Re: Create \temporary for doing overrides without pop-first set (issue 6687044)

[tdanielsmusic]

I'm not sure this is the right way to go.
Here's my reasoning:

a) Unifying the interface to context and grob properties
seems to be a desirable long-term goal; at least several
people have spoken in favour of it.  But we do not yet
have a proposal for doing this.  In particular we do not
have agreement about desirable syntax and semantics for
modifying properties, although several suggestions have
been made.

b) The present semantics of \override are clearly deficient,
as evidenced by the need for this patch, in that a proper
stack of properties is required to avoid called functions
changing the settings made by the caller.  This is of
minor importance now as few functions so that, but is
likely to increase in importance as more complex functions
are devised.

c) The scope for writing music functions is now much
greater thanks to sterling work by David K, and others
are increasingly taking advantage of them.  Functions
are frequently posted on the user list in response to
calls for aid.  So whatever is implemented in response
to (b) will inevitably filter into the user domain, and
into the documentation.  Achieving (a) is going to
take a long time, so any solution to (b) which is
introduced now will become established.

d) The discussion on -devel about the several ways of
approaching this issue has not yet come to a consensus.

So rather than introduce this change into the code base
now I would prefer to see more discussion and hopefully
agreement on the best way of approaching (a), in
particular what the optimum primitive operations should
be.  That will then inform this discussion about the
best short-term step to take to resolve (b), as a means
of facilitating progress towards (a), without the need
at some stage to withdraw established facilities.

Trevor

http://codereview.appspot.com/6687044/