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mruby-mruby/doc/mruby3.md
T
Yukihiro "Matz" Matsumoto dc886873bc Replace R-assignment by single-line pattern matching.
Since `R-assignment` in CRuby is abandoned.  Single-line pattern matching
in `mruby` only matches single local variable at the moment. Currently
it works as a right assignment to a local variable. It will be enhanced
in the future.
2020-11-02 15:14:36 +09:00

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2.4 KiB
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User visible changes in `mruby3`
===
# Build System
## `build_config` directory
Typical build configuration files are located in `build_config`
directory. For examples:
* `host-gprof`: compiles with `gprof` for performance tuning
* `host-m32`: compiles in gcc 32bit mode on 64bit platforms
* `boxing`: compiles all three boxing options
* `clang-asan`: compiles with `clang`'s Address Sanitizer
You can specify the build configration file with the
`MRUBY_CONFIG` environment variable (or `CONFIG` in short).
If the value specified by `MRUBY_CONFIG` is not the path to
the configuration file, `build_config/${MRUBY_CONFIG}.rb` is
used. So you can specify it as `rake MRUBY_CONFIG=boxing`,
for example.
# Build Configuration Contribution
When you write a new build configuration description, please
contribute. We welcome your contribution as a GitHub
pull-request.
# Language Changes
## New Syntax
We have ported some new syntax from CRuby.
* Single line pattern matching (`12 => x`);
mruby matches only with local variables at the moment
* Numbered block parameter (`x.map{_1 * 2}`)
* End-less `def` (`def double(x) = x*2`)
# Configuration Options Changed
Some configuration macro names are changed for consistency
## `MRB_NO_FLOAT`
Changed from `MRB_WITHOUT_FLOAT` to conform `USE_XXX` naming
convention.
## `MRB_USE_FLOAT32`
Changed from `MRB_USE_FLOAT` to make sure `float` here means
using single precision float, and not the opposite of
`MRB_NO_FLOAT`.
## `MRB_USE_METHOD_T_STRUCT`
Changed from `MRB_METHOD_T_STRUCT`.
To use `struct` version of `mrb_method_t`. More portable but consumes more memory.
Turned on by default on 32bit platforms.
## `MRB_NO_BOXING`
Uses `struct` to represent `mrb_value`. Consumes more memory
but easier to inveticate the internal and to debug. It used
to be default `mrb_value` representation. Now the default is
`MRB_WORD_BOXING`.
## `MRB_WORD_BOXING`
Pack `mrb_value` in an `intptr_t` integer. Consumes less
memory compared to `MRB_NO_BOXING` especially on 32 bit
platforms. `Fixnum` size is 31 bits so some integer values
does not fit in `Fixnum` integers.
## `MRB_NAN_BOXING`
Pack `mrb_value` in a floating pointer number. Nothing
changed from previous versions.
## `MRB_USE_MALLOC_TRIM`
Call `malloc_trim(0)` from mrb_full_gc() if this macro is defined.
If you are using glibc malloc, this macro could reduce memory consumption.
# Internal Changes
## `Random` now use `xoshiro128++`.
For better and faster random number generation.