big cleanup of nbconvert.utils.pandoc module. Remove useless functions, less cached values.

IPython/nbconvert/tests/test_pandoc.py

@@ -27,6 +27,7 b' from IPython.testing import decorators as dec'
 # Classes and functions
 #-----------------------------------------------------------------------------
 
+
 class TestPandoc(TestsBase):
     """Collection of Pandoc tests"""
 
@@ -36,30 +37,39 b' class TestPandoc(TestsBase):'
 
     @dec.onlyif_cmds_exist('pandoc')
     def test_pandoc_available(self):
-        """ Test behaviour of pandoc_available() """
+        """ Test behaviour that pandoc functions raise PandocMissing as documented """
+        pandoc.clean_cache()
+
         os.environ["PATH"] = ""
-        assert not pandoc.pandoc_available()
-        try:
-            pandoc.pandoc_available(failmode="raise")
-        except pandoc.PandocMissing:
-            assert True
+        assert pandoc_function_raised_missing(pandoc.get_pandoc_version) == True
+        assert pandoc_function_raised_missing(pandoc.check_pandoc_version) == True
+        assert pandoc_function_raised_missing(pandoc.pandoc, "", "markdown", "html") == True
 
+        # original_env["PATH"] should contain pandoc
         os.environ["PATH"] = self.original_env["PATH"]
-        assert pandoc.pandoc_available()
-        try:
-            pandoc.pandoc_available(failmode="raise")
-        except pandoc.PandocMissing:
-            assert False
+        assert pandoc_function_raised_missing(pandoc.get_pandoc_version) == False
+        assert pandoc_function_raised_missing(pandoc.check_pandoc_version) == False
+        assert pandoc_function_raised_missing(pandoc.pandoc, "", "markdown", "html") == False
+
         
     @dec.onlyif_cmds_exist('pandoc')        
     def test_minimal_version(self):
-        original_minversion = pandoc.minimal_version
+        original_minversion = pandoc._minimal_version
 
-        pandoc.minimal_version = "120.0"
+        pandoc._minimal_version = "120.0"
         assert not pandoc.check_pandoc_version()
 
-        pandoc.minimal_version = pandoc.get_pandoc_version()
+        pandoc._minimal_version = pandoc.get_pandoc_version()
         assert pandoc.check_pandoc_version()
         
 
         
+
+def pandoc_function_raised_missing(f, *args, **kwargs):
+    try:
+        f(*args, **kwargs)
+    except pandoc.PandocMissing as e:
+        print e
+        return True
+    else:
+        return False

IPython/nbconvert/utils/pandoc.py

@@ -22,7 +22,7 b' from io import TextIOWrapper, BytesIO'
 # IPython imports
 from IPython.utils.py3compat import cast_bytes
 from IPython.utils.version import check_version
-from IPython.utils.process import find_cmd, FindCmdError
+from IPython.utils.process import is_cmd_found, FindCmdError
 
 
 from .exceptions import ConversionException
@@ -30,12 +30,7 b' from .exceptions import ConversionException'
 #-----------------------------------------------------------------------------
 # Classes and functions
 #-----------------------------------------------------------------------------
-minimal_version = "1.12.1"
-
-# command line to make pandoc print it's version. It is also the
-# easiest way to make pandoc return at all.
-__pandoc_version_call = ['pandoc', '-v']
-
+_minimal_version = "1.12.1"
 
 def pandoc(source, fmt, to, extra_args=None, encoding='utf-8'):
     """Convert an input string in format `from` to format `to` via pandoc.
@@ -74,42 +69,6 b" def pandoc(source, fmt, to, extra_args=None, encoding='utf-8'):"
     return out.rstrip('\n')
 
 
-def pandoc_available(failmode="return", warn=False):
-    """Is pandoc available. Relies on `IPython.utils.process.find_cmd`.
-    
-    Parameters
-    ----------
-     - failmode : string
-        either "return" or "raise". See below.
-     - warn : bool
-        issue a user warning if pandoc is not available.
-
-    Return
-    ------
-    out : (Bool, Exception)
-        On success will return True. On failure and failmode=="return" 
-        will return False-valued PandocMissing instance. If failmode is
-        anything else, the function will not return but raise PandocMissing.
-    """
-    
-    try:
-        find_cmd("pandoc")
-        return True
-    except FindCmdError as e:
-        if warn:
-            warnings.warn(
-                "Pandoc cannot be found (find_cmd('pandoc') failed).\n"+
-                "Please check that pandoc is installed:\n" +
-                "http://johnmacfarlane.net/pandoc/installing.html"
-            )
-
-        exc = PandocMissing("pandoc", e)
-        if failmode == "return":
-            return exc
-        else:
-            raise exc
-
-
 def get_pandoc_version():
     """Gets the Pandoc version if Pandoc is installed.
     
@@ -123,15 +82,18 b' def get_pandoc_version():'
     ----------
     PandocMissing will be raised if pandoc is unavailable.
     """
+    global __version
 
-    if __cache['version_ok'] and __cache['version']:
-        return __cache['version']
+    if __version is not None:
+        return __version
     else:
-        pandoc_available(failmode="raise")
-        out = subprocess.check_output(__pandoc_version_call, universal_newlines=True)
+        if not is_cmd_found('pandoc'):
+            raise PandocMissing()
+
+        out = subprocess.check_output( ['pandoc', '-v'], universal_newlines=True)
         pv_re = re.compile(r'(\d{0,3}\.\d{0,3}\.\d{0,3})')
-        __cache['version'] = version = pv_re.search(out).group(0)
-        return version
+        __version = pv_re.search(out).group(0)
+        return __version
 
 
 def check_pandoc_version():
@@ -141,52 +103,33 b' def check_pandoc_version():'
     ----------
     PandocMissing will be raised if pandoc is unavailable.
     """
-    ok = __cache['version_ok']
-    if not ok:
-        __cache['version_ok'] = ok = check_version( get_pandoc_version(), minimal_version )
+    v = get_pandoc_version()
+    ok = check_version(v , _minimal_version )
         if not ok:
-            warnings.warn( "You are using an old version of pandoc (%s)\n" % __cache['version'] + 
-                           "Recommended version is %s.\nTry updating." % minimal_version + 
+        warnings.warn( "You are using an old version of pandoc (%s)\n" % v + 
+                       "Recommended version is %s.\nTry updating." % _minimal_version + 
                            "http://johnmacfarlane.net/pandoc/installing.html.\nContinuing with doubts...",
                            RuntimeWarning, stacklevel=2)
-    return __cache['version_ok']
+    return ok
 
 #-----------------------------------------------------------------------------
 # Exception handling
 #-----------------------------------------------------------------------------
 class PandocMissing(ConversionException):
     """Exception raised when Pandoc is missing. """
-    def __init__(self, cmd, exc, *args, **kwargs):
-        super(PandocMissing, self).__init__( "The command '%s' returned an error: %s.\n" %(" ".join(cmd), exc) +
+    def __init__(self, *args, **kwargs):
+        super(PandocMissing, self).__init__( "Pandoc wasn't found.\n" +
                                              "Please check that pandoc is installed:\n" +
                                              "http://johnmacfarlane.net/pandoc/installing.html" )
-        self.exc = exc
-
-    def __bool__(self):
-        return False
-
-    __nonzero__ = __bool__
-
 
 #-----------------------------------------------------------------------------
 # Internal state management
 #-----------------------------------------------------------------------------
-def clean_cache(new=False):
-    if new:
-        global __cache
-        cache = {}
-        __cache = cache
-    else:
-        cache = __cache
-        cache.clear()
-    
-    cache['version_ok'] = False
-    cache['version'] = None
-    return cache
-
-# The following holds cache values about the pandoc executable.
-__cache = clean_cache(new=True)
+def clean_cache():
+    global __version
+    __version = None
 
+__version = None