Capture scope only on exception

[vvvvalvalval]

Capture scope only on exception

[vvvvalvalval]

Hello, I would not encourage you to use with-redefs for that (or anything), but have you read the customization section from the docs? It's really meant for this sort of use case. You can also pass the inline :sc/spy-ep-pre-eval-logger-fn and :sc/spy-ep-post-eval-logger-fn opts.

When I want to catch on Exceptions only, I usually do it by wrapping the exception in a try/catch and spying inside the catch clause.

Other options are:

1. using a brk, then exiting with an error
2. spying at random: (when (zero? (rand-int 100)) (sc.api/spy))

People have very different opinions regarding such workflow optimizations; this is why I recommend writing your own spy... wrappers in your project's utility namespace.

[yuhan0]

Update: I traced the source of the logging and tried redefining these functions with no-ops:

• sc.api.logging/log-spy-ep-pre-eval
• sc.api.logging/log-spy-ep-post-eval

That alone reduced the execution time to 51ms, so it turned out the huge majority of the overhead was due to all the println logging.

There doesn't look to be a simple way of switching this logging behaviour off - perhaps a dynamic var of some sort like sc.api/*log-spy-execution* or a separate spying macro?
Here's what I'm using for the time being:

(defmacro spy' [& args]
  `(with-redefs [sc.api.logging/log-spy-ep-pre-eval (fn [~'ep])
                 sc.api.logging/log-spy-ep-post-eval (fn [~'ep])]
     (sc/spy ~@args)))

Let me know and I'd be willing to contribute a PR :)

[yuhan0]

Thanks for all the pointers! That's what I get for digging through the source but not the documentation 😅
Being able to conditionally (spy) anywhere is pretty nice, I had the wrong impression that it had to always be wrapped around an expression.

Here's my modified macro from above, for anyone interested:

(def spysl-opts
  {:sc/spy-ep-post-eval-logger (fn [ep])
   :sc/spy-ep-pre-eval-logger (fn [ep])})

(defmacro spysl
  "Spy silently - do not print anything at execution points."
  ([] (sc.api/spy-emit spysl-opts nil &env &form))
  ([expr] (sc.api/spy-emit spysl-opts expr &env &form))
  ([opts expr] (sc.api/spy-emit (merge spysl-opts opts) expr &env &form)))