Allow specifying no default subspec

[kylefleming]

I would like to be able to have the ability specify in a podspec that the pod defaults to only the root spec and does not auto-include any of the subspecs as dependencies. (the equivalent of s.default_subspecs = [])

Given that you can make a pod with no subspecs, it seems logical that a pod should be able to specify that only the root spec should be included by default. This would allow pod authors to add optional functionality as subspecs without needing to create a dummy subspec to set as the default_subspec.

[dnkoutso]

Yes! Sounds like a good enhancement. Will mark it for 1.9.0 for now. Hopefully should be fairly easy to add.

[dnkoutso]

Seems like CocoaPods does:

    def subspec_dependencies(platform = nil)
      specs = if default_subspecs.empty?
                subspecs.compact.reject(&:non_library_specification?)
              else
                default_subspecs.map do |subspec_name|
                  root.subspec_by_name("#{name}/#{subspec_name}")
                end
              end
      if platform
        specs = specs.select { |s| s.supported_on_platform?(platform) }
      end
      specs.map { |s| Dependency.new(s.name, version) }
    end

So setting s.default_subspecs = [] is possible but has a different effect than the issue description here intends to accomplish. We might be better off introducing a s.default_subspecs = :root or s.default_subspecs = :none or maybe s.default_subspecs = nil which for some reason the last one seems to me a bad idea :)

[dnkoutso]

At the very least we should ensure this change does not break the existing expected behavior unless the pod author explicitly updates their podspec to designate that all subspecs are "optional". I am also curious and want to ensure pod consumers are given a choice today which I think they do with pod 'PodA', :subspecs => [...] option.