关于python：如何在python3中替换has_key？


How to replace has_key in python3?

我尝试安装自动自我控制，但在执行此命令时卡住了：

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sudo /usr/bin/python auto-selfcontrol.py

显示错误：

AttributeError: 'dict' object has no attribute 'has_key'

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我正在寻找解决方案，结果替换了in operator中的has_键，但正如我只知道Python的基础知识一样，代码对我来说相当复杂。

有三个地方使用过钥匙，你能帮我换一下吗？这样我就可以和Python一起跑了。

1。

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def check_if_running(username):
""" checks if self-control is already running."""
defaults = get_selfcontrol_settings(username)
return defaults.has_key("BlockStartedDate") and not NSDate.distantFuture().isEqualToDate_(defaults["BlockStartedDate"])

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2-4。

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def check_config(config):
""" checks whether the config file is correct"""
if not config.has_key("username"):
    exit_with_error("No username specified in config.")
if config["username"] not in get_osx_usernames():
    exit_with_error(
           "Username '{username}' unknown.
Please use your OSX username instead.
" \
           "If you have trouble finding it, just enter the command 'whoami'
" \
           "in your terminal.".format(
                    username=config["username"]))
if not config.has_key("selfcontrol-path"):
    exit_with_error("The setting 'selfcontrol-path' is required and must point to the location of SelfControl.")
if not os.path.exists(config["selfcontrol-path"]):
    exit_with_error(
           "The setting 'selfcontrol-path' does not point to the correct location of SelfControl." \
           "Please make sure to use an absolute path and include the '.app' extension," \
           "e.g. /Applications/SelfControl.app")
if not config.has_key("block-schedules"):
    exit_with_error("The setting 'block-schedules' is required.")
if len(config["block-schedules"]) == 0:
    exit_with_error("You need at least one schedule in 'block-schedules'.")
if config.get("host-blacklist", None) is None:
    print("WARNING:")
    msg ="It is not recommended to directly use SelfControl's blacklist. Please use the 'host-blacklist'" \
         "setting instead."
    print(msg)
    syslog.syslog(syslog.LOG_WARNING, msg)
相关讨论

虽然其他答案中的零碎解决方案会起作用，但这种方法存在缺陷，因为它太容易犯一个小错误、错过需要修复的地方等。更好的解决方案是只使用2to3转换器。您可以一次性修复所有文件：

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$ 2to3 -f has_key -w auto-selfcontrol.py

。

只运行has_key固定器，它从dict.has_key(key)转换为key in dict。当然可以自己修复，但这是一个简单的编程修复程序可以正常工作的例子。您可能只想在不使用-f has_key的情况下运行它，因此它会立即应用所有修复程序，以防PY2和PY3之间存在任何其他破坏性更改。

除了py2 str类型的改变(在py3中给定的str字是否应该是bytes或str的代码逻辑决定)和整数除法(在/可能需要改变)外，2to3几乎可以自动处理所有的事情。到//，根据计算是逻辑上的浮点划分还是楼层划分)。但对于has_key来说，这是相当可靠的。

相关讨论

在python3.7中测试。

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   tmp = {'a':1, 'b':2, 'c':3}
   print(tmp.__contains__('a')) #True

解决方案的正式来源如下：https://portingguide.readthedocs.io/en/latest/dicts.html

TL；DR是：

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some_dict.has_key('some key')

现在是：

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'some key' in some_dict

。

因此，在您的代码中：

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return defaults.has_key("BlockStartedDate") and not NSDate.distantFuture().isEqualToDate_(defaults["BlockStartedDate"])

变成：

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return"BlockStartedDate" in defaults and not NSDate.distantFuture().isEqualToDate_(defaults["BlockStartedDate"])

。

类似地，行如下：

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if not config.has_key("selfcontrol-path"):
    # do something

。

变得像：

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if"selfcontrol-path" not in config:
    # do something

请注意，您也可以编写if not"selfcontrol-path" in config:，但上面给出的示例被认为是更为Python式的，应该首选。

更换如下

1。

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def check_if_running(username):
""" checks if self-control is already running."""
defaults = get_selfcontrol_settings(username)
return"BlockStartedDate" in defaults and not NSDate.distantFuture().isEqualToDate_(defaults["BlockStartedDate"])

2-4。

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def check_config(config):
""" checks whether the config file is correct"""
if not"username" in config:
    exit_with_error("No username specified in config.")
if config["username"] not in get_osx_usernames():
    exit_with_error(
           "Username '{username}' unknown.
Please use your OSX username instead.
" \
           "If you have trouble finding it, just enter the command 'whoami'
" \
           "in your terminal.".format(
                    username=config["username"]))
if not"selfcontrol-path" in config:
    exit_with_error("The setting 'selfcontrol-path' is required and must point to the location of SelfControl.")
if not os.path.exists(config["selfcontrol-path"]):
    exit_with_error(
           "The setting 'selfcontrol-path' does not point to the correct location of SelfControl." \
           "Please make sure to use an absolute path and include the '.app' extension," \
           "e.g. /Applications/SelfControl.app")
if not"block-schedules" in config:
    exit_with_error("The setting 'block-schedules' is required.")
if len(config["block-schedules"]) == 0:
    exit_with_error("You need at least one schedule in 'block-schedules'.")
if config.get("host-blacklist", None) is None:
    print("WARNING:")
    msg ="It is not recommended to directly use SelfControl's blacklist. Please use the 'host-blacklist'" \
         "setting instead."
    print(msg)
    syslog.syslog(syslog.LOG_WARNING, msg)

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