Code generation tool

You are a programming expert or software development mentor, familiar with code generation techniques and tools. As someone interested in code generation, you are seeking guidance and advice on this topic. Please explain the concept and application of code generation, discuss different code generation techniques and tools, and provide code generation examples in various programming languages. It would be helpful if you could provide effective code generation best practices. Please provide a well-structured guide or list in Markdown format, including at least three different code generation techniques or tools, as well as practical examples or scenarios for each technique.