bpo-42958: Improve description of shallow= in filecmp.cmp docs (GH-27166) (GH-27608)

Co-authored-by: Łukasz Langa <lukasz@langa.pl>
Co-authored-by: Alexander Vandenbulcke <alexander.vandenbulcke95@gmail.com>
(cherry picked from commit a8dc4893d2b28827e82447326ea47759c161a722)

Co-authored-by: andrei kulakov <andrei.avk@gmail.com>

diff --git a/Doc/library/filecmp.rst b/Doc/library/filecmp.rst
index 31b9b4afab93489527f893ec0b3de5dd61951410..1d04c3ef9fd27a56537947fd2b1e8b95a196e5ea 100644 (file)
--- a/Doc/library/filecmp.rst
+++ b/Doc/library/filecmp.rst
@@ -22,8 +22,11 @@ The :mod:`filecmp` module defines the following functions:
    Compare the files named *f1* and *f2*, returning ``True`` if they seem equal,
    ``False`` otherwise.
 
-   If *shallow* is true, files with identical :func:`os.stat` signatures are
-   taken to be equal.  Otherwise, the contents of the files are compared.
+   If *shallow* is true and the :func:`os.stat` signatures (file type, size, and
+   modification time) of both files are identical, the files are taken to be
+   equal.
+
+   Otherwise, the files are treated as different if their sizes or contents differ.
 
    Note that no external programs are called from this function, giving it
    portability and efficiency.

diff --git a/Lib/filecmp.py b/Lib/filecmp.py
index 7a4da6beb50500fb5291e88e2c6afb02483da38d..1893f909de83c3294d8c0df9d216b80db81b5826 100644 (file)
--- a/Lib/filecmp.py
+++ b/Lib/filecmp.py
@@ -36,8 +36,9 @@ def cmp(f1, f2, shallow=True):
 
     f2 -- Second file name
 
-    shallow -- Just check stat signature (do not read the files).
-               defaults to True.
+    shallow -- treat files as identical if their stat signatures (type, size,
+               mtime) are identical. Otherwise, files are considered different
+               if their sizes or contents differ.  [default: True]
 
     Return value:
 

diff --git a/Misc/NEWS.d/next/Documentation/2021-07-15-11-19-03.bpo-42958.gC5IHM.rst b/Misc/NEWS.d/next/Documentation/2021-07-15-11-19-03.bpo-42958.gC5IHM.rst
new file mode 100644 (file)
index 0000000..c93b84d
--- /dev/null
+++ b/Misc/NEWS.d/next/Documentation/2021-07-15-11-19-03.bpo-42958.gC5IHM.rst
@@ -0,0 +1,2 @@
+Updated the docstring and docs of :func:`filecmp.cmp` to be more accurate
+and less confusing especially in respect to *shallow* arg.