StopIteration exception

function

def _copying(self):
    result = self.result.toPlainText().strip().split('\n')
    to_copy = '\n'.join(result)

    pyperclip.copy(to_copy)

in the MainWindow() of my PyQt5 project raises an exception "StopIteration" in contextlib.py _GeneratorContextManager(), line 119 'next(self.gen)'. result is a ui.TextEdit object. Could u please tell me what does it mean? Google says i should wrap my func into with-construction, but i don't really inderstand how, and don't sure it's a good idea.

Debugger says:

__exception__ = {tuple} <class 'tuple'>: (<class 'StopIteration'>, StopIteration(), <traceback object at 0x045DA918>)
 0 = {type} <class 'StopIteration'>
  args = {getset_descriptor} <attribute 'args' of 'BaseException' objects>
  value = {member_descriptor} <member 'value' of 'StopIteration' objects>
 1 = {StopIteration} 
  args = {tuple} <class 'tuple'>: ()
  value = {NoneType} None
 2 = {traceback} <traceback object at 0x045DA918>
  tb_frame = {frame} __exit__ [contextlib.py:119]  id:54111736
  tb_lasti = {int} 16
  tb_lineno = {int} 119
  tb_next = {NoneType} None
 __len__ = {int} 3

Console says nothing. But the project is crashing.

Solution

That StopIteration is completely normal and expected. It's part of the normal operation of contextlib.contextmanager. It's supposed to happen, and it's caught and handled immediately; if it doesn't happen, there's a problem.

I don't know how you've even ended up at the point where you're looking at this exception, considering how it never escapes the contextlib internals, but if you're blaming it for your code's problems, you're blaming the wrong thing.