Request for Enhancement: java.io.Writer.of(Appendable) as an efficient alternative to java.io.StringWriter

[Markus KARG]

Chen,

thank you for sharing your opinion!

Thinking about what you wrote about the "trifecta" complexity, I think 
it might be better to restart my idea from scratch:

As explained in my original proposal 
(https://mail.openjdk.org/pipermail/core-libs-dev/2024-December/137807.html), 
the actual driver for my proposal was to provide a StringWriter 
alternative which solves two main problems: It shall prevent String 
copies, and it shall be non-synchronized.

What comes into mind is: Writer.of(StringBuilder).

While compared to Appendable this signature is much less flexible, it 
also makes less headaches, but solved in fact those 99% of cases that 
triggered this whole idea: It does not create String copies, and it is 
non-synchronized. What this writer would simply, simply would be routing 
all incoming "append" and "write" calls down to the provided string builder.

Hence, kindly asking for comments on this updated idea: WDYT about 
Writer.of(StringBuilder)?

Thanks!

-Markus


Am 10.02.2025 um 01:51 schrieb Chen Liang:
> Hi Mark,
> After thinking about the Appendable-Closeable-Flushable trio versus 
> Writer, I believe that one problem with Writer.of is that it goes 
> against interface segregation principle represented by the trifecta, 
> and accidentally leaking the Closeable or Flushable functionality is 
> still dubious to me. This appears simple, but it may cause unintended 
> consequences, such as if Appendable b implements Closeable too, its 
> closing behavior is not proxied and users may find this inconsistency 
> weird. And as for interface segregation principle, it means APIs 
> should request Appendable instead of Writer if they only need writing 
> abilities with no lifecycle; using Writer as the type implies 
> potential dependency on closing/flushing behavior, which can sometimes 
> be dangerous.