Am 2013-10-15 11:00, schrieb leledumbo:
> I := TagArray[ord(TagSet)];
> I := TagArray[ord([tag1,tag5])];
> It's unclear what you expect from such statements. I think you better
> explain the high level problem, I smell a misdesign in the solution.
Yes, there is always the danger of overcomplicating things.
But I think in this case it makes sense.
I have a file manager that logs whole directory branches.
Files can have attributes like "Tagged" or "matching filter mask".
There can be even more attributes like multiple tag sets or whatever:
type FlagType = (Tagged,FileMaskMatch);
FlagSetType = set of FlagTyp;
I now want to store the number of files and the bytes for each directory branch.
All possible set combination need to be considered because I may show all files
that:
are tagged = [Tagged]
match a filter mask = [FileMaskMatch]
are tagged AND match a filter mask = [Tagged,FileMaskMatch]
all files = []
This makes 4 possible combinations but for a 3rd attribute
I already have 8 and yet another doubles it to 16.
For each of these possible sets I want to store:
FileSumtype = record
Number : Cardinal;
Bytes : QWord;
end; // of record
with
type BranchSumType = array[0..(1 shl (ord(High(FlagSetTyp))+1))-1] of
FileSumType; // 0..2^n-1
I can now use a set variable
var FlagSet : FlagSetType;
to store what I want to display and use this variable for indexing the array
var BranchSum : BranchSumType;
when storing file information I can store them for all set combinations:
BranchSum[byte([ ])].Number := ...;
BranchSum[byte([ ])].Byte := ...;
BranchSum[byte([ FileMaskMatch])].Number := ...;
BranchSum[byte([ FileMaskMatch])].Byte := ...;
BranchSum[byte([Tagged ])].Number := ...;
BranchSum[byte([Tagged ])].Byte := ...;
BranchSum[byte([Tagged,FileMaskMatch])].Number := ...;
BranchSum[byte([Tagged,FileMaskMatch])].Byte := ...;
This is convenient as I need to use procedures to propagate these numbers up in
the tree,
but not always all of them (because not all of them change when I only change
the filter mask).
So I can use a FileSet variable as parameter for a procedure and index the
array with it:
procedure PropagateUp(const F : FileSetType; const Values : FileSumType);
begin
..
BranchSum[byte(F)] := Values[byte(F)];
..
end;
So far this works fine and is quite fast.
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