setup: add flag to build_ext to control building zstd
Downstream packagers will inevitably want to disable building the
vendored python-zstandard Python package. Rather than force them
to patch setup.py, let's give them a knob to use.
distutils Command classes support defining custom options. It requires
setting certain class attributes (yes, class attributes: instance
attributes don't work because the class type is consulted before it
is instantiated).
We already have a custom child class of build_ext, so we set these
class attributes, implement some scaffolding, and override
build_extensions to filter the Extension instance for the zstd
extension if the `--no-zstd` argument is specified.
Example usage:
$ python setup.py build_ext --no-zstd
--- a/setup.py Wed Nov 09 16:01:34 2016 +0000
+++ b/setup.py Thu Nov 17 20:09:10 2016 -0800
@@ -276,7 +276,30 @@
# too late for some cases
return not self.pure and Distribution.has_ext_modules(self)
+# This is ugly as a one-liner. So use a variable.
+buildextnegops = dict(getattr(build_ext, 'negative_options', {}))
+buildextnegops['no-zstd'] = 'zstd'
+
class hgbuildext(build_ext):
+ user_options = build_ext.user_options + [
+ ('zstd', None, 'compile zstd bindings [default]'),
+ ('no-zstd', None, 'do not compile zstd bindings'),
+ ]
+
+ boolean_options = build_ext.boolean_options + ['zstd']
+ negative_opt = buildextnegops
+
+ def initialize_options(self):
+ self.zstd = True
+ return build_ext.initialize_options(self)
+
+ def build_extensions(self):
+ # Filter out zstd if disabled via argument.
+ if not self.zstd:
+ self.extensions = [e for e in self.extensions
+ if e.name != 'mercurial.zstd']
+
+ return build_ext.build_extensions(self)
def build_extension(self, ext):
try: