I do think a simple String error message is all that the user of the function should provide. From there, An AssertionError can throw up something along the lines of what you said - Expected… , Found… , Message. That would give enough information for reporting at least in a test framework. To get more precise information, like you said, that AssertionError could also throw up class/file information, etc. that a debugger could use. I would guard against designing these things to accomodate a context outside of it's execution scope. In the ideal functional world, the input and output are wholly localized. Any Error/Exception thrown can be consumed or chained to give very precise failure reasoning.
As for how that would fit into the entire exception chain, that's still being thought (see here<http://dev.clojure.org/display/design/Error+Handling>). There are already a few approaches, and I think this (see here<http://dev.clojure.org/display/design/Error+Handling+Comparisons>) is the context of how the core team is approaching this problem. Cheers Tim On Tue, Jul 12, 2011 at 6:01 AM, Shantanu Kumar <kumar.shant...@gmail.com>wrote: > As I am the culprit of having introduced it with a naive example, I'd > better admit it may not be very useful in practical scenarios across a > wide variety of use cases. For example, when there is an assertion > error with message "`m` should be a map" 14 levels down the stack, I'd > really wish it said "`m` -- Expected: map, Found: vector [:foo :bar]" > so that I can debug it quickly. > > Pre-conditions and Post-conditions are a valuable debugging aid, and > to enable that we need very precise information. Unfortunately passing > a string error message cannot encapsulate enough error context. A more > complex example can be where the correctness of input must be > determined collectively (in association with other args) -- in those > cases one can only fall back on comparing input values and raise > IllegalArgumentException accordingly. > > Regards, > Shantanu > > On Jul 11, 10:40 pm, Timothy Washington <twash...@gmail.com> wrote: > > > -- You received this message because you are subscribed to the Google Groups "Clojure" group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en
