Evaluate command only at runtime--not RULE_INIT?

Hi there,

I'd like to set a variable in RULE_INIT which contains the command HTTP::host and then have it evaluated at runtime in HTTP_REQUEST:

 
 when RULE_INIT { 
  
    set ::html_content "Requested host was [HTTP::host]" 
 } 
 when HTTP_RESQUEST { 
  
    if {[HTTP::path] starts_with "/test"}{ 
  
       HTTP::respond 200 content $::html_content 
    } 
 } 
 

This example doesn't work as HTTP::host is evaluated in RULE_INIT--where the command isn't valid. I tried using eval and subst, but couldn't figure out any combination that would allow me to set the contents in RULE_INIT and force evaluation in HTTP_REQUEST.

Is there a way to only evaluate the command in HTTP_REQUEST?

I'd like to have the variable defined in RULE_INIT along with all other variables that the customer would potentially need to modify. I realize I could use a placeholder and then use string map in HTTP_REQUEST to replace it with the actual HTTP::host value, but that doesn't seem very elegant.

Thanks,

Aaron