Add a Singleton metaclass, use it with Display (#48935)

* Add a Singleton class, use it with Display

* update six import

* Move remaining failes to display singleton

* Fix rebase issues

* Singleton improvements

* Add code-smell for 'from __main__ import display'. ci_complete

* s/self/cls/g

* Add docs for no-main-display

* Address linting issues

* Add changelog fragment. ci_complete

* Implement reentrant lock for class instantiation in Singleton

* Add Display singleton porting guide

lib/ansible/cli/__init__.py

@@ -40,16 +40,13 @@ from ansible.module_utils.six import with_metaclass, string_types
 from ansible.module_utils._text import to_bytes, to_text
 from ansible.parsing.dataloader import DataLoader
 from ansible.release import __version__
+from ansible.utils.display import Display
 from ansible.utils.path import unfrackpath
 from ansible.utils.vars import load_extra_vars, load_options_vars
 from ansible.vars.manager import VariableManager
 from ansible.parsing.vault import PromptVaultSecret, get_file_vault_secret
 
-try:
-    from __main__ import display
-except ImportError:
-    from ansible.utils.display import Display
-    display = Display()
+display = Display()
 
 
 class SortedOptParser(optparse.OptionParser):

lib/ansible/cli/adhoc.py

@@ -18,8 +18,6 @@
 from __future__ import (absolute_import, division, print_function)
 __metaclass__ = type
 
-########################################################
-
 from ansible import constants as C
 from ansible.cli import CLI
 from ansible.errors import AnsibleError, AnsibleOptionsError
@@ -29,16 +27,11 @@ from ansible.parsing.splitter import parse_kv
 from ansible.playbook import Playbook
 from ansible.playbook.play import Play
 from ansible.plugins.loader import get_all_plugin_loaders
+from ansible.utils.display import Display
 
-try:
-    from __main__ import display
-except ImportError:
-    from ansible.utils.display import Display
-    display = Display()
+display = Display()
 
 
-########################################################
-
 class AdHocCLI(CLI):
     ''' is an extra-simple tool/framework/API for doing 'remote things'.
         this command allows you to define and run a single task 'playbook' against a set of hosts

lib/ansible/cli/config.py

@@ -16,14 +16,10 @@ from ansible.errors import AnsibleError, AnsibleOptionsError
 from ansible.module_utils._text import to_native, to_text
 from ansible.parsing.yaml.dumper import AnsibleDumper
 from ansible.utils.color import stringc
+from ansible.utils.display import Display
 from ansible.utils.path import unfrackpath
 
-
-try:
-    from __main__ import display
-except ImportError:
-    from ansible.utils.display import Display
-    display = Display()
+display = Display()
 
 
 class ConfigCLI(CLI):

lib/ansible/cli/console.py

@@ -46,12 +46,9 @@ from ansible.playbook.play import Play
 from ansible.plugins.loader import module_loader, fragment_loader
 from ansible.utils import plugin_docs
 from ansible.utils.color import stringc
+from ansible.utils.display import Display
 
-try:
-    from __main__ import display
-except ImportError:
-    from ansible.utils.display import Display
-    display = Display()
+display = Display()
 
 
 class ConsoleCLI(CLI, cmd.Cmd):

lib/ansible/cli/doc.py

@@ -35,13 +35,10 @@ from ansible.parsing.metadata import extract_metadata
 from ansible.parsing.plugin_docs import read_docstub
 from ansible.parsing.yaml.dumper import AnsibleDumper
 from ansible.plugins.loader import action_loader, fragment_loader
+from ansible.utils.display import Display
 from ansible.utils.plugin_docs import BLACKLIST, get_docstring
 
-try:
-    from __main__ import display
-except ImportError:
-    from ansible.utils.display import Display
-    display = Display()
+display = Display()
 
 
 class DocCLI(CLI):

lib/ansible/cli/galaxy.py

@@ -41,12 +41,9 @@ from ansible.galaxy.role import GalaxyRole
 from ansible.galaxy.token import GalaxyToken
 from ansible.module_utils._text import to_native, to_text
 from ansible.playbook.role.requirement import RoleRequirement
+from ansible.utils.display import Display
 
-try:
-    from __main__ import display
-except ImportError:
-    from ansible.utils.display import Display
-    display = Display()
+display = Display()
 
 
 class GalaxyCLI(CLI):

lib/ansible/cli/inventory.py

@@ -27,12 +27,9 @@ from ansible.inventory.host import Host
 from ansible.plugins.loader import vars_loader
 from ansible.parsing.dataloader import DataLoader
 from ansible.utils.vars import combine_vars
+from ansible.utils.display import Display
 
-try:
-    from __main__ import display
-except ImportError:
-    from ansible.utils.display import Display
-    display = Display()
+display = Display()
 
 INTERNAL_VARS = frozenset(['ansible_diff_mode',
                            'ansible_facts',

lib/ansible/cli/playbook.py

@@ -15,8 +15,6 @@
 # You should have received a copy of the GNU General Public License
 # along with Ansible.  If not, see <http://www.gnu.org/licenses/>.
 
-########################################################
-
 from __future__ import (absolute_import, division, print_function)
 __metaclass__ = type
 
@@ -28,12 +26,9 @@ from ansible.errors import AnsibleError, AnsibleOptionsError
 from ansible.executor.playbook_executor import PlaybookExecutor
 from ansible.playbook.block import Block
 from ansible.playbook.play_context import PlayContext
+from ansible.utils.display import Display
 
-try:
-    from __main__ import display
-except ImportError:
-    from ansible.utils.display import Display
-    display = Display()
+display = Display()
 
 
 class PlaybookCLI(CLI):

lib/ansible/cli/pull.py

@@ -18,7 +18,6 @@
 from __future__ import (absolute_import, division, print_function)
 __metaclass__ = type
 
-########################################################
 import datetime
 import os
 import platform
@@ -34,16 +33,11 @@ from ansible.errors import AnsibleOptionsError
 from ansible.module_utils._text import to_native, to_text
 from ansible.plugins.loader import module_loader
 from ansible.utils.cmd_functions import run_cmd
+from ansible.utils.display import Display
 
-try:
-    from __main__ import display
-except ImportError:
-    from ansible.utils.display import Display
-    display = Display()
+display = Display()
 
 
-########################################################
-
 class PullCLI(CLI):
     ''' is used to up a remote copy of ansible on each managed node,
         each set to run via cron and update playbook source via a source repository.

lib/ansible/cli/vault.py

@@ -28,12 +28,9 @@ from ansible.errors import AnsibleOptionsError
 from ansible.module_utils._text import to_text, to_bytes
 from ansible.parsing.dataloader import DataLoader
 from ansible.parsing.vault import VaultEditor, VaultLib, match_encrypt_secret
+from ansible.utils.display import Display
 
-try:
-    from __main__ import display
-except ImportError:
-    from ansible.utils.display import Display
-    display = Display()
+display = Display()
 
 
 class VaultCLI(CLI):