X-Git-Url: http://xvm.mit.edu/gitweb/invirt/packages/invirt-base.git/blobdiff_plain/b562b266e557bcb8986105029be42c5317a5f81a..59f4105b3f9c76abb0017ce6a4834408e32767a4:/python/invirt/common.py

diff --git a/python/invirt/common.py b/python/invirt/common.py
index a85d955..603b7f3 100644
--- a/python/invirt/common.py
+++ b/python/invirt/common.py
@@ -3,6 +3,7 @@ from __future__ import with_statement
 import unittest
 from fcntl import flock, LOCK_EX, LOCK_SH, LOCK_UN
 import contextlib as clib
+import subprocess
 
 class InvirtConfigError(AttributeError):
     pass
@@ -11,8 +12,11 @@ class struct(object):
     'A simple namespace object.'
     def __init__(self, d = {}, __prefix = None, **kwargs):
         'd is the dictionary or the items-iterable to update my __dict__ with.'
-        self.__dict__.update(d)
-        self.__dict__.update(kwargs)
+        dct = {}
+        dct.update(d)
+        dct.update(kwargs)
+        self.__dict__.update(dct)
+        self.__keys = set(dct)
         self.__prefix = __prefix
     def __getattr__(self, key):
         # XX ideally these would point a frame higher on the stack.
@@ -23,6 +27,9 @@ class struct(object):
         else:
             raise AttributeError("anonymous struct has no member '%s'"
                                  % (key,))
+    def __iter__(self):
+        for i in self.__keys:
+            yield i
 
 def dicts2struct(x, prefix = None):
     """
@@ -57,6 +64,29 @@ def lock_file(path, exclusive = True):
         finally:
             flock(f, LOCK_UN)
 
+def captureOutput(popen_args, stdin_str=None, *args, **kwargs):
+    """Capture stdout from a command.
+
+    This method will proxy the arguments to subprocess.Popen. It
+    returns the output from the command if the call succeeded and
+    raises an exception if the process returns a non-0 value.
+
+    This is intended to be a variant on the subprocess.check_call
+    function that also allows you access to the output from the
+    command.
+    """
+    if 'stdin' not in kwargs:
+        kwargs['stdin'] = subprocess.PIPE
+    if 'stdout' not in kwargs:
+        kwargs['stdout'] = subprocess.PIPE
+    if 'stderr' not in kwargs:
+        kwargs['stderr'] = subprocess.STDOUT
+    p = subprocess.Popen(popen_args, *args, **kwargs)
+    out, _ = p.communicate(stdin_str)
+    if p.returncode:
+        raise subprocess.CalledProcessError(p.returncode, popen_args, out)
+    return out
+
 #
 # Exceptions.
 #
@@ -94,6 +124,7 @@ class common_tests(unittest.TestCase):
         self.assertEqual(structs.dict.list,   dicts['dict']['list'])
         self.assertEqual(structs.list[0],     dicts['list'][0])
         self.assertEqual(structs.list[1].key, dicts['list'][1]['key'])
+        self.assertEqual(set(structs), set(['atom', 'dict', 'list']))
 
 if __name__ == '__main__':
     unittest.main()