Struct abi_stable::sabi_types::LateStaticRef

#[repr(C)]
pub struct LateStaticRef<T> { /* fields omitted */ }

A late-initialized static reference,with fallible initialization.

As opposed to Once, this allows initialization of its static reference to happen fallibly, by returning a Result<_,_> from the try_init function, or by panicking inside either initialization function.

On Err(_) and panics,one can try initialializing the static reference again.

Example

This lazily loads a configuration file.

use abi_stable::{
    sabi_types::LateStaticRef,
    std_types::{RBox,RBoxError,RHashMap,RString},
    utils::leak_value,
};

use std::{
    fs,
    io,
    path::Path,
};

use serde::Deserialize;


#[derive(Deserialize)]
pub struct Config{
    pub user_actions:RHashMap<RString,UserAction>,
}

#[derive(Deserialize)]
pub enum UserAction{
    Include,
    Ignore,
    ReplaceWith,
}


fn load_module(file_path:&Path)->Result<&'static Config,RBoxError>{
    static CONFIG:LateStaticRef<Config>=LateStaticRef::new();
    
    CONFIG.try_init(||{
        let file=load_file(file_path).map_err(RBoxError::new)?;
        let config=serde_json::from_str::<Config>(&file).map_err(RBoxError::new)?;
        Ok(leak_value(config))
    })
}

Methods

impl<T> LateStaticRef<T>

pub const fn new() -> Self

Constructs the late initialized static reference, in an uninitialized state.

Example

use abi_stable::sabi_types::LateStaticRef;

static LATE_REF:LateStaticRef<String>=LateStaticRef::new();

pub const fn initialized(value: &'static T) -> Self

Constructs the late initialized static reference, initialized with value.

Example

use abi_stable::sabi_types::LateStaticRef;

static LATE_REF:LateStaticRef<&'static str>=
    LateStaticRef::initialized(&"Hello!");

pub fn try_init<F, E>(&self, initializer: F) -> Result<&'static T, E> where
    F: FnOnce() -> Result<&'static T, E>, 

Lazily initializes the reference with initializer, returning the reference if either it was already initialized,or if initalizer returned Ok(..).

If initializer returns an Err(...) this returns the error and allows the reference to be initializer later.

If initializer panics,the panic is propagated, and the reference can be initalized later.

Example

use abi_stable::{
    sabi_types::LateStaticRef,
    utils::leak_value,
};

static LATE:LateStaticRef<String>=LateStaticRef::new();

static EARLY:LateStaticRef<&'static str>=
    LateStaticRef::initialized(&"Hello!");

assert_eq!( LATE.try_init(|| Err("oh no!") ), Err("oh no!") );
assert_eq!( 
    LATE
        .try_init(||->Result<&'static String,()>{
            Ok( leak_value("Yay".to_string()) )
        })
        .map(|s| s.as_str() ),
    Ok("Yay"),
);
 
assert_eq!( EARLY.try_init(|| Err("oh no!") ), Ok(&"Hello!") );

pub fn init<F>(&self, initializer: F) -> &'static T where
    F: FnOnce() -> &'static T, 

Lazily initializes the reference with initializer, returning the reference if either it was already initialized,or once initalizer returns the reference.

If initializer panics,the panic is propagated, and the reference can be initalized later.

Example

use abi_stable::{
    sabi_types::LateStaticRef,
    utils::leak_value,
};

static LATE:LateStaticRef<String>=LateStaticRef::new();

static EARLY:LateStaticRef<&'static str>=
    LateStaticRef::initialized(&"Hello!");

let _=std::panic::catch_unwind(||{
    LATE.init(|| panic!() );
});

assert_eq!( LATE.init(|| leak_value("Yay".to_string()) ), &"Yay" );

assert_eq!( EARLY.init(|| panic!() ), &"Hello!" );

pub fn get(&self) -> Option<&'static T>

Returns Some(x:&'static T) if the reference was initialized,otherwise returns None.

Example

use abi_stable::{
    sabi_types::LateStaticRef,
    utils::leak_value,
};

static LATE:LateStaticRef<String>=LateStaticRef::new();

static EARLY:LateStaticRef<&'static str>=
    LateStaticRef::initialized(&"Hello!");

let _=std::panic::catch_unwind(||{
    LATE.init(|| panic!() );
});

assert_eq!( LATE.get(), None );
LATE.init(|| leak_value("Yay".to_string()) );
assert_eq!( LATE.get().map(|s| s.as_str() ), Some("Yay") );

assert_eq!( EARLY.get(), Some(&"Hello!") );

Trait Implementations

impl<T> GetStaticEquivalent_ for LateStaticRef<T> where
    T: __StableAbi, 

type StaticEquivalent = _static_LateStaticRef<__GetStaticEquivalent<T>>

impl<T> RefUnwindSafe for LateStaticRef<T>

impl<T> SharedStableAbi for LateStaticRef<T> where
    T: __StableAbi, 

type IsNonZeroType = False

Whether this type has a single invalid bit-pattern.

type Kind = __ValueKind

The kind of abi stability of this type,there are 2:

const S_LAYOUT: &'static TypeLayout

The layout of the type provided by implementors.

const S_ABI_CONSTS: AbiConsts

impl<T> UnwindSafe for LateStaticRef<T>