Struct milter::DataHandle

pub struct DataHandle<T> { /* fields omitted */ }

A handle on user data stored in the callback context.

DataHandle<T> serves as an accessor to connection-local data T that can be shared across callback functions within a connection.

Data life cycle

By design, data life cycle management is not automatic. It is the responsibility of a milter implementation to manage the data’s life cycle by reacquiring and disposing of context data (including associated resources such as file handles etc.) at an appropriate time in the callback flow.

As a rule of thumb, every path through the callback flow must have a final call to take.

Implementations

impl<T> DataHandle<T>

pub fn replace(&mut self, data: T) -> Result<Option<T>>

Hands over data into the context, returning current context data if present.

Errors

An error variant is returned if libmilter encounters an error.

pub fn take(&mut self) -> Result<Option<T>>

Takes ownership of the current context data if present, removing it from the context.

Errors

An error variant is returned if libmilter encounters an error.

pub fn borrow(&self) -> Option<&T>

Returns a reference to (borrows) the current context data if present.

Examples

if let Some(data) = context.data.borrow() {
    println!("{}", data);
}

pub fn borrow_mut(&mut self) -> Option<&mut T>

Returns a mutable reference to (mutably borrows) the current context data if present.

Examples

if let Some(msg_count) = context.data.borrow_mut() {
    *msg_count += 1;
}

Trait Implementations

impl<T: Debug> Debug for DataHandle<T>

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

Formats the value using the given formatter.