[issue21708] Deprecate nonstandard behavior of a dumbdbm database

[Serhiy Storchaka]

New submission from Serhiy Storchaka:

Unlike to other dbm implementations, a dumpdbm database is always opened for update, and will be created if it does not exist.  We can fix this discrepancy and implement common behavior for 'r' and 'w' modes, but this will change current behavior and some deprecation period is needed.

Here is a patch (based on patch by Claudiu Popa, submitted in issue18039), which adds deprecation warnings for cases when current behavior differs from desired: invalid values for the flag parameter (will raise ValueError in future), opening non-existing database in 'r' or 'w' mode (will raise dbm.dumb.error), modifying a database opened for reading only (will raise dbm.dumb.error).

This patch needs approving by other core developer.

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assignee: serhiy.storchaka
files: dbm_dumb_deprecations.patch
keywords: patch
messages: 220185
nosy: Claudiu.Popa, r.david.murray, serhiy.storchaka
priority: normal
severity: normal
stage: patch review
status: open
title: Deprecate nonstandard behavior of a dumbdbm database
type: enhancement
versions: Python 3.5
Added file: http://bugs.python.org/file35558/dbm_dumb_deprecations.patch

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<http://bugs.python.org/issue21708>
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