On Sat, 29 Mar 2014, Anton Vodonosov wrote:
29.03.2014, 02:39, "Daniel Herring" dherring@tentpost.com:
Would it be possible to have a special header in asdf files indicate that the contained system(s) should be loaded using the new syntax mechanism?
[...]
;; asdf:config '(asdf:+clean-readtable+)
No, it's inconvenient, why use special parser if we can just directly specify what we want in a lisp expression.
I haven't checked recently, but in the past ASDF files have had significant code even before the system definition. It was common to find conditionals based on *features*, comments for users to select from a few customization options, numbers being read, etc.
Once you have read the form, it is too late to modify the environment that is used to read it. Thus I suggested that we adopt a convention to check for a "magic header" that changes the syntax used for the rest of the file. The suggested syntax was meant to make this header invisible to legacy systems, unambiguous in meaning, extensible, and fairly easy to parse for new sysetms.
- Daniel