Call Operator() for custom class std::shared_ptr instance

Question

I have my own extended 2d-array class CustomDynamicArray which cover std::vector and allow handle its items by indexes via overloaded operator()

CustomCell& CustomDynamicArray::operator()(size_t colIdx, size_t rowIdx)

until I had simple CustomDynamicArray instance

CustomDynamicArray _field;

I might adressed to array items next way:

_field(x, y) = cell;

or

const CustomCell& currentCell = _field(x, y);

But since I covered my varrible into std::shared_ptr I have an error

std::shared_ptr<CustomDynamicArray> _fieldPtr;
_fieldPtr(x, y) = cell; // Error! C2064 term does not evaluate to a function taking 2 arguments
const CustomCell& currentCell = _fieldPtr(x, y); // Error! C2064    term does not evaluate to a function taking 2 arguments

How I should fix this compile error?

Now I see only way to use this syntax:

(*_newCells)(x, y) = cell;

songyuanyao · Accepted Answer · 2019-08-05T09:17:52.277

4

std::shared_ptr is smart pointer which behaves like raw pointers, you can't call operator() on the pointer directly like that. You could dereference on the std::shared_ptr then call the operator().

(*_fieldPtr)(x, y) = cell;
const CustomCell& currentCell = (*_fieldPtr)(x, y);

Or invoke operator() explicitly (in ugly style).

_fieldPtr->operator()(x, y) = cell;
const CustomCell& currentCell = _fieldPtr->operator()(x, y);

edited Aug 05 '19 at 09:17

answered Aug 05 '19 at 09:13

songyuanyao

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Yep, I see. Is it only way? – Malov Vladimir Aug 05 '19 at 09:14
1

@MalovVladimir Yes, as a smart pointer behaves exactly in the same way as a raw pointer in this way, you have to dereference it first to get its value it's pointing to. – Hatted Rooster Aug 05 '19 at 09:15
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Shouldn't that be `_fieldPtr->operator()(x, y);` ? – Taron Aug 05 '19 at 09:17
@Taron, I have checked. I can use _newCells->operator()(x, y) = cell; syntax, but I had overloaded operator() to simplify syntax. This function call seems a little bit clumsy, but it works. Thanks! – Malov Vladimir Aug 05 '19 at 09:23

score 1 · Answer 2 · answered Aug 05 '19 at 09:13

1

You have to deref the pointer first:

(*_fieldPtr)(x, y) = cell;
const CustomCell& currentCell = (*_fieldPtr)(x, y);

answered Aug 05 '19 at 09:13

Hatted Rooster

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Thanks for answer, Sombrero Chicken – Malov Vladimir Aug 05 '19 at 09:16

Call Operator() for custom class std::shared_ptr instance

2 Answers2