[new] Add signal-allowed?

Useful for using Telemere's filtering features without generating
any signals, etc.

projects/main/src/taoensso/telemere.cljc

@@ -68,6 +68,7 @@
   #?(:clj impl/with-signal)
   #?(:clj impl/with-signals)
   #?(:clj impl/signal!)
+  #?(:clj impl/signal-allowed?)
 
   ;; Utils
   utils/format-signal-fn

projects/main/src/taoensso/telemere/impl.cljc

@@ -381,6 +381,13 @@
             sample-rate kind ns id level when rate-limit,
             ctx parent root trace?, do let data msg error run & kvs]}])
 
+       :signal-allowed?
+       '([{:as opts :keys
+           [#_defaults #_elide? #_allow? #_expansion-id, ; Undocumented
+            elidable? location #_location* #_inst #_uid #_middleware,
+            sample-rate kind ns id level when rate-limit,
+            #_ctx #_parent #_root #_trace?, #_do #_let #_data #_msg #_error #_run #_& #_kvs]}])
+
        :event! ; [id] [id level-or-opts] => allowed?
        '([id      ]
          [id level]
@@ -762,19 +769,30 @@
       (signal! {:level :info, :run "run"}))))
 
 #?(:clj
-   (defmacro signal-allowed?
-     "Used only for interop (tools.logging, SLF4J, etc.)."
+   (defmacro ^:public signal-allowed?
+     "Returns true if signal with given opts would meet filtering conditions,
+     and false otherwise, e.g.:
+
+       (when (signal-allowed? {:level :warn}) (my-custom-code))"
+
+     ;; Used also for interop (tools.logging, SLF4J), etc.
      {:arglists (signal-arglists :signal!)}
      [opts]
-     (let [{:keys [#_expansion-id #_location elide? allow?]}
+     (have? map? opts)
+     (let [defaults             (get    opts :defaults)
+           opts (merge defaults (dissoc opts :defaults))
+
+           {:keys [#_expansion-id #_location elide? allow?]}
            (sigs/filterable-expansion
              {:sf-arity 4
               :ct-sig-filter     ct-sig-filter
               :*rt-sig-filter* `*rt-sig-filter*}
              (assoc opts :location*
                (get opts :location* (enc/get-source &form &env))))]
 
-       (and (not elide?) allow?))))
+       (if elide? false `(if ~allow? true false)))))
+
+(comment (macroexpand '(signal-allowed? {:level :info})))
 
 ;;;; Interop
 

projects/main/test/taoensso/telemere_tests.cljc

@@ -275,7 +275,10 @@
 
           [(is (= sv1 (read-string (pr-str sv1))))])))
 
-   (is (sm? (with-sig (shell/signal! {:level :info})) {:level :info, :ns "taoensso.telemere-tests", :line :submap/some}) "Shell API")])
+   (testing "Shell API"
+     [(is (sm? (with-sig (shell/signal!         {:level :info})) {:level :info, :ns "taoensso.telemere-tests", :line :submap/some}))
+      (is (sm?           (shell/signal-allowed? {:level :info})  true))
+      (is (sm?           (shell/signal-allowed? {:level :trace}) false))])])
 
 (deftest _handlers
   ;; Basic handler tests are in Encore

projects/shell/src/taoensso/telemere/shell.cljc

@@ -16,9 +16,10 @@
    (defmacro ^:private compile-if [test then else]
      (if (try (eval test) (catch Throwable _ false)) then else)))
 
-(def ^:private telemere-present?
-  "Is Telemere present (not necessarily loaded)?"
-  (compile-if (jio/resource "taoensso/telemere.cljc") true false))
+#?(:clj
+   (def ^:private telemere-present?
+     "Is Telemere present (not necessarily loaded)?"
+     (compile-if (jio/resource "taoensso/telemere.cljc") true false)))
 
 #?(:clj
    (defmacro if-telemere
@@ -50,6 +51,15 @@
 
 (comment (set-min-level! nil "my-ns(.*)" :warn))
 
+#?(:clj
+   (defn- require-telemere! []
+     (try
+       (require 'taoensso.telemere) ; For macro expansion
+       (catch Exception e
+         (throw
+           (ex-info "Failed to require `taoensso.telemere` - `(require-telemere-if-present)` call missing?"
+             {} e))))))
+
 #?(:clj
    (defmacro signal!
      "Experimental, subject to change.
@@ -92,28 +102,22 @@
            ctx parent root trace?, do let data msg error run & kvs]}])}
 
      [opts]
-     (if (map? opts)
-       (if telemere-present?
-         (do
-           (try
-             (require 'taoensso.telemere) ; For macro expansion
-             (catch Exception e
-               (throw
-                 (ex-info "Failed to require `taoensso.telemere` - `(require-telemere-if-present)` call missing?"
-                   {} e))))
-
-           (with-meta ; Keep callsite
-             `(taoensso.telemere/signal! ~(dissoc opts :fallback))
-             (meta &form)))
-
-         (let      [fb-form  (get opts :fallback)]
-           (if-let [run-form (get opts :run)]
-             `(let [run-result# ~run-form] ~fb-form run-result#)
-             (do                            fb-form))))
-
+     (when-not (map? opts)
        (throw
          (ex-info "`signal!` expects map opts"
-           {:given {:value opts, :type (type opts)}})))))
+           {:given {:value opts, :type (type opts)}})))
+
+     (if telemere-present?
+       (do
+         (require-telemere!)
+         (with-meta ; Keep callsite
+           `(taoensso.telemere/signal! ~(dissoc opts :fallback))
+           (meta &form)))
+
+       (let      [fb-form  (get opts :fallback)]
+         (if-let [run-form (get opts :run)]
+           `(let [run-result# ~run-form] ~fb-form run-result#)
+           (do                            fb-form))))))
 
 (comment
   (macroexpand
@@ -123,3 +127,44 @@
         :msg  ["Hello" "world" x]
         :data {:a :A :x x}
         :fallback (println (str "Hello world " x))})))
+
+#?(:clj
+   (defmacro signal-allowed?
+     "Experimental, subject to change.
+     Returns true iff Telemere is present, and signal with given opts would meet
+     filtering conditions.
+
+     MUST be used with `require-telemere-if-present`, example:
+
+       (ns my-lib
+         (:require [taoensso.telemere.shell :as t]))
+
+       (t/require-telemere-if-present) ; Just below `ns` form!
+
+       (when (t/signal-allowed? {:level :warn})
+         (my-custom-code))"
+
+     {:arglists
+      '([{:as opts :keys
+          [#_fallback, ; Unique to shell
+           #_defaults #_elide? #_allow? #_expansion-id, ; Undocumented
+           elidable? location #_location* #_inst #_uid #_middleware,
+           sample-rate kind ns id level when rate-limit,
+           #_ctx #_parent #_root #_trace?, #_do #_let #_data #_msg #_error #_run #_& #_kvs]}])}
+
+     [opts]
+     (when-not (map? opts)
+       (throw
+         (ex-info "`signal-allowed!` expects map opts"
+           {:given {:value opts, :type (type opts)}})))
+
+     (if telemere-present?
+       (do
+         (require-telemere!)
+         (with-meta ; Keep callsite
+           `(taoensso.telemere/signal-allowed? ~(dissoc opts :fallback))
+           (meta &form)))
+
+       (get opts :fallback nil))))
+
+(comment (macroexpand '(signal-allowed? {:level :warn})))