The 4-argument form of observer functions passed to observableTable:addObserver appears to be buggy when used with popup menus. After a small number of invocations of the menu, the observer function will stop getting called. I'll report this as a bug soon unless someone points out any misunderstanding I may have.
Here's a short test program that illustrates the behavior:
local LrBinding = import 'LrBinding'
local LrDialogs = import 'LrDialogs'
local LrFunctionContext = import 'LrFunctionContext'
local LrView = import 'LrView'
LrFunctionContext.callWithContext ("Test", function (context)
LrDialogs.attachErrorDialogToFunctionContext (context)
local f = LrView.osFactory()
local p = LrBinding.makePropertyTable (context)
p:addObserver ("m3", function (p, k, v) p.e3 = v end)
p:addObserver ("m4", {}, function (t, p, k, v) p.e4 = v end)
LrDialogs.presentModalDialog {title = "Test",
contents = f:column {bind_to_object = p,
f:row {f:static_text {title = "3-arg observer: "},
f:popup_menu {value = LrView.bind ("m3"),
items = {"A", "B"}},
f:edit_field {value = LrView.bind ("e3")}},
f:row {f:static_text {title = "4-arg observer: "},
f:popup_menu {value = LrView.bind ("m4"),
items = {"A", "B"}},
f:edit_field {value = LrView.bind ("e4")}}}}
end)
You can invoke the menu "3-arg observer" as many times as you want, and its observer will continue to be called (which updates its edit field). But after invoking the menu "4-arg observer" 10 to 20 times, the observer stops getting called. (In my actual plugin, this would happen after invoking the menu just a couple of times.)
The problem occurs with my larger catalog (16K photos) but not with a small test catalog.
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