12 releases (4 breaking)
|0.4.3||Aug 1, 2020|
|0.4.2||Jul 30, 2020|
|0.4.1||May 16, 2020|
|0.3.0-alpha||Mar 25, 2020|
|0.2.1||Nov 28, 2019|
#775 in Rust patterns
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This library provides field accessor traits,and emulation of structural types.
These are some of the features this library provides:
Structuralderive macro to implement accessor traits for every public field:
IntoFieldfor structs, and
StructuralExtextension trait,which defines the main methods to access fields, so long as the type implements the accessor traits for those fields.
StrucWrapperwrapper type,defined as an alternative to
structural_aliasmacro, to declare trait aliases for accessor traits, using field-in-trait syntax.
impl_structmacro to declare structural parameter/return types, as well as
make_structto construct anonymous structs
TryFromStructuralconversion traits, similar (but not identical) to the standard library
TryFromtraits for structural types.
For examples you can look at the examples section of the documentation for the root module of the structural crate
The way that this library emulates structural types is by using traits as bounds or trait objects.
structural traits are dyn-compatible(also known as object-safe),
and no change will be made to make them not dyn-compatible.
By default all structural types are open,
structs and enums can have more variants and or fields than are required.
The only exception to this is exhaustive enums, in which the variant count and names must match exactly, this is useful for exhaustive matching of variants (in the
Every trait with the
_VSI suffixes in the examples are traits
generated by the
Structural derive macro.
These traits alias the accessor traits implemented by the type they're named after.
The only macros that are required to use this crate are the ones for
every other macro expands to code that can be written manually
(except for the
__TS type, that is an implementation detail that only macros from
this crate should use by name).
The changelog is in the "Changelog.md" file.
TryFromStructural traits derivable.
structural in no_std contexts disable the default-feature.
This crate has few items that require the
std crate (instead of core).
The "std" and "alloc" features are enabled by default so that users that are not
aware of the
alloc crates don't have to pass a feature to enable
These are the cargo features in structural:
std: Enables std support,this is enabled by default.
alloc: Enables alloc crate support,this is enabled by default.
specialization: Enables specialization inside structural,without enabling the nightly feature flag. This is for the case that specialization is stabilized after the last update to this library.
nightly_specialization: Enables specialization inside structural, requires nightly because it enables the nightly feature.
impl_fields: This allows using
field_name: impl Foofields in the
structural_aliasmacro, which as of 2020-03-21 requires the
associated_type_boundsRust nightly feature.
If this doesn't work,try using the "nightly_impl_fields" feature in Rust nightly instead.
nightly_impl_fieldsEquivalent to the
impl_fieldsfeature, as well as enabling the
associated_type_boundsnightly features required for using the feature as of 2020-03-21.
use_const_str: Changes the internal implementation of
TStr(the type level string type) to use a
&'static strconst parameter instead of types.
Use this if const generics (eg:
struct Foo<const S: &'static str>;) are usable on stable.
nightly_use_const_str: Equivalent to the
use_const_strfeature, which also enables the nightly Rust features required for const generics as of 2020-03-21.
disable_const_str: Disables const generics, useful if other crates enabling const generics causes internal errors in this Rust version.
Specialization is used inside
structural for performance reasons.
There are no benchmarks comparing when specialization is enabled and disabled yet.
Minimum Rust version
This crate support Rust back to 1.40, and uses a build script to automatically enable features from newer versions.
It requires Rust 1.40 to use proc macros in type position,eg:
Licensed under either of Apache License, Version 2.0 or MIT license at your option. Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in Structural by you, as defined in the Apache-2.0 license, shall be dual licensed as above, without any additional terms or conditions.