Revisit the String template syntax

[forax at univ-mlv.fr]

----- Original Message -----
> From: "Guy Steele" <guy.steele at oracle.com>
> To: "Brian Goetz" <brian.goetz at oracle.com>
> Cc: "Remi Forax" <forax at univ-mlv.fr>, "amber-spec-experts" <amber-spec-experts at openjdk.org>
> Sent: Wednesday, April 12, 2023 6:38:13 PM
> Subject: Re: Revisit the String template syntax

>> On Apr 12, 2023, at 12:21 PM, Brian Goetz <brian.goetz at oracle.com> wrote:
>> 
>> The backslash syntax is objectively better than the dollar-sign syntax, which is
>> why we selected it in the first place.  Reasons included:
>> 
>> - Today, “${name}” is a valid string literal, whereas “\{name}” is not.
> 
> This point is worth expanding on:. It is important to consider not only the
> effort of writing new code, but also the effort of maintaining and extending
> old code.
> 
> With the introduction of string templates, we can expect a fairly common
> activity to be the modification of an existing string literal to become a
> string template.
> 
> Under the current design, this requires doing two things:
> 
> (1) Add “STR.” to the front of the string literal.
> (2) Add “\{expression}” in various places.
> 
> Using the dollar-sign syntax would require three steps:
> 
> (1) Add “STR.” to the front of the string literal.
> (2) Add “\{expression}” in various places.
> (3) Check the_entire string literal_ for occurrences of “$” and perhaps replace
> with "\$”.
> 
> I don’t think it’s worth it just to make Java look a little bit more like
> JavaScript (and a little bit less like Java).

JavaScript is a user of the ${} syntax but it's a fairly recent addition.

In Java, Maven, Gradle through their lineage to Apache Ant, in fact, all projects using the apache common-text StringSubstitutor (or the much older StrSubstitutor) are using the ${} syntax since a very long time. All Java developers are familiar with this syntax for string interpolation.

So for a lot of Java developers, the syntax \{} feels alien to Java in comparison. So yes, you have to escape the $ sign, you have to tweak the lexer but, in my opinion, it's a case where familiarity in the whole ecosystem trumps local rationalization.

> 
> —Guy

Rémi