[#GROOVY-1150] Strange behavior on property setter - jira.codehaus.org

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Key:	GROOVY-1150
Type:	Bug
Status:	Closed
Resolution:	Fixed
Priority:	Minor
Assignee:	Paul King
Reporter:	Antti Karanta
Votes:	1
Watchers:	2

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groovy

Strange behavior on property setter

Created: 21/Nov/05 06:05 AM Updated: 08/Feb/08 01:26 AM

Component/s:

None

Affects Version/s:

1.0-JSR-3

Fix Version/s:

1.5.2

Time Tracking:

Not Specified

Environment:

Groovy jsr-03, java version "1.5.0_05", winXP

Issue Links:

Duplicate

This issue duplicates:

~~GROOVY-2244~~ Write-only JavaBeans properties cannot be set via the '=' operator

Description

Try this:

class Foo {
  private _xxx

  public void setBar(b) {
    println "before setting"
    _xxx = b
    println "after setting"  
  }
}

def x = new Foo()

x.bar = 1
x.bar = 2

When run, the output is:

C:\Temp>groovy settertest.groovy
before setting
after setting
before setting
after setting
Caught: groovy.lang.GroovyRuntimeException: Cannot read property: bar

even though the property bar was never read. If you add e.g.
println "goodbye"
as the last line of the script, the exception does not occur.

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Jochen Theodorou - 21/Nov/05 08:22 AM

this is a well known issue.
imagine:

def foo() {
x
}

x is returned here

your example is put into a method by groovy. This means x.bar=2 is transformed into:
x.bar=2
return x.bar

so it's no wonder that you will get this error message

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Peter Niederwieser - 12/May/07 03:52 PM

The transformation "x.bar = 2; return x.bar" is incorrect.¹ Instead it should be "return (x.bar = 2)", which would solve this issue.

¹ It's even more likely to have unwanted side-effects when a method is involved, for example in "x.bar().foo = 2".

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Andres Almiray - 27/Nov/07 01:47 PM

FYI this bug is still around.

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Paul King - 06/Jan/08 01:48 AM

This was fixed with ~~GROOVY-2244~~. In fact I think this was a duplcate issue.

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Paul King - 08/Feb/08 01:26 AM

close off release 1.5.4