Struct Exception 

pub struct Exception { /* private fields */ }

An exception instance.

Made by calling a Class, and after that it is an ordinary value until something raises it.

Implementations

impl Exception

pub fn new(kind: Kind, args: Vec<Object>) -> Self

An instance of this class with these arguments.

pub const fn kind(&self) -> Kind

Which class it is an instance of.

pub fn args(&self) -> &[Object]

What it was constructed with, which is e.args and is what everything it prints is made out of.

pub fn cause(&self) -> Option<Object>

What it was raised from, if it was raised from anything.

Cloned out rather than borrowed, because the cell it lives in cannot stay borrowed across the walk up a chain of them.

pub fn raised_from(&self, cause: Option<Object>)

Record what this was raised from, which is the from in a raise.

Writing a from at all is what suppresses the context, so raise x from None says “this one, and do not print whatever I happened to be handling”, which is the only way to write that sentence.

pub fn context(&self) -> Option<Object>

What was being handled when this was raised, if anything was.

Cloned out for the same reason Exception::cause is: the cell cannot stay borrowed across the walk up a chain of them.

pub fn suppresses_context(&self) -> bool

Whether a traceback should stop before printing the context.

pub fn message(&self) -> String

What str(e) says, which is the half of a traceback’s last line after the colon.

Three shapes and one exception to them. No arguments says nothing at all, one argument is that argument, and more than one is the tuple of them. KeyError is the one that prints its single argument the way repr would, which is what makes a missing key of '' visible.

Trait Implementations

impl Debug for Exception

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

Formats the value using the given formatter.

impl Native for Exception

fn repr(&self) -> String

The class name and the arguments, which is what reads back as the call that would make it again.

fn truthy(&self) -> bool

Every exception is true, including the ones with no arguments, which is worth saying because an empty tuple is not.

fn type_name(&self) -> &str

What type(x).__name__ says, which is what error messages need.

fn display(&self) -> String

What str prints, which for a type with no __str__ of its own is whatever repr prints. Almost every native type wants the default. An exception is the one that does not, because str(e) is the message and repr(e) is the call that would make it again.

fn as_any(&self) -> &dyn Any

The concrete value, for the runtime to downcast back to.

fn walking(&self) -> bool

Whether this is already an iterator, meaning iter(x) is x and a for over a half consumed one carries on rather than starting again.

fn equals(&self, _other: &dyn Native) -> bool

Whether this is equal to another native value that is not the same object as it.

fn hash(&self) -> Option<i64>

This value’s hash, or nothing to be hashed by address like an object with no __hash__ of its own.