Struct ColMut 

pub struct ColMut<'w, T: 'static> {
    cells: &'w [UnsafeCell<T>],
}

A claimed column, exclusive.

Handed out by PlanBuilder::write and kept in a query’s plan. Unlike Col it is not Copy, and ColMut::at takes the handle exclusively: that is what makes one Query::read hand out at most one exclusive reference per column, which in turn is why declaring a query needs no unsafe.

Fields

cells: &'w [UnsafeCell<T>]

Implementations

impl<'w, T: 'static> ColMut<'w, T>

pub fn at(&mut self, row: usize) -> &mut T

The value at row, exclusively.

Taking &mut self is the safety argument: the caller can reach the same cell twice only by calling this twice, and the first reference is still alive then, so the compiler refuses the second call.

pub fn len(&self) -> usize

The number of values in the column, one per row of the archetype.

pub fn is_empty(&self) -> bool

Whether the column holds no value.