Revert "Pull out high-level interfaces as an extended example"

.travis.yml

@@ -31,7 +31,6 @@ jobs:
 cache: pip
 
 install:
-- pip install -U virtualenv
-- pip install tox
+- pip install tox tox-venv
 
 script: tox

README.rst

@@ -8,21 +8,38 @@ provides:
   the current process.
 - Fallbacks for the optional hooks, so that frontends can call the hooks without
   checking which are defined.
-- Functions to load the build system table from ``pyproject.toml``, with
-  optional fallback to setuptools.
+- Higher-level functions which install the build dependencies into a
+  temporary environment and build a wheel/sdist using them.
 
 Run the tests with ``pytest`` or `tox <https://pypi.org/project/tox>`_.
 
-Usage:
+High level usage, with build requirements handled:
 
 .. code-block:: python
 
     import os
-    from pep517 import Pep517HookCaller
-    from pep517.pyproject import load_system
+    from pep517.envbuild import build_wheel, build_sdist
 
     src = 'path/to/source'  # Folder containing 'pyproject.toml'
-    build_sys = load_system(src)
+    destination = 'also/a/folder'
+    whl_filename = build_wheel(src, destination)
+    assert os.path.isfile(os.path.join(destination, whl_filename))
+
+    targz_filename = build_sdist(src, destination)
+    assert os.path.isfile(os.path.join(destination, targz_filename))
+
+Lower level usage—you are responsible for ensuring build requirements are
+available:
+
+.. code-block:: python
+
+    import os
+    import toml
+    from pep517.wrappers import Pep517HookCaller
+
+    src = 'path/to/source'  # Folder containing 'pyproject.toml'
+    with open(os.path.join(src, 'pyproject.toml')) as f:
+        build_sys = toml.load(f)['build-system']
 
     print(build_sys['requires'])  # List of static requirements
 
@@ -40,9 +57,18 @@ Usage:
     whl_filename = hooks.build_wheel(destination, config_options)
     assert os.path.isfile(os.path.join(destination, whl_filename))
 
-The caller is responsible for installing build dependencies.
-The static requirements should be installed before trying to call any hooks.
+To test the build backend for a project, run in a system shell:
+
+.. code-block:: shell
+
+    python3 -m pep517.check path/to/source  # source dir containing pyproject.toml
+
+To build a backend into source and/or binary distributions, run in a shell:
+
+.. code-block:: shell
+
+    python -m pep517.build path/to/source  # source dir containing pyproject.toml
 
-The ``buildtool_demo`` package in this repository gives a more complete
-example of how to use the hooks. This is an example, and doesn't get installed
-with the ``pep517`` package.
+This 'build' module should be considered experimental while the PyPA `decides
+on the best place for this functionality
+<https://github.com/pypa/packaging-problems/issues/219>`_.

pep517/__init__.py

@@ -2,5 +2,3 @@
 """
 
 __version__ = '0.8.2'
-
-from .wrappers import *  # noqa: F401,F403

examples/buildtool/build.py → pep517/build.py

@@ -3,16 +3,58 @@
 import argparse
 import logging
 import os
+import toml
 import shutil
 
 from .envbuild import BuildEnvironment
-from pep517 import Pep517HookCaller
-from pep517.pyproject import load_system, validate_system
+from .wrappers import Pep517HookCaller
 from .dirtools import tempdir, mkdir_p
+from .compat import FileNotFoundError
 
 log = logging.getLogger(__name__)
 
 
+def validate_system(system):
+    """
+    Ensure build system has the requisite fields.
+    """
+    required = {'requires', 'build-backend'}
+    if not (required <= set(system)):
+        message = "Missing required fields: {missing}".format(
+            missing=required-set(system),
+        )
+        raise ValueError(message)
+
+
+def load_system(source_dir):
+    """
+    Load the build system from a source dir (pyproject.toml).
+    """
+    pyproject = os.path.join(source_dir, 'pyproject.toml')
+    with open(pyproject) as f:
+        pyproject_data = toml.load(f)
+    return pyproject_data['build-system']
+
+
+def compat_system(source_dir):
+    """
+    Given a source dir, attempt to get a build system backend
+    and requirements from pyproject.toml. Fallback to
+    setuptools but only if the file was not found or a build
+    system was not indicated.
+    """
+    try:
+        system = load_system(source_dir)
+    except (FileNotFoundError, KeyError):
+        system = {}
+    system.setdefault(
+        'build-backend',
+        'setuptools.build_meta:__legacy__',
+    )
+    system.setdefault('requires', ['setuptools', 'wheel'])
+    return system
+
+
 def _do_build(hooks, env, dist, dest):
     get_requires_name = 'get_requires_for_build_{dist}'.format(**locals())
     get_requires = getattr(hooks, get_requires_name)

examples/buildtool/check.py → pep517/check.py

@@ -14,7 +14,7 @@
 
 from .colorlog import enable_colourful_output
 from .envbuild import BuildEnvironment
-from pep517 import Pep517HookCaller
+from .wrappers import Pep517HookCaller
 
 log = logging.getLogger(__name__)
 

examples/buildtool/envbuild.py → pep517/envbuild.py

@@ -9,9 +9,8 @@
 import sys
 from sysconfig import get_paths
 from tempfile import mkdtemp
-import threading
 
-from pep517 import Pep517HookCaller
+from .wrappers import Pep517HookCaller, LoggerWrapper
 
 log = logging.getLogger(__name__)
 
@@ -27,40 +26,6 @@ def _load_pyproject(source_dir):
     )
 
 
-class LoggerWrapper(threading.Thread):
-    """
-    Read messages from a pipe and redirect them
-    to a logger (see python's logging module).
-    """
-
-    def __init__(self, logger, level):
-        threading.Thread.__init__(self)
-        self.daemon = True
-
-        self.logger = logger
-        self.level = level
-
-        # create the pipe and reader
-        self.fd_read, self.fd_write = os.pipe()
-        self.reader = os.fdopen(self.fd_read)
-
-        self.start()
-
-    def fileno(self):
-        return self.fd_write
-
-    @staticmethod
-    def remove_newline(msg):
-        return msg[:-1] if msg.endswith(os.linesep) else msg
-
-    def run(self):
-        for line in self.reader:
-            self._write(self.remove_newline(line))
-
-    def _write(self, message):
-        self.logger.log(self.level, message)
-
-
 class BuildEnvironment(object):
     """Context manager to install build deps in a simple temporary environment
 

examples/buildtool/meta.py → pep517/meta.py

@@ -17,9 +17,9 @@
     from zipp import Path
 
 from .envbuild import BuildEnvironment
-from pep517 import Pep517HookCaller, quiet_subprocess_runner
-from pep517.pyproject import validate_system, load_system, compat_system
+from .wrappers import Pep517HookCaller, quiet_subprocess_runner
 from .dirtools import tempdir, mkdir_p, dir_to_zipfile
+from .build import validate_system, load_system, compat_system
 
 log = logging.getLogger(__name__)