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https://issues.apache.org/jira/browse/GROOVY-11525?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17903105#comment-17903105
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Jochen Theodorou commented on GROOVY-11525:
-------------------------------------------
[~daniel_sun]
What is the extend of what you are thinking of here? Something like
((Statement;)* Expr). Or only the initializer variants? Only one Statement or
multiple?:
{code:Java}
def <T> swapHeadAndTail(List<T> list) {
return (T h = list[0]; List<T> t=list[1..-1]; [*t, h])
}
{code}
The alternative would be of course:
{code:Java}
def <T> swapHeadAndTail(List<T> list) {
return {T h = list[0]; List<T> t=list[1..-1]; [*t, h]}()
}
{code}
This requires only 2 characters more syntax wise.
If the argument is, this will be inefficient, because it will create a Closure,
which is then executed right away... well... that does not have to be the case,
does it?
> Support expression scope variable
> ---------------------------------
>
> Key: GROOVY-11525
> URL: https://issues.apache.org/jira/browse/GROOVY-11525
> Project: Groovy
> Issue Type: New Feature
> Reporter: Daniel Sun
> Priority: Major
>
> Let's take a look at the following code first:
> {code}
> int hash(Object key) {
> int h;
> return (key == null) ? 0 : (h = key.hashCode()) ^ (h >>> 16);
> }
> {code}
> variable {{h}} is actually an expression scope variable, but current syntax
> doesn't support.
> I propose an expression scope variable syntax, e.g.
> Proposed syntax 1:
> {code}
> // Just support declaring variables of same type
> (int h, x, y; ...)
> {code}
> {code}
> int hash(Object key) {
> // h is only visible in the expression
> return (int h; (key == null) ? 0 : (h = key.hashCode()) ^ (h >>> 16))
> }
> {code}
> We can reduce the scope of {{h}} further:
> {code}
> int hash(Object key) {
> // h is only visible in the expression
> return (key == null) ? 0 : (int h; (h = key.hashCode()) ^ (h >>> 16))
> }
> {code}
> Proposed syntax 2(I prefer the syntax):
> {code}
> // Support declaring variables of different types
> (int h, X x, Y y -> ...)
> {code}
> {code}
> int hash(Object key) {
> // h is only visible in the expression
> return (int h -> (key == null) ? 0 : (h = key.hashCode()) ^ (h >>> 16))
> }
> {code}
> {code}
> int hash(Object key) {
> // h is only visible in the expression
> return (key == null) ? 0 : (int h -> (h = key.hashCode()) ^ (h >>> 16))
> }
> {code}
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