Coverage for /pythoncovmergedfiles/medio/medio/usr/local/lib/python3.8/site-packages/IPython/core/display_trap.py: 42%

1# encoding: utf-8 

2""" 

3A context manager for handling sys.displayhook. 

4 

5Authors: 

6 

7* Robert Kern 

8* Brian Granger 

9""" 

10 

11#----------------------------------------------------------------------------- 

12# Copyright (C) 2008-2011 The IPython Development Team 

13# 

14# Distributed under the terms of the BSD License. The full license is in 

15# the file COPYING, distributed as part of this software. 

16#----------------------------------------------------------------------------- 

17 

18#----------------------------------------------------------------------------- 

19# Imports 

20#----------------------------------------------------------------------------- 

21 

22import sys 

23 

24from traitlets.config.configurable import Configurable 

25from traitlets import Any 

26 

27#----------------------------------------------------------------------------- 

28# Classes and functions 

29#----------------------------------------------------------------------------- 

30 

31 

32class DisplayTrap(Configurable): 

33 """Object to manage sys.displayhook. 

34 

35 This came from IPython.core.kernel.display_hook, but is simplified 

36 (no callbacks or formatters) until more of the core is refactored. 

37 """ 

38 

39 hook = Any() 

40 

41 def __init__(self, hook=None): 

42 super(DisplayTrap, self).__init__(hook=hook, config=None) 

43 self.old_hook = None 

44 # We define this to track if a single BuiltinTrap is nested. 

45 # Only turn off the trap when the outermost call to __exit__ is made. 

46 self._nested_level = 0 

47 

48 def __enter__(self): 

49 if self._nested_level == 0: 

50 self.set() 

51 self._nested_level += 1 

52 return self 

53 

54 def __exit__(self, type, value, traceback): 

55 if self._nested_level == 1: 

56 self.unset() 

57 self._nested_level -= 1 

58 # Returning False will cause exceptions to propagate 

59 return False 

60 

61 def set(self): 

62 """Set the hook.""" 

63 if sys.displayhook is not self.hook: 

64 self.old_hook = sys.displayhook 

65 sys.displayhook = self.hook 

66 

67 def unset(self): 

68 """Unset the hook.""" 

69 sys.displayhook = self.old_hook 

70