Should marking a system preloaded drop its build information?

Faré fahree at
Wed Sep 14 23:05:16 UTC 2016

In the patch he submitted, Daniel Kochmanski modified
register-preloaded-system so that it eagerly replaces any previously
loaded system with a placeholder object that has no build information.
In the current ASDF, the preloaded system is only lazily registered if
the system is requested but not previously loaded (or is cleared). In
my current working branch, it is eagerly registered but only if no
previous system was loaded or after clearing it. [Going from lazy to
eager registration fixes a bug with already-loaded-systems and thus

The big design question is: should registering a system as preloaded
drop its build information?

Advantage of erasing the existing system information: the behavior of
the image is uniform on all machines, and trying to resume development
on a machine without the same source code at the same location won't
cause a flurry of filesystem accesses at the wrong paths. [Note that
immutable systems never try to access the filesystem, unlike regular
preloaded systems, even with build information present.]

Advantage of keeping the existing build information: you can resume
the production image and resume incremental development on a machine
that has the same source code at the same location. And if you to drop
it, you can explicitly call clear-system after you call

I am strongly inclined to keeping the build information around: it's
always easy to erase the information later, but hard to reconstitute
dropped information.

—♯ƒ • François-René ÐVB Rideau •Reflection&Cybernethics•
A Libertarian Constitutional Amendment: Congress shall make no law.

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