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  1. CLJ-1100

Reader literals cannot contain periods

    Details

    • Type: Bug
    • Status: Closed
    • Priority: Minor
    • Resolution: Declined
    • Affects versions: None
    • Fix versions: Release 1.7
    • Labels:
    • Approval:
      Incomplete
    • Patch:
      Code and Test

      Description

      The reader tries to read a record instead of a literal if the tag contains periods.

      user> (binding [*data-readers* {'foo/bar #'identity}] (read-string "#foo/bar 1"))
      1
      user> (binding [*data-readers* {'foo/bar.x #'identity}] (read-string "#foo/bar.x 1"))
      ClassNotFoundException foo/bar.x  java.lang.Class.forName0 (Class.java:-2)
      

      Summary of reader forms:

      Kind Example Constraint Status
      Record #user.Foo[1] record class name OK
      Class #java.lang.String["abc"] class name OK
      Clojure reader tag #uuid "c48d7d6e-f3bb-425a-abc5-44bd014a511d" not a class name, no "/" OK
      Library reader tag #my/card "5H" not a class name, has "/" OK
        #my.ns/card "5H" not a class name, has "/" OK
        #my/playing.card "5H" not a class name, has "/" BROKEN - read as record

      Note: reader tags should not be allowed to override the record reader.

      Cause: In LispReader, CtorReader.invoke() decides between record and tagged literal based on whether the tag has a ".".

      Proposed: Change the discriminator in CtorReader by doing more string inspection:

      • If name has a "/" -> readTagged (not a legal class name)
      • If name has no "/" or "." -> readTagged (records must have qualified names)
      • Else -> readRecord (also covers Java classes)

      Tradeoffs: Clojure-defined data reader tags must not contain periods. Not possible to read a Java class with no package. Avoids unnecessary class loading/construction for all tags.

      Patch: CLJ-1100-v2.patch

      Screened by: Alex Miller

      Alternatives considered:

      Using class checks:

      • Attempt readRecord (also covers Java classes)
      • If failed, attempt readTagged

      Tradeoffs: Clojure tags could not override Java/record constructors - not sure that's something we'd ever want to do, but this would cut that off. This alternative may attempt classloading when it would not have before.

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            • Assignee:
              Unassigned
              Reporter:
              lynaghk Kevin Lynagh
            • Votes:
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              Dates

              • Created:
                Updated:
                Resolved: