How to replace a SeeSaw widget with a dynamically created one in Clojure?

Question

I'm new to Clojure, Java and functional programming. I started working with SeeSaw for GUI and loving it. Using an example from Dave Ray i create a widget:

(defrecord Col-definition [id col-name col-position])

with associated functions to create comboboxes, labels and textboxes, by most notably using extend-type:

(extend-type Col-definition  
  MakeWidget 
  (make-widget* [col-definition] 
    (mig-panel 
      :constraints ["", "[][grow]"]
      :border [(line-border :thickness 1) 2]

      :items [["Column Name"        "gap 10"]
              ;;[(col-name-field (:id col-definition) col-definition :col-name)  "growx, wrap"]
              [(:col-name col-definition) "growx, wrap"]
              ["Ordinal Position" "gap 10"]
              [(col-name-field (:id col-definition) col-definition :col-position)  "growx"]])))

The widgets get built via instances of the defrecord, tied to a screen area as so:

(def second-combocoll '("Col0" "Col1" "Col2"))
(def second-bottom (vertical-panel :items (vec (col-defs second-combocoll))))
(def areabottom second-bottom)

where areabottom is a split area of real estate. It all works great.

But I want to read in from a database and dynamically replace the widget with a new collection of comboboxes.

I can't seem to remove the widget, (remove! areabottom second-combocol) or (replace! areabottom new-combocol) or any other clever ideas all have come up naught.

So here's the question: How do I replace or remove a custom widget, after a triggered event (such as clicking on a file path to load)?

Answer 1

After a week of trying all sorts of things I have a solution to offer, albeit a bit of a hack.

The key idea is in the specific use of the id keyword as a way to label and then find widgets.

First, to get things going, I created a "dummy" widget," adding it to an JFrame area named areabottom. This is because later on there must be something to replace.

(def initcombos (combobox  :id "newcombo" :model [ 1 2 3 ]))
(add! areabottom initcombos)

-I then modified the listbox listener and implemented replace! using the id keyword as follows:

 (listen lb 
         :selection
        (fn [e]
          (when-let [s (selection e)]
           (let [ncombo (vertical-panel :id "newcombo" :items (get-col-defs (.getPath s)))]
          ; (replace! areabottom initcombos ncombo)
          (replace! areabottom (select areabottom [:#newcombo]) ncombo)
           )))) 

Notice the ncombo in let has the identical id to the previous "dummy" widget, i.e "newcombo." This was the magic hack, so that the same id is used for finding the old widget, and the new widget has the same id, to make sure it can be found on further calls. Hope this is helpful.

Answer 2

it's been awhile since you've posted this. I looked at this post a few minutes ago because I was having the same problem with replace! not doing what I expected. Rather than continuing with replace!, I instead used something like (do (config! my-container :items (build-new-items)) (repaint! my-container)). You might want to try this if you still want to declutter your code.