gooverloading

Does the Go language have function/method overloading?

I'm porting a C library to Go. A C function (with varargs) is defined like this:

curl_easy_setopt(CURL *curl, CURLoption option, ...);

So I created wrapper C functions:

curl_wrapper_easy_setopt_str(CURL *curl, CURLoption option, char* param);
curl_wrapper_easy_setopt_long(CURL *curl, CURLoption option, long param);

If I define function in Go like this:

func (e *Easy)SetOption(option Option, param string) {
    e.code = Code(C.curl_wrapper_easy_setopt_str(e.curl, C.CURLoption(option), C.CString(param)))
}

func (e *Easy)SetOption(option Option, param long) {
    e.code = Code(C.curl_wrapper_easy_setopt_long(e.curl, C.CURLoption(option), C.long(param)))
}

The Go compiler complains:

*Easy·SetOption redeclared in this block

So does Go support function (method) overloading, or does this error mean something else?

Solution

  • No it does not.

    See the Go Language FAQ, and specifically the section on overloading.

    Method dispatch is simplified if it doesn't need to do type matching as well. Experience with other languages told us that having a variety of methods with the same name but different signatures was occasionally useful but that it could also be confusing and fragile in practice. Matching only by name and requiring consistency in the types was a major simplifying decision in Go's type system.

    Update: 2016-04-07

    While Go still does not have overloaded functions (and probably never will), the most useful feature of overloading, that of calling a function with optional arguments and inferring defaults for those omitted can be simulated using a variadic function, which has since been added. But this comes at the loss of type checking.