123 lines
3.1 KiB
Plaintext
123 lines
3.1 KiB
Plaintext
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PEP: 295
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Title: Interpretation of multiline string constants
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Version: $Revision$
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Last-Modified: $Date$
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Author: yozh@mx1.ru (Stepan Koltsov)
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Status: Draft
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Type: Standards Track
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Created: 22-Jul-2002
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Python-Version: 3.0
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Post-History:
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Abstract
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This PEP describes an interpretation of multiline string constants
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for Python. It suggests stripping spaces after newlines and
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stripping a newline if it is first character after an opening
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quotation.
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Rationale
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This PEP proposes an interpretation of multiline string constants
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in Python. Currently, the value of string constant is all the
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text between quotations, maybe with escape sequences substituted,
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e.g.:
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def f():
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"""
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la-la-la
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limona, banana
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"""
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def g():
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return "This is \
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string"
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print repr(f.__doc__)
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print repr(g())
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prints:
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'\n\tla-la-la\n\tlimona, banana\n\t'
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'This is \tstring'
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This PEP suggest two things
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- ignore the first character after opening quotation, if it is
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newline
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- second: ignore in string constants all spaces and tabs up to
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first non-whitespace character, but no more then current
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indentation.
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After applying this, previous program will print:
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'la-la-la\nlimona, banana\n'
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'This is string'
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To get this result, previous programs could be rewritten for
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current Python as (note, this gives the same result with new
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strings meaning):
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def f():
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"""\
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la-la-la
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limona, banana
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"""
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def g():
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"This is \
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string"
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Or stripping can be done with library routines at runtime (as
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pydoc does), but this decreases program readability.
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Implementation
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I'll say nothing about CPython, Jython or Python.NET.
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In original Python, there is no info about the current indentation
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(in spaces) at compile time, so space and tab stripping should be
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done at parse time. Currently no flags can be passed to the
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parser in program text (like from __future__ import xxx). I
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suggest enabling or disabling of this feature at Python compile
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time depending of CPP flag Py_PARSE_MULTILINE_STRINGS.
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Alternatives
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New interpretation of string constants can be implemented with flags
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'i' and 'o' to string constants, like
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i"""
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SELECT * FROM car
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WHERE model = 'i525'
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""" is in new style,
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o"""SELECT * FROM employee
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WHERE birth < 1982
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""" is in old style, and
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"""
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SELECT employee.name, car.name, car.price FROM employee, car
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WHERE employee.salary * 36 > car.price
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""" is in new style after Python-x.y.z and in old style otherwise.
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Also this feature can be disabled if string is raw, i.e. if flag 'r'
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specified.
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Copyright
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This document has been placed in the Public Domain.
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Local Variables:
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mode: indented-text
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indent-tabs-mode: nil
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sentence-end-double-space: t
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fill-column: 70
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End:
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