The use of classes in fnpcell (generating components)

The following code is taken from gpdk > components > bend > bend_bezier.py and belongs to the part that uses the BendBezier class to create the device and generate the layout:

if __name__ == "__main__":
    from pathlib import Path

    gds_file = Path(__file__).parent / "local" / Path(__file__).with_suffix(".gds").name
    library = fp.Library()

    TECH = get_technology()
    # =======================================================================
    # fmt: off

    library += BendBezier()
    library += BendBezier(name="q", start=(0, 0), controls=[(31, 30)], end=(60, 0), waveguide_type=TECH.WG.FWG.C.WIRE)
    # library += BendBezier(name="c", start=(0, 0), controls=[(0, 30), (60, 30)], end=(60, 0), waveguide_type=TECH.WG.FWG.C.WIRE, transform=fp.translate(0, 40))

    # fmt: on
    # =============================================================
    fp.export_gds(library, file=gds_file)
    # fp.plot(library)

Section Script Description

Import the OS path structure, create a local folder in the current folder to save the generated GDS files, and call fp.Library module in PhotoCAD to display the generated files and export the GDS files:
```
from pathlib import Path
```
Call get_technology method get information about the layout design process:
```
TECH = get_technology()
```

Generate devices using the BendBezier class through the library implementation in the function module:

library += BendBezier()
library += BendBezier(name="q", start=(0, 0), controls=[(30, 30)], end=(60, 0), waveguide_type=TECH.WG.FWG.C.WIRE)
library += BendBezier(name="c", start=(0, 0), controls=[(0, 30), (60, 30)], end=(60, 0), waveguide_type=TECH.WG.FWG.C.WIRE, transform=fp.translate(0, 40))

In this section the user can set the parameters in the BendBezier class. The parameters contain not only the parameters of the device itself for layout generation but also the relative position parameters for setting the position of the layout cell relative to the origin when called hierarchically.

The above code creates three devices using the BendBezier() class with three lines of library statements, using the default name BendBezier and two user-defined names q and c, respectively, which are prefixed with BendBezier_ by default when generating the layout, as follows BendBezier_q, BendBezier_c.

The above BendBezier example shows that in gpdk > components, each parameterized components can be generated by a python script, which first defines the component by class, second defines the structure by variable parameters, and then passes the parameters to fnpcell to achieve component design and layout generation.