I need to spend some further consideration since it looks like I was unprecise.
When the BaseArray::Append() and the capacity of a BaseArray is reached - BaseArray default size is 16 elements - the internal BaseArray::IncreaseCapacity()is called and it sequentially allocates a new memory block, copies the values of the previous block to the new one, and then the old one is released. Being the values passed to the BaseArray::Append() a reference to myArray[0], it references the first element of the old block and because the code in Append() accesses the reference after the old block has been released, that access is illegal.
@r_gigante said in Fun with maxon::BaseArray:
To temporarily mitigate it you have to cast the value returned from the [] operator before appending it to the proper type.
Actually by writing Int32(myArray[0]) - and here I was indeed unprecise because it is NOT casting but temporary local creating of a copy - a local Int32 copy of myArray[0] is made on the stack at first by the compiler (before calling Append) and then Append(Int32(myArray[0])) references that local copy which is legal.
This behavior is NOT a bug - another initial overlook of mine - but rather a behavior by design which for example is also part of std::vector::push_back().
So, as a rule of thumb, cases where references to array elements are used while the array gets resized must be avoided. This note will be added to the BaseArray Manual in our documentation.
Sorry for the confusion I initially generated and, if further clarification are needed, feel free to come back.
R.
