_(name) {
        char const* old = std::getenv(name);
        if (old != nullptr) {
            had_value_ = true;
            old_value_ = old;
        }
        if (value != nullptr) {
            setenv(name, value, 1);
        } else {
            unsetenv(name);
        }
    }
 
    ~ScopedEnvVar() {
        if (had_value_) {
            setenv(name_.c_str(), old_value_.c_str(), 1);
        } else {
            unsetenv(name_.c_str());
        }
    }
 
    ScopedEnvVar(ScopedEnvVar const&) = delete;
    ScopedEnvVar& operator=(ScopedEnvVar const&) = delete;
 
  private:
    std::string name_;
    std::string old_value_;
    bool had_value_{false};
};
 
}  // namespace rapidsmpf::rrun