classification
Title: Enhanced \N{} escapes for Unicode strings
Type: enhancement Stage:
Components: Unicode Versions: Python 3.4
process
Status: open Resolution:
Dependencies: Superseder:
Assigned To: Nosy List: ezio.melotti, mrabarnett, steven.daprano, terry.reedy
Priority: normal Keywords: patch

Created on 2013-08-01 13:54 by steven.daprano, last changed 2013-08-01 22:04 by terry.reedy.

Files
File name Uploaded Description Edit
issue18614.patch mrabarnett, 2013-08-01 16:46
Messages (3)
msg194075 - (view) Author: Steven D'Aprano (steven.daprano) * (Python committer) Date: 2013-08-01 13:54
As per the discussion here:

http://mail.python.org/pipermail/python-ideas/2013-July/022419.html

\N{} escapes should support the Unicode code point notation U+xxxx (where there are four, five or six hex digits after the U+).

E.g. '\N{U+03BB}' => 'λ'

unicodedata.lookup should also support such numeric names, e.g.:

unicodedata.lookup('U+03BB') => 'λ'

As '+' is otherwise prohibited in Unicode character names, there should never be ambiguity between 'U+xxxx' as a code point and an actual name, and a single lookup function can handle both.

(See http://www.unicode.org/versions/Unicode6.2.0/ch04.pdf#G39 for details on characters allowed in names.)


Also add a function for the reverse

unicodedata.codepoint('λ') => 'U+03BB'


def codepoint(c):
    return 'U+{:04X}'.format(ord(c))
msg194087 - (view) Author: Matthew Barnett (mrabarnett) * (Python triager) Date: 2013-08-01 16:46
I've attached a patch for this.
msg194123 - (view) Author: Terry J. Reedy (terry.reedy) * (Python committer) Date: 2013-08-01 22:04
I agree with the proposal.

Some of the code seems redundant with code we already have.
In Python, I would write

def codepoint_from_U_notation(name, namelen):
  if not (4 <= namelen <= 6): raise <wrong length>
  return chr(int(name, 16))

maybe with try-except to re-write error messages like
ValueError: invalid literal for int() with base 16: '99x3'
ValueError: chr() arg not in range(0x110000)

My point is that we already have code to convert hex strings to int; I presume PyUnicode_FromOrdinal(code) is the C version of 'chr' that already checks the max value.
History
Date User Action Args
2013-08-01 22:04:55terry.reedysetnosy: + terry.reedy
messages: + msg194123
2013-08-01 16:46:11mrabarnettsetfiles: + issue18614.patch

nosy: + mrabarnett
messages: + msg194087

keywords: + patch
2013-08-01 13:54:05steven.dapranocreate