How Can I Safely and Efficiently Cast a CGO Array to a Go Slice?

Casting a CGO Array to a Go Slice: Exploring Safer and Cunning Approaches

In Go, bridging the gap between CGO arrays and Go slices can be a recurring challenge. A typical approach involves manually casting each CGO array element to the desired Go type, as seen in the following example:

doubleSlc := [6]C.double{}

// Fill doubleSlc

floatSlc := []float64{float64(doubleSlc[0]), float64(doubleSlc[1]), float64(doubleSlc[2]),
                      float64(doubleSlc[3]), float64(doubleSlc[4]), float64(doubleSlc[5])}

While functional, this method can be tedious and prone to errors. Are there more efficient and reliable ways to achieve the same result?

Safe and Portable Casting

One straightforward approach is to utilize a for loop to explicitly convert each CGO array element:

c := [6]C.double{1, 2, 3, 4, 5, 6}
fs := make([]float64, len(c))
for i := range c {
  fs[i] = float64(c[i])
}

This method ensures type safety and portability across different platforms.

Unsafe and Cunning Trickery

Alternatively, a more unorthodox solution leverages Go's unsafe package and pointer manipulation:

c := [6]C.double{1, 2, 3, 4, 5, 6}
cfa := (*[6]float64)(unsafe.Pointer(&c))
cfs := cfa[:]

By treating the CGO array as a pointer to a float64 array (assuming underlying type compatibility), we can obtain a slice without explicit casting. However, this method relies on unsafe operations and should be handled with caution.

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