Cannot load CLoader

Hi, I’m using pyyaml in a Docker container based on bitnami/minideb:jessie, where python version is 2.7.9.

The original code is using CLoader and I cannot change it. Any reason CLoader fails to load but Loader is fine ?

>>> import yaml
>>> yaml.__version__ '3.12'
>>> from yaml import Loader
>>> from yaml import CLoader Traceback (most recent call last):   File "<stdin>", line 1, in <module> ImportError: cannot import name CLoader 
>>>

I cannot figure out what I’m missing here. Any idea ?

Running it from the Docker image python:2.7.9 does not raise any error then:

$ docker run -ti python:2.7.9 bash
#/ python
>>> from yaml import CLoader
>>> from yaml import Loader
>>>

Thanks for your help.

[immerrr]

This is because cyaml is optional and requires build dependencies, such as cython and yaml.h to be available upon building the package (yaml.h comes from libyaml-dev package in Debian/Ubuntu):

This is what it prints when libyaml-dev is not found when running $ pip --no-cache-dir install --verbose --force-reinstall -I pyyaml

<....>
    running build_ext
    creating build/temp.linux-x86_64-2.7
    checking if libyaml is compilable
    gcc -pthread -fno-strict-aliasing -g -O2 -DNDEBUG -g -fwrapv -O3 -Wall -Wstrict-prototypes -fPIC -I/home/immerrr/.conda/envs/loc-des/include/python2.7 -c build/temp.linux-x86_64-2.7/check_libyaml.c -o build/temp.linux-x86_64-2.7/check_libyaml.o
    build/temp.linux-x86_64-2.7/check_libyaml.c:2:18: fatal error: yaml.h: No such file or directory
    compilation terminated.

    libyaml is not found or a compiler error: forcing --without-libyaml
    (if libyaml is installed correctly, you may need to
     specify the option --include-dirs or uncomment and
     modify the parameter include_dirs in setup.cfg)
<..finishes up right away..>

And this is what you’ll see if everything is set up fine:

<....>
    checking if libyaml is compilable
    gcc -pthread -fno-strict-aliasing -g -O2 -DNDEBUG -g -fwrapv -O3 -Wall -Wstrict-prototypes -fPIC -I/home/immerrr/.conda/envs/loc-des/include/python2.7 -c build/temp.linux-x86_64-2.7/check_libyaml.c -o build/temp.linux-x86_64-2.7/check_libyaml.o
    checking if libyaml is linkable
    gcc -pthread build/temp.linux-x86_64-2.7/check_libyaml.o -L/home/immerrr/.conda/envs/loc-des/lib -lyaml -o build/temp.linux-x86_64-2.7/check_libyaml
    building '_yaml' extension
<..proceeds to build the extension..>

[jonas-eschle]

Thanks for the fix! This worked. But I would propose to add such a statement directly in the error message. So if cyaml cannot be compiled but is accessed, it should not just be an attribute not found-error but rather a message telling the above.