Anonymous Struct vs. Empty Struct in Go: When to Use Which?

Anonymous Struct vs. Empty Struct

In the provided Go code, we have two questions related to the use of anonymous and empty structs.

[1st Question: Anonymous Struct]

The line done <- struct{}{}` uses an anonymous struct to send a signal to the done channel. This is necessary because the done channel is declared with a type of chan struct{}, which means it can only send and receive values of type struct{}.

struct{}{}` is an anonymous struct, which means it does not have a name. It is equivalent to struct { }. An empty struct is a struct with no fields, and it has a size of 0 bytes in Go.

[2nd Question: Empty Struct Usage]

The line for _ = range langs { <-done } is used to receive and discard values from the done channel. This line is necessary to ensure that all goroutines waiting on the done channel are unblocked once they have finished their work.

Since the done channel is a semaphore (i.e., a signal channel), we are not interested in the values sent through it but only in their presence or absence. By using an empty struct as the channel's value type, we save memory and maintain the desired semantics of the signal mechanism.

In summary, anonymous structs are anonymous types that do not have a name, while empty structs are structs with no fields. In the provided code, an anonymous empty struct is used to send signals through a semaphore channel.

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