Stream: wit-bindgen

Topic: understanding question about types in interfaces

Christoph Brewing (Apr 13 2023 at 12:13):

There is the following observation related to imported interfaces and types which I do not understand:

Given the following interface/world:

interface nicestuffhere {
    my-function: func(v0: list<u8>) -> float64
}

default world whatever {
  import sth: self.nicestuffhere
}

When the implementation wants to call function my-function
Then its parameter v0 has to be of type &[u8] where my expectation was to call a Vec<u8>. I thought so based on the assumption that among module/component boundaries data is exchanged in a shared nothing style which implies an exchange by value (in my head).

My understanding is obviously wrong but in which way?

Lann Martin (Apr 13 2023 at 12:46):

The string is copied into the callee's linear memory.

Lann Martin (Apr 13 2023 at 13:02):

Another way of thinking about it is that passing a Vec isn't passing the string data by value, its passing a (smart) pointer to the string data.

Christoph Brewing (Apr 13 2023 at 13:50):

makes sense, thank you

Last updated: Dec 23 2024 at 12:05 UTC