c++ factory pattern syntax

Question

In this question, the accepted answer uses the following syntax:

typedef std::map<std::string, Base*(*)()> map_type;

Can someone explain what the (*) means, I've never seen it before?

Marco A. · Accepted Answer · 2014-10-16 09:31:05Z

5

It is a function pointer that returns a Base pointer and takes no arguments, e.g.

struct Base {}; Base* myfun() { return 0; } int main() { std::map<std::string, Base*(*)()> mymap; mymap.insert(std::make_pair("hello", myfun)); }

Example

answered Oct 16, 2014 at 9:31

Marco A.

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5 Comments

stack user Over a year ago

Thanks. I get that the return type is a Base*, what exactly is the (*) meant to signify?

Jiří Pospíšil Over a year ago

@stackuser It's a function pointer without a name. Take a look at the linked wiki page.

Marco A. Over a year ago

@stackuser That it is a pointer, a function pointer to be precise. The parenthesis are part of the syntax for specifying a function pointer. There's no name as Jiri hinted since it is not needed.

vincentB Over a year ago

can we add a name, for readability? std::map<std::string, Base*(*function)()> mymap;

Marco A. Over a year ago

@vincentB not in this case since it's a template argument

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