Building a libraries from a list

Help/Discuss
1

I have a bunch of C++ libraries that I want to build using gradle. They’re all plugins for Gazebo and all have the same exact link/compile setup. Previous, in CMake, I had a list that I iterated over to build each plugin. What is the gradle-way to do this?

I’ve tried this, but the syntax is wrong. I have no clue how groovy works, and even less about how Gradle works. I’m just doing this based on examples and intution.

Anyone know a clean solution to this?

2

I think you’re almost there. Try this:

"$it"(NativeLibrarySpec)
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3

Ok, it works. But what’s going on here?
I’m only guessing here, but I think model and components are closures. is `“gz_$it”(NativeLibrarySpec){} also some kind of closure, or is it more like a normal java function? How come I can give it a string as it’s name? Is NativeLibrarySpec a gradle defined constant, or what?

I think questions like these are why I don’t get gradle.

//iterate over each plugin
model {
  components {
    plugins.each {
      "gz_$it"(NativeLibrarySpec){
        sources {
4

Essentially what is happening here is when you do something like lib1(NativeLibrarySpec) you are creating a new NativeLibrarySpec with the name ‘lib1’. Syntactically this is actually a method call. What you really want is for the name to be the value of the current item you are iterating on, rather than the literal it. What was happening before is you were trying to create multiple components with the name ‘it’.

5

So if I have a list of plugins [‘clock’, ‘motor’, ‘encoder’], then I am calling a methods:

gz_clock(NativeLibrarySpec) 
gz_motor(NativeLibrarySpec) 
gz_encoder(NativeLibrarySpec)

But where are these functions defined?
When you say I’m "creating a new NativeLibrarySpec " you don’t mean like an object of type NativeLibrarySpec? Isn’t NativeLibrarySpec a parameter to the methods I am creating?

6

They aren’t. We interpret this at runtime as “create a new thing of type NativeLibrarySpec called 'gz_clock`”.

If you’re curious about the implementation details, we use Groovy’s method missing feature to make this work.

7

I mean, I could ask why you don’t just do new NativeLibrarySpec and pass it the gz_clock and sources closure or whatever, but I have no idea what I’m talking about.

Thanks for answering my questions! I will definitely be posting more if I stick with this.

8

Because it’s important that Gradle controls instantiation of these objects. In fact, NativeLibrarySpec is an interface, whose implementation is internal, or possibly, generated at runtime.

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