[New-bugs-announce] [issue26335] Make mmap.write return the number of bytes written like other write methods

[Jakub Stasiak]

New submission from Jakub Stasiak:

Since mmap objects are said to "behave like both bytearray and like file objects" I believe it's appropriate for the mmap.write() method to return the number of bytes written like write() of other file objects/interfaces I could find in the standard library for consistency reasons:

https://docs.python.org/3/library/io.html#io.BufferedIOBase.write
https://docs.python.org/3/library/io.html#io.BufferedWriter.write
https://docs.python.org/3/library/io.html#io.RawIOBase.write
https://docs.python.org/3/library/io.html#io.TextIOBase.write

Why I believe this would be useful: code that writes to file objects and tests the number of bytes/characters written right now will likely fail when it's passed a mmap object because its write() method returns None. With this patch applied it'll work transparently.

Please find proposed patch attached, I included information about the exception type in the documentation as it seems fitting (apologies for generating the patch using Git, I'll generate using Mercurial if necessary).

----------
components: IO, Library (Lib)
keywords: patch
messages: 260053
nosy: jstasiak
priority: normal
severity: normal
status: open
title: Make mmap.write return the number of bytes written like other write methods
type: enhancement
versions: Python 3.6
Added file: http://bugs.python.org/file41890/mmap_write_return_count.patch

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<http://bugs.python.org/issue26335>
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