(as requested by Asumu)
A witness accessor or mutator is still required to create a structure
chaperone, but `#f` can be provided in place of a redirection, and
then impersonator properties can be attached to the chaperone.
At the same time, adjust `(chaperone-of? v1 v2)` so that `v1` as a
chaperone is not required to preserve non-redirecting chaperones of
`v2`.
The overall consequence is that a redirection procedure can cooperate
with a (suitably protected) impersonator property to override
redirection behavior without running afoul of the chaperone invariant
and without requiring O(N) space for O(N) overrides. For example, the
contract system can implement the re-application of a contract with
different blame information by overriding blame information as
represented by properties, instead of adding a new chaperone layer
every time that blame changes.
... and all the same for non-chaperone impersonators, of course.
* Expect DrRacket to make a copy of the copy of the snip we give it.
* Add documentation explaining some of the trickiness involved in this code
and how it might be possible to make it less brittle.
* Add a note about editor-snip% not behaving as expected when non-textual
elements are inserted and subsequently removed (or the underlying
editor object is replaced).
Specifically, add a mechanism so that contract combinators
can accumulate contracts on a value (instead just storing
only one) and then use that in instanceof/c to avoid
putting contracts on values more often.
Also, fill in better contract-stronger implementations in
some of the combinators
This creates a catalog from the specified currently-installed
packages. The catalog can then be used to replicate some or
all of the currently-installed packages in another installation
or other context.
Also extend `pkg/command` so that `#:multi` is useful.
While a foreigh call is normally guarded by a check on the amount
of available stack space, a callbacks triggered by the
scheduler will first put Racket in no-stack-overflow mode, and
then it's too late to check stack space before making further
foreign calls. With Cocoa, there's some chance that the process
will run out of space. Avoid the mismatch by checking the stack
availability at the start of a scheduler iteration.
Fixes a mistake in commit 768b93be82, which dropped a check that is
needed to trigger GCs during a sequence of large-block allocations.
Closes PR 14738
Allow pict arguments, with or without a separation-size
argument.
The recently added contract has rules out providing a
separation size with no arguments, which had been allowed
before. The underlying problem, though, was an inconsistency
in the implementation that allowed 0 pict arguments only
in the case that a separation size is provided.
slightly less terrible
... but ->i still doesn't do as good a job as -> and ->* do for arity
errors (specifically, ->i is still letting the blame-less errors that
application constructs thru when it could be assigning blame)
