2015-09-15

Following on from last week's post about the upcoming IMAPClient
1.0 release, I'd like to draw attention to some significant,
compatibility breaking changes related to the handling of search
criteria.

IMAPClient's methods that accept search criteria (search, sort,
thread, gmail_search) have been changed to provide take criteria in
a more straightforward and robust way. In addition, the way the
charset argument interacts with search criteria has been
improved. These changes make it easier to pass search criteria and
have them handled correctly but unfortunately also mean that small
changes may be required to existing code that uses IMAPClient.

Search criteria

The preferred way to specify criteria now is as a list of strings,
ints and dates (where relevant). The list should be flat with all the
criteria parts run together. Where a criteria takes an argument, just
provide it as the next element in the list.

Some valid examples:

IMAPClient will perform all required conversion, quoting and
encoding. Callers do not need to and should not attempt to do this
themselves. IMAPClient will automatically send criteria parts as IMAP
literals when required (i.e. when the encoded part is 8-bit).

Some previously accepted ways of passing search criteria will not work
as they did in previous versions of IMAPClient. Small changes will be
required in these cases. Here are some examples of how to update code
written against older versions of IMAPClient:

It is also possible to pass a single string as the search
criteria. IMAPClient will not attempt quoting in this case, allowing
the caller to specify search criteria at a lower level. Specifying
criteria using a sequence of strings is preferable however. The
following examples (equivalent to those further above) are valid:

Search charset

The way that the search charset argument is handled has also
changed.

Any unicode criteria arguments will now be encoded by IMAPClient using
the supplied charset. The charset must refer to an encoding that is
capable of handling the criteria's characters or an error will
occur. The charset must obviously also be one that the server
supports! (UTF-8 is common)

Any criteria given as bytes will not be changed by IMAPClient, but the
provided charset will still be passed to the IMAP server. This allows
already encoding criteria to be passed through as-is. The encoding
referred to by charset should match the actual encoding used for the
criteria.

The following are valid examples:

The documentation and tests for search, gmail_search, sort and thread
has updated to account for these changes and have also been generally
improved.

For those willing to try out the changes now please install from IMAPClient's
tip. Any feedback on the changes and/or documentation would be hugely appreciated.

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