Move zsh to its own file and load it using importlib resources.

keyring/backend_complete.zsh

@@ -0,0 +1,14 @@
+# Complete keyring backends for `keyring -b` from `keyring --list-backends`
+# % keyring -b <TAB>
+# keyring priority
+# keyring.backends.chainer.ChainerBackend   10
+# keyring.backends.fail.Keyring             0
+# ...                                       ...
+
+backend_complete() {
+	local line
+	while read -r line; do
+		choices+=(${${line/ \(priority: /\\\\:}/)/})
+	done <<< "$($words[1] --list-backends)"
+	_arguments "*:keyring priority:(($choices))"
+}

keyring/completion.py

@@ -1,30 +1,15 @@
 import argparse
+import sys
 
 try:
     import shtab
 except ImportError:
     pass
 
-
-# it completes keyring backends for `keyring -b` by the output
-# of `keyring --list-backends`
-# % keyring -b <TAB>
-# keyring priority
-# keyring.backends.chainer.ChainerBackend   10
-# keyring.backends.fail.Keyring             0
-# ...                                       ...
-PREAMBLE = {
-    "zsh": r"""
-backend_complete() {
-  local line
-  while read -r line; do
-    choices+=(${${line/ \(priority: /\\\\:}/)/})
-  done <<< "$($words[1] --list-backends)"
-  _arguments "*:keyring priority:(($choices))"
-}
-"""
-}
-BACKEND_COMPLETE = {"zsh": "backend_complete"}
+if sys.version_info < (3, 9):
+    from importlib_resources import files
+else:
+    from importlib.resources import files
 
 
 class _MissingCompletionAction(argparse.Action):
@@ -49,15 +34,18 @@ def get_action(parser, option):
     return match
 
 
+def install_completion(parser):
+    preamble = dict(
+        zsh=files(__package__).joinpath('backend_complete.zsh').read_text(),
+    )
+    shtab.add_argument_to(parser, preamble=preamble)
+    get_action(parser, '--keyring-path').completion = shtab.DIR
+    get_action(parser, '--keyring-backend').completion = dict(zsh='backend_complete')
+    return parser
+
+
 def install(parser):
     try:
         install_completion(parser)
     except NameError:
         add_completion_notice(parser)
-
-
-def install_completion(parser):
-    shtab.add_argument_to(parser, preamble=PREAMBLE)
-    get_action(parser, '--keyring-path').completion = shtab.DIR
-    get_action(parser, '--keyring-backend').completion = BACKEND_COMPLETE
-    return parser

setup.cfg

@@ -24,6 +24,7 @@ install_requires =
 	jeepney>=0.4.2; sys_platform=="linux"
 	importlib_metadata >= 4.11.4; python_version < "3.12"
 	jaraco.classes
+	importlib_resources; python_version < "3.9"
 
 [options.packages.find]
 exclude =