[issue1820] Enhance Object/structseq.c to match namedtuple and tuple api

[Sunny K]

Sunny K added the comment:

Hi Stefan,

There is a comment at the top in structseq.c

/* Fields with this name have only a field index, not a field name.
   They are only allowed for indices < n_visible_fields. */
char *PyStructSequence_UnnamedField = "unnamed field";

This is the definition of os.stat_result in posixmodule.c:

static PyStructSequence_Field stat_result_fields[] = {
    {"st_mode",    "protection bits"},
    {"st_ino",     "inode"},
    {"st_dev",     "device"},
    {"st_nlink",   "number of hard links"},
    {"st_uid",     "user ID of owner"},
    {"st_gid",     "group ID of owner"},
    {"st_size",    "total size, in bytes"},
    /* The NULL is replaced with PyStructSequence_UnnamedField later. */
    {NULL,   "integer time of last access"},
    {NULL,   "integer time of last modification"},
    {NULL,   "integer time of last change"},
    {"st_atime",   "time of last access"},
    {"st_mtime",   "time of last modification"},
    {"st_ctime",   "time of last change"},
    {"st_atime_ns",   "time of last access in nanoseconds"},
    {"st_mtime_ns",   "time of last modification in nanoseconds"},
    {"st_ctime_ns",   "time of last change in nanoseconds"},
      ...


By visible i mean the values present in the repr of the object and by-extension accessible by position.

I talked about my problems with os.stat_result in points 3 and 4 of msg202333 i.e repr of os.stat_result takes the first three keys from the attribute-access only fields (the invisible part) and uses them for the last three values in the displayed structseq.

With my current patch, _fields for os.stat_result only has 7 values:

>>> x = os.stat('.')
>>> x._fields
('st_mode', 'st_ino', 'st_dev', 'st_nlink', 'st_uid', 'st_gid', 'st_size')
>>>

Is this what you expect?

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<http://bugs.python.org/issue1820>
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