makefh and which functions in utils.py

tldp/guess.py

@@ -5,19 +5,8 @@ from __future__ import absolute_import, division, print_function
 import os
 import inspect
 
+from .utils import logger, makefh
 from . import doctypes
-from .utils import logger
-
-
-def makefh(thing):
-    if isinstance(thing, file):
-        f = thing
-    elif isinstance(thing, str) and os.path.isfile(thing):
-        f = open(thing)
-    else:
-        raise TypeError("Cannot make file from type %s of %r" %
-                        (type(thing), thing,))
-    return f
 
 
 def listDoctypes():

tldp/utils.py

@@ -2,6 +2,7 @@
 
 from __future__ import absolute_import, division, print_function
 
+import os
 import sys
 import logging
 
@@ -15,8 +16,35 @@ def getLogger(**opts):
 logger = getLogger()
 
 
-def runner(cmd, env, stdin, stdout, stderr):
-    pass
+def is_executable(fpath):
+    return os.path.isfile(fpath) and os.access(fpath, os.X_OK)
+
+
+def which(program):
+    '''return None or the full path to an executable (respecting $PATH)
+http://stackoverflow.com/questions/377017/test-if-executable-exists-in-python/377028#377028
+    '''
+    fpath, fname = os.path.split(program)
+    if fpath and is_executable(program):
+            return program
+    else:
+        for path in os.environ["PATH"].split(os.pathsep):
+            path = path.strip('"')
+            sut = os.path.join(path, program)
+            if is_executable(sut):
+                return sut
+    return None
+
+
+def makefh(thing):
+    if isinstance(thing, file):
+        f = thing
+    elif isinstance(thing, str) and os.path.isfile(thing):
+        f = open(thing)
+    else:
+        raise TypeError("Cannot make file from type %s of %r" %
+                        (type(thing), thing,))
+    return f
 
 #
 # -- end of file