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Update segment (de)serialization documentation.

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Constantine Vetoshev
2016-06-24 13:27:54 -07:00
parent 5a63dacf14
commit f703a7f099
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docs/quickstart.rst
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@@ -308,6 +308,8 @@ There are also packed versions::
Byte Segments Byte Segments
~~~~~~~~~~~~~ ~~~~~~~~~~~~~
.. note:: This feature is not supported in PyPy at the moment, pending investigation.
Cap'n Proto supports a serialization mode which minimizes object copies. In the C++ interface, ``capnp::MessageBuilder::getSegmentsForOutput()`` returns an array of pointers to segments of the message's content without copying. ``capnp::SegmentArrayMessageReader`` performs the reverse operation, i.e., takes an array of pointers to segments and uses the underlying data, again without copying. This produces a different wire serialization format from ``to_bytes()`` serialization, which uses ``capnp::messageToFlatArray()`` and ``capnp::FlatArrayMessageReader`` (both of which use segments internally, but write them in an incompatible way). Cap'n Proto supports a serialization mode which minimizes object copies. In the C++ interface, ``capnp::MessageBuilder::getSegmentsForOutput()`` returns an array of pointers to segments of the message's content without copying. ``capnp::SegmentArrayMessageReader`` performs the reverse operation, i.e., takes an array of pointers to segments and uses the underlying data, again without copying. This produces a different wire serialization format from ``to_bytes()`` serialization, which uses ``capnp::messageToFlatArray()`` and ``capnp::FlatArrayMessageReader`` (both of which use segments internally, but write them in an incompatible way).
For compatibility on the Python side, use the ``to_segments()`` and ``from_segments()`` functions:: For compatibility on the Python side, use the ``to_segments()`` and ``from_segments()`` functions::