如何在Golang中将接口参数传递给可变参数函数？ [重复]

Question

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• slice of struct != slice of interface it implements? 6 answers

I have a variadic function Result func Results(messages ...Message) that accepts an interface Message. It works fine if I pass a single message of type Message, but if i pass a slice of message Result(slice...)

Here is the error I get:

prog.go:38: cannot use messages (type []*SampleMessage) as type []Message in argument to Results

Sample Code

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Answer 1

You need to restructure slightly. The issue is that a []*SampleMessage cannot convert to []Message. The way to handle this though, is to declare the messages slice as being of type []Message. Then you can append instances of SampleMessage to it without any problems and pass them into your variadic function with the ... syntax. Here's your example modified to compile; http://play.golang.org/p/cQUIZTz_vo - only change is on the first line of main where I have var messages []Message. If you try to do this in the reverse order (like use a []*SampleMessages then do a conversion with []Message(messages) as you pass it) it will fail. So as far as I know, this is the most practical way to solve your problem.