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comparison

lua_std

Trait comparison 

Source 
pub trait comparison {
    // Provided methods
    fn __eq(&self, other: any) -> boolean { ... }
    fn __lt(&self, other: any) -> boolean { ... }
    fn __le(&self, other: any) -> boolean { ... }
}
Expand description

Metamethods controlling the comparison operators.

Note that a > b is translated to b < a and a >= b to b <= a, so only three events exist.

Provided Methods§

Source

fn __eq(&self, other: any) -> boolean

The equal (==) operation. Only invoked when the values being compared are both tables or both full userdata and they are not primitively equal. The result is always converted to a boolean.

§Examples
local mt = { __eq = function(a, b) return a.x == b.x and a.y == b.y end }
local p = setmetatable({ x = 1, y = 2 }, mt)
local q = setmetatable({ x = 1, y = 2 }, mt)
print(p == q)    --> true   (same coordinates, different tables)
Source

fn __lt(&self, other: any) -> boolean

The less than (<) operation.

§Examples
local mt = { __lt = function(a, b) return a.len < b.len end }
local short = setmetatable({ len = 1 }, mt)
local long  = setmetatable({ len = 9 }, mt)
print(short < long)    --> true
print(long > short)    --> true   (a > b runs __lt(b, a))
Source

fn __le(&self, other: any) -> boolean

The less equal (<=) operation.

§Examples
mt.__le = function(a, b) return a.len <= b.len end
print(short <= long)    --> true

Dyn Compatibility§

This trait is dyn compatible.

In older versions of Rust, dyn compatibility was called "object safety".

Implementors§