Sorry, forget the first part entirely, I was still confused when I wrote it. Definitely the semantics of values are very different, but they don't matter for this. I think the rough equivalent of the capture-by-copy C++ lambda is the function definition I provided with default values. -- Devin On Tue, Jan 19, 2016 at 6:39 AM, Devin Jeanpierre <jeanpierreda@gmail.com> wrote:
On Tue, Jan 19, 2016 at 6:10 AM, <haael@interia.pl> wrote:
Hi
C++ has a nice feature of explicit variable capture list for lambdas:
int a = 1, b = 2, c = 3; auto fun = [a, b, c](int x, int y){ return a + b + c + x + y};
This allows easy construction of closures. In Python to achieve that, you need to say:
This is worded very confusingly. Python has easy construction of closures with implicit variable capture.
The difference has to do with "value semantics" in C++, which Python doesn't have. If you were using int* variables in your C++ example, you'd have the same semantics as Python does with its int references.
def make_closure(a, b, c): def fun(x, y): return a + b + c + x + y return def a = 1 b = 2 c = 3 fun = make_closure(a, b, c)
The usual workaround is actually:
a = 1 b = 1 c = 1 def fun(x, y, a=a, b=b, c=c): return a + b + c + x + y
-- Devin