Fix TCLI-97 by allowing validation msg to be a function

Author: seancorfield

.gitignore

@@ -1,5 +1,6 @@
 target
 /.lein-failures
+/.lsp
 /.cpcache
 /cljs-test-runner-out
 /.lein-repl-history

CHANGELOG.md

@@ -1,6 +1,7 @@
 # Change Log
 
 * Release 1.0.next (on **master**)
+  * Allow validation message to be a function (of the invalid argument) in addition to being a plain string [TCLI-97](https://clojure.atlassian.net/browse/TCLI-97).
   * Add `:multi true` to modify behavior of `:update-fn` [TCLI-96](https://clojure.atlassian.net/browse/TCLI-96).
 
 * Release 1.0.194 2020-02-20

README.md

@@ -174,11 +174,13 @@ be useful within your own `:summary-fn` for generating the default summary.
 
 There is a new option entry `:validate`, which takes a tuple of
 `[validation-fn validation-msg]`. The validation-fn receives an option's
-argument *after* being parsed by `:parse-fn` if it exists.
+argument *after* being parsed by `:parse-fn` if it exists. The validation-msg
+can either be a string or a function of one argument that can be called on
+the invalid option argument to produce a string:
 
     ["-p" "--port PORT" "A port number"
      :parse-fn #(Integer/parseInt %)
-     :validate [#(< 0 % 0x10000) "Must be a number between 0 and 65536"]]
+     :validate [#(< 0 % 0x10000) #(str % " is not a number between 0 and 65536")]]
 
 If the validation-fn returns a falsey value, the validation-msg is added to the
 errors vector.

src/main/clojure/clojure/tools/cli.cljc

@@ -305,6 +305,7 @@
                           ;  #(not (.isMulticastAddress %)]
    :validate-msg [String] ; [\"Must be an IPv4 host\"
                           ;  \"Must not be a multicast address\"]
+                          ; can also be a function (of the invalid argument)
    :missing      String   ; \"server must be specified\"
    }
 
@@ -383,7 +384,7 @@
 
 (defn- validation-error [opt optarg msg]
   (str "Failed to validate " (pr-join opt optarg)
-       (if msg (str ": " msg) "")))
+       (if msg (str ": " (if (string? msg) msg (msg optarg))) "")))
 
 (defn- validate [value spec opt optarg]
   (let [{:keys [validate-fn validate-msg]} spec]
@@ -707,7 +708,8 @@
 
     :validate-msg A vector of error messages corresponding to :validate-fn
                   that will be added to the :errors vector on validation
-                  failure.
+                  failure. Can be plain strings, or functions to be applied
+                  to the (invalid) option argument to produce a string.
 
   parse-opts returns a map with four entries:
 

src/test/clojure/clojure/tools/cli_test.cljc

@@ -121,7 +121,7 @@
     (let [specs (compile-option-specs
                   [["-p" "--port NUMBER"
                     :parse-fn parse-int
-                    :validate [#(< 0 % 0x10000) "Must be between 0 and 65536"]]
+                    :validate [#(< 0 % 0x10000) #(str % " is not between 0 and 65536")]]
                    ["-f" "--file PATH"
                     :missing "--file is required"
                     :validate [#(not= \/ (first %)) "Must be a relative path"
@@ -143,7 +143,7 @@
                       (peek (parse-option-tokens specs [[:short-opt "-f" "-p"]] :strict true))))
       (is (has-error? #"--file is required"
                       (peek (parse-option-tokens specs []))))
-      (is (has-error? #"Must be between"
+      (is (has-error? #"0 is not between"
                       (peek (parse-option-tokens specs [[:long-opt "--port" "0"]]))))
       (is (has-error? #"Error while parsing"
                       (peek (parse-option-tokens specs [[:long-opt "--port" "FOO"]]))))