[GitHub] [daffodil] stevedlawrence commented on a diff in pull request #948: Refactor how Main calls "generate c"

["stevedlawrence (via GitHub)" <gi...@apache.org>]

stevedlawrence commented on code in PR #948:
URL: https://github.com/apache/daffodil/pull/948#discussion_r1096111873


##########
daffodil-cli/src/main/scala/org/apache/daffodil/Main.scala:
##########
@@ -454,30 +454,37 @@ class CLIConf(arguments: Array[String]) extends scallop.ScallopConf(arguments) {
     footer("""|
               |Run 'daffodil generate <language> --help' for subcommand specific options""".stripMargin)
 
-    object c extends scallop.Subcommand("c") {
-      banner("""|Usage: daffodil generate c -s <schema> [-r <root>]
-                |                           [-c <file>] [-T<tunable>=<value>...]
-                |                           [outdir]
-                |
-                |Generate C code from a DFDL schema to parse or unparse data
-                |
-                |Generate Options:""".stripMargin)
-
-      descr("Generate C code from a DFDL schema")
+    // Takes language by name so we can pass it to scallop.Subcommand and interpolate it
+    // into strings without getting a puzzling java.lang.ClassCastException at runtime (class
+    // scala.collection.mutable.WrappedArray$ofRef cannot be cast to class java.lang.String)
+    class LanguageConf(languageArg: => String) extends scallop.Subcommand(languageArg) {
+      val language = languageArg
+
+      banner(s"""|Usage: daffodil generate $language -s <schema> [-r <root>]
+                 |                              [-c <file>] [-T<tunable>=<value>...]
+                 |                              [outdir]
+                 |
+                 |Generate ${language.toUpperCase} code from a DFDL schema to parse or unparse data

Review Comment:
   Thoughts on making `val language = languageArg.toUpperCase` and then just using `language` in the banner/options?
   
   That way if we ever support languages where the language name isn't as simple as the upper cased command then they can override it, e.g.:
   
   ```scala
   object rust extends LanguageConf("rust") {
     override val language = "Rust"
   }
   
   object rust extends LanguageConf("cpp") {
     override val language = "C++"
   } 
   
   object rust extends LanguageConf("csharp") {
     override val language = "C#"
   }
   ```



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