Draft JEP: Launch Single-File Source-Code Programs (original) (raw)

Jonathan Gibbons jonathan.gibbons at oracle.com
Sat Feb 10 16:59:31 UTC 2018

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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