1.4.3.1 Special method argument and result conversion
For certain types of argument, there is more than one useful conversion from the FLI value to a Lisp value. To control this, the argument specification can include an
arg-style
, which describes how the argument should be converted. If the
arg-style
is specified as
:foreign
then the argument is converted using normal FLI rules, but by default certain types are converted differently:
Special argument conversion for
define-objc-method
|
Argument type
|
Special argument behavior
|
|
ns-rect
|
The argument is a vector.
|
|
ns-point
|
The argument is a vector.
|
|
ns-size
|
The argument is a vector.
|
|
ns-range
|
The argument is a cons.
|
|
objc-bool
|
The argument is
nil
or
t
.
|
|
objc-object-pointer
|
Depending on the Objective-C class, allows automatic conversion to a string or array.
|
|
objc-c-string
|
The argument is a string.
|
Likewise, result conversion can be controlled by the
result-style
specification. If this is :
foreign
then the value is assumed to be suitable for conversion to the
result-type
using the normal FLI rules, but if
result-style
is :
lisp
then additional conversions are performed for specific values of
result-type
:
Special result conversion for
define-objc-method
|
Result type
|
Special result types supported
|
|
ns-rect
|
The result can be a vector.
|
|
ns-point
|
The result can be a vector.
|
|
ns-size
|
The result can be a vector.
|
|
ns-range
|
The result can be a cons.
|
|
objc-bool
|
The result can be
nil
or
t
.
|
|
objc-object-pointer
|
The result can be a string or an array.
|
|
objc-class
|
The result can be a string naming a class.
|
LispWorks Objective-C and Cocoa Interface User Guide and Reference Manual - 4 Apr 2005
