dart - call a method if it exists -

is there simple, lightweight/inexpensive call determine if object supports named method? so, in obj.respondsto great.

dynamic _tojson(dynamic obj) {   return obj.respondsto('tojson'))? obj.tojson() : obj; }  class foo {   string foo = "foo.foo";   bar bar = new bar();   map tojson() {     return {       "foo" : _tojson(foo),       "bar" : _tojson(bar)     };   } } 

one alternative call , catch nosuchmethod exception, imagine bad practice , expensive?

the short answer is, 'no'. answer provided frédéric hamidi not incorrect, not work in dart2js (dart:mirrors largely unimplemented in dart2js).

also, while checking whether object responds particular method common in other languages (ruby, example), not seem particularly dart-y me. maybe once mirrors supported in dart, change.

and hard whether reflection based on mirrors 'lightweight/inexpensive'. depends on use case , how define these terms.

i best bet call method on object, catch nosuchmethod exception, , implement default error-handling behavior. makes sense if expect method present.