PEP 784: Updates to reflect inclusion of gzip and discussed rejected ideas (#4375)

Author: emmatyping

peps/pep-0784.rst

@@ -30,10 +30,11 @@ Motivation
 ==========
 
 CPython has modules for several different compression formats, such as
-:mod:`zlib (DEFLATE) <zlib>`, :mod:`bzip2 <bz2>`, and :mod:`lzma <lzma>`,
-each widely used. Including popular compression algorithms matches Python's
-"batteries included" philosophy of incorporating widely useful standards and
-utilities. :mod:`!lzma` is the most recent such module, added in Python 3.3.
+:mod:`zlib (DEFLATE) <zlib>`, :mod:`gzip <gzip>`, :mod:`bzip2 <bz2>`, and
+:mod:`lzma <lzma>`, each widely used. Including popular compression algorithms
+matches Python's "batteries included" philosophy of incorporating widely useful
+standards and utilities. :mod:`!lzma` is the most recent such module, added in
+Python 3.3.
 
 Since then, Zstandard has become the modern *de facto* preferred compression
 library for both high performance compression and decompression attaining high
@@ -216,9 +217,10 @@ used to build libraries CPython depends on for Windows.
 Other compression modules
 -------------------------
 
-New import names ``compression.lzma``, ``compression.bz2``, and
-``compression.zlib`` will be introduced in Python 3.14 re-exporting the
-contents of the existing ``lzma``, ``bz2``, and ``zlib`` modules respectively.
+New import names ``compression.lzma``, ``compression.bz2``,
+``compression.gzip`` and ``compression.zlib`` will be introduced in Python 3.14
+re-exporting the contents of the existing ``lzma``, ``bz2``, ``gzip`` and
+``zlib`` modules respectively.
 
 The ``_compression`` module, given that it is marked private, will be
 immediately renamed to ``compression._common.streams``. The new name was
@@ -289,17 +291,80 @@ decision is reached regarding the open issues.
 Rejected Ideas
 ==============
 
-Name the module ``libzstd`` and do not make a new ``compression`` namespace
+Name the module ``zstdlib`` and do not make a new ``compression`` namespace
 ---------------------------------------------------------------------------
 
 One option instead of making a new ``compression`` namespace would be to find
-a different name, such as ``libzstd``, as the import name. However, the issue
-of existing import names is likely to persist for future compression formats
-added to the standard library. LZ4, a common high speed compression format,
-has `a package on PyPI <https://pypi.org/project/lz4/>`_, ``lz4``, with the
-import name ``lz4``. Instead of solving this issue for each compression format,
-it is better to solve it once and for all by using the already-claimed
-``compression`` namespace.
+a different name, such as ``zstdlib``, as the import name. Several other names,
+such as ``zst``, ``libzstd``, and ``zstdcomp`` were proposed as well. In
+discussion, the names were found to either be too easy to typo, or unintuitive.
+Furthermore, the issue of existing import names is likely to persist for future
+compression formats added to the standard library. LZ4, a common high speed
+compression format, has `a package on PyPI <https://pypi.org/project/lz4/>`_,
+``lz4``, with the import name ``lz4``. Instead of solving this issue for each
+compression format, it is better to solve it once and for all by using the
+already-claimed ``compression`` namespace.
+
+Introduce an experimental ``_zstd`` package in Python 3.14
+----------------------------------------------------------
+
+Since this PEP was published close to the beta cutoff for new features for
+Python 3.14, one proposal was to name the package a private module ``_zstd``
+so that packaging tools could use it sooner, but not deciding on a name. This
+would allow more time for discussion of the final module name during the 3.15
+development window. However, introducing a private module was not popular. The
+expectations and contract for external usage of a private module in the
+standard library are unclear.
+
+Introduce a standard library namespace instead of ``compression``
+-----------------------------------------------------------------
+
+One alternative to a ``compression`` namespace would be to introduce a
+``std`` namespace for the entire standard library. However, this was seen as
+too significant a change for 3.14, with no agreed upon semantics, migration
+path, or name for the package. Furthermore, a future PEP introducing a ``std``
+namespace could always define that the ``compression`` sub-modules be flattened
+into the ``std`` namespace.
+
+Include ``zipfile`` and ``tarfile`` in ``compression``
+------------------------------------------------------
+
+Compression is often used with archiving tools, so putting both :mod:`zipfile`
+and :mod:`tarfile` under the ``compression`` namespace is appealing. However,
+compression can be used beyond just archiving tools. For example, network
+requests can be gzip compressed. Furthermore, formats like tar do not include
+compression themselves, instead relying on external compression. Therefore,
+this PEP does not propose moving :mod:`!zipfile` or :mod:`!tarfile` under
+``compression``.
+
+Do not include ``gzip`` under ``compression``
+---------------------------------------------
+
+The :rfc:`GZip format RFC <1952>` defines a format which can include multiple
+blocks and metadata about its contents. In this way GZip is rather similar to
+archive formats like ZIP and tar. Despite that, in usage GZip is often treated
+as a compression format rather than an archive format. Looking at how different
+languages classify GZip, the prevailing trend is to classify it as a
+compression format and not an archiving format.
+
+========== ======================== ==============================================================================
+Language   Compression or Archive   Documentation Link
+========== ======================== ==============================================================================
+Golang     Compression              https://pkg.go.dev/compress/gzip
+Ruby       Compression              https://docs.ruby-lang.org/en/master/Zlib/GzipFile.html
+Rust       Compression              https://github.com/rust-lang/flate2-rs
+Haskell    Compression              https://hackage.haskell.org/package/zlib
+C#         Compression              https://learn.microsoft.com/en-us/dotnet/api/system.io.compression.gzipstream
+Java       Archive                  https://docs.oracle.com/javase/8/docs/api/java/util/zip/package-summary.html
+NodeJS     Compression              https://nodejs.org/api/zlib.html
+Web APIs   Compression              https://developer.mozilla.org/en-US/docs/Web/API/Compression_Streams_API
+PHP        Compression              https://www.php.net/manual/en/function.gzcompress.php
+Perl       Compression              https://perldoc.perl.org/IO::Compress::Gzip
+========== ======================== ==============================================================================
+
+In addition, the :mod:`!gzip` module in Python mostly focuses on single block
+content and has an API similar to other compression modules, making it a good
+fit for the ``compression`` namespace.
 
 
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