Should we be avoiding "zstyle -m" ?

[Bart Schaefer <schaefer@xxxxxxxxxxxxxxxx>]

I'm the main culprit here, using zstyle -m to test whether a style
exists before asserting a default, something I first did in
url-quote-magic 20 years ago -- but recently while working on
something else I realized that -m invokes code defined by zstyle -e,
which may be inappropriate at the point where the test appears.

One alternative is to use zstyle -g, but that retrieves only a
specific pattern rather than matching a context.  The other
possibility is zstyle -L, which requires capturing stdout because -L
always returns zero, and further it's uncertain whether the
metapattern matched by -L is similar enough to a context match.  Based
on a quick glance at the code I think they may be identical (that is,
that
  zstyle -L ":completion:$curcontext"
would give the desired result), but there's a lot going on in there.

So what to do here?  Ideas that occur to me ...

1) Allow -L and -g to be combined, to return the list in an array
instead of printing it.
2) Add a -q option to -L, to exit 0 or 1 on found or not found,
without printing.
3) Add an option to -m to only match the context, without interpreting
the value.  Maybe -n ?  In every case where -m is currently used in
Functions/ and Completion/, the value to match is '*'.
4) Variant of #3, which is to skip interpreting the value when
searching for '*' ... but it's possible someone is depending on -e
evaluating with -m.
5) Add an option to go along with -a/-b/-s that installs the style
only if it's not already there.  This still runs the risk of adding a
more-specific style that overrides a user's generic style covering the
context ... unless this new option also takes a context as an
argument?  Which gets ugly.

The first two require altering the way scanhashtable() is used.  The
third and fourth alter the way that lookupstyle() works.

Any thoughts?