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It seems the design team has lost its mojo. First, the lesson of Log4Shell have not been learnt. Allowing more libraries to do formatting, what can go wrong ?

It seems the design team has lost its mojo. First, the lesson of Log4Shell have not been learnt. Allowing more libraries to do formatting, what can go wrong ? And String.format() is slow because every values are boxed. This JEP repeats the same mistake with the templates.

pron 4y ago
The template instantiation itself is done by the language, not libraries, and the entire mechanism was designed for security (read the JEP); for example, templates are (virtually) limited to literals and can't come from user input. As to boxing, the built-in template processors, STR and FMT, don't do boxing (they use MethodHandle mechanisms similar to those used by lambdas) -- FMT is ~40x faster than String.format, I'm told -- but that capability hasn't been exposed as an API yet. As with other features, we try exposing basic usages first, and more sophisticated ones later.
- _old_dude_ 4y ago
  > the entire mechanism was designed for security ... I don't have the same definition of security (i've read the JEP). Unlike TypeScript, you can not type the template values. > built-in template processors, STR and FMT, don't do boxing ... but all the others user-defined template processors (think a logger) are second class citizens and will do boxing. Efficient String interpolation is hard without macros, that's why it's a macro in Rust. This JEP tries to solve a harder problem, user defined template processors but do not provide the tool to make them efficient and never will. Are you suggesting that there is a JEP about macros in the making ?
  - pron 4y ago
    > Efficient String interpolation is hard without macros Not quite. It is hard without some compile-time computation, but what's compile-time for languages relying on AOT compilation (and requires macros or compile-time introspection as in Zig), happens at runtime in Java because that's when the optimising compilation happens, and Java has a user-exposed mechanism for defining call-sites (https://docs.oracle.com/en/java/javase/19/docs/api/java.base/java/lang/invoke/CallSite.html https://docs.oracle.com/en/java/javase/19/docs/api/java.base...). It's just that, as with most of our new features, we expose a simple API first and a sophisticated API later. No need for macros.

pron 4y ago

The template instantiation itself is done by the language, not libraries, and the entire mechanism was designed for security (read the JEP); for example, templates are (virtually) limited to literals and can't come from user input. As to boxing, the built-in template processors, STR and FMT, don't do boxing (they use MethodHandle mechanisms similar to those used by lambdas) -- FMT is ~40x faster than String.format, I'm told -- but that capability hasn't been exposed as an API yet. As with other features, we try exposing basic usages first, and more sophisticated ones later.

_old_dude_ 4y ago
> the entire mechanism was designed for security ... I don't have the same definition of security (i've read the JEP). Unlike TypeScript, you can not type the template values. > built-in template processors, STR and FMT, don't do boxing ... but all the others user-defined template processors (think a logger) are second class citizens and will do boxing. Efficient String interpolation is hard without macros, that's why it's a macro in Rust. This JEP tries to solve a harder problem, user defined template processors but do not provide the tool to make them efficient and never will. Are you suggesting that there is a JEP about macros in the making ?
- pron 4y ago
  > Efficient String interpolation is hard without macros Not quite. It is hard without some compile-time computation, but what's compile-time for languages relying on AOT compilation (and requires macros or compile-time introspection as in Zig), happens at runtime in Java because that's when the optimising compilation happens, and Java has a user-exposed mechanism for defining call-sites (https://docs.oracle.com/en/java/javase/19/docs/api/java.base/java/lang/invoke/CallSite.html https://docs.oracle.com/en/java/javase/19/docs/api/java.base...). It's just that, as with most of our new features, we expose a simple API first and a sophisticated API later. No need for macros.