Fix a few formal and grammatical issues.

This commit is contained in:
Georg Brandl 2009-02-28 14:22:01 +00:00
parent e37d3b2f90
commit f464bd118b
1 changed files with 30 additions and 27 deletions

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@ -10,7 +10,6 @@ Created: 22-Feb-2009
Python-Version: 2.7, 3.1
Post-History:
.. contents::
Abstract
========
@ -21,19 +20,18 @@ This PEP proposes various enhancements for Distutils:
- An install script to install a package in Python.
- An uninstall script to uninstall a package in Python.
Rationale
=========
There are three problems right now in the way packages
are installed in Python:
- There are too many ways to install a package in
Python.
- There are too many ways to install a package in Python.
- There is no way to uninstall a package.
- There is no API to get the metadata of installed
packages.
- There is no API to get the metadata of installed packages.
How packages are installed
--------------------------
@ -56,14 +54,14 @@ This file corresponds to the file called `PKG-INFO`, built by
the `sdist` command.
The problem is that many people use `easy_install` (setuptools) or `pip`
to install their packages. And these third-party tool does not install
the packages the same way Distutils does.
to install their packages, and these third-party tools do not install
packages in the same way that Distutils does:
- `easy_install` creates an `EGG-INFO` directory inside an `.egg` directory,
and adds a `PKG-INFO` file inside this directory, amongst other files.
- `pip` creates an `.egg-info` directory inside the site-packages directory
besides the package, and adds an `PKG-INFO` file inside it.
besides the package, and adds a `PKG-INFO` file inside it.
They both add other files in the `EGG-INFO` or `.egg-info` directory, and
create or modify `.pth` files. `pip` also creates one `.pth` file
@ -77,11 +75,11 @@ a package, you have to be a power user and remove the package directory
from the right site-packages directory, then look over the right pth
files. And this method differs, depending on the tools you are using.
The worst is that you depend on the way the packager created his package.
The worst issue is that you depend on the way the packager created his package.
When you call `python setup.py install`, it will not be installed the same way
depending on the tool used by the packager (distutils or setuptools).
But there's a common behavior : files are copied in your installation.
But there's common behavior: files are copied in your installation.
And there's a way to keep track of theses file, so to remove them.
Installing a package
@ -93,7 +91,7 @@ There are too many different ways to install a package in Python:
- using `easy_install`, the script provided by setuptools
- using `pip`
The problem is: they do no install the package the same way,
The problem is: they do not install the package the same way,
and Python should provide one and only one way to do it.
What this PEP proposes
@ -104,20 +102,21 @@ To address those issues, this PEP proposes a few changes:
- a new `.egg-info` structure using a directory;
- a list of elements this directory holds;
- some new functions in `pkgutil`
- adding an install and an uninstall script
- addition of an install and an uninstall script
.egg-info becomes a directory
=============================
The first change would be to make `.egg-info` become a directory and
The first change would be to make `.egg-info` a directory and let it
hold the `PKG-INFO` file built by the `write_pkg_file` method.
This change will not impact Python itself, because this file is not
used anywhere yet in the standard library. So there's no need of
deprecation.
Although, it will impact the `setuptools` and `pip` project, but given
the fact that they already works with a directory that contains a
Although it will impact the `setuptools` and `pip` projects, but given
the fact that they already work with a directory that contains a
`PKG-INFO` file, the change will be small.
For example, if the `zlib` package is installed, two elements
@ -130,6 +129,7 @@ will be installed in `site-packages`::
To be able to implement this change, the impacted code in Distutils
is the `install_egg_info` command.
Adding MANIFEST and RECORD in the .egg-info directory
=====================================================
@ -137,12 +137,12 @@ Some files can be added inside the `.egg-info` directory at installation
time. They will all be UPPERCASE files.
- the `MANIFEST` file built by the `sdist` command. Notice that
some fixes were made lately on the default files added in `MANIFEST`
some fixes were made lately on the default file names added in `MANIFEST`
when `MANIFEST.in` is not provided (see #2279 for instance).
- the `RECORD` file will hold the list of installed files. These
correspond to the files listed by the `record` option of the `install`
command, and will always be generated. This will allow uninstallation, like
command, and will always be generated. This will allow uninstall, as
explained later in this PEP.
The `install` command will record by default installed files in the
@ -168,6 +168,7 @@ Back to our `zlib` example, we will have::
XXX See if we want to keep the 2.5.2-py2.6 part
New functions in pkgutil
========================
@ -178,10 +179,10 @@ The new functions added in the package are :
- get_egg_info(pkg_name) -> path or None
Scans all site-packages directories and look for all `pkg_name.egg-info`
directory. Returns the directory path that contains a PKG-INFO that matches
Scans all site-packages directories and looks for all `pkg_name.egg-info`
directories. Returns the directory path that contains a PKG-INFO that matches
`pkg_name` for the `name` metadata. Notice that there should be at most
one result. If moe that one path matches the pkg_name, a DistutilsError
one result. If more than one path matches the pkg_name, a DistutilsError
is raised.
If the directory is not found, returns None.
@ -197,9 +198,9 @@ The new functions added in the package are :
Uses `get_egg_info` and gets any file inside the directory,
pointed by filename.
filename is any value founded in `distutils.sdist.EGG_INFO_FILES`
filename can be any value found in `distutils.sdist.EGG_INFO_FILES`.
Let's use it over our `zlib` example::
Let's use it with our `zlib` example::
>>> from pkgutil import get_egg_info, get_metadata, get_egg_info_file
>>> get_egg_info('zlib')
@ -213,6 +214,7 @@ Let's use it over our `zlib` example::
...
files
Adding an install and an uninstall script
=========================================
@ -225,24 +227,26 @@ that are not discussed here.
- they add an entry in a .pth file
A new script called `install.py` is added in a new directory called `scripts`
in Distutils, and let people run an installation using::
in Distutils, and lets people run an installation using::
$ python -m 'distutils.scripts.install' zlib
$ python -m distutils.scripts.install zlib
An uninstall command is added as well, that removes the files recorded
in the RECORD file. This removal will warn on file that no longer exists
An uninstall command is added as well that removes the files recorded
in the RECORD file. This removal will warn on files that no longer exist
and will not take care of side effects, like the removal of a file
used by another element of the system.
XXX work to be done here : specification of the two commands
(probably a mix of easy_install and pip)
Copyright
=========
This document has been placed in the public domain.
..
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