dotmethod

8.12

dotmethod🔗ℹ

This package provides both a dotmethod/dotmethod module to be required and a #lang dotmethod lang-extension.

Both of these provide functionality for obj.method(x)-style method definitions and method calls, but generalized to be used for all data types that can be distinguished by predicates.

1 dotmethod/dotmethod🔗ℹ

(require dotmethod/dotmethod)

package: dotmethod

A require module intended to be used along with the sweet-exp and postfix-dot-notation lang-extensions together, for example:

#lang postfix-dot-notation sweet-exp racket
require dotmethod/dotmethod

syntax
dotmethod

#lang postfix-dot-notation sweet-exp racket
require dotmethod/dotmethod
dotmethod pred-expr obj-id.method(args ...)
  method-body
  ...+
;or
dotmethod pred-expr obj-id.method
  method-expr ; a function expression

Examples:

>

require dotmethod/dotmethod

>

dotmethod list? lst.ref(i)
  (list-ref lst i)

>

dotmethod hash? hsh.ref
  (case-lambda ; can use case-lambda or any other expression here
    [(key) (hash-ref hsh key)]
    [(key else) (hash-ref hsh key else)])

>

let ([lox '(a b c d)])
  lox.ref(2) ; you could also write (lox.ref 2) or lox.ref 2 if you prefer
             ; this actually means ((ref lox) 2) in normal lisp notation

'c
>

let ([ht (hash 'a 1 'b 2 'c 3)])
  values
    ht.ref('a)
    ht.ref('d 'not-found)

1
'not-found
>

define adder%
  class object% (super-new)
    init-field a
    define/public add(b)
      (+ a b)

>

dotmethod (is-a?/c adder%) adder.add(b)
  (send adder add b)

>

define five-adder (make-object adder% 5)

>

five-adder.add(2)
7

syntax
dotmethods

#lang postfix-dot-notation sweet-exp racket
require dotmethod/dotmethod
dotmethods
  pred-expr obj-id.method(args ...)
    method-body
    ...+
  ...

Examples:

>

require dotmethod/dotmethod

>

dotmethods
  list? lst.ref(i)
    (list-ref lst i)
  hash? hsh.ref
    (case-lambda
      [(key) (hash-ref hsh key)]
      [(key else) (hash-ref hsh key else)])

>

let ([lox '(a b c d)])
  lox.ref(2)

'c
>

let ([ht (hash 'a 1 'b 2 'c 3)])
  ht.ref('a)
1

2 #lang dotmethod🔗ℹ

#lang dotmethod

package: dotmethod

A lang-extension for dotmethods so that

#lang dotmethod your-base-language

Is roughly equivalent to

#lang afl postfix-dot-notation sweet-exp your-base-language
(require dotmethod/dotmethod)

I say roughly, because unlike with just blindly adding a require, it still works properly if your-base-language doesn’t allow require forms to be inserted like that.

Example:

#lang dotmethod racket
dotmethods
  list? lst.ref(i)
    (list-ref lst i)
  hash? hsh.ref
    (case-lambda
      [(key) (hash-ref hsh key)]
      [(key else) (hash-ref hsh key else)])
let ([lox '(a b c d)])
  lox.ref(2)
let ([ht (hash 'a 1 'b 2 'c 3)])
  ht.ref('a)