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Posted to dev@groovy.apache.org by 孙 岚 <re...@hotmail.com> on 2016/10/29 02:24:25 UTC
An issue about comparing arrays
Hi all,
I found "new int[2]" is equal to "new int[2][]". It is a bug or feature?
Cheers,
Daniel.Sun
Re: An issue about comparing arrays
Posted by "Daniel.Sun" <re...@hotmail.com>.
I see, it is Groovy's friendly behavior.
Thank you, Paul.
Cheers,
Daniel.Sun
在 "paulk_asert [via Groovy]" <ml...@n5.nabble.com>，2016年11月3日 下午2:43写道：
We just have to be a little careful. Rightly or wrongly (search the mailing lists for many discussions), current Groovy's '==' tries to do 'friendly coercion' between types to try to give a business domain friendly meaning to equality:
String[] one = ['a', 'b', 'c']
List<String> two = ['a', 'b', 'c']
assert one.class != two.class
assert one == two
int[] ints = [1, 2]
long[] longs = [1L, 2L]
assert ints == longs
So as long as we can tell that we have two things that can't possibly be equal, then we should return false.
Cheers, Paul.
On Thu, Nov 3, 2016 at 11:38 AM, Daniel.Sun <[hidden email]> wrote:
I verified the comparing of Java, which will check the type first. e.g.
new int[2][][].equals(new int[2][]) // false
new int[2].equals(new long[2]) // false
Cheers,
Daniel.Sun
在 "bo zhang [via Groovy]" <ml-node+[hidden email]>，2016年11月3日 上午9:24写道：
Yes, that's my first instinct too, but a few minutes later I found test cases as follows:
assert [[[5, 6], [7, 8]]] as int[][][] == [[[5, 6], [7, 8]]] as Long[][][]
See https://github.com/groovy/groovy-core/blob/master/src/test/groovy/ArrayTest.groovy#L207
I think this issue can be discussed, anybody has opinions?
2016-11-03 7:51 GMT+08:00 Daniel.Sun <[hidden email]>:
IMO, we should compare their type first. If not same, the comparing result should be 'false'.
Cheers,
Daniel.Sun
在 "bo zhang [via Groovy]" <ml-node+[hidden email]>，2016年11月3日 06:53写道：
I'm afraid it's not a bug.
Actually, `def a=new int[2][]` means that a is an array of two null pointers with type "int []", and `def b=new int[2][][]` means that b is an array of two null pointers with type "int[][]", it seems that they should be equal.
See https://github.com/groovy/groovy-core/blob/master/src/test/groovy/ArrayTest.groovy#L198
[http://groovy.329449.n5.nabble.com/attachment/5736458/0/QQ20161103-0%402x.png]
2016-10-30 18:50 GMT+08:00 Daniel.Sun <[hidden email]>:
Hi Jochen,
I create JIRA issue
GROOVY-7983(https://issues.apache.org/jira/browse/GROOVY-7983) to track the
issue.
BTW, the code in the email should be corrected as follow:
def a = new int[2][]
def b = new int[2][][]
assert a == b // expect faling
Cheers,
Daniel.Sun
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Re: An issue about comparing arrays
Posted by Paul King <pa...@asert.com.au>.
We just have to be a little careful. Rightly or wrongly (search the mailing
lists for many discussions), current Groovy's '==' tries to do 'friendly
coercion' between types to try to give a business domain friendly meaning
to equality:
String[] one = ['a', 'b', 'c']
List<String> two = ['a', 'b', 'c']
assert one.class != two.class
assert one == two
int[] ints = [1, 2]
long[] longs = [1L, 2L]
assert ints == longs
So as long as we can tell that we have two things that can't possibly be
equal, then we should return false.
Cheers, Paul.
On Thu, Nov 3, 2016 at 11:38 AM, Daniel.Sun <re...@hotmail.com> wrote:
> I verified the comparing of Java, which will check the type first. e.g.
>
> new int[2][][].equals(new int[2][]) // false
> new int[2].equals(new long[2]) // false
>
> Cheers,
> Daniel.Sun
>
>
>
> 在 "bo zhang [via Groovy]" <ml-node+[hidden email]
> <http:///user/SendEmail.jtp?type=node&node=5736462&i=0>>，2016年11月3日
> 上午9:24写道：
>
> Yes, that's my first instinct too, but a few minutes later I found test
> cases as follows:
>
> assert [[[5, 6], [7, 8]]] as int[][][] == [[[5, 6], [7, 8]]] as Long[][][]
>
> See https://github.com/groovy/groovy-core/blob/master/src/
> test/groovy/ArrayTest.groovy#L207
>
> I think this issue can be discussed, anybody has opinions?
>
> 2016-11-03 7:51 GMT+08:00 Daniel.Sun <[hidden email]>:
>
>> IMO, we should compare their type first. If not same, the comparing
>> result should be 'false'.
>>
>> Cheers,
>> Daniel.Sun
>>
>>
>>
>> 在 "bo zhang [via Groovy]" <ml-node+[hidden email]>，2016年11月3日 06:53写道：
>>
>> I'm afraid it's not a bug.
>>
>> Actually, `def a=new int[2][]` means that a is an array of two null
>> pointers with type "int []", and `def b=new int[2][][]` means that b is an
>> array of two null pointers with type "int[][]", it seems that they should
>> be equal.
>>
>> See https://github.com/groovy/groovy-core/blob/master/src/
>> test/groovy/ArrayTest.groovy#L198
>>
>>
>>
>>
>> 2016-10-30 18:50 GMT+08:00 Daniel.Sun <[hidden email]>:
>>
>>> Hi Jochen,
>>>
>>> I create JIRA issue
>>> GROOVY-7983(https://issues.apache.org/jira/browse/GROOVY-7983) to track
>>> the
>>> issue.
>>>
>>> BTW, the code in the email should be corrected as follow:
>>>
>>> def a = new int[2][]
>>> def b = new int[2][][]
>>> assert a == b // expect faling
>>>
>>> Cheers,
>>> Daniel.Sun
>>>
>>>
>>>
>>> --
>>> View this message in context: http://groovy.329449.n5.
>>> nabble.com/An-issue-about-comparing-arrays-tp5736379p5736398.html
>>> Sent from the Groovy Dev mailing list archive at Nabble.com.
>>>
>>
>>
>>
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Re: An issue about comparing arrays
Posted by "Daniel.Sun" <re...@hotmail.com>.
I verified the comparing of Java, which will check the type first. e.g.
new int[2][][].equals(new int[2][]) // false
new int[2].equals(new long[2]) // false
Cheers,
Daniel.Sun
在 "bo zhang [via Groovy]" <ml...@n5.nabble.com>，2016年11月3日 上午9:24写道：
Yes, that's my first instinct too, but a few minutes later I found test cases as follows:
assert [[[5, 6], [7, 8]]] as int[][][] == [[[5, 6], [7, 8]]] as Long[][][]
See https://github.com/groovy/groovy-core/blob/master/src/test/groovy/ArrayTest.groovy#L207
I think this issue can be discussed, anybody has opinions?
2016-11-03 7:51 GMT+08:00 Daniel.Sun <[hidden email]>:
IMO, we should compare their type first. If not same, the comparing result should be 'false'.
Cheers,
Daniel.Sun
在 "bo zhang [via Groovy]" <ml-node+[hidden email]>，2016年11月3日 06:53写道：
I'm afraid it's not a bug.
Actually, `def a=new int[2][]` means that a is an array of two null pointers with type "int []", and `def b=new int[2][][]` means that b is an array of two null pointers with type "int[][]", it seems that they should be equal.
See https://github.com/groovy/groovy-core/blob/master/src/test/groovy/ArrayTest.groovy#L198
[http://groovy.329449.n5.nabble.com/attachment/5736458/0/QQ20161103-0%402x.png]
2016-10-30 18:50 GMT+08:00 Daniel.Sun <[hidden email]>:
Hi Jochen,
I create JIRA issue
GROOVY-7983(https://issues.apache.org/jira/browse/GROOVY-7983) to track the
issue.
BTW, the code in the email should be corrected as follow:
def a = new int[2][]
def b = new int[2][][]
assert a == b // expect faling
Cheers,
Daniel.Sun
--
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Re: An issue about comparing arrays
Posted by bo zhang <zh...@gmail.com>.
Yes, that's my first instinct too, but a few minutes later I found test
cases as follows:
assert [[[5, 6], [7, 8]]] as int[][][] == [[[5, 6], [7, 8]]] as Long[][][]
See
https://github.com/groovy/groovy-core/blob/master/src/test/groovy/ArrayTest.groovy#L207
I think this issue can be discussed, anybody has opinions?
2016-11-03 7:51 GMT+08:00 Daniel.Sun <re...@hotmail.com>:
> IMO, we should compare their type first. If not same, the comparing result
> should be 'false'.
>
> Cheers,
> Daniel.Sun
>
>
>
> 在 "bo zhang [via Groovy]" <ml-node+[hidden email]
> <http:///user/SendEmail.jtp?type=node&node=5736460&i=0>>，2016年11月3日
> 06:53写道：
>
> I'm afraid it's not a bug.
>
> Actually, `def a=new int[2][]` means that a is an array of two null
> pointers with type "int []", and `def b=new int[2][][]` means that b is an
> array of two null pointers with type "int[][]", it seems that they should
> be equal.
>
> See https://github.com/groovy/groovy-core/blob/master/src/
> test/groovy/ArrayTest.groovy#L198
>
>
>
>
> 2016-10-30 18:50 GMT+08:00 Daniel.Sun <[hidden email]>:
>
>> Hi Jochen,
>>
>> I create JIRA issue
>> GROOVY-7983(https://issues.apache.org/jira/browse/GROOVY-7983) to track
>> the
>> issue.
>>
>> BTW, the code in the email should be corrected as follow:
>>
>> def a = new int[2][]
>> def b = new int[2][][]
>> assert a == b // expect faling
>>
>> Cheers,
>> Daniel.Sun
>>
>>
>>
>> --
>> View this message in context: http://groovy.329449.n5.
>> nabble.com/An-issue-about-comparing-arrays-tp5736379p5736398.html
>> Sent from the Groovy Dev mailing list archive at Nabble.com.
>>
>
>
>
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Re: An issue about comparing arrays
Posted by "Daniel.Sun" <re...@hotmail.com>.
IMO, we should compare their type first. If not same, the comparing result should be 'false'.
Cheers,
Daniel.Sun
在 "bo zhang [via Groovy]" <ml...@n5.nabble.com>，2016年11月3日 06:53写道：
I'm afraid it's not a bug.
Actually, `def a=new int[2][]` means that a is an array of two null pointers with type "int []", and `def b=new int[2][][]` means that b is an array of two null pointers with type "int[][]", it seems that they should be equal.
See https://github.com/groovy/groovy-core/blob/master/src/test/groovy/ArrayTest.groovy#L198
[http://groovy.329449.n5.nabble.com/attachment/5736458/0/QQ20161103-0%402x.png]
2016-10-30 18:50 GMT+08:00 Daniel.Sun <[hidden email]>:
Hi Jochen,
I create JIRA issue
GROOVY-7983(https://issues.apache.org/jira/browse/GROOVY-7983) to track the
issue.
BTW, the code in the email should be corrected as follow:
def a = new int[2][]
def b = new int[2][][]
assert a == b // expect faling
Cheers,
Daniel.Sun
--
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Re: An issue about comparing arrays
Posted by bo zhang <zh...@gmail.com>.
I'm afraid it's not a bug.
Actually, `def a=new int[2][]` means that a is an array of two null
pointers with type "int []", and `def b=new int[2][][]` means that b is an
array of two null pointers with type "int[][]", it seems that they should
be equal.
See
https://github.com/groovy/groovy-core/blob/master/src/test/groovy/ArrayTest.groovy#L198
2016-10-30 18:50 GMT+08:00 Daniel.Sun <re...@hotmail.com>:
> Hi Jochen,
>
> I create JIRA issue
> GROOVY-7983(https://issues.apache.org/jira/browse/GROOVY-7983) to track
> the
> issue.
>
> BTW, the code in the email should be corrected as follow:
>
> def a = new int[2][]
> def b = new int[2][][]
> assert a == b // expect faling
>
> Cheers,
> Daniel.Sun
>
>
>
> --
> View this message in context: http://groovy.329449.n5.
> nabble.com/An-issue-about-comparing-arrays-tp5736379p5736398.html
> Sent from the Groovy Dev mailing list archive at Nabble.com.
>
Re: An issue about comparing arrays
Posted by "Daniel.Sun" <re...@hotmail.com>.
Hi Jochen,
I create JIRA issue
GROOVY-7983(https://issues.apache.org/jira/browse/GROOVY-7983) to track the
issue.
BTW, the code in the email should be corrected as follow:
def a = new int[2][]
def b = new int[2][][]
assert a == b // expect faling
Cheers,
Daniel.Sun
--
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Re: An issue about comparing arrays
Posted by Jochen Theodorou <bl...@gmx.org>.
On 29.10.2016 04:24, \u5b59 \u5c9a wrote:
> Hi all,
>
> I found "new int[2]" is equal to "new int[2][]". It is a bug or
> feature?
that looks like a bug to me... not sure if that is legal in Java,but if
I would expect the creation of a 2 elements array of int[] with null values
bye Jochen