Hi, Often I'd like to make a wrapper for a given function that has default values (possibly with keywords). So if I want my function to have the same default values for one particular optional argument, I need to redefine it myself.
For example, suppose there already exists a function foo like this: (define (foo arg1 [arg2 <some-complicated-default-value>]) ....) And I want to make a wrapper for foo on arg1, but keep foo's arg2 default value: (define (bar [arg2 <the-same-complicated-default-value>]) (foo 5 arg2)) But I don't feel right when I need to redefine the default argument, for a few reasons: - I feel bar should not need to know foo's arg2 default value. - if arg2 has a complicated default argument, it is "painful" and error-prone to rewrite it (and if the docs for the default value for arg2 are simplified, it may be problematic), - if the specification of foo's arg2 changes, I need to change bar too (though sometimes bar's arg2 needs not reflect the change, but often it does), I would prefer something like: (define (bar [arg2 (get-default-value foo arg2)]) (foo 5 arg2)) which is transparent w.r.t. foo. Does this feature exist, or does it even have a name? Or can it be easily implemented (maybe keywords could help)? Thanks, Laurent
____________________ Racket Users list: http://lists.racket-lang.org/users
