Please don't change the lang_hooks into virtual methods. Speaking from a
plugin development viewpoint, C hooks are very easy to override
individually, without having to change the entire object or create a new
one.
I realize that it's not the intended use for the hooks, and not why they
were created. But they enable plugins to do a whole lot more, despite
the limited plugin event callbacks already present (*especially* the
targetm hooks!).
For example, I wanted to add some plugin processing (actually a
top-level asm statement) at the end of a translation unit (with gathered
data) to add some special symbols / GAS directives (not instructions).
But there's no "normal" plugin event for this.
So instead I simply saved the original lang_hooks.parse_file hook
(pointer), overrode the hook with the plugin's, which calls the original
first and then does whatever plugin does. And it works fine. This kind
of thing wouldn't be easily changed with virtual methods I believe.
Once again, I realize that was not the intended use for hooks, but it's
a nice side effect and IMO should be kept.
Plugins suffer a lot from the "chicken and egg" problem (nobody wants to
add events that would not be needed, but nobody codes plugins without
enough events) and hooks kind of solve a lot of it, so that's a good
thing (especially targetm, more so than lang_hooks).
I mean, if you had to first suggest an event and *hope* it gets added
before even starting your plugin (otherwise it would be a waste of
time), you'd just give up. Or at least, the majority would. At least
with hooks, nobody needs to add anything for plugins, since you can
override the C hooks directly from the plugin (while maintaining a chain
for the old one).
