On Tue, 8 Oct 2024 11:54:28 GMT, Jaikiran Pai <j...@openjdk.org> wrote:
>> Markus KARG has updated the pull request incrementally with six additional
>> commits since the last revision:
>>
>> - renamed source to cs; cs is final; close sets boolean; no adouble
>> reference to source
>> - Fixed Typo: 'resect' -> 'respect'
>> - Improved wording: 'The returned reader supports the {@link #mark mark()}
>> operation'
>> - Improved wording: 'Returns a {@code Reader} that reads characters from a
>> {@code CharSequence}, starting at the first character in the sequence'
>> - test for generic read(char, int, int) case
>> - Remove useless test
>
> src/java.base/share/classes/java/io/Reader.java line 174:
>
>> 172:
>> 173: return new Reader() {
>> 174: private final int length = cs.length();
>
> Hello Markus, as far as I can see, a `CharSequence` is allowed to have a
> non-fixed `length()` (typically allowed to increase?). Is there a reason why
> the length is captured at construction time instead of being evaluated during
> the read operations of the `Reader`?
As the anonymous class MUST NOT be used with be used with multiple threads, I
always have seen the `CharSequence` as *fixed/static* text in the moment the
`Reader` is getting used. But indeed, technically one could interleave
`Reader::read()` invocations by `CharSequence.append()` (or even worse,
`CharSequence.delete()`) invocations. The question is: Would that make *any*
sense in the end? I mean, what happens if one has `read()` text that in the
next step gets `delete()`'d? I cannot image *any* scenario where such a program
would result in *useful* outcome.
<fun>The fact that nobody so far (before you) brought up this question seems
to proof that nobody (besides you) would write such a program. 😄 </fun>
So I would plea for clearly saying in the JavaDocs that `cs` MUST NOT be
modified before `close()` is called. Every other solution implies strange side
effects and slower and error-prone implementation of both, anoynous reader
*and* test.
@AlanBateman WDYT?
-------------
PR Review Comment: https://git.openjdk.org/jdk/pull/21371#discussion_r1791754907
