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https://issues.apache.org/jira/browse/GROOVY-11453?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]
Eric Milles updated GROOVY-11453:
---------------------------------
Description:
The spread-safe operator -- aka {{a*.b}} or {{a*.b(c)}} -- has some differences
and inefficiencies.
# When the receiver is null, the expression produces null for dynamic mode and
an empty list for static compilation. Can this difference be safely resolved?
# When the method return type is {{void}}, there is no need for a list to
collect up nulls. This is producing "Useless object stored in variable var$1"
warnings from SpotBugs. The only benefit of this is the ability to detect the
number of elements.
# The SC bytecode has a redundant null test in it. Since a for loop is also
null-safe, guarding the loop bytecode by a null check is producing "Redundant
check for null" warnings from SpotBugs. *NOTE:* If (1) above is changed in the
SC classgen, the null check may not be redundant as it would guard list
construction.
For reference, {{object*.method(arguments)}} is written by the static compiler
like this:
{code:groovy}
def result = new ArrayList()
if (object != null) {
for (InferredType element : object) { // also null-safe
result.add(element?.method(arguments)
}
}
result
{code}
And the dynamic impl:
https://github.com/apache/groovy/blob/f46103d31b7574ce883ff3b6c01fa8a412f225be/src/main/java/org/codehaus/groovy/runtime/ScriptBytecodeAdapter.java#L189
GROOVY-7177
was:
The spread-safe operator -- aka {{a*.b}} or {{a*.b(c)}} -- has some differences
and inefficiencies.
# When the receiver is null, the expression produces null for dynamic mode and
an empty list for static compilation. Can this difference be safely resolved?
# When the method return type is {{void}}, there is no need for a list to
collect up nulls. This is producing "Useless object stored in variable var$1"
warnings from SpotBugs. The only benefit of this is the ability to detect the
number of elements.
# The SC bytecode has a redundant null test in it. Since a for loop is also
null-safe, guarding the loop bytecode by a null check is producing "Redundant
check for null" warnings from SpotBugs. *NOTE:* If (1) above is changed in the
SC classgen, the null check may not be redundant as it would guard list
construction.
For reference, {{object*.method(arguments)}} is written by the static compiler
like this:
{code:groovy}
def result = new ArrayList()
if (object != null) {
for (element in object) { // also null-safe
result.add(element?.method(arguments)
}
}
result
{code}
And the dynamic impl:
https://github.com/apache/groovy/blob/f46103d31b7574ce883ff3b6c01fa8a412f225be/src/main/java/org/codehaus/groovy/runtime/ScriptBytecodeAdapter.java#L189
GROOVY-7177
> Spread-safe operator differences and efficiencies
> -------------------------------------------------
>
> Key: GROOVY-11453
> URL: https://issues.apache.org/jira/browse/GROOVY-11453
> Project: Groovy
> Issue Type: Bug
> Reporter: Eric Milles
> Assignee: Eric Milles
> Priority: Major
>
> The spread-safe operator -- aka {{a*.b}} or {{a*.b(c)}} -- has some
> differences and inefficiencies.
> # When the receiver is null, the expression produces null for dynamic mode
> and an empty list for static compilation. Can this difference be safely
> resolved?
> # When the method return type is {{void}}, there is no need for a list to
> collect up nulls. This is producing "Useless object stored in variable
> var$1" warnings from SpotBugs. The only benefit of this is the ability to
> detect the number of elements.
> # The SC bytecode has a redundant null test in it. Since a for loop is also
> null-safe, guarding the loop bytecode by a null check is producing "Redundant
> check for null" warnings from SpotBugs. *NOTE:* If (1) above is changed in
> the SC classgen, the null check may not be redundant as it would guard list
> construction.
> For reference, {{object*.method(arguments)}} is written by the static
> compiler like this:
> {code:groovy}
> def result = new ArrayList()
> if (object != null) {
> for (InferredType element : object) { // also null-safe
> result.add(element?.method(arguments)
> }
> }
> result
> {code}
> And the dynamic impl:
> https://github.com/apache/groovy/blob/f46103d31b7574ce883ff3b6c01fa8a412f225be/src/main/java/org/codehaus/groovy/runtime/ScriptBytecodeAdapter.java#L189
> GROOVY-7177
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