I am new to Go, but my understanding is that assignments create copies. The "new" function returns a pointer, which makes sense because then when you assign the return value to a variable, it will only copy the pointer. However, since "make" does not return a pointer, will the newly allocated object not be copied when assigning it to a variable, resulting in a second allocation for the copy?
variable := make([]int, 4, 7)
[]int is a slice, not an array; and slices are basically pointer views into an underlying array:
A slice is a descriptor for a contiguous segment of an underlying array and provides access to a numbered sequence of elements from that array.
Your make line (a) instantiates a [7]int which you never see, and then (b) returns a slice that is essentially just a pointer into the first 4 elements into that array. Since that slice is just a pointer and a length, it is cheap to pass by value. I'm not sure if Go actually creates the slice "internally" to make and then returns it to your variable, or whether it inlines that directly; but the effect either way would be negligible.
From the docs:
That is, executing
make([]T, length, capacity)produces the same slice as allocating an array and slicing it, so these two expressions are equivalent:
make([]int, 50, 100) new([100]int)[0:50]
