From 6040d65843198ded82c479eff790d66910cd8435 Mon Sep 17 00:00:00 2001 From: Sam Bull Date: Fri, 1 May 2026 20:32:50 +0100 Subject: [PATCH] Clarify `max_length` in zstd & zlib decompressor documentation (#143805) Also provide examples of how to decompress data using max_length for zstd and zlib. Co-authored-by: Emma Smith --- Doc/library/compression.zstd.rst | 10 +++++++--- Doc/library/zlib.rst | 5 +++++ 2 files changed, 12 insertions(+), 3 deletions(-) diff --git a/Doc/library/compression.zstd.rst b/Doc/library/compression.zstd.rst index 7ca843f27f5..6d99e36e1e5 100644 --- a/Doc/library/compression.zstd.rst +++ b/Doc/library/compression.zstd.rst @@ -331,10 +331,14 @@ Compressing and decompressing data in memory If *max_length* is non-negative, the method returns at most *max_length* bytes of decompressed data. If this limit is reached and further - output can be produced, the :attr:`~.needs_input` attribute will - be set to ``False``. In this case, the next call to + output can be produced (or EOF is reached), the :attr:`~.needs_input` + attribute will be set to ``False``. In this case, the next call to :meth:`~.decompress` may provide *data* as ``b''`` to obtain - more of the output. + more of the output. The full content can thus be read like:: + + process_output(d.decompress(data, max_length)) + while not d.eof and not d.needs_input: + process_output(d.decompress(b"", max_length)) If all of the input data was decompressed and returned (either because this was less than *max_length* bytes, or because diff --git a/Doc/library/zlib.rst b/Doc/library/zlib.rst index ce0a22b9456..f043915c0f4 100644 --- a/Doc/library/zlib.rst +++ b/Doc/library/zlib.rst @@ -308,6 +308,11 @@ Decompression objects support the following methods and attributes: :attr:`unconsumed_tail`. This bytestring must be passed to a subsequent call to :meth:`decompress` if decompression is to continue. If *max_length* is zero then the whole input is decompressed, and :attr:`unconsumed_tail` is empty. + For example, the full content could be read like:: + + process_output(d.decompress(data, max_length)) + while chunk := d.decompress(d.unconsumed_tail, max_length): + process_output(chunk) .. versionchanged:: 3.6 *max_length* can be used as a keyword argument.