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January 23, 2017 Multiple return type or callback function | ||||
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I'm creating a function to authenticate user login. I want to determine login failure (Boolean) and error message (will be sent to frontend) but D does have multiple return type (IMO could use struct but will make code dirty with too much custom types). struct Result { bool success = false string message; } Result authen(){} auto r = authen() if (r.success) writeln(r.message); In such use case, would you use a callback delegates function or will use a string (str == "ok", str == "no") or go with a struct? string authen(){} string r = authen(); //check if string contains success message to take action. Or void authen(void delegate callback(bool success, string message) ) { //authenticate callback (resultBoolean, message); } //use authen( (success, msg) { req.writeBody(msg); // to frontend }); |
January 23, 2017 Re: Multiple return type or callback function | ||||
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Posted in reply to aberba | On Monday, 23 January 2017 at 15:15:35 UTC, aberba wrote:
> I'm creating a function to authenticate user login. I want to determine login failure (Boolean) and error message (will be sent to frontend) but D does have multiple return type (IMO could use struct but will make code dirty with too much custom types).
>
> struct Result
> {
> bool success = false
> string message;
> }
> Result authen(){}
> auto r = authen()
> if (r.success) writeln(r.message);
I use structs like this quite frequently, myself. It works well and I don't think it's particularly ugly. And if you don't want to pollute the namespace with one-off structs, you can also place them inside the function that's returning them (making them voledmort types).
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January 23, 2017 Re: Multiple return type or callback function | ||||
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Posted in reply to aberba | On Monday, 23 January 2017 at 15:15:35 UTC, aberba wrote:
> I'm creating a function to authenticate user login. I want to determine login failure (Boolean) and error message (will be sent to frontend) but D does have multiple return type
> [...]
Yes, MRV can be done with a tuple
auto foo()
{
import std.typecons;
return tuple(true, "123456");
}
void main(string[] args)
{
auto auth = foo;
if (auth[0])
auth[1].writeln;
}
It's more or less like returning a Voldemort struct.
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