Update on String Templates (JEP 459)

[Guy Steele]

On general principle, I would agree about instance methods often being better than static methods for various reasons, other things being equal.

But in this specific discussion we have heard concerns about confusing templates with string interpolation. When it comes to safety of (say) SQL processing, which of the following would we prefer:

SQL($"SELECT * FROM \{tableName} blah blah blah”.xyzpdq());

SQL(xyzpdq($"SELECT * FROM \{tableName} blah blah blah”));

The first one avoids nested parentheses. The second one says right up front, “Danger, Will Robinson, danger! The template will not be processed in the way you might think!"

On Mar 19, 2024, at 2:53 PM, Maurizio Cimadamore <maurizio.cimadamore at oracle.com> wrote:


Of course a static method is enough (I find the name “process” not very clear on what that method does though).

One case where the instance syntax comes out on top if in method context:

foo($"Hello, \{world}".xyz())


Which reads better than:

 foo(xyz($"Hello, \{world}"))


at least IMHO (no doubly nested parens).

Even though, at the end of the day, interpolation is just a processor, just a method which takes a StringTemplate and returns a String, it is also a very common one, so allowing for an instance method could be a possible way to offset the loss of the STR syntax.

Maurizio

On 19/03/2024 18:33, Brian Goetz wrote:



Here I set forth your three examples with new names that are related
to those already used in the existing preview implementation of
StringTemplate in JDK 21 (and JDK 22—I just checked). I do this not to
suggest that these other names should be used, but only in the hopes
of reducing confusion as we begin this discussion. Later we can decide
whether the names “process” and “interpolate” and “combine” should be
changed (possibly all into the same single name).

    // on String
    static String process(StringTemplate)    // previously STR

    // on StringTemplate
    String interpolate()                             // STR, instance/suffix version
    static StringTemplate combine(StringTemplate...) // + for string templates


Maybe I’m missing something, but: Why do we need both `String::process`
and `StringTemplate::interpolate`?  What are the use cases?


For a similar reason we currently have String::valueOf(int) and Integer::toString(int).  In some use cases, the "prefix" usage (static method) feels more natural, whereas in others, the "suffix" usage (instance method) feels more natural.

Even if we end up with only one, I would rather not bias towards "of course it is the static version" at this early point; I am trying to sketch out scope right now.




​

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://mail.openjdk.org/pipermail/amber-spec-observers/attachments/20240319/99bdd6a8/attachment.htm>