Improve import time of mimetypes: defer os, sys, posixpath

Lib/mimetypes.py

@@ -23,10 +23,6 @@
 read_mime_types(file) -- parse one file, return a dictionary or None
 """
 
-import os
-import sys
-import posixpath
-
 try:
     from _winapi import _mimetypes_read_windows_registry
 except ImportError:
@@ -119,6 +115,7 @@ def guess_type(self, url, strict=True):
         but non-standard types.
         """
         # Lazy import to improve module import time
+        import os
         import urllib.parse
 
         # TODO: Deprecate accepting file paths (in particular path-like objects).
@@ -148,13 +145,20 @@ def guess_type(self, url, strict=True):
             if '=' in type or '/' not in type:
                 type = 'text/plain'
             return type, None           # never compressed, so encoding is None
+
+        # Lazy import to improve module import time
+        import posixpath
+
         return self._guess_file_type(url, strict, posixpath.splitext)
 
     def guess_file_type(self, path, *, strict=True):
         """Guess the type of a file based on its path.
 
         Similar to guess_type(), but takes file path instead of URL.
         """
+        # Lazy import to improve module import time
+        import os
+
         path = os.fsdecode(path)
         path = os.path.splitdrive(path)[1]
         return self._guess_file_type(path, strict, os.path.splitext)
@@ -401,6 +405,9 @@ def init(files=None):
     else:
         db = _db
 
+    # Lazy import to improve module import time
+    import os
+
     for file in files:
         if os.path.isfile(file):
             db.read(file)
@@ -639,6 +646,7 @@ def _default_mime_types():
 
 def _main():
     import getopt
+    import sys
 
     USAGE = """\
 Usage: mimetypes.py [options] type