JShell: three small proposal/feedback

[Robert Field]

Thank you Yuji!

Comments inline.

On 04/04/16 03:33, KUBOTA Yuji wrote:
> Hi REPL team,
>
> I enjoyed debugging by using very good REPL - JShell.
> And I would like to add following (small) changes for usability.
>
> 1. /edit display warn instead of quit by HeadlessException in headless mode
>
> Unfortunately, I did not think the default editor uses swing, so I got
> HeadlessException when I used /edit on a headless server, then
> my working log has gone. So I want that JShell warn instead of
> suddenly quit, as [1].

That would be good.

>
> 2. /-n return the available range rather than calculated "n"
>
> Just to avoid small confusion as below.
>
> Example:
> -> /-9
> |  Cannot find snippet 0 ( - current implementation)
> |  Cannot find snippet, select <n> between 1 - 8  ( - proposal [2])

How would this be useful to you?  I'm thinking there might be a more 
intuitive approach.

>
> 3. Implement /show command to confirm the current configuration
>
> We can set configuration, but cannot check current configuration
> except defined feedback modes by /help /set feedback.
> Should we provide /show command for easy check as below?
>
> Example for feedback mode:
> -> /set newmode test
> |  Created new feedback mode: test
>
> -> /show feedback
> |  Currently feedback mode: normal
> |  All defined feedback mode: normal, test, off

Indeed, some kind of query for configuration is needed.  However start 
can be big (though that can be saved), and format can be huge.  How 
would prompt be displayed?

>
>
> If they accepted, I want to file them to JBS and to upload webrev when ready.
> note: I'm jdk9 author, not committer.

Certainly file the first one.  I'm about to push internationalization of 
the JShell, so that will change anything with output.

Let's kick the other two around a bit more.

Thanks,
Robert

>
> Thanks!
> Yuji
>
> [1]: patch for /edit
> diff --git a/src/jdk.jshell/share/classes/jdk/internal/jshell/tool/JShellTool.java
> b/src/jdk.jshell/share/classes/jdk/internal/jshell/tool/JShellTool.java
> --- a/src/jdk.jshell/share/classes/jdk/internal/jshell/tool/JShellTool.java
> +++ b/src/jdk.jshell/share/classes/jdk/internal/jshell/tool/JShellTool.java
> @@ -1523,7 +1585,11 @@
>           Consumer<String> saveHandler = new SaveHandler(src, srcSet);
>           Consumer<String> errorHandler = s -> hard("Edit Error: %s", s);
>           if (editor == null) {
> -            EditPad.edit(errorHandler, src, saveHandler);
> +            try {
> +                EditPad.edit(errorHandler, src, saveHandler);
> +            } catch (HeadlessException ex) {
> +               hard("Cannot launch editor in headless mode. Try /set
> editor to use external editor.");
> +            }
>           } else {
>               ExternalEditor.edit(editor, errorHandler, src, saveHandler, input);
>           }
>
> [2]: patch for /-n
> diff --git a/src/jdk.jshell/share/classes/jdk/internal/jshell/tool/JShellTool.java
> b/src/jdk.jshell/share/classes/jdk/internal/jshell/tool/JShellTool.java
> --- a/src/jdk.jshell/share/classes/jdk/internal/jshell/tool/JShellTool.java
> +++ b/src/jdk.jshell/share/classes/jdk/internal/jshell/tool/JShellTool.java
> @@ -1777,7 +1843,7 @@
>           if (index >= 0 && index < keys.size()) {
>               rerunSnippet(keys.get(index));
>           } else {
> -            hard("Cannot find snippet %d", index + 1);
> +            hard("Cannot find snippet, select <n> between 1 - %d",
> keys.size());
>               return false;
>           }
>           return true;