Add support for editable installs (#1460)

* Add support for editable installs

Signed-off-by: Jean-Christophe Morin <jean_christophe_morin@hotmail.com>

.gitignore

@@ -21,3 +21,5 @@ docs/_build
 .tox
 cpp_cov_html/
 lcov_html_report/
+*.so
+*.pyd

MANIFEST.in

@@ -23,6 +23,8 @@ exclude */.DS_Store
 exclude .clang-format
 exclude OTIO_VERSION.json
 global-exclude *.pyc
+global-exclude *.so
+global-exclude *.pyd
 
 prune maintainers
 prune tsc

docs/tutorials/quickstart.md

@@ -62,7 +62,7 @@ with OpenTimelineIO due to spaces in the path.
 
 ## To build OTIO for Python development:
 
-+ `python -m pip install .`
++ `python -m pip install -e .`
 
 ## To build OTIO for both C++ and Python development:
 

setup.py

@@ -16,7 +16,6 @@
 import sys
 import platform
 import subprocess
-import unittest
 import tempfile
 import shutil
 
@@ -46,23 +45,30 @@ def join_args(args):
     return ' '.join(map(shlex.quote, args))
 
 
-class CMakeExtension(Extension):
-    def __init__(self, name):
-        Extension.__init__(self, name, sources=[])
-
-
 class OTIO_build_ext(setuptools.command.build_ext.build_ext):
     """
     def initialize_options(self):
         super(setuptools.command.build_ext.build_ext, self).initialize_options()
     """
 
+    built = False
+
     def run(self):
-        # This works around the fact that we build _opentime and _otio
-        # extensions as a one-shot cmake invocation. Usually we'd build each
-        # separately using build_extension.
         self.announce('running OTIO build_ext', level=2)
-        self.build()
+        # Let the original build_ext class do its job.
+        # This is rather important because build_ext.run takes care of a
+        # couple of things, one of which is to copy the built files into
+        # the source tree (in src/py-opentimelineio/opentimelineio)
+        # when building in editable mode.
+        super().run()
+
+    def build_extension(self, _ext: Extension):
+        # This works around the fact that we build _opentime and _otio
+        # extensions as a one-shot cmake invocation. Setuptools calls
+        # build_extension for each Extension registered in the setup function.
+        if not self.built:
+            self.build()
+            self.built = True
 
     def build(self):
         self.build_temp_dir = (
@@ -256,22 +262,17 @@ class OTIO_build_py(setuptools.command.build_py.build_py):
     """Stamps PROJECT_METADATA into __init__ files."""
 
     def run(self):
-        setuptools.command.build_py.build_py.run(self)
-
-        if not self.dry_run:
+        super().run()
+
+        if not self.dry_run and not self.editable_mode:
+            # Only run when not in dry-mode (a dry run should not have any side effect)
+            # and in non-editable mode. We don't want to edit files when in editable
+            # mode because that could lead to modifications to the source files.
+            # Note that setuptools will set self.editable_mode to True
+            # when "pip install -e ." is run.
             _append_version_info_to_init_scripts(self.build_lib)
 
 
-def test_otio():
-    """Discovers and runs tests"""
-    try:
-        # Clear the environment of a preset media linker
-        del os.environ['OTIO_DEFAULT_MEDIA_LINKER']
-    except KeyError:
-        pass
-    return unittest.TestLoader().discover('tests')
-
-
 # copied from first paragraph of README.md
 LONG_DESCRIPTION = """OpenTimelineIO is an interchange format and API for
 editorial cut information. OTIO is not a container format for media, rather it
@@ -339,8 +340,13 @@ def test_otio():
     ),
 
     ext_modules=[
-        CMakeExtension('_opentimelineio'),
-        CMakeExtension('_opentime'),
+        # The full and correct module name is required here because
+        # setuptools needs to resolve the name to find the built file
+        # and copy it into the source tree. (Because yes, editable install
+        # means that the install should point to the source tree, which
+        # means the .sos need to also be there alongside the python files).
+        Extension('opentimelineio._otio', sources=[]),
+        Extension('opentimelineio._opentime', sources=[]),
     ],
 
     package_dir={
@@ -382,8 +388,6 @@ def test_otio():
         ]
     },
 
-    test_suite='setup.test_otio',
-
     # because we need to open() the adapters manifest, we aren't zip-safe
     zip_safe=False,