Add cprop example (#648) [skip ci]

examples/README.md

@@ -283,7 +283,7 @@ which finds unused vars. It uses
 $ bb examples/hsqldb_unused_vars.clj src
 
 |                   :VARS/NS |               :VARS/NAME |                     :VARS/FILENAME | :VARS/ROW | :VARS/COL |
-|----------------------------+--------------------------+------------------------------------+-----------+-----------|
+|----------------------------|--------------------------|------------------------------------|-----------|-----------|
 | babashka.impl.bencode.core |           read-netstring | src/babashka/impl/bencode/core.clj |       162 |         1 |
 | babashka.impl.bencode.core |          write-netstring | src/babashka/impl/bencode/core.clj |       201 |         1 |
 |      babashka.impl.classes | generate-reflection-file |      src/babashka/impl/classes.clj |       230 |         1 |
@@ -345,3 +345,15 @@ $ examples/torrent-viewer.clj file.torrent
 ```
 
 See [torrent-viewer.clj](torrent-viewer.clj).
+
+### [cprop.clj](cprop.clj)
+
+This script uses [tolitius/cprop](https://github.com/tolitius/cprop) library. 
+
+See [cprop.clj](cprop.clj)
+
+Example usage:
+
+```shell
+cd ./examples && chmod +x cprop.clj && ./cprop.clj
+```

examples/cprop-override.properties

@@ -0,0 +1,12 @@
+datomic.url=datomic:sql://?jdbc:postgresql://localhost:5432/datomic?user=datomic&password=datomic
+
+source.account.rabbit.host=localhost
+
+aws.access-key=super secret key
+aws.secret_key=super secret s3cr3t!!!
+aws.region=us-east-2
+
+io.http.pool.conn_timeout=42
+io.http.pool.max_per_route=42
+
+other_things=1,2,3,4,5,6,7

examples/cprop.clj

@@ -0,0 +1,56 @@
+#!/usr/bin/env bb
+(require '[babashka.classpath :refer [add-classpath]])
+(require '[clojure.java.shell :refer [sh]])
+(require '[clojure.pprint :refer [pprint]])
+
+(def deps '{:deps {cprop {:mvn/version "0.1.17"}}})
+(def cp (:out (sh "clojure" "-Spath" "-Sdeps" (str deps))))
+(add-classpath cp)
+
+(require '[cprop.core :refer [load-config]])
+(require '[cprop.source :refer [from-props-file]])
+
+;; Load sample configuration from the file system
+(def conf (load-config :file "cprop.edn"))
+
+;; Print the configuration we just read in
+(pprint conf)
+
+;;=>
+#_{:datomic {:url "CHANGE ME"}
+   :aws {:access-key "AND ME"
+         :secret-key "ME TOO"
+         :region "FILL ME IN AS WELL"
+         :visiblity-timeout-sec 30
+         :max-conn 50
+         :queue "cprop-dev"}
+   :io {:http {:pool {:socket-timeout 600000
+                      :conn-timeout :I-SHOULD-BE-A-NUMBER
+                      :conn-req-timeout 600000
+                      :max-total 200
+                      :max-per-route :ME-ALSO}}}
+   :other-things ["I am a vector and also like to place the substitute game"]}
+(let [conf (load-config
+            :file "cprop.edn"
+            :merge [(from-props-file "cprop-override.properties")])]
+  (pprint conf))
+
+;;=>
+#_{:datomic
+   {:url "datomic:sql://?jdbc:postgresql://localhost:5432/datomic?user=datomic&password=datomic"},
+   :aws
+   {:access-key "super secret key",
+    :secret-key "super secret s3cr3t!!!",
+    :region "us-east-2",
+    :visiblity-timeout-sec 30,
+    :max-conn 50,
+    :queue "cprop-dev"},
+   :io
+   {:http
+    {:pool
+     {:socket-timeout 600000,
+      :conn-timeout 42,
+      :conn-req-timeout 600000,
+      :max-total 200,
+      :max-per-route 42}}},
+   :other-things ["1" "2" "3" "4" "5" "6" "7"]}

examples/cprop.edn

@@ -0,0 +1,26 @@
+#_
+{:datomic
+ {:url "datomic:sql://?jdbc:postgresql://localhost:5432/datomic?user=datomic&password=datomic"}
+ :source
+ {:account
+  {:rabbit
+   {:host "127.0.0.1"
+    :port 5672
+    :vhost "/z-broker"
+    :username "guest"
+    :password "guest"}}}
+ :answer 42}
+
+{:datomic {:url "CHANGE ME"}
+ :aws {:access-key "AND ME"
+       :secret-key "ME TOO"
+       :region "FILL ME IN AS WELL"
+       :visiblity-timeout-sec 30
+       :max-conn 50
+       :queue "cprop-dev"}
+ :io {:http {:pool {:socket-timeout 600000
+                    :conn-timeout :I-SHOULD-BE-A-NUMBER
+                    :conn-req-timeout 600000
+                    :max-total 200
+                    :max-per-route :ME-ALSO}}}
+ :other-things ["I am a vector and also like to place the substitute game"]}