Compile Davenport library if not present at installation

[wbreeze]

This Gem doesn't compile properly when it is installed. The native C code ext/davenport/davenport.c needs compiling. It would be nice if it brought-in the davenport C implementation to compile and install as well.

[wbreeze]

This repository, wbreeze/dvt has a smoke test.

[wbreeze]

I've been working from:

• https://guides.rubygems.org/gems-with-extensions/ which itself references

Writing and compiling

• http://tenderlovemaking.com/2009/12/18/writing-ruby-c-extensions-part-1.html
• http://tenderlovemaking.com/2010/12/11/writing-ruby-c-extensions-part-2.html
• https://github.com/ruby/ruby/blob/trunk/doc/extension.rdoc
• https://ruby-doc.com/docs/ProgrammingRuby/html/ext_ruby.html

Compiling and distributing

• https://rubydoc.info/gems/rake-compiler
• https://github.com/ruby/ruby/blob/trunk/lib/mkmf.rb and mkmf rdoc
• https://stackoverflow.com/questions/29818711/ruby-c-extension-gem-doesnt-compile-at-installation

which I am also using. All of this is mixed up with the Hoe set of rake tasks that I'm trying to use, with the difficulty that I still don't have the gem installing its native component properly. Hoe is perhaps more distraction than value add due to it promises a lot but I'm reading the code as documentation. Not sure.

[wbreeze]

It's possible that rake-compiler wants me to cross-compile and prepare all of the platforms from the dev environment, rather than compile on the native platform. I want to compile on the native platform at installation. That means the native platform will have to have the C compiler installed, which isn't such a long throw. It already has it for installing the davenport C library.

[wbreeze]

The gem now properly installs and compiles the C extension. Having the install take care of installing the Davenport library, if it isn't already present, might work if it compiles the library locally as a static library, and compiles the C extension against that static library. Dynamic libraries require LOAD_PATH hacks although... Well, I think it's possible. It isn't high on my list.