CODEWITHSUNDEEP
javathriftidl
FuriousGeorge
FuriousGeorge

Reputation: 4681

Thrift service default parameter

My question is very similar to the question Default arguments with default values in Thrift Python client which was never completely resolved (one answer was a guess and the other was very hard to understand).

The question is, can you have a default parameter for service method without resorting to creating a struct for every method that needs one. I have the following Java service that I'd like to wrap with a Thrift handler

class MyService {
    public void foo(){ foo(false); } 
    public void foo(boolean someAdvancedFeature){...}
}

so I'd like to create the Thrift IDL

service MyServiceThrift {
    void foo(),
    void foo(1:bool),
}

but that is not valid as you can't have 2 methods named foo. So I tried

service MyServiceThrift {
    void foo(1:optional bool someAdvancedFeature = false)
}

but I get a parse error saying Cannot use reserved language keyword: "false" So I though well maybe I could just make it optional

service MyServiceThrift {
    void foo(1: optional bool someAdvancedFeature)
}

but I get the warning optional keyword is ignored in argument lists., which in hindsight makes some sense as it's just creating creating interfaces.

So is the only way to do this to create a new struct for every single method that takes an optional parameter? (Yes, you could re-use the struct for some methods, but I'd need one for every permutation of parameters, plus that'd break things down the road if one method added a parameter and the others didn't). It seems silly to make the users create a (potentially empty) class just to pass parameters to a method, and I really don't like the idea of having to generate/maintain a separate class for every single method in my services. Am I missing something?

Upvotes: 4

Views: 6307

Answers (1)

JensG
JensG

Reputation: 13411

That's a really good question, because technically the struct is already there - behind the scenes. I'm afraid, however, that the behaviour is as you describe and - at least currently - there is no other way other than maybe some workaround like that:

enum TriState {
   Unused = 0
   Yes = 1
   No = 2
}

service Foobar {
  void DoIt( 1: TriState someAdvancedFeature)
  void Ints( 1: set<byte> usedArgs, 2: i32 value, 3: string foobarbaz)
}

Upvotes: 1

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