[asdf-devel] Alternate take on the intended use of component-property

Dan Lentz danlentz at gmail.com
Fri Feb 1 22:03:26 UTC 2013

I was always under the impression that the intent of C-P was to provide a means of annotation primarily to be used at runtime by the ”end-user".  For example, say if one were interested in some type of statistic, say SLOC, for comparison and analysis of a (possibly large) number of systems, One might conveniently calculate and store that value as the :SLOC property within each component while being visited, and then aggregate the result at some later time.  Deprecating the expectation of standardized property access for use by the actual day-to-day developer working with asdf systems would seem to lead to a profusion of half-baked off the cuff "solutions" reimplemented each time such a need presents itself.  

Also, the property slot is a direct slot of component, very early in the hierarchy, and so is transparently inherited by each increasingly complex subclass of component on upwards through the class hierarchy.  Are you saying that if one needs it then one should subclass component to include some property slot, and also then subclass module likewise, and then system also, etc?  So to get this scratchpad working space means essentially one needs to reimplement the whole asdf class hierarchy?

FWIW, I think there are many situations in which the component-property provides a more sensible facility than would ad-hoc archetypal extension of ASDF's fundamental object model.  Am I misunderstanding the proposed changes?


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