From a36dbf75bd6b1283fd3da28c25fd583f20025c36 Mon Sep 17 00:00:00 2001
From: "Jason R. Coombs" <jaraco@jaraco.com>
Date: Sun, 1 Jan 2017 23:12:23 -0500
Subject: In the bootstrap script, generate a requirements.txt file and use it
 to install the dependencies just in time to make them available long enough
 to generate the egg info.

---
 bootstrap.py | 40 +++++++++++++++++++++++++++++++++++++---
 1 file changed, 37 insertions(+), 3 deletions(-)

(limited to 'bootstrap.py')

diff --git a/bootstrap.py b/bootstrap.py
index 761b8dfc..705a8720 100644
--- a/bootstrap.py
+++ b/bootstrap.py
@@ -5,13 +5,18 @@ environment by creating a minimal egg-info directory and then invoking the
 egg-info command to flesh out the egg-info directory.
 """
 
-__requires__ = ['packaging', 'six', 'appdirs']
-
 import os
+import io
+import re
+import contextlib
+import tempfile
+import shutil
 import sys
 import textwrap
 import subprocess
 
+import pip
+
 minimal_egg_info = textwrap.dedent("""
     [distutils.commands]
     egg_info = setuptools.command.egg_info:egg_info
@@ -54,6 +59,35 @@ def run_egg_info():
     subprocess.check_call(cmd)
 
 
+def gen_deps():
+    with io.open('setup.py', encoding='utf-8') as strm:
+        text = strm.read()
+    pattern = r'install_requires=\[(.*?)\]'
+    match = re.search(pattern, text, flags=re.M|re.DOTALL)
+    reqs = eval(match.group(1).replace('\n', ''))
+    with io.open('requirements.txt', 'w', encoding='utf-8') as reqs_file:
+        reqs_file.write('\n'.join(reqs))
+
+
+@contextlib.contextmanager
+def install_deps():
+    "Just in time make the deps available"
+    gen_deps()
+    tmpdir = tempfile.mkdtemp()
+    args = [
+        'install',
+        '-t', tmpdir,
+        '-r', 'requirements.txt',
+    ]
+    pip.main(args)
+    os.environ['PYTHONPATH'] = tmpdir
+    try:
+        yield tmpdir
+    finally:
+        shutil.rmtree(tmpdir)
+
+
 if __name__ == '__main__':
     ensure_egg_info()
-    run_egg_info()
+    with install_deps():
+        run_egg_info()
-- 
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