Daniel Bünzli <daniel.buen...@erratique.ch> writes:
> Le jeudi, 5 avril 2012 à 11:05, Goswin von Brederlow a écrit :
>> If you are writing a module then consider providing both flavours for
>> functions, one with exceptions and one with options. Even if you only do
>> something like this:
>
>
> I don't think it's a rule that should be applied consistently, I don't like
> libraries that provide tons of convenience functions, too many names. If you
> stick with the option type (or variant cases) the user can quickly wrap the
> function if it needs an exception (or vice-versa but I prefer it that way
> since it's then documented by the function signature and is in my opinion
> better behaved in general).
>
> However in the particular case of finding something in a data structure where
> the user could be confronted with a situation where he can prove that the
> datum will be found I think it's justified to provide both flavours. For
> these cases, in my own code I settled on the following pattern :
>
> val find : 'a t -> key -> 'a option
> (** [find d k] is the value bound to [k] in [d], if any. *)
>
> val get : 'a t -> key -> 'a
> (** [get d k] is like {!find} but raises [Invalid_argument] if [k] is not
> bound in [d]. *)
That pattern works well if you have just one or few such functions and
can think of nice names to differentiate them.
Otherwise submodules are usefull:
module Foo = Foo.Options
or
module Foo = Foo.Exceptions
Foo.do_things ()
or
open Foo.Options
do_things ()
The option and exception raising functions would be named the same and
the user selects one or the other by selecting a submodule.
As said, it is usualy a matter of taste and the users tastes might
differ from the module authors taste. By providing an option and
execption flavour of a function (by different names or submodules hardly
matters) the user can use what he likes as opposed to what the modules
author imposes on him.
MfG
Goswin
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