Implement --output parameter

- Implement --output parameter to specify output file.

- Add input validation for --format parameter.

Signed-off-by: Derek G Foster <[email protected]>

docs/scripts/p4cpconfig.rst

@@ -66,19 +66,25 @@ General
 
 ``--format=FORMAT``, ``-f FORMAT``
   Output file format.
-
   Valid formats are ``cmake``, ``env``, and ``json``.
 
+  Defaults to ``cmake`` if no value is specified.
+
 ``--load=FILEPATH``, ``-L FILEPATH``
   JSON file specifying default configuration settings.
 
-  If this parameter is not specified, p4cpconfig will check first
-  for a file named ``.p4cpconfig`` in the current directory, then for
+  If no value is specified, p4cpconfig will check first for
+  a file named ``.p4cpconfig`` in the current directory, then for
   a file of the same name in the user's home directory.
 
   May be suppressed by using an *explicitly unspecified* value
   (e.g., ``-L-`` or ``--load=None``).
 
+``--output=FILEPATH``, ``-o FILEPATH``
+  Output file path.
+
+  Defaults to standard output if no value is specified.
+
 Paths
 -----
 
@@ -166,8 +172,8 @@ You can duplicate this behavior by creating a default configuration file:
 
 .. code-block:: bash
 
-  ./scripts/p4cpconfig.py -L None -f json --target=dpdk \
-      -O ovs/install -P install > .p4cpconfig
+  ./scripts/p4cpconfig.py -L- -f json --target=dpdk \
+      -O ovs/install -P install -o .p4cpconfig
 
 The file it generates will be something like this:
 
@@ -181,5 +187,5 @@ The file it generates will be something like this:
 
 Notes:
 
-* ``-L None`` keeps p4cpconfig from loading the current defaults.
+* ``-L-`` keeps p4cpconfig from loading the current defaults.
 * ``-f json`` tells it to create a json file.

scripts/p4cpconfig.py

@@ -332,6 +332,8 @@ def load_defaults(args):
 def process_args(args):
     args.variant = None
     process_build_type_param(args)
+    process_format_param(args)
+    process_output_param(args)
     process_target_param(args)
     process_path_params(args)
     return
@@ -355,6 +357,25 @@ def process_build_type_param(args):
         errcount += 1
     return
 
+def process_format_param(args):
+    global errcount
+    if args.format in UNSPECIFIED:
+        logging.error("No output format specified")
+        errcount += 1
+        return
+    format = args.format.lower()
+    if format in ['cmake', 'env', 'json']:
+        args.format = format
+    else:
+        logging.error("Invalid output format: '%s'", args.format)
+        errcount += 1
+    return
+
+def process_output_param(args):
+    if args.outfile in UNSPECIFIED:
+        args.outfile = '/dev/stdout'
+    return
+
 def process_target_param(args):
     global errcount
     if args.target in UNSPECIFIED:
@@ -400,10 +421,12 @@ def parse_args():
     parser.add_argument('--format', '-f', type=str,
                         default='cmake',
                         help='output file format (cmake|json|env)')
+
     parser.add_argument('--load', '-L', dest='default_cfg',
                         help='default configuration file')
-#   parser.add_argument('--output', '-o',
-#                       help='output file path')
+
+    parser.add_argument('--output', '-o', dest='outfile',
+                        help='output file path')
 
     # 'paths' group
     paths = parser.add_argument_group(title='paths')
@@ -468,11 +491,13 @@ def str2bool(v):
     defaults = load_defaults(args)
     config = define_config(args, defaults)
 
-    if args.format == 'cmake':
-        config.write_cmake_variables(sys.stdout)
-    elif args.format == 'env':
-        config.write_env_variables(sys.stdout)
-    elif args.format == 'json':
-        config.write_json_params(sys.stdout)
+    with open(args.outfile, 'w') as outfile:
+        if args.format == 'cmake':
+            config.write_cmake_variables(outfile)
+        elif args.format == 'env':
+            config.write_env_variables(outfile)
+        elif args.format == 'json':
+            config.write_json_params(outfile)
+    # end with
 # end __main__