Curiously recurring template pattern (CRTP) and derived constructor arguments

Question

I'm using curiously recurring template pattern for creating shared pointer in the following way (below). On Derived::create(...) Visual Studio IntelliSense shows than available arguments are (Args &&...args). How to pass Derived class constructor argument list to Base so that IntelliSense would show me that available arguments are (const std::string &str, int i)?

#include <memory>
#include <string>

template<typename T>
class Base
{
public:
    template<typename... Args >
    static std::shared_ptr<T> create(Args&&... args)
    {
        return std::make_shared<T>(std::forward<Args>(args)...);
    }
};

class Derived : public Base<Derived>
{
public:
    Derived(const std::string &str, int i) {}
};

int main()
{
    auto derived = Derived::create("text", 123);
}

You would have to remove the forwarding version and create overloads for each constructor. Intellisense sees the function interface for what it is, how is it supposed to know that you forward to the constructor (it would additionally have to go through make_shared to figure that out). — jepio
– jepio, Commented Feb 7, 2015 at 21:11
@jepio I seriously disagree! That's exactly, what I mean one shouldn't do: "and you shouldn't orient your designs about your IDE's capabilities, but what compiles and works well." — πάντα ῥεῖ
– πάντα ῥεῖ, Commented Feb 7, 2015 at 21:17
I'm not saying he should do it. I'm telling him what he would have to do and that it is impossible/unreasonable to expect it to work. — jepio
– jepio, Commented Feb 7, 2015 at 21:35

πάντα ῥεῖ · Accepted Answer · 2015-02-07 21:11:10Z

0

"How to pass Derived class constructor argument list to Base so that IntelliSense would show me that available arguments are (const std::string &str, int i)?"

#include <string>
#include <memory>

template<typename T>
class Base {
public:
    template<typename... Args >
    static std::shared_ptr<T> create(Args&&... args) {
        return std::make_shared<T>(std::forward<Args>(args)...);
    }
};

class Derived : public Base<Derived> {
public:
    Derived(const std::string &str, int i) {}
};

int main() {
    auto derived = Derived::create("text", 123);
}

Well, your code just compiles fine.

Intellisense features of any IDE are always just as good as the c++ parser used for them. That's completly dependent on the IDE actually used, and you shouldn't orient your designs about your IDE's capabilities, but what compiles and works well.

answered Feb 7, 2015 at 21:11

πάντα ῥεῖ

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4 Comments

ildjarn Over a year ago

He didn't ask how to make the code compile (it was already fine), he asked how to modify the code to play nice with IntelliSense. This in no way answers that question.

πάντα ῥεῖ Over a year ago

@ildjarn I well stated that the code compiles. Visual Studio doesn't use thes same parser for the c++ code as it's used for the compiler. There are a number of cases where intellisense may not work well AFAIK. Hence my statement to rely on the compiler rather than intellisense.

ildjarn Over a year ago

Which still doesn't answer the actual question.

πάντα ῥεῖ Over a year ago

@Zulis Then your solution would be to create overloads for the constructor, as proposed in the 1st comment on your question.

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