title: ngx_http_script_compile vs ngx_http_compile_complex_value
body: <p>I'm trying to introduce a new directive which takes either a string or a variable as input and saves the values on configuration struct for later user in my code. I found that some directives in nginx are using ngx_http_compile_complex_value(&amp;ccv) to compile the variables and ngx_http_complex_value() to get the original value of the directive's argument during the runtime. Similarly, some other directives are using ngx_http_script_compile(&amp;sc) and ngx_http_script_run() to achieve the same.  </p>
  
  <p>I have found some documentation about scripts and complex values in nginx but I'm still not clear about the difference between these two.
  Can anyone help me understand the difference and when to use complex_value vs script?</p>