John Darrington <[EMAIL PROTECTED]> writes: > Another problem I've encountered: I'm getting this assertion in > casefile_append : > > assert (cf->mode == WRITE); > > Would it not be appropriate to allow write-after-read for random > casereaders ?
It should be possible, although I'll note that writing is not associated with a casereader. I'm beginning to believe that casefiles should not be used for GUI access. Instead, we should create a new, more dynamic structure for GUI access, one that supports the casefile operations. For convenience, I'll call it a "flexfile", because it's flexible. The GUI would use flexfiles where the TUI uses casefiles. I'd write a wrapper that allowed them to be used interchangeably. I've been thinking about how to implement such a data structure. I think what would be wanted is a B-tree (as I think you mentioned), where each item in the tree is a group of columns. Inserting or deleting cases inserts or deletes items in the B-tree. Initially there would only be a single B-tree. Inserting columns would create additional B-trees parallel to the initial one. Because each B-tree would have the same structure, only a single index would be necessary. This could be easily prototyped with Berkeley DB. It sounds like you don't know about Berkeley DB, but it's enormously useful, so I'd recommend looking it up: http://dev.sleepycat.com/index.html -- Ben Pfaff email: [EMAIL PROTECTED] web: http://benpfaff.org _______________________________________________ pspp-dev mailing list [email protected] http://lists.gnu.org/mailman/listinfo/pspp-dev
