Terry J. Reedy added the comment:
This issue is really about managing the set of var,callback pairs. The idea of
wrapping vars just clouded the issue.
class VarTrace:
def __init__(self):
self.tracers = [] # or set if need to delete
def add(self, var, callback):
if isinstance(callback, tuple):
callback = self.make_callback(var, callback)
self.vartrace.add((var, callback))
return var
def make_callback(self, var, args): # Used for 6 vars.
def var_callback(*params):
changes.add_item(*args, var.get())
return var_callback
def attach(self):
for var, callback in self.tracers:
var.trace_add('write', callback)
def remove(cls): # detach?
for var, _ in self.tracers:
var.trace_remove('write', var.trace_info()[0][1]) # doc this
# A functionalist would define a function that returns a sequence of closures.
tracers = VarTrace()
# write tests, then patch creation of tested vars, retest, patch rest.
- self.font_name = StringVar(parent)
+ self.font_name = tracers.add(StringVar(parent), var_changed_font)
----------
nosy: +csabella
title: IDLE: configdialog -- factor out Variable subclass -> IDLE: configdialog
-- factor out Tracer subclass
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Python tracker <rep...@bugs.python.org>
<http://bugs.python.org/issue30853>
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