On 2013-03-22 09:14, Dmitry Olshansky wrote:
OK so c points to [1, 2, 3, 4, 5] (and who knows if it's 5 bytes or 5
ints) slice. *c is that slice, (cast(int[])*c)[1..3] is pieces of that
slice an r-value.
Mmm so you are returning a pointer to r-value (a local temporary)?
What's the point of the code?
I'm showing here a reduced minimal test case, that's why it looks
strange. The full source code is here:
https://github.com/jacob-carlborg/orange/blob/master/orange/serialization/Serializer.d#L1672
private T* getDeserializedSlice (T) (Slice slice)
{
if (auto array = slice.id in deserializedSlices)
return &(cast(T) *array)[slice.offset .. slice.offset +
slice.length];
return null;
}
In my serializer I'm storing already deserialized arrays in a
associative array, looking like this:
void[][size_t] deserializedSlices;
The "size_t" is a unique identification. What I'm doing here is
returning a slice from an already deserialized array. "Slice" is a
struct as follows:
struct Slice
{
size_t id; // id of the array the slice originates to
size_t offset; // start position of the slice in the array
size_t length; // length of the slice
}
What I'm doing in "getDeserializedSlice" is checking if the slice id is
available in the associative array. If it is I deference the array
(since I'm getting a pointer from the "in" expression), then casting it
to the correct array type. After that I'm slicing the array and returns
a pointer to it. I figured that was safe since it's always stored in the
associative array, but that might not be the case.
I guess I could return the slice by an out parameter instead and return
a bool from the function.
--
/Jacob Carlborg
