Python package sage_conf: Provides optional configuration information for sagelib

[mkoeppe]

This ticket introduces a new Python package sage_conf.

• sage-the-distribution will generate this Python package at ./configure time and install it at build time before starting to build/install sagelib using src/setup.py.
• Distributions will generate and install their own sage_conf by a method of their choice before starting to build/install sagelib.

A console_script allows to query individual variable values from the shell, or output all variables in .env format:

$ local/bin/sage-config MAXIMA
/Users/mkoeppe/s/sage/sage-rebasing/worktree-algebraic-2018-spring/local/bin/maxima
$ local/bin/sage-config
VERSION=9.1.beta0
MAXIMA=/Users/mkoeppe/s/sage/sage-rebasing/worktree-algebraic-2018-spring/local/bin/maxima
SAGE_LOCAL=/Users/mkoeppe/s/sage/sage-rebasing/worktree-algebraic-2018-spring/local
SAGE_ROOT=/Users/mkoeppe/s/sage/sage-rebasing/worktree-algebraic-2018-spring

The module and the script are used as follows:

1. It provides configuration information to sagelib at installation time (src/setup.py).

   Ultimately we want to be able to install sagelib with pip. To support installation by pip from PyPI, from an URL, etc., we cannot expect to configure the build like we do now, by writing the configuration to the file src/sage-env-config. Moreover, if pip is running in --isolated mode, also no environment variables are passed. Then the only information flow is through arguments to pip build and through the installed Python packages. By installing sage_conf first, we make the configuration available to the pip install of sagelib.

2. It provides configuration information to the docbuild, in particular about the install locations of documentation of external packages.

3. It provides configuration information to the runtime of sagelib, making sagelib more independent from the environment variables set by src/bin/sage-env (local/bin/sage-env).

a. By providing SAGE_LOCAL as one the configuration variables, it removes assumptions regarding install locations of sagelib relative to $SAGE_LOCAL. This enables the following:

• Installing an experimental version of sagelib in other install locations, such as in a user site packages directory.

• Making sagelib available in a user's venv, as in the following example:
  Without this ticket:

  $ sage -python -m venv --system-site-packages ~/personal-sage-venv/
  $ source ~/personal-sage-venv/bin/activate
  (personal-sage-venv) $ python
  >>> import sage.env
  >>> sage.env.SAGE_LOCAL
  '/Users/mkoeppe/personal-sage-venv'                                     # wrong
  >>> import sage.all
  RuntimeError: You must get the file local/bin/sage-maxima.lisp
  

  With this ticket:

  >>> sage.env.SAGE_LOCAL
  '/Users/mkoeppe/s/sage/sage-rebasing/worktree-algebraic-2018-spring/local'
  >>> import sage.all
  >>> sage.all.maxima('1')
  1
  

• Add configure option --with-sage-venv=SAGE_VENV to create venv there instead of in SAGE_LOCAL #29013/spkg-configure.m4 for python3 #27824: Using the system python3 via spkg-configure.m4
  b. For a broader context: see Meta-ticket: Split sage-env into 5 to clean up sage configuration #21707 Task: Split sage-env into 5

CC: @kiwifb @antonio-rojas @isuruf @embray @infinity0 @timokau @jdemeyer @dimpase @jhpalmieri @vbraun

Component: build

Author: Matthias Koeppe

Branch: af18a01

Reviewer: Dima Pasechnik, Erik Bray

Issue created by migration from https://trac.sagemath.org/ticket/29038

[mkoeppe]

Author: Matthias Koeppe

[mkoeppe]

Description changed:

--- 
+++ 
@@ -1,5 +1,6 @@
 This ticket introduces a new Python package `sage_conf` that solves the problem of providing configuration information to sagelib at installation time (`src/setup.py`), including the docbuild, and to the runtime of sagelib.
 
-- sage-the-distribution will generate this Python package at `./configure` time and install it before attempting to install sagelib using `src/setup.py`.
-- Distributions will generate and install their own `sage_conf` by a method of their choice.
+- sage-the-distribution will generate this Python package at `./configure` time and install it before starting to build/install sagelib using `src/setup.py`.
+- Distributions will generate and install their own `sage_conf` by a method of their choice before starting to build/install sagelib.
 
+(This ticket provides an alternative implementation of #29022 - see there for additional motivation.)

[mkoeppe]

Branch: u/mkoeppe/python_package_sage_conf__provides_optional_configuration_information_for_sagelib

[mkoeppe]

New commits:

fe5c890

29038: Python package sage_conf: Provides configuration information for sagelib

[mkoeppe]

Commit: fe5c890

[sagetrac-git]

Branch pushed to git repo; I updated commit sha1. New commits:

aefd827

build/pkgs/sage_conf/spkg-install: Fix up path

[sagetrac-git]

Changed commit from fe5c890 to aefd827

[dimpase]

comment:5

why are you checking in files which apparently are meant to be generated from .in templates?

[mkoeppe]

comment:6

A mistake, which I will fix in a moment. Thanks!

[sagetrac-git]

Changed commit from aefd827 to 88fd03c

[sagetrac-git]

Branch pushed to git repo; I updated commit sha1. New commits:

981e864	Move .gitignore to the right place, remove generated files
88fd03c	Add console_scripts entry_point sage-config

[mkoeppe]

Description changed:

--- 
+++ 
@@ -4,3 +4,16 @@
 - Distributions will generate and install their own `sage_conf` by a method of their choice before starting to build/install sagelib.
 
 (This ticket provides an alternative implementation of #29022 - see there for additional motivation.)
+
+A `console_script` allows to query individual variable values from the shell, or output all variables in .env format:
+
+```
+$ local/bin/sage-config MAXIMA
+/Users/mkoeppe/s/sage/sage-rebasing/worktree-algebraic-2018-spring/local/bin/maxima
+$ local/bin/sage-config
+VERSION=9.1.beta0
+MAXIMA=/Users/mkoeppe/s/sage/sage-rebasing/worktree-algebraic-2018-spring/local/bin/maxima
+SAGE_LOCAL=/Users/mkoeppe/s/sage/sage-rebasing/worktree-algebraic-2018-spring/local
+SAGE_ROOT=/Users/mkoeppe/s/sage/sage-rebasing/worktree-algebraic-2018-spring
+```
+

[mkoeppe]

Description changed:

--- 
+++ 
@@ -1,6 +1,6 @@
 This ticket introduces a new Python package `sage_conf` that solves the problem of providing configuration information to sagelib at installation time (`src/setup.py`), including the docbuild, and to the runtime of sagelib.
 
-- sage-the-distribution will generate this Python package at `./configure` time and install it before starting to build/install sagelib using `src/setup.py`.
+- sage-the-distribution will generate this Python package at `./configure` time and install it at build time before starting to build/install sagelib using `src/setup.py`.
 - Distributions will generate and install their own `sage_conf` by a method of their choice before starting to build/install sagelib.
 
 (This ticket provides an alternative implementation of #29022 - see there for additional motivation.)

[mkoeppe]

Description changed:

--- 
+++ 
@@ -17,3 +17,5 @@
 SAGE_ROOT=/Users/mkoeppe/s/sage/sage-rebasing/worktree-algebraic-2018-spring
 ```
 
+See also, for a broader context,
+- #21707 Task: Split sage-env into 5

[mkoeppe]

Description changed:

--- 
+++ 
@@ -1,9 +1,7 @@
-This ticket introduces a new Python package `sage_conf` that solves the problem of providing configuration information to sagelib at installation time (`src/setup.py`), including the docbuild, and to the runtime of sagelib.
+This ticket introduces a new Python package `sage_conf`.
 
 - sage-the-distribution will generate this Python package at `./configure` time and install it at build time before starting to build/install sagelib using `src/setup.py`.
 - Distributions will generate and install their own `sage_conf` by a method of their choice before starting to build/install sagelib.
-
-(This ticket provides an alternative implementation of #29022 - see there for additional motivation.)
 
 A `console_script` allows to query individual variable values from the shell, or output all variables in .env format:
 
@@ -17,5 +15,38 @@
 SAGE_ROOT=/Users/mkoeppe/s/sage/sage-rebasing/worktree-algebraic-2018-spring
 ```
 
-See also, for a broader context,
-- #21707 Task: Split sage-env into 5
+The module and the script are used as follows:
+
+1. It provides configuration information to sagelib at installation time (`src/setup.py`).
+
+2. It provides configuration information to the docbuild, in particular about the install locations of documentation of external packages.
+
+3. It provides configuration information to the runtime of sagelib, making sagelib more independent from the environment variables set by `src/bin/sage-env` (`local/bin/sage-env`).
+
+a. By providing SAGE_LOCAL as one the configuration variables, it removes assumptions regarding install locations of sagelib relative to $SAGE_LOCAL. This enables the following: 
+- Installing an experimental version of sagelib in other install locations, such as in a user site packages directory.
+- Making sagelib available in a user's venv, as in the following example:
+   Without this ticket:
+
+   ```
+   $ sage -python -m venv --system-site-packages ~/personal-sage-venv/
+   $ source ~/personal-sage-venv/bin/activate
+   (personal-sage-venv) $ python
+   >>> import sage.env
+   >>> sage.env.SAGE_LOCAL
+   '/Users/mkoeppe/personal-sage-venv'                                     # wrong
+   >>> import sage.all
+   RuntimeError: You must get the file local/bin/sage-maxima.lisp
+   ```
+   With this ticket:
+
+   ```
+   >>> sage.env.SAGE_LOCAL
+   '/Users/mkoeppe/s/sage/sage-rebasing/worktree-algebraic-2018-spring/local'
+   >>> import sage.all
+   >>> sage.all.maxima('1')
+   1
+   ```
+- #29013/#27824: Using the system python3 via spkg-configure.m4
+b. For a broader context: see #21707 Task: Split sage-env into 5
+