[jira] [Updated] (GROOVY-8857) Add various 'object != null' syntactic sugar operators.

["Eric Holley (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/GROOVY-8857?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Eric Holley updated GROOVY-8857:
--------------------------------
    Description: 
The Elvis operator is great in that is simplifies your code and makes it easier to read. The problem is that when the referenced object is a String or Number, and you want to use a default value when the object is null, unintended results can occurs due to the null String and zero being false in Groovy truth. I find myself have to frequently use more syntactically complex code due this the issue.

My proposal is to introduce some new operators to Groovy to address this:

The first would be variation of the Elvis operator '??:' that would work just like  '?:' except that the test for truth would always be 'is the referenced object null'. So, for example:
{code:java}
def xyz = abc ??: 'default'{code}
  would be compiled as:
{code:java}
def xyz = abc != null ? abc : 'default' {code}
The second would be a unary '?' operator that would look like:
{code:java}
if (?abc) {
   // Do something if abc is not equal null.
}{code}
which would be compiled as:
{code:java}
if (abc != null) {
   // Do something if abc is not equal null.
}{code}
The third would be the non-null Elvis assignment operator:
{code:java}
a ??= 'default'{code}
which would compile as:
{code:java}
a = a != null ? a : 'default'{code}
This class of operators could be referred to as the 'non-null' operators. I think that they would be a good addition to the new 3.x operators.

  was:
The Elvis operator is great in that is simplifies your code and makes it easier to read. The problem is that when the referenced object is a String or Number, and you want to use a default value when the object is null, unintended results can occurs due to the null String and zero being false in Groovy truth. I find myself have to frequently use more syntactically complex code due this the issue.

My proposal is to introduce some new operators to Groovy to address this:

The first would be variation of the Elvis operator '??:' that would work just like  '?:' except that the test for truth would always be 'is the referenced object null'. So, for example:

 
{code:java}
def xyz = abc ??: 'default'{code}
  would be compiled as:

 

 
{code:java}
def xyz = abc != null ? abc : 'default'{code}
 

The second would be a unary '?' operator that would look like:

 
{code:java}
if (?abc) {
   // Do something if abc is not equal null.
}{code}
which would be compiled as:
{code:java}
if (abc != null) {
   // Do something if abc is not equal null.
}{code}
The third would be the non-null Elvis assignment operator:
{code:java}
a ??= 'default'{code}
which would compile as:
{code:java}
a = a != null ? a : 'default'{code}
This class of operators could be referred to as the 'non-null' operators. I think that they would be a good addition to the new 3.x operators.

 

 


> Add various 'object != null' syntactic sugar operators.
> -------------------------------------------------------
>
>                 Key: GROOVY-8857
>                 URL: https://issues.apache.org/jira/browse/GROOVY-8857
>             Project: Groovy
>          Issue Type: Improvement
>          Components: Compiler
>    Affects Versions: 3.x
>            Reporter: Eric Holley
>            Priority: Minor
>
> The Elvis operator is great in that is simplifies your code and makes it easier to read. The problem is that when the referenced object is a String or Number, and you want to use a default value when the object is null, unintended results can occurs due to the null String and zero being false in Groovy truth. I find myself have to frequently use more syntactically complex code due this the issue.
> My proposal is to introduce some new operators to Groovy to address this:
> The first would be variation of the Elvis operator '??:' that would work just like  '?:' except that the test for truth would always be 'is the referenced object null'. So, for example:
> {code:java}
> def xyz = abc ??: 'default'{code}
>   would be compiled as:
> {code:java}
> def xyz = abc != null ? abc : 'default' {code}
> The second would be a unary '?' operator that would look like:
> {code:java}
> if (?abc) {
>    // Do something if abc is not equal null.
> }{code}
> which would be compiled as:
> {code:java}
> if (abc != null) {
>    // Do something if abc is not equal null.
> }{code}
> The third would be the non-null Elvis assignment operator:
> {code:java}
> a ??= 'default'{code}
> which would compile as:
> {code:java}
> a = a != null ? a : 'default'{code}
> This class of operators could be referred to as the 'non-null' operators. I think that they would be a good addition to the new 3.x operators.



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