Fortran object oriented support

[danbeibei]

This PR sits on top of #230, #231, #232, #237 and #238
It adds partial support for Fortran object oriented syntax

Support for:

• Specific binding
• Generic binging
• Binding overload
• abstract fortran keyword
• deferred fortran keyword
• Type inheritance
• Explicite fortran constructor (if unique)
• Polymorphic variable (class(...))

No support for:

• Operator binding
• Multiple explicite constructors for one type
• non_overridable fortran keyword
• Procedure pointer component
• pass/nopass fortran keywords
• Final binding
• Implicite fortran constructors

[danbeibei]

@jameskermode I'm not sure what is wrong with the builds, could you help me figure out?

[krystophny]

@danbeibei this looks great! Looks like we did some work in parallel in #233 and #236 in the last week (what a coincidence). Does this already allow also allocatable output of polymorphic class instances in factory procedures? If yes, did you follow the same strategy of wrapping a class into another type container? It would be great if we could cross-check our example cases in the each others branch and then see how to proceed with merging.

[danbeibei]

Hi @krystophny, great stuff! No, it does not allow allocatable output. I have rapidly checked out the examples in your branch and can confirm my changes do not actually address what you changes do. I'll take the time in a few weeks to have a look into the code you pushed.

[krystophny]

@danbeibei @jameskermode I have now summarized all PRs on #240 in order, rebased mine on top of this one here, and merged everything in master of https://github.com/itpplasma/f90wrap for testing until you can dig through the reviews. Until then, happy holidays!

[krystophny]

Two questions here:

1. Should pytest-dependency really be used? Avoiding dependencies between tests is usually considered good practice.
2. If 1) can be avoided, is pytest even necessary, or better stick to good old unittest (I rewrote my tests after realizing that pytest has not been a requirement up to now)?

[jameskermode]

I would indeed prefer to stick to unittest and avoid adding dependencies if possible

[jameskermode]

Happy to merge this if the pytest dependency can be removed