Dimension existence

[Tuukka Hastrup <Tuukka.Hastrup@xxxxxx>]

Hello again,
Now that I have first versions of FlatRaster ready, I need some more
accurate specs: In what states of existence can a dimension be? (I
suggest we name cell-in-the-middle-and-all-dimensions aka SingleCell
raster as FlatRaster.)

As I wrote earlier (but you didn't have anything to say of it), at the
moment dimensions are created the first time they're used. 'Usage' means
creating a cell along the dimension or trying to go along the
dimension. This way most dimensions are created when gZZ creates the
client space or when the user cycles to the dimension in a view.

This policy is good for most of cases. It doesn't assure existence of
any implicit dimensions, however. At the moment such dimensions are
d.cellcreation, d.slices and d.masterdim. d.cellcreation is the one
revealing the problem: it should exist always, but as it isn't
referenced during normal startup procedure, it isn't there (visible)
before the user creates it (using it as a view dimension). I think it
should be. The effect is visible in FlatRaster (I haven't commited it
yet, though.)

Possible solutions: (kinda dirty ones)
- have a list of these implicit dimensions and "touch" them during
startup
- initialize d.masterdim with these implicit dimensions (also from a
list)


Tuukka

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