..

type UnixfsAPI CoreAPI

背景 1

type BlockAPI CoreAPI

都是对 CoreAPI 的别名。

实现 coreapi.go

// Unixfs returns the UnixfsAPI interface implementation backed by the go-ipfs node
func (api *CoreAPI) Unixfs() coreiface.UnixfsAPI {
	return (*UnixfsAPI)(api)
}

// Block returns the BlockAPI interface implementation backed by the go-ipfs node
func (api *CoreAPI) Block() coreiface.BlockAPI {
	return (*BlockAPI)(api)
}

其中 coreapiface.xxx 是一系列的 interface, 如

// UnixfsAPI is the basic interface to immutable files in IPFS
// NOTE: This API is heavily WIP, things are guaranteed to break frequently
type UnixfsAPI interface {
	// Add imports the data from the reader into merkledag file
	//
	// TODO: a long useful comment on how to use this for many different scenarios
	Add(context.Context, files.Node, ...options.UnixfsAddOption) (path.Resolved, error)

	// Get returns a read-only handle to a file tree referenced by a path
	//
	// Note that some implementations of this API may apply the specified context
	// to operations performed on the returned file
	Get(context.Context, path.Path) (files.Node, error)

	// Ls returns the list of links in a directory. Links aren't guaranteed to be
	// returned in order
	Ls(context.Context, path.Path, ...options.UnixfsLsOption) (<-chan DirEntry, error)
}

而通过 type UnixfsAPI CoreAPI 后，相当于给 CoreAPI 实现了 UnixfsAPI interface。
类似的其他 type xxx CoreAPI，让 CoreAPI 实现多个 interface。

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