Draft JEP: Launch Single-File Source-Code Programs

Roger Riggs Roger.Riggs at Oracle.com
Mon Feb 12 14:22:40 UTC 2018

Hi Jonathan,

It would be  a great convenience to developers to NOT to have two types 
of java source files.
Those that can be run directly and those that cannot. According to the 
JLS, the former can not
be called java source files, they are something else.

$.02, Roger

On 2/10/2018 11:59 AM, Jonathan Gibbons wrote:
> Volker,
> I don't see a compelling need to change the JLS to accommodate 
> "shebang" files. Most Java source files don't need the `#!` line, 
> including any source file passed to an explicit invocation of the Java 
> launcher. The line is only needed when the file is set up to be 
> directly executed by the "shebang" mechanism, in which case the line 
> can be thought of as a "wrapper" supported by the host system to 
> enable such use. If the feature is sufficiently popular, it may even 
> be that editors will recognize and support the use of such lines, in 
> the same way that some editors recognize and support the manipulation 
> of javadoc comments, which are also not defined in the JLS (beyond the 
> basic definition of a comment in JLS 3.7).
> -- Jon
> On 2/9/18 2:51 AM, Volker Simonis wrote:
>> Hi Jonathan,
>> that's an interesting proposal. It is just unfortunate that a Java
>> source file starting with "shebang" won't be a legal Java file
>> according to the Java Language Specification. Or do you plan to change
>> the JLS to allow (and ignore) "shebang" in the first line?
>> Thanks,
>> Volker
>> On Fri, Feb 9, 2018 at 12:18 AM, Jonathan Gibbons
>> <jonathan.gibbons at oracle.com> wrote:
>>> This draft JEP contains a proposal to enhance the java launcher to 
>>> support
>>> running a
>>> program supplied as a single file of Java source code. The program 
>>> will be
>>> compiled
>>> and run, without the need to explicit invoke javac, or to package up 
>>> a jar
>>> file.
>>> For more details, see:
>>> http://openjdk.java.net/jeps/8192920
>>> -- Jon

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