On 17/02/2014 19:34, Marco van de Voort wrote:
In our previous episode, Martin Frb said:
Just because there is a function, that includes copying (when modifying
the array), does not mean there is copy on write.
So basically, if for a given size x, setlength(x,1) always reallocates, then
it is COW, otherwise not :-)
Not sure what you mean?
(and even if it does, one could still argue it is an implementation detail)
But if you want to use the term, IMHO it would be:
"Dynamic arrays have no copy-on-write. But SetLength perform a
copy-on-write on dynamic arrays."
I am not sure, if that makes to much sense either. copy-on-write should
apply to the data type, not to the/a function that acts on data of that
type.
And the data type "dyn array" does not have copy-on-write.
If it had, the *ALL* [1] write operation would have to trigger the COW.
[1] this excludes access via pointer, that is designed to bypass the
type specific behaviour.
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