Implicit 'this' return for void methods
brucechapman at paradise.net.nz
Thu Apr 3 07:54:13 UTC 2014
On 3/04/2014 6:01 p.m., Peter Levart wrote:
> On 04/01/2014 11:28 AM, Bruce Chapman wrote:
>> Slightly preceding Ulf's coin proposal by a few hours was
>> Where I suggested the "naked dot" notation (coined in
>> has better value as ".. a
>> syntax for referring to the receiver of a method inside arguments to the
>> More formally, the naked dot (at the start of an expression, not
>> following an invocation to a void method) would refer to the receiver
>> of the innermost surrounding invocation expression.
> A: What is the receiver of the invocation of a static method?
> B: What is the receiver of the invocation of a constructor?
I haven't checked the JLS formal terminology but in both cases it is the
class's static context, such that a naked dot could only precede static
methods and fields.
> Regards, Peter
>> and so to answer Guy's question below in terms of my original
>> intention rather than Ulf's proposal, .indexof("Q") would use
>> myVeryLongNamedString as its receiver.
>> I see particular value for these naked dot expressions in creating
>> fluent APIs such as builder patterns. As suggested in my coin post,
>> there is also value for passing enums or named constants to methods
>> when (as is often the case) these named constants are defined in the
>> same class as the method being invoked. In a highly informal sense,
>> the naked dot enables on demand changing of the scope to be that of
>> the invocation expression's receiver,
>> I think with this interpretation of the meaning of naked or leading
>> dot, Guy's compromise restriction below is not required.
>> On 27/03/2014 4:51 a.m., Guy Steele wrote:
>>> I am a bit more skeptical about expressions that begin with a dot
>>> because of potential
>>> confusion about which expression is referred to:
>>> myVeryLongNamedString.subString(.indexOf("C”), .indexOf("Q”))
>>> seems clear enough, but what about:
>>> myVeryLongNamedString.subString(.indexOf("C”) +
>>> otherString.length(), .indexOf("Q”))
>>> Does the second occurrence of .indexOf use myVeryLongNamedString or
>>> A compromise would be to allow leading-dot expressions to occur only
>>> within the arguments
>>> of the method call whose target is the object which the leading-dot
>>> expressions are expected
>>> to use as their target, and if there are such leading-dot
>>> expressions within the arguments
>>> then the arguments must not contain any non-leading-dot field
>>> references or method calls.
>>> Just a thought for discussion. This would be considered a separate
>>> mechanism from the
>>> chaining-of-void-methods mechanism (it was a very clever idea to try
>>> to unify them in Ulf's
>>> original proposal, though).
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