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Diffstat (limited to 'txr.1')
| -rw-r--r-- | txr.1 | 81 |
1 files changed, 81 insertions, 0 deletions
@@ -18250,6 +18250,56 @@ in a function slot. increment #<function: type 0>) .cble +.coNP Macro @ umeth +.synb +.mets (umeth << slot ) +.syne +.desc +The +.code umeth +macro binds the symbol +.meta slot +to a function and returns that function. + +When that function is called, it expects at least one argument. +The leftmost argument must be an object of struct type. + +The slot named +.meta slot +is retrieved from that object, and is expected to be a function. +That function is called with the same arguments. + +The syntax can be understood as a translation to a call of the +.code umethod +function: + +.cblk + (umeth s) <--> (umethod 's) +.cble + +The macro merely provides the syntactic sugar of not having to quote the +symbol. + +.TP* Example: + +.cblk + ;; seal and dog are variables which hold structures of + ;; different types. Both have a method called bark. + + (let ((bark-fun (umeth bark))) + (bark-fun dog) ;; same effect as dog.(bark) + (bark-fun seal)) ;; same effect as seal.(bark) +.cble + +The +.code u +in +.code umeth +stands for "unbound". The function produced by +.code umeth +is not bound to any specific object; it binds to an object whenever it is +invoked by retrieving the actual method from the object's slot at call time. + .coNP Function @ make-struct-type .synb .mets (make-struct-type < name < super < static-slots < slots @@ -18610,6 +18660,37 @@ the supertype's static slot, passing to that function as the leftmost argument, followed by the function's own arguments. +.coNP Function @ umethod +.synb +.mets (umethod << slot-name ) +.syne +.desc +The +.code umethod +returns a function which represents the set of all methods named by +the slot +.meta slot-name +in all structure types, including ones not yet defined. +The +.meta slot-name +argument must be a symbol. + +This function must be called with at least one argument. The leftmost +argument must be an object of structure type, which has a slot named +.meta slot-name . +The function will retrieve the value of the slot from that object, +expecting it to be a function, and calls it, passing to it all of its +arguments. + +Note: the +.code umethod +name stands for "unbound method". Unlike the +.code method +function, +.code umethod +doesn't return a method whose leftmost argument is already bound to +an object; the binding occurs at call time. + .coNP Function @ slot-p .synb .mets (slot-p < type << name ) |