动态开关取决于启动时加载的参数[关闭]

最简单的方法是使用函子映射来处理选项。但这取决于你的任务。大概是这样的:

std::map< std::string, std::function< void( const std::string& ) > > handlers;
// In can be std::variant instead of std::string

handlers[ "key1" ] = []( const std::string& value )
{
    std::cout << "Processing key1 in JSON, value is = " << value ;
};
handlers[ "key2" ] = []( const std::string& value )
{
    std::cout << "Processing key1 in JSON, value is = " << value ;
}; //...

defaultHandler = [](const std::string&)
{
    throw "Not supported param";
};

// Somehow iterate, depends on your json parser
// Can be recursive
for ( const auto& keyVal : json ) 
{
    const auto& key = keyVal.first; // JSON key
    const auto& value= keyVal.second; // JSON value
    const auto itHandler = handlers.find( key ); // Looking for handler
    if ( itHandler != handlers.end() )
    {
        const auto& handler = itHandler.second;
        handler( value ); // Use handler, it's a "content" of your "case" block
    }
    else
        defaultHandler( value );
}