# F2PY frontend Study

**f2py2e.py**
- **scaninoutline()**
- Command line parsing is done by iteratively reading CL options, modifying flag variables, and removing CL options from `sys.argv` array.

- **main()** :
- Root function
- Checks for some dependency flags first.
- If `-c` flag present --> `run_compile()` method
- `run_compile()` method parses command line seperately from `scaninputline()`
- For all other flag handling, `run_main()` handles it.
- **run_main()** :
- Handles all flags except (-c).
- Uses `scaninputline()` to parse CL and get files and options
- options include verbosity, skip and include functions, latex and rest docs, build paths and include paths
- `auxfuncs.options = options` [here](https://github.com/NamamiShanker/numpy/blob/acfc1cc1d177e06002d87a10185dda1ef3192662/numpy/f2py/f2py2e.py#L439)
- [L440](https://github.com/NamamiShanker/numpy/blob/acfc1cc1d177e06002d87a10185dda1ef3192662/numpy/f2py/f2py2e.py#L440)`capi_maps.load_f2cmap_file(options['f2cmap_file'])` Is this line used to convert Fortran code to dictionaries? Also what is f2cmap file?
- [name=Rohit] This is used to do type matching, i.e. `real*8`-->`double`
- Callcrackfortran looks complicated, need [name=Rohit Goswami]'s help in figuring out code after [L441](https://github.com/NamamiShanker/numpy/blob/acfc1cc1d177e06002d87a10185dda1ef3192662/numpy/f2py/f2py2e.py#L441)
- [name=Rohit] This is used to convert to the nested dictionary
- [name=Namami] Move callcrackfortran to `crackfortran.py`
- Possible bug, [L470](https://github.com/NamamiShanker/numpy/blob/acfc1cc1d177e06002d87a10185dda1ef3192662/numpy/f2py/f2py2e.py#L470) variable `i` is not defined. +1
- [name=Rohit] --> `plist['block']` instead of `postlist[i]['block']`

- **buildmodules(postlist)**
- Creates C wrapper to be compiled and used in Python.
- Invoked with `-m` flag is present?

- `run_compile()` --> should be implemented with `argparse` subparsers, and so there shouldn't be any need to parse the commandline again

# Things to do
- [x] Non `distutils` tests
- [x] Pull request for the [L470] bug
- [ ] Classify functions as `distutils` needed, and if yes, `meson` equivalents
- e.g. `--fcompiler` is used to choose a compiler (fortran) --> `meson` will set the `FC` environment variable
- [x] Look at the `argparse` structure --> https://github.com/numpy/numpy/pull/20056/files
- [x] Consider the workflow options
- [x] Within NumPy -->
- [ ] Out of tree, e.g. https://github.com/HaoZeke/f2py_skel