Differences between revisions 6 and 7
Revision 6 as of 2009-11-22 19:28:45
Size: 4577
Editor: p5B126851
Comment: changed prefix format
Revision 7 as of 2009-11-24 11:28:40
Size: 4738
Editor: p5B127112
Comment: Incorporated changes suggested by ronny
Deletions are marked like this. Additions are marked like this.
Line 24: Line 24:
    Valid identifiers must adhere to the regular expression `^$[a-z_]+`, i.e a `$` followed by any      combination of lowercase ASCII characters and the underscore.     Valid identifiers must adhere to the regular expression `^[a-z_]+`, i.e any combination of lowercase      ASCII characters and the underscore.
Line 29: Line 29:
    The full path for the prefix identifier for this distribution. A `/` seperated path will be used
    regardless of the target system. All paths except those for `$base` and `$platbase` are relative to
    those two as detailed below.
    The path for the prefix identifier for this distribution.

    A `/` seperated path will be used regardless of the target system. The path definition can be
    either absolute or prefixed with one of the identifiers defined below. An absolute path is only
    used if the installation location is not relative to sys.prefix ($base) or sys.exec_prefix
    ($platbase).
Line 66: Line 69:
}}}

Custom installation scheme:

{{{
base,/home/sirrobin/.local
platbase,/home/sirrobin/.local
purelib,$base/lib/pythonX.Y/site-packages
platlib,$platbase/lib/pythonX.Y/site-packages
scripts,/usr/local/bin
data,/usr/local/share/
Line 104: Line 118:
The Distribution class will get the following new methods: The Distribution class will get a new attribute `prefixes` which holds a dictionary
mapping prefix identifiers to their absolute paths.
Line 106: Line 121:
 * `get_prefixes()` returns a dictionary with prefix identifiers as keys and local absolute paths as values
 * `get_prefix(identifier)` returns the local absolute path for prefix with given identifier
Line 111: Line 124:
>>> prefixes = pkgutil.get_distribution('foo').get_prefixes()
>>> prefixes['$base']
>>> foo_dist = pkgutil.get_distribution('foo')
>>> foo_dist.prefixes['$base']
Line 114: Line 127:
>>> prefixes[$data'] >>> foo_dist.prefixes['$data']
Line 116: Line 129:
>>> ni_wish = open(os.path.join(prefixes['$data'], 'foo', 'shrubbery.jpg'))

>>> foo_dist = pkgutil.get_distribution('foo')
>>> foo_dist.get_prefix('$base')
'/usr'

>>> unladen = open(os.path.join(foo_dist.get_prefix('$data'), 'foo', 'european.swallow'))
>>> ni_wish = open(os.path.join(foo_dist.prefixes.get('$data'), 'foo', 'shrubbery.jpg'))
>>> unladen = open(os.path.join(foo_dist.prefixes['$data'], 'foo', 'european.swallow'))

Rationale

It is not possible to retrieve the installation paths of data, or other, files for all installation schemes supported by distutils right now. I propose the inclusion of a PREFIX file within the .egg-info directory that holds information on all prefixes set at installation time and a suitable API within pkgutil.

Proposal

PREFIX

The RECORD file is a CSV file, composed of records, one line per prefix. The csv module is used to read the file, with these options:

  • field delimiter : ,

  • quoting char : "

  • line terminator : os.linesep (so \r\n or \n)

Each record is composed of two elements:

  • prefix identifier

    • Prefix identifiers differentiate between the various prefixes used within the installation process.

      Valid identifiers must adhere to the regular expression ^[a-z_]+, i.e any combination of lowercase ASCII characters and the underscore.

  • path

    • The path for the prefix identifier for this distribution.

      A / seperated path will be used regardless of the target system. The path definition can be either absolute or prefixed with one of the identifiers defined below. An absolute path is only used if the installation location is not relative to sys.prefix ($base) or sys.exec_prefix ($platbase).

Identifiers

The list of standard identifiers comprises:

  • $base - Base prefix

  • $platbase - Platform specific base prefix

  • $purelib - Pure Python distribution

  • $platlib - Non-pure Python distribution (i.e one with extensions)

  • $scripts - Executable Python scripts

  • $data - Data files

Example

Standard scheme installation on posix:

base,/usr
platbase,/usr
purelib,$base/lib/pythonX.Y/site-packages
platlib,$platbase/lib/pythonX.Y/site-packages
scripts,$base/bin
data,$base/share

User scheme installation on posix:

base,/home/sirrobin/.local
platbase,/home/sirrobin/.local
purelib,$base/lib/pythonX.Y/site-packages
platlib,$platbase/lib/pythonX.Y/site-packages
scripts,$base/bin
data,share

Custom installation scheme:

base,/home/sirrobin/.local
platbase,/home/sirrobin/.local
purelib,$base/lib/pythonX.Y/site-packages
platlib,$platbase/lib/pythonX.Y/site-packages
scripts,/usr/local/bin
data,/usr/local/share/

Default values

Tables summarising the default values on different operating systems:

posix

Prefix identifier

Default value: Standard scheme

Default value: User scheme

Environment variable

Command line option

$base

sys.prefix

~/.local

$PYDIST_BASE

--prefix

$platbase

sys.exec_prefix

~/.local

$PYDIST_PLATBASE

--exec-prefix

$purelib

$base/lib/pythonX.Y/site-packages

$base/lib/pythonX.Y/site-packages

$PYDIST_PURELIB

--install-purelib

$platlib

$platbase/lib/pythonX.Y/site-packages

$platbase/lib/pythonX.Y/site-packages

$PYDIST_PLATLIB

--install-platlib

$scripts

$base/bin

$base/bin

$PYDIST_SCRIPTS

--install-scripts

$data

$base/share

$base/share

$PYDIST_DATA

--install-data

nt

Prefix identifier

Default value: Standard scheme

Default value: User scheme

Environment variable

Command line option

$base

sys.prefix

os.environ.get('%APPDATA%')

$PYDIST_BASE

--prefix

$platbase

sys.exec_prefix

os.environ.get('%APPDATA%')

$PYDIST_PLATBASE

--exec-prefix

$purelib

$base/Python

$base/Python/PythonXY/site-packages

$PYDIST_PURELIB

--install-purelib

$platlib

$platbase/Python

$platbase/Python/PythonXY/site-packages

$PYDIST_PLATLIB

--install-platlib

$scripts

$base/Scripts

$base/Python/Scripts

$PYDIST_SCRIPTS

--install-scripts

$data

$base/Data

$base/Python/Python26

$PYDIST_DATA

--install-data

mac

os2

ce

java

riscos

API

The Distribution class will get a new attribute prefixes which holds a dictionary mapping prefix identifiers to their absolute paths.

Usage example:

>>> foo_dist = pkgutil.get_distribution('foo')
>>> foo_dist.prefixes['$base']
'/usr'
>>> foo_dist.prefixes['$data']
'/usr/share'
>>> ni_wish = open(os.path.join(foo_dist.prefixes.get('$data'), 'foo', 'shrubbery.jpg'))
>>> unladen = open(os.path.join(foo_dist.prefixes['$data'], 'foo', 'european.swallow'))

Distutils/DiscussionOverview/FilePrefixes (last edited 2009-11-24 11:28:40 by p5B127112)

Unable to edit the page? See the FrontPage for instructions.