J. Landman Gay wrote:
Richard Gaskin wrote:
1. Using a function for a sortKey expression introduces a "sometimes"
rule in terms of understanding the order of expression evaluation in the
engine, in which most of the time functions are evaluated first but in
this case the function is applied repeatedly for each line of the sort
container as the sort command is run.
Well, not really. It's more like a substitution for what the engine does
anyway. When the engine sorts a container, it has to assign a position
for each element being sorted. A custom sort function does the same
thing; the engine will use the number returned by the function when
arranging the elements.
The order of evaluation hasn't changed, and functions are still
evaluated first. But when sorting, each element has to be evaluated
individually.
Right. That's what initially threw me.
As far as I can recall, this optional form of the sort command is the
only way to call a function iteratively without using a repeat loop.
Are there others I've forgotten?
It's very handy, but a cognitive hurdle for me at first. I'd never seen
anything like it before.
Anyone else have a mental hiccup when they first encountered this?
--
Richard Gaskin
Managing Editor, revJournal
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