Iíve seen discussions about this on the arduino forums, people asking for a config file that is located inside the same folder as the .ino file, this config can have macros or pre-processors that can be globly accessible inside the ino and any library included in the project, this seems like a great option because you can have multiple projects that all use a different config file with things like pin numbers, the size for certain arrays, etc.

With this a library can make use of those values to cater to each project automatically, specially large complex libraries

I think teensyduino could do this, check if a specifically named file is present in the ino folder and then include like a core file to access those values globally.

Its just a suggestion, i dont really know what the cons of this would be but it would be great to have the option 😊