1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
from contextlib import contextmanager
import os
from os.path import dirname, abspath, join as pjoin
import shutil
from subprocess import check_call
import sys
from tempfile import mkdtemp
from . import compat
_in_proc_script = pjoin(dirname(abspath(__file__)), '_in_process.py')
@contextmanager
def tempdir():
td = mkdtemp()
try:
yield td
finally:
shutil.rmtree(td)
class BackendUnavailable(Exception):
"""Will be raised if the backend cannot be imported in the hook process."""
class UnsupportedOperation(Exception):
"""May be raised by build_sdist if the backend indicates that it can't."""
def default_subprocess_runner(cmd, cwd=None, extra_environ=None):
"""The default method of calling the wrapper subprocess."""
env = os.environ.copy()
if extra_environ:
env.update(extra_environ)
check_call(cmd, cwd=cwd, env=env)
class Pep517HookCaller(object):
"""A wrapper around a source directory to be built with a PEP 517 backend.
source_dir : The path to the source directory, containing pyproject.toml.
backend : The build backend spec, as per PEP 517, from pyproject.toml.
"""
def __init__(self, source_dir, build_backend):
self.source_dir = abspath(source_dir)
self.build_backend = build_backend
self._subprocess_runner = default_subprocess_runner
# TODO: Is this over-engineered? Maybe frontends only need to
# set this when creating the wrapper, not on every call.
@contextmanager
def subprocess_runner(self, runner):
prev = self._subprocess_runner
self._subprocess_runner = runner
yield
self._subprocess_runner = prev
def get_requires_for_build_wheel(self, config_settings=None):
"""Identify packages required for building a wheel
Returns a list of dependency specifications, e.g.:
["wheel >= 0.25", "setuptools"]
This does not include requirements specified in pyproject.toml.
It returns the result of calling the equivalently named hook in a
subprocess.
"""
return self._call_hook('get_requires_for_build_wheel', {
'config_settings': config_settings
})
def prepare_metadata_for_build_wheel(
self, metadata_directory, config_settings=None):
"""Prepare a *.dist-info folder with metadata for this project.
Returns the name of the newly created folder.
If the build backend defines a hook with this name, it will be called
in a subprocess. If not, the backend will be asked to build a wheel,
and the dist-info extracted from that.
"""
return self._call_hook('prepare_metadata_for_build_wheel', {
'metadata_directory': abspath(metadata_directory),
'config_settings': config_settings,
})
def build_wheel(
self, wheel_directory, config_settings=None,
metadata_directory=None):
"""Build a wheel from this project.
Returns the name of the newly created file.
In general, this will call the 'build_wheel' hook in the backend.
However, if that was previously called by
'prepare_metadata_for_build_wheel', and the same metadata_directory is
used, the previously built wheel will be copied to wheel_directory.
"""
if metadata_directory is not None:
metadata_directory = abspath(metadata_directory)
return self._call_hook('build_wheel', {
'wheel_directory': abspath(wheel_directory),
'config_settings': config_settings,
'metadata_directory': metadata_directory,
})
def get_requires_for_build_sdist(self, config_settings=None):
"""Identify packages required for building a wheel
Returns a list of dependency specifications, e.g.:
["setuptools >= 26"]
This does not include requirements specified in pyproject.toml.
It returns the result of calling the equivalently named hook in a
subprocess.
"""
return self._call_hook('get_requires_for_build_sdist', {
'config_settings': config_settings
})
def build_sdist(self, sdist_directory, config_settings=None):
"""Build an sdist from this project.
Returns the name of the newly created file.
This calls the 'build_sdist' backend hook in a subprocess.
"""
return self._call_hook('build_sdist', {
'sdist_directory': abspath(sdist_directory),
'config_settings': config_settings,
})
def _call_hook(self, hook_name, kwargs):
# On Python 2, pytoml returns Unicode values (which is correct) but the
# environment passed to check_call needs to contain string values. We
# convert here by encoding using ASCII (the backend can only contain
# letters, digits and _, . and : characters, and will be used as a
# Python identifier, so non-ASCII content is wrong on Python 2 in
# any case).
if sys.version_info[0] == 2:
build_backend = self.build_backend.encode('ASCII')
else:
build_backend = self.build_backend
with tempdir() as td:
compat.write_json({'kwargs': kwargs}, pjoin(td, 'input.json'),
indent=2)
# Run the hook in a subprocess
self._subprocess_runner(
[sys.executable, _in_proc_script, hook_name, td],
cwd=self.source_dir,
extra_environ={'PEP517_BUILD_BACKEND': build_backend}
)
data = compat.read_json(pjoin(td, 'output.json'))
if data.get('unsupported'):
raise UnsupportedOperation
if data.get('no_backend'):
raise BackendUnavailable
return data['return_val']