关于python：pip3安装PyYAML失败。（python3.7，macOS High Sierra）

pip3 install PyYAML failed.(python3.7, macOS High Sierra)

今天我用brew upgrade命令升级了python3.7。

我试着用pip3安装pyyaml包。

我有这个错误，不知道……

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% pip3 install PyYAML

checking if libyaml is linkable
clang build/temp.macosx-10.13-x86_64-3.7/check_libyaml.o -L/usr/local/lib -L/usr/local/opt/openssl/lib -L/usr/local/opt/sqlite/lib -lyaml -o build/temp.macosx-10.13-x86_64-3.7/check_libyaml
building '_yaml' extension
creating build/temp.macosx-10.13-x86_64-3.7/ext
clang -Wno-unused-result -Wsign-compare -Wunreachable-code -fno-common -dynamic -DNDEBUG -g -fwrapv -O3 -Wall -I/usr/local/include -I/usr/local/opt/openssl/include -I/usr/local/opt/sqlite/include -I/usr/local/Cellar/python/3.7.0/Frameworks/Python.framework/Versions/3.7/include/python3.7m -c ext/_yaml.c -o build/temp.macosx-10.13-x86_64-3.7/ext/_yaml.o
In file included from ext/_yaml.c:271:
ext/_yaml.h:10:9: warning: 'PyString_CheckExact' macro redefined [-Wmacro-redefined]
#define PyString_CheckExact PyBytes_CheckExact
^
ext/_yaml.c:139:11: note: previous definition is here
#define PyString_CheckExact PyUnicode_CheckExact
^
ext/_yaml.c:1410:17: warning: assigning to 'char *' from 'const char *' discards qualifiers [-Wincompatible-pointer-types-discards-qualifiers]
__pyx_v_value = yaml_get_version_string();
^ ~~~~~~~~~~~~~~~~~~~~~~~~~
ext/_yaml.c:2577:52: warning: incompatible pointer types passing 'int (void *, char *, size_t, size_t *)' (aka 'int (void *, char *, unsigned long, unsigned long *)') to parameter of type 'yaml_read_handler_t *' (aka 'int (*)(void *, unsigned char *, unsigned long, unsigned long *)') [-Wincompatible-pointer-types]
yaml_parser_set_input((&__pyx_v_self->parser), __pyx_f_5_yaml_input_handler, ((void *)__pyx_v_self));
^~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/local/include/yaml.h:1370:30: note: passing argument to parameter 'handler' here

.......

最后

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/usr/local/Cellar/python/3.7.0/Frameworks/Python.framework/Versions/3.7/include/python3.7m/pystate.h:238:15: note: 'curexc_traceback' declared here
PyObject *curexc_traceback;
^
51 warnings and 15 errors generated.
error: command 'clang' failed with exit status 1

----------------------------------------
Command"/usr/local/opt/python/bin/python3.7 -u -c"import setuptools, tokenize;__file__='/private/tmp/pip-install-exbgmayz/PyYAML/setup.py';f=getattr(tokenize, 'open', open)(__file__);code=f.read().replace('

', '
');f.close();exec(compile(code, __file__, 'exec'))" install --record /private/tmp/pip-record-n11vy5s0/install-record.txt --single-version-externally-managed --compile" failed with error code 1 in /private/tmp/pip-install-exbgmayz/PyYAML/

我试过解决这个问题，但还是不知道。

https://github.com/yaml/pyyaml/issues/126
如何安装python的yaml包？

如何解决此问题….

相关讨论

pyyaml的C扩展不在3.7上编译，这就是错误消息的内容，以及126版线程中的一些消息所指的内容。pyyaml安装程序中有一种机制，它应该测试C扩展是否可以编译，它主要检查libyaml是否可用。

我假设你升级到3.7.0(而不是你写的时候升级python3.7)，所以我建议你降级到3.6。虽然pyyaml在pypi上的页面表明只支持3.4和3.5，但3.6似乎还可以。

如果您不能降级python，并且现在需要3.7的功能，您可以考虑使用ruamel.yaml(免责声明：我是该包的作者)。它本质上是一个pyyaml的超集，所以通常

1	import ruamel.yaml as yaml

应该让你的程序正常工作。由于3.7版的MacOS车轮在Pypi安装中可用，因此不应导致任何问题。