The Return of "does not work on derived classes?"

[devleaks]

Hello,

I have the same problem as #94 with other function calls: An Edge is a subclass of a Feature and point_to_line_distance fails to recognize an edge as a Feature...

I think that there is a more general issue with type/subtype checking.

Also, the documentation does not always reflect the code: For exemple, distance is documented as distance(Feature, Feature). But distance(Point, Point) also works and is not documented.

I have the feeling that more generally, type should be enforced at function parameter level: point_to_line_distance(Feature, Feature) is too loose. The coder must check that the Feature geometry has the appropriate type. point_to_line_distance(Point, Line) is more precise and type checking is done by Python at runtime. There is no need to add more checks inside the code of the function.

BTW, point_to_line_distance should return the closest point somehow as well. May be a function nearest_point_on_line(Point, Line) returns the nearest point, and its distance to the line can be determined with distance.

Here is a piece of code that exhibit the issue:

`
from geojson import Point, LineString, Feature
from turfpy.measurement import point_to_line_distance

class Edge(Feature):
def init(self, node: str, start: Feature, end: Feature):
Feature.init(self, geometry=LineString((start["geometry"]["coordinates"], end["geometry"]["coordinates"])))
self.name = node

p1 = Point((25.25458, 51.623879))
f1 = Feature(geometry=p1)
p2 = Point((25.254626, 51.624053))
f2 = Feature(geometry=p2)

e1 = Edge("e1", start=f1, end=f2)

p0 = Point((25.0, 51.0))
f0 = Feature(geometry=p0)

fline = Feature(geometry=LineString((f1["geometry"]["coordinates"], f2["geometry"]["coordinates"])))
print(point_to_line_distance(f0, fline))
#71.59329853730718

fedge = Edge(node="e1", start=f1, end=f2)
print(isinstance(fedge, Feature))
#True
print(point_to_line_distance(f0, fedge))
Traceback (most recent call last):
File "/Users/pierre/Developer/Internet/js/gip/emitpy/tests/ft3.py", line 28, in
print(point_to_line_distance(f0, fedge))
File "/usr/local/miniconda3/lib/python3.9/site-packages/turfpy/measurement.py", line 1004, in point_to_line_distance
feature_of(line, "LineString", "line")
File "/usr/local/miniconda3/lib/python3.9/site-packages/turfpy/helper.py", line 120, in feature_of
raise Exception(
Exception: Invalid input to line, Feature with geometry required
`

P.

[devleaks]

I also have the issue of classes with the following hierarchy:
A Line is a subclass of a LineString (a Line is a LineString with just 2 points, start and end). I create a Feature from the Line.
nearest_point_on_line(Feature, Feature) fails, telling the Line is not a regognized LineString, although isinstance(aLine, LineString) is True.

[sackh]

@devleaks Thanks again, I think we need to check at the project level and see where ever possible to make types/subtypes specific. It will take some time to fix all the possible functions. Please feel free to open PR. We can do it iteratively each function level.

[devleaks]

Issue actually resides in GeoJSON package. See here.