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Change PyObject_AsCharBuffer() error message #54825

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vstinner opened this issue Dec 3, 2010 · 8 comments
Closed

Change PyObject_AsCharBuffer() error message #54825

vstinner opened this issue Dec 3, 2010 · 8 comments
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interpreter-core Interpreter core (Objects, Python, Grammar, and Parser dirs)

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@vstinner
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vstinner commented Dec 3, 2010

BPO 10616
Nosy @pitrou, @vstinner, @merwok, @bitdancer

Note: these values reflect the state of the issue at the time it was migrated and might not reflect the current state.

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GitHub fields:

assignee = None
closed_at = <Date 2011-05-30.21:21:38.161>
created_at = <Date 2010-12-03.16:43:34.519>
labels = ['interpreter-core']
title = 'Change PyObject_AsCharBuffer() error message'
updated_at = <Date 2011-05-30.21:21:38.160>
user = 'https://github.com/vstinner'

bugs.python.org fields:

activity = <Date 2011-05-30.21:21:38.160>
actor = 'python-dev'
assignee = 'none'
closed = True
closed_date = <Date 2011-05-30.21:21:38.161>
closer = 'python-dev'
components = ['Interpreter Core']
creation = <Date 2010-12-03.16:43:34.519>
creator = 'vstinner'
dependencies = []
files = []
hgrepos = []
issue_num = 10616
keywords = []
message_count = 8.0
messages = ['123263', '123265', '123266', '124316', '134386', '134390', '134545', '137332']
nosy_count = 7.0
nosy_names = ['pitrou', 'vstinner', 'eric.araujo', 'r.david.murray', 'sijinjoseph', 'santoso.wijaya', 'python-dev']
pr_nums = []
priority = 'normal'
resolution = 'fixed'
stage = 'resolved'
status = 'closed'
superseder = None
type = None
url = 'https://bugs.python.org/issue10616'
versions = ['Python 3.1', 'Python 3.2', 'Python 3.3']

@vstinner
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vstinner commented Dec 3, 2010

b'abc'.partition(':') raises a confusing TypeError('expected an object with the buffer interface'): what is a buffer? what is the buffer interface?

The error comes from PyObject_AsCharBuffer() which is used by:

  • bytes methods: partition, rpartition, find, index, rfind, rindex, count, translate, replace, startswith, endswith
  • complex(): raise a better but incomplete error message on error ("complex() arg is not a string"), incomplete because number is not mentionned
  • float(): raise a better error message on error ("float() argument must be a string or a number")
  • PyArg_Parse*() with the "e" format -> posix.spawnvpe(), imp.load_compiled(), imp.load_source(), imp.load_package()

The error message should be changed to something mentioning classic Python terms. Eg. TypeError("expected bytes, bytearray or buffer compatible object").

@vstinner vstinner added the interpreter-core Interpreter core (Objects, Python, Grammar, and Parser dirs) label Dec 3, 2010
@vstinner
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vstinner commented Dec 3, 2010

See also bpo-6780.

@vstinner
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vstinner commented Dec 3, 2010

complex(): raise a better but incomplete error message on error
("complex() arg is not a string"), incomplete because number is not
mentionned

Fixed by r86977.

@bitdancer
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bitdancer commented Dec 18, 2010

Victor, I think you attached msg123266 to the wrong issue.

@pitrou
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pitrou commented Apr 25, 2011

+1 to Victor's proposal ("expected bytes, bytearray or buffer compatible object").

@sijinjoseph
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sijinjoseph mannequin commented Apr 25, 2011

Looking at object.h the buffer interface is defined as

/* buffer interface */
typedef struct bufferinfo {
    void *buf;
    PyObject *obj;        /* owned reference */
    Py_ssize_t len;
    Py_ssize_t itemsize;  /* This is Py_ssize_t so it can be
                             pointed to by strides in simple case.*/
    int readonly;
    int ndim;
    char *format;
    Py_ssize_t *shape;
    Py_ssize_t *strides;
    Py_ssize_t *suboffsets;
    Py_ssize_t smalltable[2];  /* static store for shape and strides of
                                  mono-dimensional buffers. */
    void *internal;
} Py_buffer;

typedef int (*getbufferproc)(PyObject *, Py_buffer *, int);
typedef void (*releasebufferproc)(PyObject *, Py_buffer *);

typedef struct {
     getbufferproc bf_getbuffer;
     releasebufferproc bf_releasebuffer;
} PyBufferProcs;

The code that's throwing that error looks like

if (pb == NULL || pb->bf_getbuffer == NULL) {
        PyErr_SetString(PyExc_TypeError,
                        "expected an object with the buffer interface");

I would argue that the error message gives appropriate information because it is expecting the object to have a bf_getbuffer member.

Maybe the friendly error message is best handled at a higher level?

@merwok
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merwok commented Apr 27, 2011

+1 to Antoine’s +1.

@python-dev
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python-dev mannequin commented May 30, 2011

New changeset 7ed75bb4f37c by Victor Stinner in branch 'default':
Close bpo-10616: mention bytes and bytearray in PyObject_AsCharBuffer() error
http://hg.python.org/cpython/rev/7ed75bb4f37c

@python-dev python-dev mannequin closed this as completed May 30, 2011
@ezio-melotti ezio-melotti transferred this issue from another repository Apr 10, 2022
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