I have a function signature as follows:

```
void analyze(Image * x, std::array<bool, 4> smooth);

```

What I would like is to give this array smooth a default value if the user does not explicitly set this in the call. So I tried something like:

```
std::array<bool, 4> smooth = std::array<bool, 4>
                               ({true, true, true, false}));
void analyze(Image * x, std::array<bool, 4> smooth = std::array<bool, 4>(({true, true, true, false})));

```

No matter what I try, I cannot get it to compile. The example above says "error: expected expression".