Explicitly convert a lambda to function pointer

Question

I have a legacy template function I'm trying to call that has a slew of specializations for function pointers with different numbers of arguments. I'm writing a new template function of my own that take some arbitrary kind of non-capturing lambda and needs to pass it to the other library. If I do this directly, then the template resolution fails. If however I explicitly cast it to be related function pointer type, things work.

The problem then is how to make my template code get that function pointer type from the lambda's type or force the explicit conversion without explicitly referencing the type.

Nevin · Accepted Answer · 2014-02-13 17:28:01Z

8

Just use unary-plus to convert a lambda to a function pointer, as in:

 auto* f = +[]{ std::cout << "Hello, world!\n"; }; // f is of type void (*)()

answered Feb 13, 2014 at 17:28

Nevin

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BCS Over a year ago

A slight more intuitive syntax (but less understandable as to why it works) option is *[]{...}

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