For controlling custom printing of a struct, you can use
`gen:custom-write` generic interface. An example is like the use of
make-cosntructor-style-printer:
https://docs.racket-lang.org/reference/structutils.html#%28def._%28%28lib._racket%2Fstruct..rkt%29._make-constructor-style-printer%29%29
Under the hood, the `struct` form is expanded down to the primitive
`make-struct-type` API and code for creating associated accessor
bindings, mutator bindings and reflection information bindings. In
`make-struct-type`, all arguments and configurations are made
explicit. For example, `#:transparent` option compiles down to passing
#f for the `inspector` argument.
You can use the expand function to expand struct definitions and see
its underlying implementation:
> (pretty-write (syntax->datum (expand '(struct foo (A B)))))
(begin
...
(define-values
(struct:foo foo1 foo? foo-A foo-B)
(let-values (((struct: make- ? -ref -set!)
(let-values ()
(let-values ()
(#%app
make-struct-type
'foo
'#f
'2
'0
'#f
null
(#%app current-inspector)
'#f
'(0 1)
'#f
'foo)))))
...
A struct type can be associated with many struct type properties. The
`props` argument is what `#:property` expands down to. With struct
type properties, you associate arbitrary data with a struct type (not
their instances). The generic method interfaces like
`gen:custom-write` also use struct type property to attach custom
printing function to a struct type. In David's reply, gen:custom-write
is documented as part of the struct printing protocols.
Shu-Hung
On Mon, Mar 26, 2018 at 10:58 AM, Kevin Forchione <lyss...@gmail.com> wrote:
> In another thread on structs it was confirmed that structs are in essence a
> vector with some fancy bindings associated. But there must be more going on,
> for instance, the definition (struct foo (A B)) creates a function foo that
> when applied does not print like a vector. Is there any documentation
> instructs that does into the details of what they are and are doing under the
> hood?
>
> Kevin
>
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