STR behavior

[Alex Buckley]

Looking at the API spec of STR [1], which will be extremely widely read, 
I agree that more normative text is needed about the form of the result 
string. A single example-led mention of an "interleaving concatenation" 
is insufficient, and the example's use of arithmetic + in the string 
template is confusing given that everyone will be thinking about Java's 
concatenating +. (The 10+20 example is already shown in the 
interface-level javadoc anyway.)

I also have some sympathy with the complaint that a reference to the 
field STR in a template expression is not being compiled in line with 
JLS 13.1 (item 4), which demands a symbolic reference to StringTemplate 
and thus predicts that the interface will be loaded. 13.1 doesn't 
specify how every construct is compiled, so it's legitimate for a 
compiler to implement a template expression without the JLS having to 
define "string template runtime" ... but it would be best for 13.1 to 
carve out some fields (STR, RAW) from the usual rules.

Alex

[1] 
https://download.java.net/java/early_access/jdk22/docs/api/java.base/java/lang/StringTemplate.html#STR 
-- I note that the field STR is basically unfindable with javadoc 
search, despite being omnipresent (auto-imported) in new Java programs.

On 7/25/2023 2:38 AM, Remi Forax wrote:
> Currently javac uses a trick to rewrite STR."" template to more or less the string concatenation equivalent, by passing the call to the bootstrap method of the string template runtime.
> 
> But this rewriting
> - has a side effect at runtime, the class StringTemplate is not loaded.
> - exact behavior is slightly different from the string concatenation, constant strings are not pre-computed, so the exact behavior is not an existing behavior.
> - only works with the unqualified STR (where STR is a static import implicit or explicit) but not with a qualified reference to StringTemplate.STR.
> 
> I think we need something in the spec saying that this is a valid source code transformation specific to STR, that it works in the qualified and unqualified case and that the transformations should be the same as with the string concatenation.
> 
> regards,
> Rémi
> 
>