Merge pull request #125 from swinman/master

make find and find_descriptor easier to understand
pyusb · Jan 25, 2016 · 69662f7 · 69662f7
2 parents c1544b0 + d03669c
commit 69662f7
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Showing 3 changed files with 16 additions and 31 deletions.
diff --git a/usb/_interop.py b/usb/_interop.py
@@ -46,6 +46,12 @@
 except (ImportError, AttributeError):
     _reduce = reduce
 
+# all, introduced in Python 2.5
+try:
+    _all = all
+except NameError:
+    _all = lambda iter_ : _reduce( lambda x, y: x and y, iter_, True )
+
 # we only have the builtin set type since 2.5 version
 try:
     _set = set
@@ -90,4 +96,3 @@ def as_array(data=None):
         a = array.array('B')
         a.fromstring(data) # deprecated since 3.2
         return a
-
diff --git a/usb/core.py b/usb/core.py
@@ -1242,19 +1242,11 @@ def is_printer(dev):
 
     Backends are explained in the usb.backend module.
     """
-
-    def device_iter(k, v):
+    def device_iter(**kwargs):
         for dev in backend.enumerate_devices():
             d = Device(dev, backend)
-            if  _interop._reduce(
-                        lambda a, b: a and b,
-                        map(
-                            operator.eq,
-                            v,
-                            map(lambda i: getattr(d, i), k)
-                        ),
-                        True
-                    ) and (custom_match is None or custom_match(d)):
+            tests = (val == getattr(d, key) for key, val in kwargs.items())
+            if _interop._all(tests) and (custom_match is None or custom_match(d)):
                 yield d
 
     if backend is None:
@@ -1270,13 +1262,11 @@ def device_iter(k, v):
         else:
             raise NoBackendError('No backend available')
 
-    k, v = args.keys(), args.values()
-
     if find_all:
-        return device_iter(k, v)
+        return device_iter(**args)
     else:
         try:
-            return _interop._next(device_iter(k, v))
+            return _interop._next(device_iter(**args))
         except StopIteration:
             return None
 

diff --git a/usb/util.py b/usb/util.py
@@ -177,27 +177,17 @@ def find_descriptor(desc, find_all=False, custom_match=None, **args):
     find_descriptor function also accepts the find_all parameter to get
     an iterator instead of just one descriptor.
     """
-    def desc_iter(k, v):
+    def desc_iter(**kwargs):
         for d in desc:
-            if (custom_match is None or custom_match(d)) and \
-                _interop._reduce(
-                        lambda a, b: a and b,
-                        map(
-                            operator.eq,
-                            v,
-                            map(lambda i: getattr(d, i), k)
-                        ),
-                        True
-                    ):
+            tests = (val == getattr(d, key) for key, val in kwargs.items())
+            if _interop._all(tests) and (custom_match is None or custom_match(d)):
                 yield d
 
-    k, v = args.keys(), args.values()
-
     if find_all:
-        return desc_iter(k, v)
+        return desc_iter(**args)
     else:
         try:
-            return _interop._next(desc_iter(k, v))
+            return _interop._next(desc_iter(**args))
         except StopIteration:
             return None