Codegeneration vs text string evaluation

Question

What are the advantages and disadvantages of the following approaches to the management of repetitive code:

1) Use exec(), eval(), and similar functions in other languages

for Keyword in KeywordsUpperCase:
    exec(Keyword + " = \"" + Keyword.lower() + "\"")

2) Use external code generator which uses its own language (which is interleaved with your code) (you can browse and debug generated files)

3) Write tens of lines of repetitive code manually

4) Your version?

Try to elaborate your answer.