Clojure

defmulti doc string doesn't mention needing to be passed a var for the value of :hierarchy

Details

  • Type: Defect Defect
  • Status: Open Open
  • Priority: Minor Minor
  • Resolution: Unresolved
  • Affects Version/s: Release 1.2
  • Fix Version/s: None
  • Component/s: None
  • Labels:
    None
  • Environment:
    1.2, 1.3 beta3
  • Patch:
    Code
  • Approval:
    Incomplete

Description

The :hierarchy option for defmulti should be passed a var, but this is not mentioned in the doc string.

The error message from passing the hierarchy directly is rather cryptic:

Evaluation aborted on java.lang.ClassCastException: clojure.lang.PersistentArrayMap cannot be cast to clojure.lang.IRef (SOURCE_FORM_44:19).

Activity

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Meikel Brandmeyer added a comment -

Modified doctoring to clarify the usage of :hierarchy.

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Meikel Brandmeyer added a comment - Modified doctoring to clarify the usage of :hierarchy.
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Scott Lowe added a comment -

New patch: '0001-CLJ-835-Refine-doc-string-for-defmulti-hierarchy-opt.patch' 10/May/12.

I've attached a new doc string patch in response to Andy Fingerhut's request posted here: https://groups.google.com/forum/?fromgroups#!topic/clojure-dev/i7H82fJYL-U

Andy's request stated "Attached patch seems to have spelling mistakes, and perhaps could be worded more clearly."

I hope my new patch is an improvement upon what was there.

This patch supersedes '0001-Clarify-docstring-for-defmulti.patch' from 14/Sep/11.

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Scott Lowe added a comment - New patch: '0001-CLJ-835-Refine-doc-string-for-defmulti-hierarchy-opt.patch' 10/May/12. I've attached a new doc string patch in response to Andy Fingerhut's request posted here: https://groups.google.com/forum/?fromgroups#!topic/clojure-dev/i7H82fJYL-U Andy's request stated "Attached patch seems to have spelling mistakes, and perhaps could be worded more clearly." I hope my new patch is an improvement upon what was there. This patch supersedes '0001-Clarify-docstring-for-defmulti.patch' from 14/Sep/11.
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Fogus added a comment -

This is a million times better than what was there before, but (who knew!?) it could be better. A couple points of contention:

  • The order under the :hierarchy section seems off. I would start with an overview of what a hierarchy is including a definition of the global hierarchy map (it's mentioned, but glossed over). I'd then move on to an example impl. Finally, I'd then add the discussion starting "Multimethods expect..." immediately followed by an example.
  • In the isa? example it would be great to show the return value.
  • You mention that the hierarchy should be supplied as a reference, which is correct, however you talk about #'. The link between e.g. var and #' could be a bit more explicit. Maybe the sentence about #' could be parenthetical?
  • It's ok to finish with a very small example of its use in defmethod, in fact a simple example specifying methods for ::shape and ::circle would clarify the intent nicely.
Show
Fogus added a comment - This is a million times better than what was there before, but (who knew!?) it could be better. A couple points of contention:
  • The order under the :hierarchy section seems off. I would start with an overview of what a hierarchy is including a definition of the global hierarchy map (it's mentioned, but glossed over). I'd then move on to an example impl. Finally, I'd then add the discussion starting "Multimethods expect..." immediately followed by an example.
  • In the isa? example it would be great to show the return value.
  • You mention that the hierarchy should be supplied as a reference, which is correct, however you talk about #'. The link between e.g. var and #' could be a bit more explicit. Maybe the sentence about #' could be parenthetical?
  • It's ok to finish with a very small example of its use in defmethod, in fact a simple example specifying methods for ::shape and ::circle would clarify the intent nicely.
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Rich Hickey added a comment -

Please leave examples out of docs strings. Use precise language.

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Rich Hickey added a comment - Please leave examples out of docs strings. Use precise language.

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Dates

  • Created:
    Updated:
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