Rhai Release Notes ================== Version 0.14.2 ============== Regression fix -------------- * Do not optimize script with `eval_expression` - it is assumed to be one-off and short. Breaking changes ---------------- * `Engine::compile_XXX` functions now return `ParseError` instead of `Box`. * The `RegisterDynamicFn` trait is merged into the `RegisterResutlFn` trait which now always returns `Result>`. * Default maximum limit on levels of nested function calls is fine-tuned and set to a different value. * Some operator functions are now built in (see _Speed enhancements_ below), so they are available even under `Engine::new_raw`. * Strings are now immutable. The type `rhai::ImmutableString` is used instead of `std::string::String`. This is to avoid excessive cloning of strings. All native-Rust functions taking string parameters should switch to `rhai::ImmutableString` (which is either `Rc` or `Arc` depending on whether the `sync` feature is used). New features ------------ * Set limit on maximum level of nesting expressions and statements to avoid panics during parsing. * New `EvalPackage` to disable `eval`. * More benchmarks. Speed enhancements ------------------ * Common operators (e.g. `+`, `>`, `==`) now call into highly efficient built-in implementations for standard types (i.e. `INT`, `FLOAT`, `bool`, `char`, `()` and `ImmutableString`) if not overridden by a registered function. This yields a 5-10% speed benefit depending on script operator usage. Scripts running tight loops will see significant speed-up. * Common assignment operators (e.g. `+=`, `%=`) now call into highly efficient built-in implementations for standard types (i.e. `INT`, `FLOAT`, `bool`, `char`, `()` and `ImmutableString`) if not overridden by a registered function. * Implementations of common operators for standard types are removed from the `ArithmeticPackage` and `LogicPackage` (and therefore the `CorePackage`) because they are now always available, even under `Engine::new_raw`. * Operator-assignment statements (e.g. `+=`) are now handled directly and much faster. * Strings are now _immutable_ and use the `rhai::ImmutableString` type, eliminating large amounts of cloning. Version 0.14.1 ============== The major features for this release is modules, script resource limits, and speed improvements (mainly due to avoiding allocations). New features ------------ * Modules and _module resolvers_ allow loading external scripts under a module namespace. A module can contain constant variables, Rust functions and Rhai functions. * `export` variables and `private` functions. * _Indexers_ for Rust types. * Track script evaluation progress and terminate script run. * Set limit on maximum number of operations allowed per script run. * Set limit on maximum number of modules loaded per script run. * A new API, `Engine::compile_scripts_with_scope`, can compile a list of script segments without needing to first concatenate them together into one large string. * Stepped `range` function with a custom step. Speed improvements ------------------ ### `StaticVec` A script contains many lists - statements in a block, arguments to a function call etc. In a typical script, most of these lists tend to be short - e.g. the vast majority of function calls contain fewer than 4 arguments, while most statement blocks have fewer than 4-5 statements, with one or two being the most common. Before, dynamic `Vec`'s are used to hold these short lists for very brief periods of time, causing allocations churn. In this version, large amounts of allocations are avoided by converting to a `StaticVec` - a list type based on a static array for a small number of items (currently four) - wherever possible plus other tricks. Most real-life scripts should see material speed increases. ### Pre-computed variable lookups Almost all variable lookups, as well as lookups in loaded modules, are now pre-computed. A variable's name is almost never used to search for the variable in the current scope. _Getters_ and _setter_ function names are also pre-computed and cached, so no string allocations are performed during a property get/set call. ### Pre-computed function call hashes Lookup of all function calls, including Rust and Rhai ones, are now through pre-computed hashes. The function name is no longer used to search for a function, making function call dispatches much faster. ### Large Boxes for expressions and statements The expression (`Expr`) and statement (`Stmt`) types are modified so that all of the variants contain only one single `Box` to a large allocated structure containing _all_ the fields. This makes the `Expr` and `Stmt` types very small (only one single pointer) and improves evaluation speed due to cache efficiency. Error handling -------------- Previously, when an error occurs inside a function call, the error position reported is the function call site. This makes it difficult to diagnose the actual location of the error within the function. A new error variant `EvalAltResult::ErrorInFunctionCall` is added in this version. It wraps the internal error returned by the called function, including the error position within the function.