improve installing via pip

[JonnyJD]

isrcsubmit needs at least one non-python package (libdiscid, C library), so it can't be installed completely via pip.
However, when installing all python modules you will get a better error message like:

OSError: libdiscid.so.0: cannot open shared object file: No such file or directory

Pip then probably only installs into /usr/local/bin, which might or might not be in the $PATH.

This was probably the purpose of #116, even though was not mentioned in the subject.

[JonnyJD]

I nearly forgot: the recommended install of the dependencies is either via the package manager (on linux), as that installs also libdiscid or to use one of the packages mentioned here (also including a libdiscid binary for Windows and Mac):
http://jonnyjd.github.io/musicbrainz-isrcsubmit/download

[eli-schwartz]

The current use of:

musicbrainz-isrcsubmit/setup.py

Lines 54 to 55 in cb034c6

	# we load isrcsubmit on setup
	args["setup_requires"] = args["install_requires"],

Does not work. By the time setuptools has parsed this, the previous use of from isrcsubmit import __version__ has already run, and the setup.py has either successfully imported discid or aborted with a fatal error. This breaks the ability for setuptools to list and install the required dependencies.

There are three possible solutions:

• Embrace https://www.python.org/dev/peps/pep-0518/ which can list buildsystem dependencies, it is supported by pip at least (but not plain setuptools)
• refactor the imports to allow importing the version via a minimal import graph, probably requires having this in a separate version.py file usable by setup.py
• Bump the version in two places on every release.

[JonnyJD]

This is basically implemented, but currently not active because I somehow can't deploy to PyPI:
Pypa/warehouse#5466

[JonnyJD]

After also fixing python-discid and testing with docker run -it ubuntu this seems to work now:

# pip3 install --no-cache-dir isrcsubmit
Collecting isrcsubmit
  Downloading https://files.pythonhosted.org/packages/a9/cf/bc0d85d52a0fb6735d02d8c6ccd7e852808e1d59370ebb741e22aa15558a/isrcsubmit-2.1.0.tar.gz (49kB)
    100% |################################| 51kB 837kB/s 
Collecting discid>=1.0.0 (from isrcsubmit)
  Downloading https://files.pythonhosted.org/packages/d5/fa/c8856ae3eb53393445d84589afbd49ded85527563a7c0457f4e967d5b7af/discid-1.2.0.tar.gz
Collecting musicbrainzngs>=0.4 (from isrcsubmit)
  Downloading https://files.pythonhosted.org/packages/63/cc/67ad422295750e2b9ee57c27370dc85d5b85af2454afe7077df6b93d5938/musicbrainzngs-0.6.tar.gz (111kB)
    100% |################################| 112kB 3.3MB/s 
Installing collected packages: discid, musicbrainzngs, isrcsubmit
  Running setup.py install for discid ... done
  Running setup.py install for musicbrainzngs ... done
  Running setup.py install for isrcsubmit ... done
Successfully installed discid-1.2.0 isrcsubmit-2.1.0 musicbrainzngs-0.6

Of course:

$ isrcsubmit.py
Traceback (most recent call last):
  File "/usr/local/bin/isrcsubmit.py", line 47, in <module>
    import discid
  File "/usr/local/lib/python3.6/dist-packages/discid/__init__.py", line 30, in <module>
    from discid.disc import read, put, Disc, DiscError, TOCError
  File "/usr/local/lib/python3.6/dist-packages/discid/disc.py", line 24, in <module>
    from discid.libdiscid import _LIB, FEATURES
  File "/usr/local/lib/python3.6/dist-packages/discid/libdiscid.py", line 108, in <module>
    _LIB = _open_library(_LIB_NAME)
  File "/usr/local/lib/python3.6/dist-packages/discid/libdiscid.py", line 99, in _open_library
    return ctypes.cdll.LoadLibrary(lib_name)
  File "/usr/lib/python3.6/ctypes/__init__.py", line 426, in LoadLibrary
    return self._dlltype(name)
  File "/usr/lib/python3.6/ctypes/__init__.py", line 348, in __init__
    self._handle = _dlopen(self._name, mode)
OSError: libdiscid.so.0: cannot open shared object file: No such file or directory

I am not going to fix this now, as it would be a bit more complex.

Just for reference there is another alternative library, python-libdiscid which is using the same C library libdiscid. It is not using ctypes but is compiled against libdiscid directly. This fails on install:

# pip3 install --no-cache-dir python-libdiscid
Collecting python-libdiscid
  Downloading https://files.pythonhosted.org/packages/b8/be/88ffe177fef362fca0a12e67d400ce92cd96274c15cbe7d7d1674f8dec5c/python-libdiscid-1.0.tar.gz (64kB)
    100% |################################| 71kB 1.4MB/s 
Installing collected packages: python-libdiscid
  Running setup.py install for python-libdiscid ... error
    Complete output from command /usr/bin/python3 -u -c "import setuptools, tokenize;__file__='/tmp/pip-build-_n7uygih/python-libdiscid/setup.py';f=getattr(tokenize, 'open', open)(__file__);code=f.read().replace('\r\n', '\n');f.close();exec(compile(code, __file__, 'exec'))" install --record /tmp/pip-zeav4qaw-record/install-record.txt --single-version-externally-managed --compile:
    running install
    running build
    running build_py
    creating build
    creating build/lib.linux-x86_64-3.6
    creating build/lib.linux-x86_64-3.6/libdiscid
    copying libdiscid/discid.py -> build/lib.linux-x86_64-3.6/libdiscid
    copying libdiscid/exceptions.py -> build/lib.linux-x86_64-3.6/libdiscid
    copying libdiscid/__init__.py -> build/lib.linux-x86_64-3.6/libdiscid
    creating build/lib.linux-x86_64-3.6/libdiscid/tests
    copying libdiscid/tests/test_libdiscid.py -> build/lib.linux-x86_64-3.6/libdiscid/tests
    copying libdiscid/tests/test_compat_discid.py -> build/lib.linux-x86_64-3.6/libdiscid/tests
    copying libdiscid/tests/common.py -> build/lib.linux-x86_64-3.6/libdiscid/tests
    copying libdiscid/tests/__init__.py -> build/lib.linux-x86_64-3.6/libdiscid/tests
    creating build/lib.linux-x86_64-3.6/libdiscid/compat
    copying libdiscid/compat/discid.py -> build/lib.linux-x86_64-3.6/libdiscid/compat
    copying libdiscid/compat/__init__.py -> build/lib.linux-x86_64-3.6/libdiscid/compat
    running build_ext
    building 'libdiscid._discid' extension
    creating build/temp.linux-x86_64-3.6
    creating build/temp.linux-x86_64-3.6/libdiscid
    x86_64-linux-gnu-gcc -pthread -DNDEBUG -g -fwrapv -O2 -Wall -g -fstack-protector-strong -Wformat -Werror=format-security -Wdate-time -D_FORTIFY_SOURCE=2 -fPIC -I/usr/include/python3.6m -c libdiscid/_discid.c -o build/temp.linux-x86_64-3.6/libdiscid/_discid.o
    In file included from libdiscid/_discid.c:445:0:
    libdiscid/discid-wrapper.h:25:10: fatal error: discid/discid.h: No such file or directory
     #include <discid/discid.h>
              ^~~~~~~~~~~~~~~~~
    compilation terminated.
    error: command 'x86_64-linux-gnu-gcc' failed with exit status 1
    
    ----------------------------------------
Command "/usr/bin/python3 -u -c "import setuptools, tokenize;__file__='/tmp/pip-build-_n7uygih/python-libdiscid/setup.py';f=getattr(tokenize, 'open', open)(__file__);code=f.read().replace('\r\n', '\n');f.close();exec(compile(code, __file__, 'exec'))" install --record /tmp/pip-zeav4qaw-record/install-record.txt --single-version-externally-managed --compile" failed with error code 1 in /tmp/pip-build-_n7uygih/python-libdiscid/

So it has the advantage to fail early, but it also needs the header files (which python-discid doesn't) and the error message you get might not be "straightforward".