python - Swig tool and C++. Being too clever -


http://www.swig.org/papers/pytutorial98/pytutorial98.pdf comes above link:

enter image description here

i know old publication possible information outdated.

i ask:

"seems work fine c++ if aren't being clever" mean, clever?

is there known situation/case shuold careful programming c++ modules , extending python using swig tool?

the slide strange , misleading. swig not transform pass-by-value pass-by-reference @ all. let me try clarify example:

let's in example have c++ function

double dot_product(vector a, vector b);

now in plain c++ (no swig, no wrapping) may use function in following examples:

1.

vector = vector(1,0); vector b = vector(0,1); double 0 = dot_product(a, b);

2.

vector *a = new vector(1,0); vector *b = new vector(0,1); double 0 = dot_product(*a, *b);

in both cases, function in fact called in same way using call-by-value.

swig wraps objects structure contains pointer object, under hood swig passes pointers around everything, , therefore uses syntax in second example. there no conversion / transformation of call semantics going on whatsoever.

to answer questions:

"seems work fine c++ if aren't being clever" mean, clever?

i have no idea. stated in answer, joke.

is there known situation/case shuold careful programming c++ modules , extending python using swig tool?

this broad question, , there pitfalls, related memory management. however, particular "transformation" not issue.

for reference, here relevant entry in swig manual. note worded differently: function transformed accept pointers. nothing said "call semantics" (since non-issue).


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