[pro] User defined format functions

[Matthew D. Swank]

On 01/25/2011 02:12 PM, Didier Verna wrote:
> Daniel Weinreb wrote:
>
>> > Yes, we use it heavily, mainly for date/time processing, which can be
>> > very complicated when you're dealing with time zones and such. 
>> > Example:
>> >
>> > (list :departure-time (format nil "~/zul%ISO8601/" departure-time-zul)
>   OK, but does it really buy you anything, compared to just calling a
> specific function directly? Your examples all seem to contain only one
> format directive.
>
Even a single directive is helpful if it's short enough.  I try to
mitigate some of the more cumbersome aspects of using ~// by defining a
single generic function, format-value, that has a ~// compatible
argument list.  There is an in-lined wrapper function, f, that resides
in a package that has a single letter nickname (of course that invites
other problems).  Anyway, I end up using ~/p:f/ in a lot of format
control strings.

Matt