Unable to resolve symbol while attempting to use fn args

[Szymon Kuryło]

Hi,

I'm learning clojure-android using Emacs CIDER 0.8.1, neko 3.2.0.

The usual way for updating UI is evaluating the (set-content-view! (*a) (my-ui-def (*a)) using Ctrl+E, e.g.

(defactivity com.szymonkurylo.MainActivity

  :key :main

  :on-create

  (fn [this bundle]

    (keep-screen-on (*a))

    (on-ui

      (set-content-view! (*a)

                         (ui/make-ui (*a) (my-ui-def (*a)))))

    ))

Every time I use `this` instead of `(*a)` I get the following error:

Unable to resolve symbol: this in this context ...

The same error happens for example while defining :on-click callbacks, e.g.

(defn my-ui-def

  [activity]

  (concat [:linear-layout {:orientation :vertical}]

          (map (fn [i]

                 [:button {:text (str i)

                           :on-click (fn [_] (toast activity (str "clicked " i)))}])

               (range 10))))

 Unable to resolve symbol: activity in this context

Both of these snippets are slightly modified examples taken from https://github.com/clojure-android/neko/wiki/User-interface

Is this my code error, or is it some CIDER issue with evaluating macros?

[Alexander Yakushev]

This is not an error. `this` is a Activity instance for the activity you generate with `defactivity`. It comes as a first argument into all Activity methods, but you can't draw it out of thin air (by default). `*a` is a debugging macro I created exactly for this reason, it keeps references to the Activity objects, and allows to grab them in the REPL. The general workflow is you use (*a) in the REPL, and then for release you replace (*a) with `this`.

Hope this helps.

[Szymon Kuryło]

Ok, what about the second example?

This is a normal `defn` function definition, and `activity` is the function's argument. Why cannot I refer it inside its body?

[Alexander Yakushev]

Second example works for me. I thought you were trying to evaluate only the highlighted part. Are you sure you are evaluating the whole top-level expresion?

[Szymon Kuryło]

Yep, sorry, my mistake. Indeed, I was trying to evaluate the (map ...) part.