Re: Foxpro goto command and deleted records

Discussion in 'Python' started by Ethan Furman, Jul 18, 2012.

  1. Ethan Furman

    Ethan Furman Guest

    MRAB wrote:
    > On 17/07/2012 23:57, Ethan Furman wrote:
    >> In Foxpro if you do a
    >>
    >> GOTO 7
    >>
    >> with deleted off and record 7 is deleted, the record pointer doesn't
    >> move (at least in version 6).
    >>
    >> I don't like that.
    >>
    >> I see four other options:
    >>
    >> 0) don't move the pointer (listed for completeness)
    >> 1) go to that record anyway
    >> 2) go to the next undeleted record
    >> 3) go to the seventh undeleted record (possibly the least practical)
    >> 4) raise an exception
    >>
    >> Any opinions?
    >>

    > What happens when you 'delete' a record? Does it disappear immediately,
    > or is it merely marked for deletion?


    Marked for deletion.

    > If it is marked for deletion, can it be unmarked? Will a marked record
    > be removed when the file is closed, or does the file need to be
    > explicitly purged/compacted?


    Yes, it can be unmarked. No, the table must be explicitly packed.

    > If it is merely marked, then I think the best option is 1, or possibly
    > 4 if the file is compacted when closed.


    There is a use_deleted setting that controls whether deleted records are
    accessed or skipped. Skipping is fine when looping, not so fine when
    going directly to a particular record.

    ~Ethan~
     
    Ethan Furman, Jul 18, 2012
    #1
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