suppose you have a SwiftPM project that contains two executable targets, tool-a, and tool-b. the tool-a binary should be able to launch an instance of tool-b as a child process, and wait for its result. but this is challenging because tool-a does not know where to find the tool-b binary.
i could think of a few possible solutions, but none stuck out to me as a clear winner.
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push problem onto users. you could force the user of
tool-ato specify the path (.build/release/tool-b,/usr/bin/tool-b, etc.) explicitly. -
subsume tool-b into tool-a.
tool-acould provide an adapter interface for escaping command line arguments and forwarding them to the backing implementation fortool-b.tool-acould then spawn another instance of itself and pass the child process the intended arguments through its own argument escaping format. because we spawned a new context, the exit logic that already exists intool-bwill Just Work. -
fork tool-a into a parent and child process. you could do something similar to #2, except fork the current process instead of spawning a new context. this avoids the problem of passing arguments to
tool-b, but replaces it with the problem of getting its exit status. this doesn’t fit neatly into static typing patterns, so you need to (conditionally!) import the low-level_exitfunction wherever you fork a process, and call theNever-returning C function.
what is the best way for an executable to depend on another tool written in Swift?