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Bug 370232

Summary:	Casts don't appear to coerce closures
Product:	[Tools] Xtend	Reporter:	William R. Burdick Jr. <bill>
Component:	Core	Assignee:	Project Inbox <xtend-inbox>
Status:	NEW ---	QA Contact:
Severity:	enhancement
Priority:	P3	CC:	dennis.huebner, moritz.eysholdt, sebastian.zarnekow, sven.efftinge
Version:	2.3.0
Target Milestone:	---
Hardware:	All
OS:	All
Whiteboard:
Bug Depends on:	376037
Bug Blocks:

Description William R. Burdick Jr.

2012-01-31 10:43:04 EST

Build Identifier: 

Closures don't get type information from a cast.

This works:

var Function<Integer,Integer> s = [x|x * 2]


but this doesn't:

var s = [x|x * 2] as Function<Integer,Integer>

Reproducible: Always

Steps to Reproduce:
1. try to compile this declaraion:

var s = [x|x * 2] as Function<Integer,Integer>

Comment 1 Sven Efftinge

2012-01-31 11:04:03 EST

*** Bug 370173 has been marked as a duplicate of this bug. ***

Comment 2 Sven Efftinge

2012-01-31 11:05:10 EST

Casts are generally not used in expected type inference. See also : http://groups.google.com/group/xtend-lang/browse_thread/thread/63a2181439fef757

Comment 3 William R. Burdick Jr.

2012-02-01 12:02:20 EST

This becomes more important when closures can coerce to abstract classes, because you may have several abstract classes implementing the same interface.

With your patch to allow casts to work for this, I can now choose an abstract class by casting a literal closure.  I have a closure-compatible abstract class (given my patch), called SimpleSelectionAdapter, that implements SWT's SelectionListener interface and leaves only widgetSelected() abstract and I can use a closure for it, like this:


menuItem.addSelectionListener([e|...] as SimpleSelectionAdapter)


If the cast doesn't work, I need to declare a new variable for this, which seems counter to Xtend's focus on programmer convenience.

Comment 4 Sven Efftinge

2012-04-04 02:25:16 EDT

Something we should look at while reworking the linking / type system

Comment 5 Dennis Huebner

2013-02-14 04:35:44 EST

Is an enhancement.

Comment 6 Sebastian Zarnekow

2013-03-12 09:06:19 EDT

see also bug 403032

Comment 7 Sven Efftinge

2013-03-12 09:07:07 EDT

*** Bug 403032 has been marked as a duplicate of this bug. ***