Inconsistency in pretty printer documentation

The documentation for the gdb.printing module [1] says the following:

PrettyPrinter (name, subprinters=None)
   ... Pretty-printers should generally inherit from this class.

However, in the "writing a pretty printer" section [2], there are
several examples of pretty printers (StdStringPrinter, fooPrinter,
barPrinter), none of which inherit from gdb.printing.PrettyPrinter.
Many of the third-party pages describing third-party printers around
the web (e.g. [3-5]) do not inherit from anything except object.

In the printers I've written, I've not been using PrettyPrinter and
things seem to mostly work, but I also haven't really messed around
with enable/disable pretty-printer etc.

Am I missing out on something by not using the PrettyPrinter class? If
I were to use it, do I just implement the same API? Is PrettyPrinter a
largely-defunct class that is no longer needed? Is it a newer class
and the other docs haven't been updated, and get new functionaliy from
it?

Evan


[1] https://sourceware.org/gdb/onlinedocs/gdb/gdb_002eprinting.html#gdb_002eprinting
[2] https://sourceware.org/gdb/onlinedocs/gdb/Writing-a-Pretty_002dPrinter.html#Writing-a-Pretty_002dPrinter
[3] https://www.rethinkdb.com/blog/make-debugging-easier-with-custom-pretty-printers/
[4] http://tromey.com/blog/?p=524
[5] http://tromey.com/blog/?p=546