Adds bytes-typed alternative response to Python client.

In Python 2, 'bytes' and 'str' are synonyms, but in Python 3 they are
not.  Since the client may return binary data in some cases, 'bytes'
is a more appropriate data type.  Rather than requiring double
conversions in this case (the socket returns 'bytes'), this adds an
alternative response item which is typed as 'bytes'.

Although the accessor method 'data()' has always existed, it's
shadowed by a name collision in some cases, resulting in the
requirement that the caller access the 'response' item directly (as
noted in the documentation).  Thus, it's not possible to avoid the
conversion to 'str' in the cases where it isn't actually used.

This change doesn't bother to add an accessor method for 'bresponse',
for consistency with the way the API is normally used, though that
should be fixed if this aspect of the API is ever cleaned up.

TESTED:
Ran "scons check" on OSX with all supported versions of Python.

1 files changed, 12 insertions, 5 deletions

diff --git a/gps/client.py b/gps/client.py
index 5715dfe7..464ce689 100644
--- a/gps/client.py
+++ b/gps/client.py
@@ -16,7 +16,7 @@ class gpscommon(object):
 
     def __init__(self, host="127.0.0.1", port=GPSD_PORT, verbose=0):
         self.sock = None        # in case we blow up in connect
-        self.linebuffer = ""
+        self.linebuffer = b''
         self.verbose = verbose
         if host is not None:
             self.connect(host, port)
@@ -74,10 +74,10 @@ class gpscommon(object):
         "Wait for and read data being streamed from the daemon."
         if self.verbose > 1:
             sys.stderr.write("poll: reading from daemon...\n")
-        eol = self.linebuffer.find('\n')
+        eol = self.linebuffer.find(b'\n')
         if eol == -1:
             # RTCM3 JSON can be over 4.4k long, so go big
-            frag = polystr(self.sock.recv(8192))
+            frag = self.sock.recv(8192)
             self.linebuffer += frag
             if self.verbose > 1:
                 sys.stderr.write("poll: read complete.\n")
@@ -86,7 +86,7 @@ class gpscommon(object):
                     sys.stderr.write("poll: returning -1.\n")
                 # Read failed
                 return -1
-            eol = self.linebuffer.find('\n')
+            eol = self.linebuffer.find(b'\n')
             if eol == -1:
                 if self.verbose > 1:
                     sys.stderr.write("poll: returning 0.\n")
@@ -99,7 +99,9 @@ class gpscommon(object):
 
         # We got a line
         eol += 1
-        self.response = self.linebuffer[:eol]
+        # Provide the response in both 'str' and 'bytes' form
+        self.bresponse = self.linebuffer[:eol]
+        self.response = polystr(self.bresponse)
         self.linebuffer = self.linebuffer[eol:]
 
         # Can happen if daemon terminates while we're reading.
@@ -111,6 +113,11 @@ class gpscommon(object):
         # We got a \n-terminated line
         return len(self.response)
 
+    # Note that the 'data' method is sometimes shadowed by a name
+    # collision, rendering it unusable.  The documentation recommends
+    # accessing 'response' directly.  Consequently, no accessor method
+    # for 'bresponse' is currently provided.
+
     def data(self):
         "Return the client data buffer."
         return self.response