Re: Add support for cksum --algorithm [sm3]

[Michael Stone]

On Thu, Sep 09, 2021 at 01:20:56PM +0100, Pádraig Brady wrote:
> On 09/09/2021 00:39, Michael Stone wrote:
> > On Tue, Sep 07, 2021 at 04:45:23PM +0100, Pádraig Brady wrote:
> > > This patch set refactors all digest implementations
> > > to their own modules, all interfaced through digest.c.
> > > All file operations and diagnostics are done in digest.c.
> > > All digests are made available through `cksum -a`.
> > > Also we add support for SM3 through `cksum -a sm3` only.
> >
> > Might be nice if there was something like "-a list-available" to see
> > what algorithms are available without parsing the --help output.
>
> That's pretty much supported already in the argmatch functionality.
> I.e. if you use `cksum -a list-available`, the list of possibilities are 
> printed.
> I generally use that feature like:
>
> $ cksum --algo=

I don't think that's all that much better than just parsing --help -- 
there's still a lot of formatting and unnecessary verbiage to weed out. 
If that is the preferred approach, though, then document that as the 
preferred/stable way to programatically detect the available algorithms. 
(In general I think one of the problems with the way the unix command 
line has evolved is that it's generally easier to just stick with 
whatever functionality existed 20 years ago than it is to write shell 
scripts that can discover what new functionality is present and fall 
back gracefully. Designing a new command that's intended to be 
extensible without building in a way for consumers to easily find out 
what extensions are present seems like a bad idea.)