setup.py improved, git installation works (#14)

* setup.py improved

* PEP8 fixed, comments added

README.rst

@@ -86,7 +86,13 @@ of directly from GIT::
 Documentation
 =============
 
-https://pymchelper.readthedocs.io/
+
+Execute::
+
+    bdo2txt --help
+
+
+More on https://pymchelper.readthedocs.io/
 
 
 Features

setup.py

@@ -1,26 +1,112 @@
 import setuptools
 from pkg_resources import parse_version
-try:
-    import versioneer
-except ImportError:
-    # dirty hack needed by readthedoc generation tool
-    import subprocess
-    subprocess.call(["versioneer", "install"])
+
+
+def pip_command_output(pip_args):
+    '''
+    Get output (as a string) from pip command
+    :param pip_args: list o pip switches to pass
+    :return: string with results
+    '''
+    import sys
+    import pip
+    from io import StringIO
+    # as pip will write to stdout we use some nasty hacks
+    # to substitute system stdout with our own
+    old_stdout = sys.stdout
+    sys.stdout = mystdout = StringIO()
+    pip.main(pip_args)
+    output = mystdout.getvalue()
+    mystdout.truncate(0)
+    sys.stdout = old_stdout
+    return output
+
+
+def setup_versioneer():
+    '''
+    Generate (temporarily) versioneer.py file in project root directory
+    :return:
+    '''
+    try:
+        # assume versioneer.py was generated using "versioneer install" command
+        import versioneer
+        versioneer.get_version()
+    except ImportError:
+        # it looks versioneer.py is missing
+        # lets assume that versioneer package is installed
+        # and versioneer binary is present in $PATH
+        import subprocess
+        try:
+            # call versioneer install to generate versioneer.py
+            subprocess.check_output(["versioneer", "install"])
+        except OSError:
+            # it looks versioneer is missing from $PATH
+            # probably versioneer is installed in some user directory
+
+            # query pip for list of files in versioneer package
+            output = pip_command_output(["show", "-f", "versioneer"])
+
+            # now we parse the results
+            main_path = [x[len("Location: "):] for x in output.split('\n')
+                         if x.startswith("Location")][0]
+            bin_path = [x[len("  "):] for x in output.split('\n')
+                        if x.endswith("/versioneer")][0]
+
+            # exe_path is absolute path to versioneer binary
+            import os
+            exe_path = os.path.join(main_path, bin_path)
+            # call versioneer install to generate versioneer.py
+            subprocess.check_output([exe_path, "install"])
+
+
+def clean_cache():
+    '''
+    Python won't realise that new module has appeared in the runtime
+    We need to clean the cache of module finders. Hacking again
+    :return:
+    '''
+    import importlib
+    try:  # Python ver < 3.3
+        vermod = importlib.import_module("versioneer")
+        globals()["versioneer"] = vermod
+    except ImportError:
+        importlib.invalidate_caches()
+
+
+def get_version():
+    '''
+    Get project version (using versioneer)
+    :return:
+    '''
+    setup_versioneer()
+    clean_cache()
     import versioneer
+    version = versioneer.get_version()
+    parsed_version = parse_version(version)
+    if '*@' in parsed_version[1]:
+        import time
+        version += str(int(time.time()))
+    return version
 
-version = versioneer.get_version()
-parsed_version = parse_version(version)
-if '*@' in parsed_version[1]:
-    import time
-    version += str(int(time.time()))
+
+def get_cmdclass():
+    '''
+    Get setuptools command class
+    :return:
+    '''
+    setup_versioneer()
+    clean_cache()
+    import versioneer
+    return versioneer.get_cmdclass()
 
 
 with open('README.rst') as readme_file:
     readme = readme_file.read()
 
+
 setuptools.setup(
     name='pymchelper',
-    version=version,
+    version=get_version(),
     packages=['pymchelper'],
     url='https://github.com/DataMedSci/pymchelper',
     license='GPL',
@@ -57,6 +143,5 @@
             'pymchelper.bdo2txt:main',
         ],
     },
-    cmdclass=versioneer.get_cmdclass(),
-
+    cmdclass=get_cmdclass()
 )