v0.10.1 - support for positional args in argparse

Author: kpe

.travis.yml

@@ -18,7 +18,7 @@ env:
 # command to install dependencies
 install:
   - pip install --upgrade pip
-  - pip install -r requirements-dev.txt
+  - pip install -r requirements-dev.txt PyYAML
 
 # command to run tests
 # require 100% coverage (not including test files) to pass Travis CI test

params/params.py

@@ -14,7 +14,8 @@
 
 class Param:
     """ Provides a parameter specification to be used within a Params instance. """
-    def __init__(self, value, doc: Text = None, dtype: Type = None, required: bool = False, params_class=None):
+    def __init__(self, value, doc: Text = None, dtype: Type = None, required: bool = False,
+                 positional: bool = False, params_class=None):
         """
         Constructs a parameter specification to be used in a Params instance:
 
@@ -30,9 +31,12 @@ class MyParams(pp.Params):
         :param doc: (Optional) document string
         :param dtype: (Optional) type
         :param required:  default is True.
+        :param positional: defaults to False for making a CLI option argument like --foo. Set to True,
+                           for a positional argument.
         """
         self.params_class = params_class
         self._default_value = value
+        self.positional = positional
         self.doc_string = doc
         self.required = required
         self.dtype = dtype
@@ -233,8 +237,7 @@ def from_yaml_string(cls, yaml_string: Text, check_params=False):
             return cls.from_dict(lparams, return_instance=True, return_unused=False)
 
     @classmethod
-    @property
-    def _open_file(cls):
+    def _open_file(cls, *args, **kwargs):
         """ Selects an open() implementation.
         Tries to with Tensorflows first (tf.io.gfile.GFile)
         and if not available fall backs to python's default open().
@@ -244,7 +247,7 @@ def _open_file(cls):
             open_file = tf.io.gfile.GFile  # pragma: no cover
         except Exception:                  # pragma: no cover
             open_file = open
-        return open_file
+        return open_file(*args, **kwargs)
 
     @classmethod
     def from_json_file(cls, json_file, check_params=False):
@@ -309,8 +312,13 @@ def arg_name(param_name: Text):
             result = param_name.lower().replace("_", "-")
             return result
 
+        def sort_positional_args(attribs: dict):
+            res = list(filter(lambda t: t[1].positional, attribs.items()))
+            res += list(filter(lambda t: not t[1].positional, attribs.items()))
+            return res
+
         parser = argparse.ArgumentParser()
-        for attr, spec in cls.__specs.items():
+        for attr, spec in sort_positional_args(cls.__specs):
             if spec.doc_string is None:
                 continue
             name = arg_name(spec.name)
@@ -324,7 +332,11 @@ def arg_name(param_name: Text):
                 add_argument_args.update({
                     "type": _str2bool, "nargs": "?", "const": True
                 })
-            parser.add_argument("--{}".format(name), **add_argument_args)
+            if spec.positional:
+                del add_argument_args['required']
+                parser.add_argument("{}".format(name), **add_argument_args)
+            else:
+                parser.add_argument("--{}".format(name), **add_argument_args)
         return parser
 
 

params/version.py

@@ -1 +1 @@
-__version__ = "0.10.0"
+__version__ = "0.10.1"

tests/test_decoration.py

@@ -27,6 +27,10 @@ def get_something_else(self, value: int):   # a derived callable
         return self.number_of_things + value
 
 
+class MyParamsWithCommand(MyParams):
+    cmd = pp.Param(None, doc="Command to execute", positional=True)
+
+
 class ParamsDecorationTest(unittest.TestCase):
 
     def test_decoration(self):
@@ -71,5 +75,21 @@ class AParams(pp.Params):
         except Exception:
             pass
 
+    def test_arg_parser_with_command(self):
+        parser = MyParamsWithCommand.to_argument_parser()
+        parser.print_help()
+
+        def error_fn(msg, *args, **kwargs):
+            raise Exception(msg)
+        parser.error = error_fn  # supress sys.exit
+
+        args = parser.parse_args(["start", "--use-other-things", False, "--number-of-things", "7"])
+        self.assertEqual(args.use_other_things, False)
+        inst = MyParamsWithCommand(args._get_kwargs())
+        self.assertEqual(inst.cmd, 'start')
 
+        args = parser.parse_args(["--use-other-things", False, "--number-of-things", "7", "stop"])
+        self.assertEqual(args.use_other_things, False)
+        inst = MyParamsWithCommand(args._get_kwargs())
+        self.assertEqual(inst.cmd, 'stop')