Fixes #1875: parse-args requires values to be representable as Hy models

* Update argument spec parse logic of parse-args function.
* Update test case of parse-args function.
* Update document of parse-args function.
* Describe the change in NEWS file.

NEWS.rst

@@ -1,5 +1,13 @@
 .. default-role:: code
 
+Unreleased
+==============================
+
+Other Breaking Changes
+------------------------------
+* `parse-args` is no longer implemented with `eval`; so e.g. you should
+  now say `:type int` instead of `:type 'int`.
+
 0.18.0
 ==============================
 

docs/language/core.rst

@@ -804,7 +804,7 @@ may be a list of keyword arguments to pass to the
 .. code-block:: hy
 
     => (parse-args [["strings" :nargs "+" :help "Strings"]
-                    ["-n" "--numbers" :action "append" :type 'int :help "Numbers"]]
+                    ["-n" "--numbers" :action "append" :type int :help "Numbers"]]
                    ["a" "b" "-n" "1" "-n" "2"]
                    :description "Parse strings and numbers from args")
     Namespace(numbers=[1, 2], strings=['a', 'b'])

hy/core/language.hy

@@ -401,7 +401,17 @@ constructor."
   (import argparse)
   (setv parser (argparse.ArgumentParser #** parser-args))
   (for [arg spec]
-    (eval `(.add-argument parser ~@arg)))
+    (setv positional-arguments []
+          keyword-arguments []
+          value-of-keyword? False)
+    (for [item arg]
+      (if value-of-keyword?
+          (.append (get keyword-arguments -1) item)
+          (if (keyword? item)
+              (.append keyword-arguments [(name item)])
+              (.append positional-arguments item)))
+      (setv value-of-keyword? (and (not value-of-keyword?) (keyword? item))))
+    (parser.add-argument #* positional-arguments #** (dict keyword-arguments)))
   (.parse-args parser args))
 
 (setv EXPORTS

tests/native_tests/core.hy

@@ -480,9 +480,10 @@ result['y in globals'] = 'y' in globals()")
 
 (defn test-parse-args []
   "NATIVE: testing the parse-args function"
+  ; https://github.com/hylang/hy/issues/1875
   (setv parsed-args (parse-args [["strings" :nargs "+" :help "Strings"]
-                                 ["-n" "--numbers" :action "append" :type 'int :help "Numbers"]]
-                                ["a" "b" "-n" "1" "-n" "2"]
+                                 ["-n" :action "append" :type int :help "Numbers" "--numbers"]]
+                                ["a" "b" "-n" "1" "--numbers" "2"]
                                 :description "Parse strings and numbers from args"))
   (assert-equal parsed-args.strings ["a" "b"])
   (assert-equal parsed-args.numbers [1 2]))