On 2013-11-04 15:47, David Cole wrote:
My question is still not answered completely:
When should the new variable be added? On startup is not really
possible because it might be the case that your src/binary directory
is not set properly.
So you would agree that it makes sense to do it "on configure" but
only if the cache is empty? This will not allow to overwrite the
variable via parameter but I guess that usecase is not very
common?
On startup is the only time it does make sense. After that, the user
should be in charge, and the command line settings should not be
re-applied again after a user makes an edit. You don't need the
src/binary directories set properly necessarily in order to add a cache
entry to the UI.
There are two mostly separate issues here.
As far as the bug, the ccmake behavior is (IMO, but seems generally
shared) is just wrong. physhh's questions (above) don't apply to this
case because there is no concept of interactively selecting the build
directory in ccmake. So fixing this is, if not easy, at least easy to
understand how it should behave.
As far as cmake-gui, there are no backward compatibility issues because
right now it just doesn't support -D at all.
It does however get more complicated...
- What should happen with a -D option if there is not initially a build
directory selected?
- What should happen if the wrong build directory is initially selected
and subsequently changed? It seems non-desirable here to forget -D
(etc.) entirely at that point.
ccmake and cmake-gui *should* behave (in *my* opinion) as follows:
- on startup, load the CMakeCache.txt values (if there are any) from the
previous run
- then apply the -D arguments so that any -D arguments given on the
command line overwrite previous cache entries (just like command line
cmake does already)
- then put the user in charge and wait for user input
I suppose if I were writing the patch, I would have cmake-gui remember
whatever -D/-U/etc. options are given and apply them to any build
directory when it is selected, after loading the cache (if any). But
*don't* pass them on the cmake (except inasmuch as the initial cache
will contain them, modulo any changes the user made in the mean time).
IOW, if I specify a -D to cmake-gui, change that value, then change to
some other build directory, that -D would reset to the value from the
command line. This is consistent with the current behavior that any
other changes to the cache of the initial build directory are also lost.
Hmm... a corner case comes to mind, however; if I configure build
directory A after changing a -D value, then switch to build directory B,
then back to A, I probably don't want to reapply the -D. So maybe
cmake-gui would keep track of what build directories have been
configured in that instance and not apply -D/etc. to them. (However,
it's probably not very common for that to happen.)
Make sense?
--
Matthew
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