Closure ¶

G-Golf closure high level API.
The G-Golf integration with GObject Closures.

Classes ¶

<closure>

Accessors and Methods ¶

!g-closure

!function

!return-type

!param-types

invoke

Description ¶

The GLib/GObject type system supports the creation and invocation of ‘Closures’, which represents a callback supplied by the programmer (see Closures if you are curious about the low-level description and API, though you don’t need to to understand and use the high level API described here).

Its infrastructure allows one to pass a Scheme function to C, and have C call into Scheme, and vice versa. In Scheme, a <closure> instance holds a pointer to a GClosure instance, a Scheme procedure, the type of its return value, and a list of the type of its arguments.

Closures can be invoked with invoke, for example:

,use (g-golf)

(make <closure>
      #:function (lambda (a b) (+ a b))
      #:return-type 'int
      #:param-types '(int int))
⇒ $2 = #<<closure> 55f24a0228d0>

(invoke $2 3 2)
⇒ $3 = 5

Classes ¶

Class: <closure> ¶

Its slots are:

g-closure

#:accessor !g-closure

function

#:accessor !function
#:init-keyword #:function

return-type

#:accessor !return-type
#:init-keyword #:return-type

param-types

#:accessor !param-types
#:init-keyword #:param-types

The #:return-type and #:param-types accept respectively one symbol and a list of symbols that are members of the %g-type-fundamental-types.

Instances of the <closure> class are immutable (to be precise, there are not meant to be mutated, see GOOPS Notes and Conventions, ’Slots are not Immutable’).

Accessors and Methods ¶

Note: in this section, the closure argument is [must be] a <closure> instance.

Accessor: !g-closure closure ¶

Accessor: !function closure ¶

Accessor: !return-type closure ¶

Accessor: !param-types closure ¶

Returns the content of their respective slot for closure.

Method: invoke closure . args ¶

Returns the result of the invocation of closure, using (the possibly empty list of) args.

This is a ‘low level’ method, not used internally, provided mainly for debugging (or demonstration) purposes, so you may test and verify your callbacks and signals procedures³⁵.