Deepcopy: Difference between revisions

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=={{header|Phix}}==

Handled natively. Phix uses reference counting with copy-on-write semantics; the initial copy is fast even for huge complex and deeply nested structures (copying a single machine-word-sized reference and incrementing a single machine-word-sized reference count), and when a shared object (anything with a refcount>1) is modified, an internal clone of just one affected level occurs, with all the rest of the structure remaining shared (but obviously still properly protected in the same way).

<lang Phix>object a, b

a = {1,{2,3},"four",{5.6,7.{8.9}}}

b = a

b[3] = 4

?a

?b</lang>

{{out}}

<pre>

{1,{2,3},"four",{5.6,7,{8.9}}}

{1,{2,3},4,{5.6,7,{8.9}}}

</pre>

It is worth noting that this mechanism is also used for parameter passing, and when a local variable is both passed as a parameter and assigned on return, automatic pass-by-reference handling kicks in to avoid any unnecessary internal cloning.

Should you for some (probably misguided) reason really want it, a recursive clone function might look like this:

<lang Phix>function deep_copy(object o)

object res

if atom(o) then

res = o

else

res = repeat(' ',length(o))

for i=1 to length(o) do

res[i] = deep_copy(o[i])

end for

end if

return res

end function

object c = deep_copy(b)

?c</lang>

Or you could just serialize and deserialize:

<lang Phix>include builtins\serialize.e

object d = deserialize(serialize(a))

?d</lang>

{{out}}

<pre>

{1,{2,3},4,{5.6,7,{8.9}}}

{1,{2,3},"four",{5.6,7,{8.9}}}