使用非BMP字符引发错误会重新启动shell

Question

我正在编写一个python模块，用于在pygame中显示和输入表情符号。这意味着我经常使用非BMP Unicode字符，显然python shell不喜欢。

我已经制作了一个自定义的类似字符串的对象，通过将表情符号序列存储为单个字符，可以更轻松地处理表情符号字符和序列。但是，尽管我希望str（self）返回对象的原始Unicode表示，但这会在尝试打印时产生问题，或者更糟糕的是，当它包含在错误消息中时。

这是错误消息中包含非BMP字符时发生的情况的示例。在Windows 10上运行Python 3.7.3。

>>> raise ValueError('Beware the non-BMP! \U0001f603')
Traceback (most recent call last):
  File "<pyshell#0>", line 1, in <module>
    raise ValueError('Beware the non-BMP! \U0001f603')
Traceback (most recent call last):
  File "<pyshell#0>", line 1, in <module>
    raise ValueError('Beware the non-BMP! \U0001f603')
Traceback (most recent call last):
  File "D:\Python37\lib\idlelib\run.py", line 474, in runcode
    exec(code, self.locals)
  File "<pyshell#0>", line 1, in <module>
Traceback (most recent call last):
  File "D:\Python37\lib\idlelib\run.py", line 474, in runcode
    exec(code, self.locals)
  File "<pyshell#0>", line 1, in <module>
ValueError: 

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "D:\Python37\lib\idlelib\run.py", line 144, in main
    ret = method(*args, **kwargs)
  File "D:\Python37\lib\idlelib\run.py", line 486, in runcode
    print_exception()
  File "D:\Python37\lib\idlelib\run.py", line 234, in print_exception
    print_exc(typ, val, tb)
  File "D:\Python37\lib\idlelib\run.py", line 232, in print_exc
    print(line, end='', file=efile)
  File "D:\Python37\lib\idlelib\run.py", line 362, in write
    return self.shell.write(s, self.tags)
  File "D:\Python37\lib\idlelib\rpc.py", line 608, in __call__
    value = self.sockio.remotecall(self.oid, self.name, args, kwargs)
  File "D:\Python37\lib\idlelib\rpc.py", line 220, in remotecall
    return self.asyncreturn(seq)
  File "D:\Python37\lib\idlelib\rpc.py", line 251, in asyncreturn
    return self.decoderesponse(response)
  File "D:\Python37\lib\idlelib\rpc.py", line 271, in decoderesponse
    raise what
UnicodeEncodeError: 'UCS-2' codec can't encode characters in position 32-32: Non-BMP character not supported in Tk

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "D:\Python37\lib\idlelib\run.py", line 158, in main
    print_exception()
  File "D:\Python37\lib\idlelib\run.py", line 234, in print_exception
    print_exc(typ, val, tb)
  File "D:\Python37\lib\idlelib\run.py", line 220, in print_exc
    print_exc(type(context), context, context.__traceback__)
  File "D:\Python37\lib\idlelib\run.py", line 232, in print_exc
    print(line, end='', file=efile)
  File "D:\Python37\lib\idlelib\run.py", line 362, in write
    return self.shell.write(s, self.tags)
  File "D:\Python37\lib\idlelib\rpc.py", line 608, in __call__
    value = self.sockio.remotecall(self.oid, self.name, args, kwargs)
  File "D:\Python37\lib\idlelib\rpc.py", line 220, in remotecall
    return self.asyncreturn(seq)
  File "D:\Python37\lib\idlelib\rpc.py", line 251, in asyncreturn
    return self.decoderesponse(response)
  File "D:\Python37\lib\idlelib\rpc.py", line 271, in decoderesponse
    raise what
UnicodeEncodeError: 'UCS-2' codec can't encode characters in position 32-32: Non-BMP character not supported in Tk

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "<string>", line 1, in <module>
  File "D:\Python37\lib\idlelib\run.py", line 162, in main
    traceback.print_exception(type, value, tb, file=sys.__stderr__)
  File "D:\Python37\lib\traceback.py", line 105, in print_exception
    print(line, file=file, end="")
  File "D:\Python37\lib\idlelib\run.py", line 362, in write
    return self.shell.write(s, self.tags)
  File "D:\Python37\lib\idlelib\rpc.py", line 608, in __call__
    value = self.sockio.remotecall(self.oid, self.name, args, kwargs)
  File "D:\Python37\lib\idlelib\rpc.py", line 220, in remotecall
    return self.asyncreturn(seq)
  File "D:\Python37\lib\idlelib\rpc.py", line 251, in asyncreturn
    return self.decoderesponse(response)
  File "D:\Python37\lib\idlelib\rpc.py", line 271, in decoderesponse
    raise what
UnicodeEncodeError: 'UCS-2' codec can't encode characters in position 32-32: Non-BMP character not supported in Tk

=============================== RESTART: Shell ===============================

正如您所看到的，看起来shell进入无限循环尝试处理错误，然后重新启动shell以防止卡住。有什么方法可以a）使错误处理程序的str工作方式不同或b）防止shell重启，以便错误显示错误？

Answer 1

从snakecharmerb和these two问题中获取想法，我已经实现了一些代码，用于检查模块是否在IDLE中运行，如果是，则是否由错误处理程序调用该函数。测试似乎工作正常。我有以下检查IDLE运行环境

IN_IDLE = False
for item in ['idlelib.__main__','idlelib.run','idlelib']:
    IN_IDLE = IN_IDLE or item in sys.modules

以下是新的__str__功能

    def __str__(self):
        """ Return str(self). """
        if IN_IDLE:
            # Check for caller. If string is being printed, modify
            # output to be IDLE-friendly (no non-BMP characters)
            callername = sys._getframe(1).f_code.co_name
            if callername == '_some_str':
                rstr = ''
                for char in self.__raw:
                    if ord(char) > 0xFFFF:
                        rstr += '\\U'+hex(ord(char))[2:].zfill(8)
                    else:
                        rstr += repr(char)[1:-1]
                return rstr
            else:
                return self.__raw
        else:
            return self.__raw

其中self.__raw保存对象的原始文本表示。我正在缓存它以提高效率，因为对象是不可变的。

当然，虽然这确实解决了这个问题，但我觉得python在发生这种情况时不应该重新启动整个shell。将发布在bugs.python.org上

编辑：发布在bugs.python.org上作为issue 36698