[Laszlo-dev] For Review: Change 20081021-dda-p Summary: Add return type declarations to SWF9

Tue Oct 21 09:20:52 PDT 2008

If a function's return type is Number, you must not return ?undefined?:
- either remove the return type
- or return ?NaN?
(Because AS3 coerces ?undefined? automatically to ?NaN?. By returning 
'undefined', we'll get different behaviour across runtimes.)
For example LzAudio#getVolume(), LzAudio#getPan() and the counterparts 
in LzView.

I guess it's the same with Boolean. So if the return type is Boolean, 
returning 'undefined' will produce different behaviour across runtimes.
For example in LzAnimatorGroup/LzAnimator#update(), #checkRepeat() you 
can safely return ?false?.

On 10/21/2008 5:45 PM, André Bargull wrote:
> Was it already decided how to declare return types in LZX? So, how to 
> name the attribute which specifies the type? It's now named "type", 
> any other proposals? Like "return" or "returns"?
> Any cast needs to be: "foo cast Bar", "Bar(foo)" is only available in 
> plain AS3 code, in cross-runtime code the latter form is a function 
> call. (That's why DHTML broke for you.)
>
> We should consider to drop the lowercase "type"-declarations for 
> <attribute> and instead prefer the JavaScript alternatives, because 
> you need to use the Javascript-form anywhere else (typing for function 
> arguments, variables, function return types).
>
>
>> Change 20081021-dda-p by dda at lester.local 
>> <http://www.openlaszlo.org/mailman/listinfo/laszlo-dev> on 2008-10-21 
>> 10:03:53 EDT
>> in /Users/dda/laszlo/src/svn/openlaszlo/trunk-a
>> for http://svn.openlaszlo.org/openlaszlo/trunk
>>
>> Summary: Add return type declarations to SWF9
>>
>> New Features:
>>
>> Bugs Fixed: LPP-7031 (swf9 back-end is dropping return type 
>> declarations)
>>
>> Technical Reviewer: ptw (pending)
>> QA Reviewer: promanik (pending)
>> Doc Reviewer: (pending)
>>
>> Documentation:
>>
>> Release Notes:
>>
>> Details:
>>
>> WEB-INF/lps/server/src/org/openlaszlo/sc/ParseTreePrinter.java
>> WEB-INF/lps/server/src/org/openlaszlo/sc/SWF9ParseTreePrinter.java
>>
>> Explicit return types like Boolean in 'function foo () : Boolean { }' 
>> were
>> not being emitted by the SWF9 backend. The fix was straightforward,
>> the fallout was not...
>>
>>
>> WEB-INF/lps/server/src/org/openlaszlo/compiler/NodeModel.java
>> WEB-INF/lps/server/src/org/openlaszlo/sc/Method.java
>> WEB-INF/lps/server/src/org/openlaszlo/sc/Function.java
>>
>> Added a "type" attribute to <method> to set the return type.
>> This was needed to get a few cases where lzx code overrides LFC 
>> functions (now with return typing!)
>> to compile. This type must be 'Javascript' (i.e. Boolean, not 
>> 'boolean' is used).
>> Some cleanup to reduce the number of constructors for Method/ 
>> Function. I think
>> this makes the code a bit clearer.
>>
>> lps/components/base/datalistselector.lzx
>> lps/components/base/listselector.lzx
>> demos/lzpix/app.lzx
>>
>> Added type="Boolean" to a few methods that override to allow them to 
>> compile and
>> run in SWF9.
>>
>>
>> Fixing return typing exposed a lot of 'new' typing in LFC and some in 
>> application code,
>> which caused various consistency errors in several categories.
>>
>> - in many .lzs files, functions marked as returning a type did not 
>> always
>> explicitly call return, or when they did they did not return a value.
>> Initially, I tried to make intelligent guesses about values returned 
>> (favoring 'null'),
>> but testing revealed many problems. Ultimately, I needed to be
>> very conservative, returning 'undefined' in most cases, and false
>> for Boolean functions. This seems to be the default behavior for JS
>> when returns are missing values. Cases that seemed most questionable
>> I marked with:
>> TODO: [20081020 dda] review this return value change from LPP-7031
>>
>>
>> - in several .lzs files, functions marked as override did not always 
>> match return types.
>>
>>
>> - in several .lzs files, toString() is marked as :String, but in 
>> others it is not.
>> For the moment, it was too big of a job to fix all these as part of 
>> this (already
>> large) commit, so typing for this function was commented whenever a
>> compile error showed a mismatch.
>>
>>
>> - in several .lzs files, functions with new typing returned a value 
>> but without proper typing.
>> Type casting was added as appropriate.
>>
>>
>> WEB-INF/lps/lfc/kernel/swf9/LzMouseKernel.as:
>>
>> - type of a local variable wasn't narrowly typed enough, leading to
>> errors in return statements.
>>
>>
>> WEB-INF/lps/lfc/debugger/LzDebug.lzs:
>>
>> - __StringDescription() needed to be defined with exactly the same 
>> argument signature
>> I don't know why return typing exposed this as a problem.
>>
>>
>> WEB-INF/lps/lfc/data/LzLazyReplicationManager.lzs:
>>
>> - Certain local variables typed as LzView needed typing commented. 
>> Initial attempts
>> to fix the typing errors in this file involved casting, e.g.
>> var v:LzView = LzView(this.getNewClone( true ));
>> But these changes broke smokecheck for DHTML. It seems that some 
>> assumption
>> about typing is being violated and will need to be tracked down later.
>> I commented out the typing for the local variables, and left TODOs to 
>> clean
>> this up later.
>>
>>
>> Note that the compile errors fixed here only show up when building 
>> the LFC (or app) for SWF9.
>> In debugging these problems it was most helpful to build the debuglfc 
>> to get line number information.
>>
>> Tests:
>> tests: (smokecheck) * (swf8+dhtml)
>> apps: (weather+lzpix) * (swf8+swf9+dhtml), hello(swf9)
>>
>> Files:
>> M WEB-INF/lps/lfc/kernel/swf9/LFCApplication.as
>> M WEB-INF/lps/lfc/kernel/swf9/LzMouseKernel.as
>> M WEB-INF/lps/lfc/services/LzAudio.lzs
>> M WEB-INF/lps/lfc/debugger/LzDebug.lzs
>> M WEB-INF/lps/lfc/debugger/platform/swf9/LzFlashRemote.as
>> M WEB-INF/lps/lfc/debugger/platform/swf9/LzDebug.as
>> M WEB-INF/lps/lfc/views/LaszloView.lzs
>> M WEB-INF/lps/lfc/controllers/LzAnimatorGroup.lzs
>> M WEB-INF/lps/lfc/controllers/LaszloAnimation.lzs
>> M WEB-INF/lps/lfc/data/LzLazyReplicationManager.lzs
>> M WEB-INF/lps/lfc/data/LzReplicationManager.lzs
>> M WEB-INF/lps/lfc/data/LzDatapointer.lzs
>> M WEB-INF/lps/lfc/data/LzDataText.lzs
>> M WEB-INF/lps/lfc/data/LzDataNode.lzs
>> M WEB-INF/lps/lfc/data/LzDataElement.lzs
>> M WEB-INF/lps/lfc/data/LzDatapath.lzs
>> M WEB-INF/lps/lfc/data/LzResizeReplicationManager.lzs
>> M WEB-INF/lps/lfc/data/LzParam.lzs
>> M WEB-INF/lps/lfc/data/LzDataAttrBind.lzs
>> M WEB-INF/lps/lfc/compiler/LzBootstrapDebugService.lzs
>> M WEB-INF/lps/server/src/org/openlaszlo/sc/Method.java
>> M WEB-INF/lps/server/src/org/openlaszlo/sc/ SWF9ParseTreePrinter.java
>> M WEB-INF/lps/server/src/org/openlaszlo/sc/Function.java
>> M WEB-INF/lps/server/src/org/openlaszlo/sc/ParseTreePrinter.java
>> M WEB-INF/lps/server/src/org/openlaszlo/compiler/NodeModel.java
>> M lps/components/base/datalistselector.lzx
>> M lps/components/base/listselector.lzx
>> M demos/lzpix/app.lzx
>>
>> Changeset: 
>> http://svn.openlaszlo.org/openlaszlo/patches/20081021-dda-p.tar
>>
>>
>>
>> -- 
>>
>> Don Anderson
>> Java/C/C++, Berkeley DB, systems consultant
>>
>> voice: 617-547-7881
>> email: dda at ddanderson.com 
>> <http://www.openlaszlo.org/mailman/listinfo/laszlo-dev>
>> www: http://www.ddanderson.com
>
>