Re: Foxpro goto command and deleted records

Discussion in 'Python' started by MRAB, Jul 18, 2012.

  1. MRAB

    MRAB Guest

    On 18/07/2012 03:19, Ethan Furman wrote:
    > 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.
    >

    If use_deleted is false, does that mean that deleted records are
    hidden, or just that when iterating through the records the deleted
    ones aren't yielded?
     
    MRAB, Jul 18, 2012
    #1
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