From: Collin Funk <collin.funk1@gmail.com>
To: bug-gnulib@gnu.org
Subject: gnulib-tool.py: Don't use mutable default arguments.
Date: Sat, 13 Apr 2024 19:03:17 -0700 [thread overview]
Message-ID: <0ddf04f4-e11a-4715-bed3-b4d9201f464a@gmail.com> (raw)
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This patch fixes an interesting warning given by PyCharm.
With this line:
def __init__(self, config: GLConfig, transformers: dict[str, tuple[re.Pattern, str] | None] = dict()) -> None:
Under '= dict()', I see a warning about mutable default arguments.
Here is a test program to demonstrate:
--------------------------------
#!/usr/bin/env python3
def function(arg1, arg2 = dict()):
arg2[arg1] = 0
print(arg2)
function('one')
function('two')
function('three')
--------------------------------
When executing the following is printed:
{'one': 0}
{'one': 0, 'two': 0}
{'one': 0, 'two': 0, 'three': 0}
To avoid this behavior we can set the default value of 'transformers'
to None. Then in the body of __init__() we can set it to an empty
dictionary if it is None.
Collin
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From 07dcab221be80ca4d8dae4bfafc0dd80bff85c69 Mon Sep 17 00:00:00 2001
From: Collin Funk <collin.funk1@gmail.com>
Date: Sat, 13 Apr 2024 18:51:06 -0700
Subject: [PATCH] gnulib-tool.py: Don't use mutable default arguments.
* pygnulib/GLFileSystem.py (GLFileAssistant.__init__): Set the default
argument for 'transformers' to None. If it is None then set it to an
empty dictionary in the body.
---
ChangeLog | 7 +++++++
pygnulib/GLFileSystem.py | 6 ++++--
2 files changed, 11 insertions(+), 2 deletions(-)
diff --git a/ChangeLog b/ChangeLog
index f57cb59b81..9a1618e833 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,10 @@
+2024-04-13 Collin Funk <collin.funk1@gmail.com>
+
+ gnulib-tool.py: Don't use mutable default arguments.
+ * pygnulib/GLFileSystem.py (GLFileAssistant.__init__): Set the default
+ argument for 'transformers' to None. If it is None then set it to an
+ empty dictionary in the body.
+
2024-04-13 Bruno Haible <bruno@clisp.org>
bootstrap: Implement phase 1 as documented in the --help output.
diff --git a/pygnulib/GLFileSystem.py b/pygnulib/GLFileSystem.py
index ee78181d82..4bd8b1f386 100644
--- a/pygnulib/GLFileSystem.py
+++ b/pygnulib/GLFileSystem.py
@@ -154,7 +154,7 @@ def shouldLink(self, original: str, lookedup: str) -> bool:
class GLFileAssistant:
'''GLFileAssistant is used to help with file processing.'''
- def __init__(self, config: GLConfig, transformers: dict[str, tuple[re.Pattern, str] | None] = dict()) -> None:
+ def __init__(self, config: GLConfig, transformers: dict[str, tuple[re.Pattern, str] | None] | None = None) -> None:
'''Create GLFileAssistant instance.
config stores information shared between classes.
@@ -164,7 +164,9 @@ def __init__(self, config: GLConfig, transformers: dict[str, tuple[re.Pattern, s
if type(config) is not GLConfig:
raise TypeError('config must be a GLConfig, not %s'
% type(config).__name__)
- if type(transformers) is not dict:
+ if transformers == None:
+ transformers = dict()
+ elif type(transformers) is not dict:
raise TypeError('transformers must be a dict, not %s'
% type(transformers).__name__)
for key in ['lib', 'aux', 'main', 'tests']:
--
2.44.0
next reply other threads:[~2024-04-14 2:03 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-04-14 2:03 Collin Funk [this message]
2024-04-14 6:13 ` gnulib-tool.py: Don't use mutable default arguments Bruno Haible
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