parameters: introduce cli_metavar keyword argument

Add new Param keyword argument cli_metavar to specify the stand-in for CLI
option arguments in command help text. Uppercase class name is used by
default.

https://fedorahosted.org/freeipa/ticket/4739

Reviewed-By: David Kupka <dkupka@redhat.com>

ipalib/cli.py

@@ -1163,10 +1163,8 @@ class cli(backend.Executioner):
                     kw['action'] = 'store_false'
                 else:
                     kw['action'] = 'store_true'
-            elif isinstance(option, Enum):
-                kw['metavar'] = list(str(x) for x in option.values)
             else:
-                kw['metavar'] = option.__class__.__name__.upper()
+                kw['metavar'] = option.cli_metavar
 
             cli_name = to_cli(option.cli_name)
             option_names = ['--%s' % cli_name]

ipalib/parameters.py

@@ -413,6 +413,7 @@ class Param(ReadOnly):
         ('alwaysask', bool, False),
         ('sortorder', int, 2), # see finalize()
         ('option_group', unicode, None),
+        ('cli_metavar', str, None),
 
         # The 'default' kwarg gets appended in Param.__init__():
         # ('default', self.type, None),
@@ -503,6 +504,9 @@ class Param(ReadOnly):
         if kw.get('cli_name') is None:
             kw['cli_name'] = self.name
 
+        if kw.get('cli_metavar') is None:
+            kw['cli_metavar'] = self.__class__.__name__.upper()
+
         if kw.get('label') is None:
             kw['label'] = FixMe(self.name)
 
@@ -1514,6 +1518,7 @@ class Enum(Param):
     )
 
     def __init__(self, name, *rules, **kw):
+        kw['cli_metavar'] = str([str(v) for v in kw.get('values', tuple())])
         super(Enum, self).__init__(name, *rules, **kw)
         for (i, v) in enumerate(self.values):
             if type(v) not in self.allowed_types:

makeapi

@@ -47,6 +47,7 @@ API_DOC_ERROR = 8
 # attributes removed from Param.__kw dictionary
 PARAM_IGNORED_KW_ATTRIBUTES = (
     'attribute',
+    'cli_metavar',
     'default_from',
     'doc',
     'exclude',