http://www.perlmonks.org?node_id=140249


in reply to Re^2: Refactor method calls or not?
in thread Refactor method calls or not?

It's not exactly the same. For example, there would be no need to go through any contortions for dispatching and so forth. Two calls to the macro would create two normal functions called add_company and add_financial_data, which one would then just use as usual.

E.g. the Lisp code might look something like this (first the macro is defined, then it is called twice to create the methods, then a couple of calls to the methods).:

(defmacro make-add-method (method-name table-name) `(defmethod ,method-name ((self my-class) data) (let ((returned-data (generic-insert self data ,table-name))) (unless (check-error self) (commit (database-handle self))) returned-data))) (make-add-method 'add-company "company") (make-add-method 'add-financial-diary "financialDiary") (add-company my-object company-data) (add-financial-diary my-object financial-data)

The macro does indeed work something like the method of using closures in the previous node - it takes a template for the code that we want (the form following the backquote) and fills in the parts that we want to vary (the forms introduced by ,). There's no need for any of the dispatching contortions, though; it's just as though we typed in the methods ourselves. While Lisp macros are great for many more things than this, they work well for this sort of thing as well, where pieces of code have very similar form, which can then be easily and naturally abstracted out.