[patch] add --init

build.gradle

@@ -19,6 +19,7 @@ dependencies {
  implementation 'com.offbytwo:docopt:0.6.0.20150202'
 
  implementation 'info.picocli:picocli:4.1.4'
+ //implementation 'io.quarkus.qute:qute-core:1.1.0.Final'
 
  implementation("com.jcabi:jcabi-aether:0.10.1") {
  exclude group: "org.hibernate", module: "hibernate-validator"

readme.adoc

@@ -79,6 +79,10 @@ chmod +x helloworld.java
 There are experimental support to run `.jsh` via `jshell`. The advantage of `jshell` is that you do not need to have a class or static main method, downside is that
 at least for now you have no way to read the command line arguments.
 
+## Getting started
+
+To get started you can run `jbang --init helloworld.java` and a simple java class with a static main is generated.
+
 ## Declare dependencies with `//DEPS`
 
 If you want to write real scripts you will want to use some java libraries.

src/main/java/dk/xam/jbang/ExitException.java

@@ -11,6 +11,11 @@ public ExitException(int status) {
  this.status = status;
  }
 
+ public ExitException(int status, Exception cause) {
+ super(cause);
+ this.status = status;
+ }
+
  public int getStatus() {
  return status;
  }

src/main/java/dk/xam/jbang/Main.java

@@ -3,9 +3,8 @@
 import static java.lang.System.*;
 import static picocli.CommandLine.*;
 
-import java.io.File;
-import java.io.FileNotFoundException;
-import java.io.PrintWriter;
+import java.io.*;
+import java.nio.file.Files;
 import java.util.*;
 import java.util.concurrent.Callable;
 import java.util.stream.Collectors;
@@ -34,6 +33,9 @@ public class Main implements Callable<Integer> {
  @Parameters(index = "1..*", arity = "0..*", description = "Parameters to pass on to the script")
  List<String> params = new ArrayList<String>();
 
+ @Option(names = {"--init"}, description = "Init script with a java class useful for scripting.")
+ boolean initScript;
+
  void info(String msg) {
  spec.commandLine().getErr().println(msg);
  }
@@ -65,7 +67,7 @@ static CommandLine getCommandLine() {
  }
 
  @Override
- public Integer call() throws FileNotFoundException {
+ public Integer call() throws IOException {
 
  if (helpRequested) {
  spec.commandLine().usage(err);
@@ -75,13 +77,46 @@ public Integer call() throws FileNotFoundException {
  quit(0);
  }
 
- String cmdline = generateCommandLine();
+ if (initScript) {
+ var f = new File(scriptOrFile);
+ if (f.exists()) {
+ warn("File " + f + " already exists. Will not initialize.");
+ } else {
+ // Use try-with-resource to get auto-closeable writer instance
+ try (BufferedWriter writer = Files.newBufferedWriter(f.toPath())) {
+ String result = renderInitClass(f);
+ writer.write(result);
+ }
+ }
 
- out.println(cmdline);
+ } else {
+ String cmdline = generateCommandLine();
 
+ out.println(cmdline);
+ }
  return 0;
  }
 
+ static String initTemplate = "//usr/bin/env jbang \"$0\" \"$@\" ; exit $?\n"
+ + "// //DEPS <dependency1> <dependency2>\n" + "\n" + "import static java.lang.System.*;\n" + "\n"
+ + "public class {className} {\n" + "\n" + " public static void main(String... args) {\n"
+ + " out.println(\"Hello World\");\n" + " }\n" + "}";
+
+ String renderInitClass(File f) {
+
+ return initTemplate.replace("{className}", getBaseName(f.getName()));
+
+ }
+
+ public static String getBaseName(String fileName) {
+ int index = fileName.lastIndexOf('.');
+ if (index == -1) {
+ return fileName;
+ } else {
+ return fileName.substring(0, index);
+ }
+ }
+
  String generateCommandLine() throws FileNotFoundException {
  prepareScript = prepareScript(scriptOrFile);
 

src/test/java/dk/xam/jbang/TestInit.java

@@ -0,0 +1,22 @@
+package dk.xam.jbang;
+
+import static org.hamcrest.MatcherAssert.assertThat;
+import static org.hamcrest.Matchers.*;
+
+import java.io.File;
+
+import org.junit.jupiter.api.Test;
+
+public class TestInit {
+
+ @Test
+ void testInit() {
+
+ var m = new Main();
+
+ String s = m.renderInitClass(new File("test.java"));
+
+ assertThat(s, not(containsString("NOT_FOUND")));
+
+ }
+}

src/test/java/dk/xam/jbang/TestMain.java

@@ -86,6 +86,6 @@ void testDependencies() throws FileNotFoundException {
  assertThat(result, not(containsString(" ")));
  assertThat(result, containsString("classpath"));
  assertThat(result, containsString("log4j"));
- }
+ } 
 
 }