Follow-up Comment #3, bug #22565 (project gnustep):
Lets have closer look at some key paths...
(I'm not using @count because it's special since the parameter is optional)
[EMAIL PROTECTED]
Currently implementation starts evaluating from left to right:
#define vfk valueForKey
t = [displayGroup vfk: @"allObjects"]
t = [t vfk: @"@sum.value"]
Now NSArray's implementation would invoke computeSumForKey:@"value" on
itself. That implementation iterates over the receivers objects and asks each
item:
sum += [[currentItem valueForKey:@"value"] decimalValue]
and return the sum. Fine...
Now let's look at:
[EMAIL PROTECTED]@avg.value
The current proposed implementation would send:
t = [displayGroup vfk: @"allObjects"]
t = [t vfk: @"@sum.detailArray"]
for each item in the array
sum += [[currentItem vfk:@"detailArray"] decimalValue]
this is broken... we do not want to send detailArray's decimalValue.
What we actually want is to send:
t = [displayGroup vfk: @"allObjects"]
t = [t vfk: @"@[EMAIL PROTECTED]"]
And then possibly have NSArray's implementation send something like:
for each item in detailArray
[item vfk:@"avg.value"]
collect an interim array of {@"value"=<numbers>} then invoke
[interimArray vfk:@"sum.value"]
and return that result.
Given a key path like:
[EMAIL PROTECTED]@avg.value.stringValue.length
We would still want to merely group the aggregate keys I believe...
So I guess wrt NSArray's implementation I guess the part I quoted is OK, but
the calculation of the range is wrong. We want to group the aggregate key
paths. And then we need to look into NSArray's valueForKey: implementation to
be able to handle arbitrary aggregate key paths...
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