Re: [libgpiod v2][PATCH v2] treewide: rework line configuration

[Andy Shevchenko <andriy.shevchenko@linux.intel.com>]

On Tue, Sep 13, 2022 at 06:14:07PM +0200, Bartosz Golaszewski wrote:
> This tries to get rid of the concept of defaults and overrides for line
> properties from the library (or rather hide them from the users). While
> this makes the C API a bit more complex, it allows for a more elegant
> high-level interface.
> 
> This patch is pretty big but I'll just give an overview here. I don't
> expect a detailed review of every line.
> 
> Low-level data structure model (as seen in the C API):
> 
> We're adding a new structure - line_settings. It's a basic data class
> that stores a set of line properties. The line_config object is simplified
> and becomes a storage for the mappings between offsets and line_settings.
> 
> We no longer require the user to store the offsets array in the
> request_config. The offsets to request are simply those for which the
> user explicitly added settings to the line_config. Subsequently, the
> request_config structure becomes optional for the request.
> 
> In C++ bindings this allows us to implement an elegant interface with
> rust-like chained mutators. To that end, we're also introducing a new
> intermediate class called request_builder that's returned by the chip's
> prepare_request() method which exposes routines for storing the line
> and request configs for the request we're making. For examples of
> usage - see C++ tests and samples.

It's a huge change and my knowledge of C++ is a bare minimum from dozen of
years ago, can you point out to the file with an example how this APIs (which
are suggested by a new code) look like for developer in practice? Some test
cases or simple example? This can help to understand the prettiness of the
API.

-- 
With Best Regards,
Andy Shevchenko