c++ - How are signal signatures in `boost::signals2` implemented? -


i have been using boost::signals2 time in projects. shame, still not understand how implemented under hood. problems start @ definition of signal. how definition such as

boost::signals2::signal< void (bool, double) >

handled? can see implementation details signature becomes template parameter aptly named signature. however, not understand syntax. syntax permitted c++ standard? how can signal "store" function signature when provided in form?

i tried looking @ sources, unable find explanation syntax. appreciated.

yes, syntax allowed; type denotes reference function taking bool , double , returning void. if typedef it, awkward, because name sit in middle:

typedef void signature(bool, double);

with new alias syntax becomes more readable:

using signature = void(bool, double);

the parallel pointers functions be:

typedef void (*pointer)(bool, double);  using pointer = void (*)(bool, double);

afterwards, there template tricks tease apart various elements (extract return type, , type of each argument).


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