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