Coverage for redirector.py: 18%

1from tkinter import TclError (empty)

2 

3class WidgetRedirector: (empty)

4 """Support for redirecting arbitrary widget subcommands. 

5 

6 Some Tk operations don't normally pass through tkinter. For example, if a 

7 character is inserted into a Text widget by pressing a key, a default Tk 

8 binding to the widget's 'insert' operation is activated, and the Tk library 

9 processes the insert without calling back into tkinter. 

10 

11 Although a binding to <Key> could be made via tkinter, what we really want 

12 to do is to hook the Tk 'insert' operation itself. For one thing, we want 

13 a text.insert call in idle code to have the same effect as a key press. 

14 

15 When a widget is instantiated, a Tcl command is created whose name is the 

16 same as the pathname widget._w. This command is used to invoke the various 

17 widget operations, e.g. insert (for a Text widget). We are going to hook 

18 this command and provide a facility ('register') to intercept the widget 

19 operation. We will also intercept method calls on the tkinter class 

20 instance that represents the tk widget. 

21 

22 In IDLE, WidgetRedirector is used in Percolator to intercept Text 

23 commands. The function being registered provides access to the top 

24 of a Percolator chain. At the bottom of the chain is a call to the 

25 original Tk widget operation. 

26 """ 

27 def __init__(self, widget): (empty)

28 '''Initialize attributes and setup redirection. 

29 

30 _operations: dict mapping operation name to new function. 

31 widget: the widget whose tcl command is to be intercepted. 

32 tk: widget.tk, a convenience attribute, probably not needed. 

33 orig: new name of the original tcl command. 

34 

35 Since renaming to orig fails with TclError when orig already 

36 exists, only one WidgetDirector can exist for a given widget. 

37 ''' 

38 self._operations = {} 

39 self.widget = widget # widget instance 

40 self.tk = tk = widget.tk # widget's root 

41 w = widget._w # widget's (full) Tk pathname 

42 self.orig = w + "_orig" 

43 # Rename the Tcl command within Tcl: 

44 tk.call("rename", w, self.orig) 

45 # Create a new Tcl command whose name is the widget's pathname, and 

46 # whose action is to dispatch on the operation passed to the widget: 

47 tk.createcommand(w, self.dispatch) 

48 

49 def __repr__(self): (empty)

50 return "%s(%s<%s>)" % (self.__class__.__name__, 

51 self.widget.__class__.__name__, 

52 self.widget._w) 

53 

54 def close(self): (empty)

55 "Unregister operations and revert redirection created by .__init__." 

56 for operation in list(self._operations): 

57 self.unregister(operation) 

58 widget = self.widget 

59 tk = widget.tk 

60 w = widget._w 

61 # Restore the original widget Tcl command. 

62 tk.deletecommand(w) 

63 tk.call("rename", self.orig, w) 

64 del self.widget, self.tk # Should not be needed 

65 # if instance is deleted after close, as in Percolator. 

66 

67 def register(self, operation, function): (empty)

68 '''Return OriginalCommand(operation) after registering function. 

69 

70 Registration adds an operation: function pair to ._operations. 

71 It also adds a widget function attribute that masks the tkinter 

72 class instance method. Method masking operates independently 

73 from command dispatch. 

74 

75 If a second function is registered for the same operation, the 

76 first function is replaced in both places. 

77 ''' 

78 self._operations[operation] = function 

79 setattr(self.widget, operation, function) 

80 return OriginalCommand(self, operation) 

81 

82 def unregister(self, operation): (empty)

83 '''Return the function for the operation, or None. 

84 

85 Deleting the instance attribute unmasks the class attribute. 

86 ''' 

87 if operation in self._operations: 

88 function = self._operations[operation] 

89 del self._operations[operation] 

90 try: 

91 delattr(self.widget, operation) 

92 except AttributeError: 

93 pass 

94 return function 

95 else: 

96 return None 

97 

98 def dispatch(self, operation, *args): (empty)

99 '''Callback from Tcl which runs when the widget is referenced. 

100 

101 If an operation has been registered in self._operations, apply the 

102 associated function to the args passed into Tcl. Otherwise, pass the 

103 operation through to Tk via the original Tcl function. 

104 

105 Note that if a registered function is called, the operation is not 

106 passed through to Tk. Apply the function returned by self.register() 

107 to *args to accomplish that. For an example, see colorizer.py. 

108 

109 ''' 

110 m = self._operations.get(operation) 

111 try: 

112 if m: 

113 return m(*args) 

114 else: 

115 return self.tk.call((self.orig, operation) + args) 

116 except TclError: 

117 return "" 

118 

119 

120class OriginalCommand: (empty)

121 '''Callable for original tk command that has been redirected. 

122 

123 Returned by .register; can be used in the function registered. 

124 redir = WidgetRedirector(text) 

125 def my_insert(*args): 

126 print("insert", args) 

127 original_insert(*args) 

128 original_insert = redir.register("insert", my_insert) 

129 ''' 

130 

131 def __init__(self, redir, operation): (empty)

132 '''Create .tk_call and .orig_and_operation for .__call__ method. 

133 

134 .redir and .operation store the input args for __repr__. 

135 .tk and .orig copy attributes of .redir (probably not needed). 

136 ''' 

137 self.redir = redir 

138 self.operation = operation 

139 self.tk = redir.tk # redundant with self.redir 

140 self.orig = redir.orig # redundant with self.redir 

141 # These two could be deleted after checking recipient code. 

142 self.tk_call = redir.tk.call 

143 self.orig_and_operation = (redir.orig, operation) 

144 

145 def __repr__(self): (empty)

146 return "%s(%r, %r)" % (self.__class__.__name__, 

147 self.redir, self.operation) 

148 

149 def __call__(self, *args): (empty)

150 return self.tk_call(self.orig_and_operation + args) 

151 

152 

153def _widget_redirector(parent): # htest # (empty)

154 from tkinter import Toplevel, Text 

155 

156 top = Toplevel(parent) 

157 top.title("Test WidgetRedirector") 

158 x, y = map(int, parent.geometry().split('+')[1:]) 

159 top.geometry("+%d+%d" % (x, y + 175)) 

160 text = Text(top) 

161 text.pack() 

162 text.focus_set() 

163 redir = WidgetRedirector(text) 

164 def my_insert(*args): 

165 print("insert", args) 

166 original_insert(*args) 

167 original_insert = redir.register("insert", my_insert) 

168 

169if __name__ == "__main__": 169 ↛ 170line 169 didn't jump to line 170, because the condition on line 169 was never true(empty)

170 from unittest import main 

171 main('idlelib.idle_test.test_redirector', verbosity=2, exit=False) 

172 

173 from idlelib.idle_test.htest import run 

174 run(_widget_redirector)