How to set complex properties on a target

[davidchisnall]

I would like to convey some structured data from a target to a rule. I had hoped that I could write something like:

on_load(function (target)
    target:set("my property", { { key=value, key2=value2 }, { key=value3, key2=value4} })
end)

This doesn't raise an error, but it also doesn't appear to preserve the data. I can set it as a JSON string, but it would be nice if I coudl use a Lua table literal so that I get parse errors early.

[waruqi]

please use target:set_values or set_values() and target:values()

[davidchisnall]

I don't think I'm using this correctly. In my target, I have tried doing:

set_values("my property", { { key=value, key2=value2 }, { key=value3, key2=value4} })

And then in my rule, doing:

target:values("my property")

But I do not get the object back. I can pass multiple arguments to set_values and end up with an array containing numbers or strings, but any object that I insert seems to be gone. This is also true if I use target:values_set (target:set_values does not exist) in script scope.

The information that I need to communicate is an array of objects, so mapping this to a set of strings and integers would be very error prone. Using JSON works for now, but it feels very clunky in a language that has native support for objects to have to serialise and deserialise an array of objects as a string.

If I understand the code correctly, it appears that each set calls a different API based on a key, and set_values is in the keyvalues set. There are some examples in comments such as shflags that appear to be successfully storing objects, so I'm not quite sure what is happening here. Do I need to pass something to set_values / values_set to indicate that it should not try to coerce? The code is quite light on comments, but I eventually discovered that adding {expand=false} as the last argument to target:values_set did the right thing.

This also works with target:values_add in the script scope but not with add_values in the description scope.

This almost works, but it has a couple of annoyances:

• If I just add one object with values_add, I get a single object. If I add another, I get an array of objects. Lua arrays are just tables and so there's no simple way of differentiating between the two cases in the rule. It would be nice if add, when given an object, would always give you a one-element array containing that object, though that's probably going to break some existing code. Failing that, an accessor that can be used with ipairs to give an iterable list for a value would be convenient.
• The objects always have a __wrap_locked__ field in them. If I create the array myself with values_set, then the array contains this, in addition to my objects, which can be confusing in iteration (though it appears that ipairs is happy to skip this one, so it's probably not important).

[waruqi]

It works for me.

add_rules("mode.debug", "mode.release")

target("testc")
    set_kind("binary")
    add_files("src/*.c")
    set_values("my property", { { key=1, key2=2 }, { key=2, key2=1} })
    on_load(function (target)
        print(target:values("my property"))
    end)

$ xmake
{
  {
    key2 = 2,
    key = 1
  },
  {
    key2 = 1,
    key = 2
  }
}

[ 25%]: cache compiling.release src/main.c
[ 50%]: linking.release testc
[100%]: build ok!