Replace py36-compatible type annotation comments with newer syntax

4 files changed, 29 insertions, 36 deletions

diff --git a/yoyo/backends/base.py b/yoyo/backends/base.py
index 8ca956e..100849a 100644
--- a/yoyo/backends/base.py
+++ b/yoyo/backends/base.py
@@ -107,7 +107,7 @@ class SavepointTransactionManager(TransactionManager):
 
 class DatabaseBackend:
 
-    driver_module = ""  # type: str
+    driver_module = ""
 
     log_table = "_yoyo_log"
     lock_table = "yoyo_lock"
diff --git a/yoyo/config.py b/yoyo/config.py
index 0569a12..9517874 100644
--- a/yoyo/config.py
+++ b/yoyo/config.py
@@ -18,15 +18,11 @@ Handle config file and argument parsing
 from collections import deque
 from configparser import ConfigParser
 from pathlib import Path
-from typing import Dict
-from typing import List
-from typing import Optional
-from typing import Tuple
-from typing import Union
 import configparser
 import functools
 import itertools
 import os
+import typing as t
 
 CONFIG_FILENAME = "yoyo.ini"
 CONFIG_EDITOR_KEY = "editor"
@@ -44,7 +40,7 @@ class CircularReferenceError(configparser.Error):
 
 class CustomInterpolation(configparser.BasicInterpolation):
 
-    defaults = {}  # type:  Dict[str, str]
+    defaults: t.Dict[str, str] = {}
 
     def __init__(self, defaults):
         self.defaults = defaults or {}
@@ -57,7 +53,7 @@ class CustomInterpolation(configparser.BasicInterpolation):
         )
 
 
-def get_interpolation_defaults(path: Optional[str] = None):
+def get_interpolation_defaults(path: t.Optional[str] = None):
     parser = configparser.ConfigParser()
     defaults = {
         parser.optionxform(k): v.replace("%", "%%") for k, v in os.environ.items()
@@ -82,7 +78,7 @@ def update_argparser_defaults(parser, defaults):
     parser.set_defaults(**{k: v for k, v in defaults.items() if k in known_args})
 
 
-def read_config(src: Optional[str]) -> ConfigParser:
+def read_config(src: t.Optional[str]) -> ConfigParser:
     """
     Read the configuration file at ``src`` and construct a ConfigParser instance.
 
@@ -95,9 +91,9 @@ def read_config(src: Optional[str]) -> ConfigParser:
     config = _read_config(path)
     config_files = {path: config}
     merge_paths = deque([path])
-    to_process = [
-        ((), path, config)
-    ]  # type: List[Tuple[Union[Tuple, Tuple[Path]], Path, ConfigParser]]
+    to_process: t.List[t.Tuple[t.Union[t.List[Path]], Path, ConfigParser]] = [
+        ([], path, config)
+    ]
     while to_process:
         ancestors, path, config = to_process.pop()
         inherits, includes = find_includes(path, config)
@@ -108,7 +104,7 @@ def read_config(src: Optional[str]) -> ConfigParser:
                 )
             config = _read_config(p)
             config_files[p] = config
-            to_process.append((ancestors + (path,), p, config))
+            to_process.append((ancestors + [path], p, config))
 
         merge_paths.extendleft(inherits)
         merge_paths.extend(includes)
@@ -120,7 +116,7 @@ def read_config(src: Optional[str]) -> ConfigParser:
     return merged
 
 
-def _make_path(s: str, basepath: Optional[Path] = None) -> Path:
+def _make_path(s: str, basepath: t.Optional[Path] = None) -> Path:
     """
     Return a fully resolved Path. Raises FileNotFoundError if the path does not
     exist.
@@ -152,9 +148,9 @@ def _read_config(path: Path) -> ConfigParser:
 
 def find_includes(
     basepath: Path, config: ConfigParser
-) -> Tuple[List[Path], List[Path]]:
+) -> t.Tuple[t.List[Path], t.List[Path]]:
 
-    result = {INCLUDE: [], INHERIT: []}  # type: Dict[str, List[Path]]
+    result: t.Dict[str, t.List[Path]] = {INCLUDE: [], INHERIT: []}
     for key in [INHERIT, INCLUDE]:
         try:
             paths = config["DEFAULT"][key].split()
@@ -177,7 +173,7 @@ def find_includes(
     return result[INHERIT], result[INCLUDE]
 
 
-def merge_configs(configs: List[ConfigParser]) -> ConfigParser:
+def merge_configs(configs: t.List[ConfigParser]) -> ConfigParser:
     def merge(c1, c2):
         c1.read_dict(c2)
         return c1
diff --git a/yoyo/internalmigrations/v2.py b/yoyo/internalmigrations/v2.py
index e81c9e3..1887307 100644
--- a/yoyo/internalmigrations/v2.py
+++ b/yoyo/internalmigrations/v2.py
@@ -13,8 +13,8 @@ def upgrade(backend):
     cursor = backend.execute(
         "SELECT id, ctime FROM {}".format(backend.migration_table_quoted)
     )
-    migration_id = ""  # type: str
-    created_at = datetime(1970, 1, 1)  # type: datetime
+    migration_id = ""
+    created_at = datetime(1970, 1, 1)
     for migration_id, created_at in iter(cursor.fetchone, None):  # type: ignore
         migration_hash = get_migration_hash(migration_id)
         log_data = dict(
diff --git a/yoyo/migrations.py b/yoyo/migrations.py
index 5b30049..79d371d 100755
--- a/yoyo/migrations.py
+++ b/yoyo/migrations.py
@@ -21,10 +21,7 @@ from itertools import chain
 from itertools import count
 from itertools import zip_longest
 from logging import getLogger
-from typing import Dict
-from typing import Iterable
-from typing import List
-from typing import Tuple
+import typing as t
 import hashlib
 import importlib.util
 import os
@@ -72,7 +69,7 @@ def get_migration_hash(migration_id):
 
 
 # eg: "-- depends: 1 2"
-DirectivesType = Dict[str, str]
+DirectivesType = t.Dict[str, str]
 
 LeadingCommentType = str
 
@@ -81,7 +78,7 @@ SqlType = str
 
 def parse_metadata_from_sql_comments(
     s: str,
-) -> Tuple[DirectivesType, LeadingCommentType, SqlType]:
+) -> t.Tuple[DirectivesType, LeadingCommentType, SqlType]:
     directive_names = ["transactional", "depends"]
     comment_or_empty = re.compile(r"^(\s*|\s*--.*)$").match
     directive_pattern = re.compile(
@@ -90,7 +87,7 @@ def parse_metadata_from_sql_comments(
 
     lineending = re.search(r"\n|\r\n|\r", s + "\n").group(0)  # type: ignore
     lines = iter(s.split(lineending))
-    directives = {}  # type: DirectivesType
+    directives: DirectivesType = {}
     leading_comments = []
     sql = []
     for line in lines:
@@ -117,8 +114,8 @@ def parse_metadata_from_sql_comments(
 
 def read_sql_migration(
     path: str,
-) -> Tuple[DirectivesType, LeadingCommentType, List[str]]:
-    directives = {}  # type: DirectivesType
+) -> t.Tuple[DirectivesType, LeadingCommentType, t.List[str]]:
+    directives: DirectivesType = {}
     leading_comment = ""
     statements = []
     if os.path.exists(path):
@@ -137,7 +134,7 @@ def read_sql_migration(
 
 class Migration(object):
 
-    __all_migrations = {}  # type: Dict[str, "Migration"]
+    __all_migrations: t.Dict[str, "Migration"] = {}
 
     def __init__(self, id, path, source_dir):
         self.id = id
@@ -451,7 +448,7 @@ class StepGroup(MigrationStep):
             item.rollback(backend, force)
 
 
-def _expand_sources(sources) -> Iterable[Tuple[str, List[str]]]:
+def _expand_sources(sources) -> t.Iterable[t.Tuple[str, t.List[str]]]:
     package_match = re.compile(r"^package:([^\s\/:]+):(.*)$").match
     for source in sources:
         mo = package_match(source)
@@ -482,7 +479,7 @@ def read_migrations(*sources):
     """
     Return a ``MigrationList`` containing all migrations from ``sources``.
     """
-    migrations = OrderedDict()  # type: Dict[str, MigrationList]
+    migrations: t.Dict[str, MigrationList] = OrderedDict()
 
     for source, paths in _expand_sources(sources):
         for path in paths:
@@ -526,7 +523,7 @@ class MigrationList(abc.MutableSequence):
         return "{}({})".format(self.__class__.__name__, repr(self.items))
 
     def check_conflicts(self):
-        c = Counter()  # type: Dict[str, int]
+        c: t.Dict[str, int] = Counter()
         for item in self:
             c[item.id] += 1
             if c[item.id] > 1:
@@ -601,9 +598,9 @@ class StepCollector(object):
 
         def do_add(use_transactions):
             wrapper = TransactionWrapper if use_transactions else Transactionless
-            t = MigrationStep(next(self.step_id), apply, rollback)  # type: StepBase
-            t = wrapper(t, ignore_errors)
-            return t
+            step: StepBase = MigrationStep(next(self.step_id), apply, rollback)
+            step = wrapper(step, ignore_errors)
+            return step
 
         self.steps[do_add] = 1
         return do_add
@@ -721,7 +718,7 @@ def heads(migration_list):
     return heads
 
 
-def topological_sort(migrations: Iterable[Migration]) -> Iterable[Migration]:
+def topological_sort(migrations: t.Iterable[Migration]) -> t.Iterable[Migration]:
     from yoyo.topologicalsort import topological_sort as topological_sort_impl
     from yoyo.topologicalsort import CycleError