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1 | """Infrastructure for registering and firing callbacks on application events. |
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1 | """Infrastructure for registering and firing callbacks on application events. | |
2 |
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2 | |||
3 | Unlike :mod:`IPython.core.hooks`, which lets end users set single functions to |
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3 | Unlike :mod:`IPython.core.hooks`, which lets end users set single functions to | |
4 | be called at specific times, or a collection of alternative methods to try, |
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4 | be called at specific times, or a collection of alternative methods to try, | |
5 | callbacks are designed to be used by extension authors. A number of callbacks |
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5 | callbacks are designed to be used by extension authors. A number of callbacks | |
6 | can be registered for the same event without needing to be aware of one another. |
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6 | can be registered for the same event without needing to be aware of one another. | |
7 |
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7 | |||
8 | The functions defined in this module are no-ops indicating the names of available |
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8 | The functions defined in this module are no-ops indicating the names of available | |
9 | events and the arguments which will be passed to them. |
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9 | events and the arguments which will be passed to them. | |
10 |
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10 | |||
11 | .. note:: |
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11 | .. note:: | |
12 |
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12 | |||
13 | This API is experimental in IPython 2.0, and may be revised in future versions. |
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13 | This API is experimental in IPython 2.0, and may be revised in future versions. | |
14 | """ |
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14 | """ | |
15 |
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15 | |||
16 | from backcall import callback_prototype |
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16 | from backcall import callback_prototype | |
17 |
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17 | |||
18 |
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18 | |||
19 | class EventManager(object): |
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19 | class EventManager(object): | |
20 | """Manage a collection of events and a sequence of callbacks for each. |
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20 | """Manage a collection of events and a sequence of callbacks for each. | |
21 |
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21 | |||
22 | This is attached to :class:`~IPython.core.interactiveshell.InteractiveShell` |
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22 | This is attached to :class:`~IPython.core.interactiveshell.InteractiveShell` | |
23 | instances as an ``events`` attribute. |
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23 | instances as an ``events`` attribute. | |
24 |
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24 | |||
25 | .. note:: |
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25 | .. note:: | |
26 |
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26 | |||
27 | This API is experimental in IPython 2.0, and may be revised in future versions. |
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27 | This API is experimental in IPython 2.0, and may be revised in future versions. | |
28 | """ |
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28 | """ | |
29 | def __init__(self, shell, available_events): |
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29 | ||
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30 | def __init__(self, shell, available_events, print_on_error=True): | |||
30 | """Initialise the :class:`CallbackManager`. |
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31 | """Initialise the :class:`CallbackManager`. | |
31 |
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32 | |||
32 | Parameters |
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33 | Parameters | |
33 | ---------- |
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34 | ---------- | |
34 | shell |
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35 | shell | |
35 | The :class:`~IPython.core.interactiveshell.InteractiveShell` instance |
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36 | The :class:`~IPython.core.interactiveshell.InteractiveShell` instance | |
36 | available_events |
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37 | available_events | |
37 | An iterable of names for callback events. |
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38 | An iterable of names for callback events. | |
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39 | print_on_error: | |||
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40 | A boolean flag to set whether the EventManager will print a warning which a event errors. | |||
38 | """ |
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41 | """ | |
39 | self.shell = shell |
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42 | self.shell = shell | |
40 | self.callbacks = {n:[] for n in available_events} |
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43 | self.callbacks = {n:[] for n in available_events} | |
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44 | self.print_on_error = print_on_error | |||
41 |
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45 | |||
42 | def register(self, event, function): |
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46 | def register(self, event, function): | |
43 | """Register a new event callback. |
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47 | """Register a new event callback. | |
44 |
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48 | |||
45 | Parameters |
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49 | Parameters | |
46 | ---------- |
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50 | ---------- | |
47 | event : str |
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51 | event : str | |
48 | The event for which to register this callback. |
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52 | The event for which to register this callback. | |
49 | function : callable |
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53 | function : callable | |
50 | A function to be called on the given event. It should take the same |
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54 | A function to be called on the given event. It should take the same | |
51 | parameters as the appropriate callback prototype. |
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55 | parameters as the appropriate callback prototype. | |
52 |
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56 | |||
53 | Raises |
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57 | Raises | |
54 | ------ |
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58 | ------ | |
55 | TypeError |
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59 | TypeError | |
56 | If ``function`` is not callable. |
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60 | If ``function`` is not callable. | |
57 | KeyError |
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61 | KeyError | |
58 | If ``event`` is not one of the known events. |
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62 | If ``event`` is not one of the known events. | |
59 | """ |
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63 | """ | |
60 | if not callable(function): |
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64 | if not callable(function): | |
61 | raise TypeError('Need a callable, got %r' % function) |
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65 | raise TypeError('Need a callable, got %r' % function) | |
62 | callback_proto = available_events.get(event) |
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66 | callback_proto = available_events.get(event) | |
63 | if function not in self.callbacks[event]: |
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67 | if function not in self.callbacks[event]: | |
64 | self.callbacks[event].append(callback_proto.adapt(function)) |
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68 | self.callbacks[event].append(callback_proto.adapt(function)) | |
65 |
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69 | |||
66 | def unregister(self, event, function): |
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70 | def unregister(self, event, function): | |
67 | """Remove a callback from the given event.""" |
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71 | """Remove a callback from the given event.""" | |
68 | if function in self.callbacks[event]: |
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72 | if function in self.callbacks[event]: | |
69 | return self.callbacks[event].remove(function) |
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73 | return self.callbacks[event].remove(function) | |
70 |
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74 | |||
71 | # Remove callback in case ``function`` was adapted by `backcall`. |
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75 | # Remove callback in case ``function`` was adapted by `backcall`. | |
72 | for callback in self.callbacks[event]: |
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76 | for callback in self.callbacks[event]: | |
73 | try: |
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77 | try: | |
74 | if callback.__wrapped__ is function: |
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78 | if callback.__wrapped__ is function: | |
75 | return self.callbacks[event].remove(callback) |
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79 | return self.callbacks[event].remove(callback) | |
76 | except AttributeError: |
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80 | except AttributeError: | |
77 | pass |
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81 | pass | |
78 |
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82 | |||
79 | raise ValueError('Function {!r} is not registered as a {} callback'.format(function, event)) |
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83 | raise ValueError('Function {!r} is not registered as a {} callback'.format(function, event)) | |
80 |
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84 | |||
81 | def trigger(self, event, *args, **kwargs): |
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85 | def trigger(self, event, *args, **kwargs): | |
82 | """Call callbacks for ``event``. |
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86 | """Call callbacks for ``event``. | |
83 |
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87 | |||
84 | Any additional arguments are passed to all callbacks registered for this |
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88 | Any additional arguments are passed to all callbacks registered for this | |
85 | event. Exceptions raised by callbacks are caught, and a message printed. |
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89 | event. Exceptions raised by callbacks are caught, and a message printed. | |
86 | """ |
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90 | """ | |
87 | for func in self.callbacks[event][:]: |
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91 | for func in self.callbacks[event][:]: | |
88 | try: |
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92 | try: | |
89 | func(*args, **kwargs) |
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93 | func(*args, **kwargs) | |
90 | except (Exception, KeyboardInterrupt): |
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94 | except (Exception, KeyboardInterrupt): | |
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95 | if self.print_on_error: | |||
91 | print("Error in callback {} (for {}):".format(func, event)) |
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96 | print("Error in callback {} (for {}):".format(func, event)) | |
92 | self.shell.showtraceback() |
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97 | self.shell.showtraceback() | |
93 |
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98 | |||
94 | # event_name -> prototype mapping |
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99 | # event_name -> prototype mapping | |
95 | available_events = {} |
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100 | available_events = {} | |
96 |
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101 | |||
97 | def _define_event(callback_function): |
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102 | def _define_event(callback_function): | |
98 | callback_proto = callback_prototype(callback_function) |
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103 | callback_proto = callback_prototype(callback_function) | |
99 | available_events[callback_function.__name__] = callback_proto |
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104 | available_events[callback_function.__name__] = callback_proto | |
100 | return callback_proto |
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105 | return callback_proto | |
101 |
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106 | |||
102 | # ------------------------------------------------------------------------------ |
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107 | # ------------------------------------------------------------------------------ | |
103 | # Callback prototypes |
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108 | # Callback prototypes | |
104 | # |
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109 | # | |
105 | # No-op functions which describe the names of available events and the |
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110 | # No-op functions which describe the names of available events and the | |
106 | # signatures of callbacks for those events. |
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111 | # signatures of callbacks for those events. | |
107 | # ------------------------------------------------------------------------------ |
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112 | # ------------------------------------------------------------------------------ | |
108 |
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113 | |||
109 | @_define_event |
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114 | @_define_event | |
110 | def pre_execute(): |
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115 | def pre_execute(): | |
111 | """Fires before code is executed in response to user/frontend action. |
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116 | """Fires before code is executed in response to user/frontend action. | |
112 |
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117 | |||
113 | This includes comm and widget messages and silent execution, as well as user |
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118 | This includes comm and widget messages and silent execution, as well as user | |
114 | code cells. |
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119 | code cells. | |
115 | """ |
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120 | """ | |
116 | pass |
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121 | pass | |
117 |
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122 | |||
118 | @_define_event |
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123 | @_define_event | |
119 | def pre_run_cell(info): |
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124 | def pre_run_cell(info): | |
120 | """Fires before user-entered code runs. |
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125 | """Fires before user-entered code runs. | |
121 |
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126 | |||
122 | Parameters |
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127 | Parameters | |
123 | ---------- |
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128 | ---------- | |
124 | info : :class:`~IPython.core.interactiveshell.ExecutionInfo` |
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129 | info : :class:`~IPython.core.interactiveshell.ExecutionInfo` | |
125 | An object containing information used for the code execution. |
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130 | An object containing information used for the code execution. | |
126 | """ |
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131 | """ | |
127 | pass |
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132 | pass | |
128 |
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133 | |||
129 | @_define_event |
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134 | @_define_event | |
130 | def post_execute(): |
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135 | def post_execute(): | |
131 | """Fires after code is executed in response to user/frontend action. |
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136 | """Fires after code is executed in response to user/frontend action. | |
132 |
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137 | |||
133 | This includes comm and widget messages and silent execution, as well as user |
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138 | This includes comm and widget messages and silent execution, as well as user | |
134 | code cells. |
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139 | code cells. | |
135 | """ |
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140 | """ | |
136 | pass |
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141 | pass | |
137 |
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142 | |||
138 | @_define_event |
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143 | @_define_event | |
139 | def post_run_cell(result): |
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144 | def post_run_cell(result): | |
140 | """Fires after user-entered code runs. |
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145 | """Fires after user-entered code runs. | |
141 |
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146 | |||
142 | Parameters |
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147 | Parameters | |
143 | ---------- |
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148 | ---------- | |
144 | result : :class:`~IPython.core.interactiveshell.ExecutionResult` |
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149 | result : :class:`~IPython.core.interactiveshell.ExecutionResult` | |
145 | The object which will be returned as the execution result. |
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150 | The object which will be returned as the execution result. | |
146 | """ |
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151 | """ | |
147 | pass |
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152 | pass | |
148 |
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153 | |||
149 | @_define_event |
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154 | @_define_event | |
150 | def shell_initialized(ip): |
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155 | def shell_initialized(ip): | |
151 | """Fires after initialisation of :class:`~IPython.core.interactiveshell.InteractiveShell`. |
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156 | """Fires after initialisation of :class:`~IPython.core.interactiveshell.InteractiveShell`. | |
152 |
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157 | |||
153 | This is before extensions and startup scripts are loaded, so it can only be |
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158 | This is before extensions and startup scripts are loaded, so it can only be | |
154 | set by subclassing. |
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159 | set by subclassing. | |
155 |
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160 | |||
156 | Parameters |
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161 | Parameters | |
157 | ---------- |
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162 | ---------- | |
158 | ip : :class:`~IPython.core.interactiveshell.InteractiveShell` |
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163 | ip : :class:`~IPython.core.interactiveshell.InteractiveShell` | |
159 | The newly initialised shell. |
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164 | The newly initialised shell. | |
160 | """ |
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165 | """ | |
161 | pass |
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166 | pass |
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