tree 4d34d9d7fc8212d53a7c67cd49ad470d2089e104
parent f0bdadb9ea08ddafc04b1484d0c945a899d9b88a
author Robert Griesemer <gri@golang.org> 1560371575 -0700
committer Robert Griesemer <gri@golang.org> 1560383452 +0000

design/32437-try-builtin.md: adjustment to `try` signature

The proposal defines `try` as a built-in taking n+1 arguments and
returning n results. It relies on the "usual" assignment rules which
make it possible to call `try` with a multi-valued function call
as argument. The proposal also suggests that if need be, `try` may
be "easily" extended to take an addition argument such as a handler.
This is not possible with the current signature as was pointed out
by Andrew Ekstedt (https://github.com/magical) in the discussion of
the corresponding issue (#32437).

This change modifies `try` such that it accepts a single, possibly
multi-valued expression as argument instead. Because only a single
argument is expected now, it's easy to extend `try` to accept an
optional 2nd argument in the future, if so desired.

This change has no substantial impact on this proposal. It does
make it impossible to use `try` with more than one explicitly
provided incoming arguments, such as in

	x, y, z := try(a, b, c, err)

but such code is mostly pathological and can always be rewritten
using `if` statements if necessary.

Change-Id: I687e0e1ab63328c1b381715cee7f77fdfac45b67
Reviewed-on: https://go-review.googlesource.com/c/proposal/+/181878
Reviewed-by: Ian Lance Taylor <iant@golang.org>