[Python-ideas] High time for a builtin function to manage packages (simply)?
ncoghlan at gmail.com
Mon Sep 7 07:09:03 CEST 2015
On 7 September 2015 at 12:18, Steven D'Aprano <steve at pearwood.info> wrote:
> On Sat, Sep 05, 2015 at 05:03:36PM -0400, Terry Reedy wrote:
>> On 9/5/2015 3:08 AM, Stephen J. Turnbull wrote:
>> >So let's fix it, already! Now that we have a blessed package
>> >management module, why not have a builtin that handles the simple
>> >cases? Say
>> > def installer(package, command='install'):
>> > ...
>> Because new builtins have a high threashold to reach, and this doesn't
>> reach it? Installation is a specialized and rare operation.
> You're right about the first part, but as Chris has already suggested,
> this need not be *literally* a built-in. Like help() it could be
> imported at REPL startup.
Technically it's "import site" that injects those - you have to run
with "-S" to prevent them from being installed:
$ python3 -c "quit()"
$ python3 -Sc "quit()"
Traceback (most recent call last):
File "<string>", line 1, in <module>
NameError: name 'quit' is not defined
Regardless, I agree a "site builtin" like help() or quit() is a better
option here than a true builtin, and I also think it's a useful idea.
I'd make it simpler than the proposed API though, and instead just
offer an "install(specifier)" API that was a thin shell around
cmd = ["install"]
if sys.prefix == sys.base_prefix:
cmd.append("--user") # User installs only when outside a venv
# TODO: throw exception when there's a problem
If folks want more flexibility, then they'll need to access (and
understand) the underlying installer.
As far as other possible objections go:
* the pkg_resources global state problem we should be able to work
around just by reloading pkg_resources (if already loaded) after
installing new packages (I've previously tried to address some aspects
of that particular problem upstream, but doing so poses significant
backwards compatibility challenges)
* I believe integration with systems like conda, PyPM, and the
Enthought installer should be addressed through a plugin model in pip,
rather than directly in the standard library
* providing a standard library API for querying the set of installed
packages independently of pip is a separate question
Nick Coghlan | ncoghlan at gmail.com | Brisbane, Australia
More information about the Python-ideas