Struct magnus::value::Value

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#[repr(transparent)]
pub struct Value(_);

Expand description

Ruby’s VALUE type, which can represent any Ruby object.

Implementations§

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impl Value

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pub fn is_nil(self) -> bool

Returns whether self is Ruby’s nil value.

pub fn equal<T>(self, other: T) -> Result<bool, Error>where
T: Deref<Target = Value>,

Checks for equality, delegating to the Ruby method #==.

Ruby optimises this check if self and other are the same object or some built-in types, then calling the #== method will be skipped.

Returns Err if #== raises.

pub fn eql<T>(self, other: T) -> Result<bool, Error>where
T: Deref<Target = Value>,

Checks for equality, delegating to the Ruby method #eql?.

See Value::equal for the equivalent of the #== method.

Ruby optimises this check if self and other are the same object or some built-in types, then calling the #== method will be skipped.

Returns Err if #eql? raises.

pub fn class(self) -> RClass

Returns the class that self is an instance of.

pub fn is_frozen(self) -> bool

Returns whether self is ‘frozen’.

Ruby prevents modifying frozen objects.

pub fn check_frozen(self) -> Result<(), Error>

Returns an error if self is ‘frozen’.

Useful for checking if an object is frozen in a function that would modify it.

pub fn freeze(self)

Mark self as frozen.

pub fn to_bool(self) -> bool

Convert self to a bool, following Ruby’s rules of false and nil as boolean false and everything else boolean true.

pub fn funcall<M, A, T>(self, method: M, args: A) -> Result<T, Error>where
 M: Into<Id>,
 A: ArgList,
 T: TryConvert,

Call the method named method on self with args.

Returns Ok(T) if the method returns without error and the return value converts to a T, or returns Err if the method raises or the conversion fails.

pub fn check_funcall<M, A, T>(
 self,
 method: M,
 args: A
) -> Option<Result<T, Error>>where
 M: Into<Id>,
 A: ArgList,
 T: TryConvert,

If self responds to the method named method, call it with args.

Returns Some(Ok(T)) if the method exists and returns without error, None if it does not exist, or Some(Err) if an exception was raised.

pub fn funcall_with_block<M, A, T>(
 self,
 method: M,
 args: A,
 block: Proc
) -> Result<T, Error>where
 M: Into<Id>,
 A: ArgList,
 T: TryConvert,

Call the method named method on self with args and block.

Similar to funcall, but passes block as a Ruby block to the method.

pub fn block_call<M, A, R, T>(
 self,
 method: M,
 args: A,
 block: fn(_: &[Value], _: Option<Proc>) -> R
) -> Result<T, Error>where
 M: Into<Id>,
 A: ArgList,
 R: BlockReturn,
 T: TryConvert,

Call the method named method on self with args and block.

Similar to funcall, but passes block as a Ruby block to the method.

As block is a function pointer, only functions and closures that do not capture any variables are permitted. For more flexibility (at the cost of allocating) see Proc::from_fn and funcall_with_block.

The function passed as block will receive values yielded to the block as a slice of Values, plus Some(Proc) if the block itself was called with a block, or None otherwise.

The block function may return any R or Result<R, Error> where R implements Into<Value>. Returning Err(Error) will raise the error as a Ruby exception.

Examples

use magnus::{eval, RArray, Value};

let values = eval::<RArray>(r#"["foo", 1, :bar]"#).unwrap();
let _: Value = values.block_call("map!", (), |args, _block| args.first().unwrap().to_r_string()).unwrap();
assert_eq!(values.to_vec::<String>().unwrap(), vec!["foo", "1", "bar"]);

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pub fn respond_to<M>(
 self,
 method: M,
 include_private: bool
) -> Result<bool, Error>where
 M: Into<Id>,

Check if self responds to the given Ruby method.

The include_private agument controls whether self’s private methods are checked. If false they are not, if true they are.

Examples

use magnus::RString;

let s = RString::new("example");
assert!(s.respond_to("to_str", false).unwrap());
assert!(!s.respond_to("puts", false).unwrap());
assert!(s.respond_to("puts", true).unwrap());
assert!(!s.respond_to("non_existant", false).unwrap());
assert!(!s.respond_to("non_existant", true).unwrap());

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pub fn to_r_string(self) -> Result<RString, Error>

Convert self to a Ruby String.

If self is already a String is it wrapped as a RString, otherwise the Ruby to_s method is called.

Examples

use magnus::{eval, class, Value};

let value = eval::<Value>("[]").unwrap();
assert!(value.to_r_string().unwrap().is_kind_of(class::string()));

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pub unsafe fn to_s(&self) -> Result<Cow<'_, str>, Error>

Convert self to a Rust string.

Safety

This may return a direct view of memory owned and managed by Ruby. Ruby may modify or free the memory backing the returned str, the caller must ensure this does not happen.

This can be used safely by immediately calling into_owned on the return value.

Examples

use magnus::{eval, QTRUE};

let value = QTRUE;
// safe as we neve give Ruby a chance to free the string.
let s = unsafe { value.to_s() }.unwrap().into_owned();
assert_eq!(s, "true");

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pub fn inspect(self) -> String

Convert self to its Ruby debug representation.

Examples

use magnus::{eval, Symbol, QNIL};

assert_eq!(QNIL.inspect(), "nil");
assert_eq!(Symbol::new("foo").inspect(), ":foo");

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pub unsafe fn classname(&self) -> Cow<'_, str>

Return the name of self’s class.

Safety

Ruby may modify or free the memory backing the returned str, the caller must ensure this does not happen.

This can be used safely by immediately calling into_owned on the return value.

Examples

use magnus::{eval, RHash};

let value = RHash::new();
// safe as we never give Ruby a chance to free the string.
let s = unsafe { value.classname() }.into_owned();
assert_eq!(s, "Hash");

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pub fn is_kind_of<T>(self, class: T) -> boolwhere
T: Deref<Target = Value> + Module,

Returns whether or not self is an instance of class.

Examples

use magnus::{class, eval, Value};

let value = eval::<Value>("[]").unwrap();
assert!(value.is_kind_of(class::array()));

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pub fn enumeratorize<M, A>(self, method: M, args: A) -> Enumerator ⓘwhere
M: Into<Symbol>,
A: ArgList,

Generate an Enumerator from method on self, passing args to method.

Examples

use magnus::{class, eval, r_string};

let s = r_string!("foo\\bar\\baz");
let mut i = 0;
for line in s.enumeratorize("each_line", ("\\",)) {
    assert!(line.unwrap().is_kind_of(class::string()));
    i += 1;
}
assert_eq!(i, 3);

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pub fn try_convert<T>(self) -> Result<T, Error>where
T: TryConvert,

Convert self to the Rust type T.

See the types that TryConvert is implemented on for what this method can convert to.

Examples

use magnus::{eval, Value};

assert_eq!(eval::<Value>("42").unwrap().try_convert::<i64>().unwrap(), 42);
assert_eq!(eval::<Value>("1.23").unwrap().try_convert::<i64>().unwrap(), 1);
assert_eq!(eval::<Value>("1").unwrap().try_convert::<f64>().unwrap(), 1.0);
assert_eq!(eval::<Value>("nil").unwrap().try_convert::<Option<i64>>().unwrap(), None);
assert_eq!(eval::<Value>("42").unwrap().try_convert::<Option<i64>>().unwrap(), Some(42));

Trait Implementations§

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impl AsRawValue for Value

Available on crate feature rb-sys-interop only.

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fn as_raw(self) -> VALUE

Convert magnus::Value to rb_sys::VALUE. Read more

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impl Clone for Value

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fn clone(&self) -> Value

Returns a copy of the value. Read more

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fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source. Read more

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impl Debug for Value

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fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter. Read more

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impl Default for Value

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fn default() -> Self

Returns the “default value” for a type. Read more

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impl Display for Value

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fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter. Read more

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