Crate negate

  

negate is a simple attribute macro that negates a given function.

• [negate]

  Given a function of the form is_* that returns a boolean value, the macro will create a is_not_* that negates the given function.

  use negate::negate;
  #[negate]
  pub fn is_even(x: i32) -> bool {
    x % 2 == 0
  }
  
  // The `is_not_even` function was generated!
  assert!(is_not_even(5));

  For reference, this is how the generated function looks like:

  /// This is an automatically generated function that denies [`is_even`].
  /// Consult the original function for more information.
  pub fn is_not_even(x: i32) -> bool {
    !is_even(x)
  }

• [negate(name = "...")]

  Using the name attribute allows you to set the name of the generated function. This also allows the usage of the [negate] macro with functions that do not start with is_.

use negate::negate;
use std::collections::HashMap;

pub enum TaskState {
    Ready,
    Finished,
}

pub struct Reactor {
    tasks: HashMap<usize, TaskState>,
}

impl Reactor {
    // Generates the `is_finished` function
    #[negate(name = "is_finished")]
    pub fn is_ready(&self, id: usize) -> bool {
        self.tasks.get(&id).map(|state| match state {
            TaskState::Ready => true,
            _ => false,
        }).unwrap_or(false)
    }
}

• [negate(docs = "...")]

  Using the docs attribute allows you to customize the doc-string of the generated function

use negate::negate;
#[negate(name = "is_odd", docs = "returns true if the given number is odd")]
fn is_even(x: i32) -> bool {
   x % 2 == 0
}
assert!(is_odd(5));

Attribute Macros

negate

The negate attribute macro creates a new function that negates the function it was given. For example, if applied to a function titled is_student, the macro will create a new function named is_not_student, which simply negates the previous function.