Issue PRINT-READABLY-BEHAVIOR Writeup

Issue:        PRINT-READABLY-BEHAVIOR

Forum:        X3J13 Letter Ballot

References:   *PRINT-READABLY* (X3J13/92-102, p22-74)

	      Public review comment Loosemore-24

Category:     CLARIFICATION

Edit history: 21-Jun-93, Version 1 by Steele (based on text by Loosemore)

Status:		Proposal CLARIFY passed (9+2)-0 on letter ballot 93-304.


Problem Description:


  In E-mail amongst the public review committee, we had agreed that this

  was another case of a previous cleanup vote that had not been adequately

  integrated with the rest of the document.  Supposedly, there are no

  technical changes being recommended here.


  The proposal DATA-IO:ADD-SUPPORT that was the basis for adding

  *PRINT-READABLY* to the language is clear on this issue.  However,

  the document as it now stands does not accurately reflect

  the proposal, or contain adequate cross-references.


Proposal (PRINT-READABLY-BEHAVIOR:CLARIFY):


  Make the following changes to the dpANS:


  (1) Remove this inaccurate statement from the "Notes" section for

  *PRINT-READABLY*:


    The printing of interned \term{symbols}, of \term{strings}, 

    and of \term{bit vectors} is not affected by \varref{*print-readably*}.


  (2) In the "Description" section for *PRINT-READABLY*, add after the

  first paragraph:


    Specifically, if \varref{*print-readably*} is \term{true}, printing

    proceeds as if \varref{*print-escape*}, \varref{*print-array*}, and

    \varref{*print-gensym*} were also \term{true}, and as if 

    \varref{*print-length*}, \varref{*print-level*}, and 

    \varref{*print-lines*} were \term{false}.


  (3) In section 22.1.3, change numerous references to *PRINT-ESCAPE*

  to include both *PRINT-ESCAPE* and *PRINT-READABLY*.


  (4) Rewrite section 22.1.3.10 as follows.  Prefix the first paragraph

  with:


    If \varref{*print-array*} is \term{true} and \varref{*print-readably*}

    is \term{false}, any \term{vector} ....


  Change the beginning of the next-to-last paragraph to:


    If both \varref{*print-array*} and \varref{*print-readably*} are 

    \term{false}, the \term{vector} is not printed ...


  Add a new paragraph before the last paragraph:


    If \varref{*print-readably*} is true, the \term{vector} prints in an

    \term{implementation-defined} manner.  See \varref{*print-readably*}.



  (5) Rewrite section 22.1.3.11 as follows.  Prefix the first paragraph

  with:


    If \varref{*print-array*} is \term{true} and \varref{*print-readably*}

    is \term{false}, any \term{array} ...


  Change the beginning of the next-to-last paragraph to:


    If both \varref{*print-array*} and \varref{*print-readably*} are 

    \term{false}, the \term{array} is printed ...


  Add a new paragraph before the last paragraph:


    If \varref{*print-readably*} is true, the \term{array} prints in an

    \term{implementation-defined} manner.  See \varref{*print-readably*}.

  

Test Case:


  Not provided.


Rationale:


  We should better document the relationship between *PRINT-READABLY* and

  other printer control variables such as *PRINT-ESCAPE*.


Current Practice:


  Not provided.


Cost to Implementors:


  Probably relatively small.


Cost to Users:


  None.  This change doesn't affect anything already guaranteed to the user.


Cost of Non-Adoption:


  Vagueness in the language specification.


Benefits:


  Better program portability.


Editorial Impact:


  Small.  A few small, localized edits.


Aesthetics:


  Mostly neutral.


Discussion:

  

  This addresses comment Loosemore #24.