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Various changes inspired by Thomas Heller's c.l.p comments

This commit is contained in:
Andrew M. Kuchling 2002-03-25 13:36:05 +00:00
parent 8e48462a3c
commit 8dd23c1dcf
1 changed files with 46 additions and 41 deletions
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pep-0262.txt
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@ -22,10 +22,10 @@ Requirements
* Is package X on a system?
* What version of package X is installed?
* Where can the new version of package X be found?
XXX Does this mean "a home page where the user can go and
* Where can the new version of package X be found? (This can
be defined as either "a home page where the user can go and
find a download link", or "a place where a program can find
the newest version?" Perhaps both...
the newest version?" Both should probably be supported.)
* What files did package X put on my system?
* What package did the file x/y/z.py come from?
* Has anyone modified x/y/z.py locally?
@ -46,18 +46,9 @@ Database Location
The rationale for scanning subdirectories is that we can move to a
directory-based indexing scheme if the package directory contains
too many entries. That is, instead of INSTALLDB/Numeric, we
could switch to INSTALLDB/N/Nu/Numeric or some similar scheme.
XXX how much do we care about performance? Do we really need to
use an anydbm file or something similar?
XXX is the actual filename important? Let's say the installation
data for PIL is in the file INSTALLDB/Numeric. Is this OK? When
we want to figure out if Numeric is installed, do we want to open
a single file, or have to scan them all? Note that for
human-interface purposes, we'll often have to scan all the
packages anyway, for a case-insensitive or keyword search.
too many entries. For example, this would let us transparently
switch from INSTALLDB/Numeric to INSTALLDB/N/Nu/Numeric or some
similar hashing scheme.
Database Contents
@ -70,31 +61,31 @@ Database Contents
FILES'. This is for future-proofing; if we add a new section,
for example to list documentation files, then we'd add a DOCS
section and list it in the contents. Sections are always
separated by blank lines. XXX too simple?
separated by blank lines.
[PKG-INFO section] An initial set of RFC-822 headers
containing the package information for a file, as described in
PEP 241, "Metadata for Python Software Packages".
PKG-INFO section
An initial set of RFC-822 headers containing the package
information for a file, as described in PEP 241, "Metadata for
Python Software Packages".
A blank line indicating the end of the PKG-INFO section.
FILES section
An entry for each file installed by the package.
XXX Are .pyc and .pyo files in this list? What about compiled
.so files? AMK thinks "no" and "yes", respectively.
Each file's entry is a single tab-delimited line that contains the
following fields:
XXX should each file entry be all on one line and
tab-delimited? More RFC-822 headers? AMK thinks tab-delimited
seems sufficent.
Each file's entry is a single tab-delimited line that contains
the following fields:
* The file's size
* XXX do we need to store permissions? The owner/group?
* An MD5 digest of the file, written in hex. (XXX All 16
bytes of the digest seems unnecessary; first 8 bytes only,
maybe? Is a zlib.crc32() hash sufficient?)
* The file's permissions, and the owner/group of the file.
XXX what to do on Windows?
* An MD5 digest of the file, encoded in hex.
* The file's full path, as installed on the system. (XXX
should it be relative to sys.prefix, or sys.prefix +
@ -104,28 +95,42 @@ Database Contents
* XXX some sort of type indicator, to indicate whether this is
a Python module, binary module, documentation file, config
file? Do we need this?
file? Do we need this?
A package that uses the Distutils for installation will
A package that uses the Distutils for installation should
automatically update the database. Packages that roll their own
installation
installation will have to use the database's API to to manually
add or update their own entry. System package managers such as
RPM or pkgadd can just create the new 'package name' file in the
INSTALLDB directory.
XXX what's the relationship between this database and the RPM or
DPKG database? I'm tempted to make the Python database completely
optional; a distributor can preserve the interface of the package
management tool and replace it with their own wrapper on top of
their own package manager. (XXX but how would the Distutils know
that, and not bother to update the Python database?)
Deliverables
A description of the database API, to be added to this PEP.
Patches to the Distutils that 1) implement a InstallationDatabase
Patches to the Distutils that 1) implement an InstallationDatabase
class, 2) Update the database when a new package is installed. 3)
a simple package management tool, features to be added to this
PEP. (Or a separate PEP?)
Rejected Suggestions
Instead of using one text file per package, one large text file or
an anydbm file could be used. This has been rejected for a few
reasons. First, performance is probably not an extremely pressing
concern as the package database is only used when installing or
removing packages, a relatively infrequent task. Scalability also
likely isn't a problem, as people may have hundreds of Python
packages installed, but thousands seems unlikely. Finally,
individual text files are compatible with installers such as RPM
or DPKG because a package can just drop the new database file into
the database directory. If one large text file or a binary file
were used, the Python database would then have to be updated by
running a postinstall script.
References
[1] Michael Muller's patch (posted to the Distutils-SIG around 28
@ -135,7 +140,7 @@ References
Acknowledgements
Ideas for this PEP originally came from postings by Greg Ward,
Fred Drake, Mats Wichmann, and others.
Fred L. Drake Jr., Thomas Heller, Mats Wichmann, and others.
Many changes and rewrites to this document were suggested by the
readers of the Distutils SIG.