Is it possible to dynamically create targets from a rule?

[davidchisnall]

I have a target kind that needs to depend on another target, with custom configuration. I'm currently adding it as a dependency and then modifying it in after_load in the rule, but this means that I can only have one instance of something that uses my rule, because otherwise they will both modify the target of the dependency in conflicting ways.

Is it possible to clone a target from a rule and then add the clone as a dependency? Or explicitly construct a new target? The constructor for target appears to need a targetinfo and I'm not sure how to create one of those.

[waruqi]

Clone target in rule is not supported and it is not recommended to modify the configuration of dependent targets in sub-targets.

[waruqi]

We can also dynamically create targets in the description scope.

function add_firmware(name)
    target("component_" .. name)
        add_rules("build_component_" .. name)
end

add_firmware("xxx")
add_firmware("yyy")

[davidchisnall]

I hadn't managed to write functions in the description scope yet, but that might be feasible. Is there a way of running code at the end? Ideally I'd like adding firmware to look as much like adding any other kind of target, so someone could do something like:

firmware("example")
  add_files(...)
  add_cflags(...)
  ...

If I return a target that has uses the after_load hook, I could do the setup there, so my function would create the dependent targets and then configure them after the target that depends on them has been configured. (More generally, does it leave the last target that I define open? Do I need to explicitly return it somehow?)

[davidchisnall]

It looks as if this does work, thanks!

Unfortunately, when I declare the function, the directory that os.scriptdir() returns is the directory of the script for the project, not the script for the file containing the function (which has a fixed path relative to the source files that I want to include). Is there a simple way of getting the path of the file containing the currently executing function? Or of capturing this when the file is loaded so that I can refer to it later (I couldn't work out how to create / initialise variables in the description scope)?

[waruqi]

you can use os.projectdir(), it is always project root directory.

Is there a simple way of getting the path of the file containing the currently executing function?

try

local scriptdir = os.scriptdir()
function add_firmware()
    print(scriptdir)
end

[davidchisnall]

I am encountering problems with this and I suspect that the root cause is the same as some of my other issues.

The xmake.lua that provided the firmware description-scope function was in the root of my repo, for historical reasons. It's now been refactored so that it's in the sdk directory and now suddenly the firmware function is not visible to other things. I think the implicit scoping from having it in the root was the problem.

How do I provide a set of description-scope functions that I can include (or import) into a file that is not in a subdirectory of them?

[waruqi]

I am supporting create target/rule dynamically in script scope. #2879

maybe you can try it later, but it has been not merged yet. I am still developing it.