[remkop#1348] example of hiding specific positional parameters

Author: remkop

picocli-examples/src/main/java/picocli/examples/customhelp/HideSomePositionalParams.java

@@ -0,0 +1,74 @@
+package picocli.examples.customhelp;
+
+import picocli.CommandLine;
+import picocli.CommandLine.Command;
+import picocli.CommandLine.Model.CommandSpec;
+import picocli.CommandLine.Model.PositionalParamSpec;
+import picocli.CommandLine.Parameters;
+
+import java.io.File;
+import java.io.PrintWriter;
+import java.io.StringWriter;
+import java.util.ArrayList;
+import java.util.List;
+
+/**
+ * https://github.com/remkop/picocli/issues/1348
+ */
+@Command(name = "rename")
+public class HideSomePositionalParams {
+
+    static class MyHelpFactory implements CommandLine.IHelpFactory {
+        @Override
+        public CommandLine.Help create(CommandSpec commandSpec, CommandLine.Help.ColorScheme colorScheme) {
+            return new CommandLine.Help(commandSpec, colorScheme) {
+                @Override
+                public String parameterList(List<PositionalParamSpec> positionalParams) {
+                    return super.parameterList(filter(positionalParams));
+                }
+
+                private List<PositionalParamSpec> filter(List<PositionalParamSpec> optionList) {
+                    List<PositionalParamSpec> shown = new ArrayList<PositionalParamSpec>();
+                    for (PositionalParamSpec param : optionList) {
+
+                        // exclude parameters whose type has the IExcluded marker interface
+                        if (!IExcluded.class.isAssignableFrom(param.auxiliaryTypes()[0])) {
+                            shown.add(param);
+                        }
+                    }
+                    return shown;
+                }
+            };
+        }
+    }
+    interface IExcluded {}
+    enum ToKeyword implements IExcluded {to}
+
+    @Parameters(index = "0", description = "File to rename.")
+    File file;
+
+    @Parameters(index = "1", paramLabel = "to")
+    ToKeyword to;
+
+    @Parameters(index = "2", description = "New file name.")
+    File newFile;
+
+    public static void main(String[] args) {
+        StringWriter sw = new StringWriter();
+
+        CommandLine cmd = new CommandLine(new HideSomePositionalParams())
+                .setHelpFactory(new MyHelpFactory())
+                .setErr(new PrintWriter(sw, true));
+        
+        String expected = String.format("" +
+                "Missing required parameters: '<file>', 'to', '<newFile>'%n" +
+                "Usage: rename <file> to <newFile>%n" +
+                "      <file>      File to rename.%n" +
+                "      <newFile>   New file name.%n");
+
+        cmd.execute(); // no args
+        if (!expected.equals(sw.toString())) {
+            throw new IllegalStateException(expected + " != " + sw.toString());
+        }
+    }
+}