[Laszlo-dev] For Review: Change 20071107-dda-g Summary: Allow type information for vars, even though ignored in SWF7/8 and DHTML.

[Donald Anderson]

Hi Phil,

I agree with you - that case I think is nonsensical.  I was going to  
get some more wisdom
by experimenting with the flex compiler, but it doesn't support !  
or ? in types.
At all - syntax error.  These cases are shown in the ECMAScript 4
Language Overview final draft, but that's not a standard yet, so maybe
nobody is implementing it.

BTW, there will be many other cases in this area that we cannot catch  
in the grammar,
like basic type snafus:

    var v_typed_q:int = "hello";

and is this:

    var v:int! = 1;

even valid?  (A primitive type like int may not accept nullability -  
it wouldn't make sense in Java).
My first temptation is to accept any such cases in our grammar and  
let the backend compiler flag them
as errors for us.

But given that the language feature isn't in flex, I'm not sure what  
to do, leave '!' '?'
in for a future day, or take them out.  ?!

Tucker - opinion on this?  Am I wrong to be looking at the ECMAScript  
4 overview?

- Don


On Nov 7, 2007, at 8:22 PM, Philip Romanik wrote:

> Approved.
>
> If I write this line of code, no error is generated, but it doesn't  
> seem right. Is this legal ecma4?
>
>       var v_typed_q:?int! = 123;
>
>
> (Perhaps somebody else can chime in here. Is /test/lztest still the  
> preferred way to write a unit test? If so, this test can be  
> converted into lztest format.)
>
>
>> Change 20071107-dda-g by dda at freddie.local on 2007-11-07 18:14:27 EST
>>      in /Users/dda/laszlo/src/svn/openlaszlo/trunk
>>      for http://svn.openlaszlo.org/openlaszlo/trunk
>>
>> Summary: Allow type information for vars, even though ignored in
>> SWF7/8 and DHTML.
>>
>> New Features:
>>      Allow type information accepted in ActionScript 3.0, that is:
>>        var x:int;
>>        var y:String = "hello";
>>        var z:?String = null;   // ? means can set to null (default)
>>        var z:String! = "bonjour";   // ! means cannot set to null
>>      Please note that the type information is merely accepted as  
>> part of the language, and ignored for now.
>>
>> Bugs Fixed: LPP-5059
>>
>> Technical Reviewer: ptw
>> QA Reviewer: philip
>> Doc Reviewer: (pending)
>>
>> Documentation:
>>     Requires documentation if we describe in detail our language  
>> (or subset).  If we point
>>     users to the published standards, then we can continue to do  
>> that.
>>     We should note that type information is ignored except for the
>> (upcoming) SWF9 runtime.
>>
>> Release Notes:
>>      Variables declared using the 'var' statement now allow type  
>> specifications as
>>      described by Ecmascript 4 (that is, ActionScript 3.0).
>>
>> Details:
>>      No type checking is done by the SWF7/8 and DHTML runtimes  
>> (nor is planned), any
>>      type information is thrown away.  However, when SWF9 is  
>> available, the type information
>>      will be accepted and passed through to the 3rd party SWF9  
>> compiler, which will do type
>>      checking for any variable with type information.  This change  
>> allows users and developers
>>      to write code that can be useful with either runtime.  Even  
>> if they don't use with SWF9,
>>      this is a useful feature for self documenting usage of  
>> variables.
>>
>>      We currently allow type information on 'var' declarations,  
>> also method parameters and
>>      method return values.  I believe only information for 'var'
>> declarations can be done
>>      in .lzx, but the latter two are also accepted (and ignored  
>> for current runtimes) in .lzs files.
>>
>> Tests:
>>      Ran new test test/typevar.lzx for both SWF7/8 and DHTML, to  
>> make sure syntax is accepted.
>>      Ran smokecheck.lzx to assure there are no regressions.
>>
>> Files:
>> A      test/typevar.lzx
>> M      WEB-INF/lps/server/sc/src/org/openlaszlo/sc/Parser.jjt
>> M      WEB-INF/lps/server/sc/src/org/openlaszlo/sc/parser/
>> ASTIdentifier.java
>>
>> Changeset: http://svn.openlaszlo.org/openlaszlo/patches/20071107-dda-
>> g.tar
>>
>>
>>
>> --
>>
>> Don Anderson
>> Java/C/C++, Berkeley DB, systems consultant
>>
>> Voice:  617-547-7881
>> Email:  dda at ddanderson.com
>> WWW:    http://www.ddanderson.com
>>


--

Don Anderson
Java/C/C++, Berkeley DB, systems consultant

Voice:  617-547-7881
Email:  dda at ddanderson.com
WWW:    http://www.ddanderson.com

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