Local Variable Type Inference - prototype

[Maurizio Cimadamore]

On 10/03/16 22:55, Robert Field wrote:
>
> On 03/10/16 14:21, Remi Forax wrote:
>> At least, jshell need some tweaks :)
>
> Yes, it will.  Thanks Remi!
>
> It will need the analysis pass of the compiler run so that the type 
> can be determined.  Variables are implemented as fields.
>
> Is this something I should work on now?
One question for you Robert: currently javac does not parse 'var' as a 
special Token - as doing that requires even more jshell changes; I'm 
happy to leave the code as is, but if, when hacking on the jshell side, 
you discover that a VAR token would be useful please let me know.

Maurizio
>
> -Robert
>
>>
>> $ /usr/jdk/jdk-9/bin/java 
>> -Xbootclasspath/p:langtools/dist/lib/jdk.compiler.jar:langtools/dist/lib/jdk.jshell.jar:langtools/dist/lib/jdk.internal.le.jar:langtools/dist/lib/jdk.jdi.jar 
>> jdk.internal.jshell.tool.JShellTool
>> |  Welcome to JShell -- Version 9-internal
>> |  Type /help for help
>>
>> -> void m() {
>>>> var a = 3;
>>>> }
>> |  Added method m()
>>
>> -> m()
>>
>> -> var a = 3;
>> Exception in thread "main" java.lang.StringIndexOutOfBoundsException: 
>> begin -1, end -1, length 10
>>     at java.lang.String.checkBoundsBeginEnd(String.java:3122)
>>     at java.lang.String.substring(String.java:1910)
>>     at jdk.jshell.Wrap$Range.part(Wrap.java:168)
>>     at jdk.jshell.Wrap$RangeWrap.<init>(Wrap.java:350)
>>     at jdk.jshell.Wrap.varWrap(Wrap.java:97)
>>     at jdk.jshell.Eval.processVariables(Eval.java:227)
>>     at jdk.jshell.Eval.eval(Eval.java:116)
>>     at jdk.jshell.JShell.eval(JShell.java:355)
>>     at 
>> jdk.internal.jshell.tool.JShellTool.processCompleteSource(JShellTool.java:1923)
>>     at 
>> jdk.internal.jshell.tool.JShellTool.processSource(JShellTool.java:1911)
>>     at 
>> jdk.internal.jshell.tool.JShellTool.processSourceCatchingReset(JShellTool.java:652)
>>     at jdk.internal.jshell.tool.JShellTool.run(JShellTool.java:632)
>>     at jdk.internal.jshell.tool.JShellTool.start(JShellTool.java:427)
>>     at jdk.internal.jshell.tool.JShellTool.start(JShellTool.java:400)
>>     at jdk.internal.jshell.tool.JShellTool.main(JShellTool.java:390)
>>
>> Rémi
>>
>> ----- Mail original -----
>>> De: "Maurizio Cimadamore" <maurizio.cimadamore at oracle.com>
>>> À: platform-jep-discuss at openjdk.java.net
>>> Envoyé: Jeudi 10 Mars 2016 15:48:25
>>> Objet: Local Variable Type Inference - prototype
>>>
>>> Hi,
>>> I've pushed the first iteration of the local variable type inference
>>> prototype in the sandbox repository[1]. For those willing and brave
>>> enough to experiment, the branch name is "JEP-286-branch". We are also
>>> working to get some ready-made binary snapshots out of the door and 
>>> hope
>>> to have an update on that soon.
>>>
>>> This first iteration supports the 'var-only' syntax style:
>>>
>>> var s = "Hello!";
>>>
>>> That is, the type of 's' is inferred from the initializer, and no
>>> special assumption is made about mutability.
>>>
>>> Please share your experience with the prototype. For comments on this
>>> feature please refer to the survey[2] that Brian posted few days ago.
>>>
>>> Maurizio
>>>
>>> [1] - http://cr.openjdk.java.net/~chegar/docs/sandbox.html
>>> [2] -
>>> http://mail.openjdk.java.net/pipermail/platform-jep-discuss/2016-March/000037.html 
>>>
>>>
>