Make base objects hashable, use it for equality check, including srid

srid defaults to 0, as ST_SRID does:

```
 st_srid
---------
       0
(1 row)
```

Author: yohanboniface

postgis/geometry.py

@@ -1,14 +1,15 @@
 import warnings
 
+from .ewkb import Reader, Typed, Writer
+from .geojson import GeoJSON
+
 try:
     # Do not make psycopg2 a requirement.
     from psycopg2.extensions import ISQLQuote
 except ImportError:
     warnings.warn('psycopg2 not installed', ImportWarning)
 
 
-from .ewkb import Reader, Typed, Writer
-from .geojson import GeoJSON
 
 
 class Geometry(object, metaclass=Typed):
@@ -56,9 +57,13 @@ def __repr__(self):
         return '<{} {}>'.format(self.__class__.__name__, self.wkt)
 
     def __eq__(self, other):
-        if isinstance(other, self.__class__):
-            other = other.coords
-        return self.coords == other
+        return hash(self) == hash(other)
+
+    def __hash__(self):
+        values = self.coords
+        if self.srid:
+            values = values + (self.srid,)
+        return hash(values)
 
     @property
     def name(self):

postgis/geometrycollection.py

@@ -1,18 +1,17 @@
-from .geometry import Geometry
 from .geojson import GeoJSON
+from .geometry import Geometry
 
 
 class GeometryCollection(Geometry):
 
     TYPE = 7
 
-    def __init__(self, geoms, srid=None):
+    def __init__(self, geoms, srid=0):
         for geom in geoms:
             if not isinstance(geom, Geometry):
                 raise ValueError('{} is not instance of Geometry'.format(geom))
         self.geoms = list(geoms)
-        if srid:
-            self.srid = srid
+        self.srid = srid
 
     def __iter__(self):
         return self.geoms.__iter__()

postgis/multi.py

@@ -1,15 +1,15 @@
 from .geometry import Geometry
 from .point import Point
 
+
 class Multi(Geometry):
 
-    __slots__ = ['geoms', 'srid']
+    __slots__ = ["geoms", "srid"]
     SUBCLASS = None
 
-    def __init__(self, geoms, srid=None):
+    def __init__(self, geoms, srid=0):
         self.geoms = [self.SUBCLASS(g, srid=srid) for g in geoms]
-        if srid:
-            self.srid = srid
+        self.srid = srid
 
     def __iter__(self):
         return iter(self.geoms)
@@ -31,8 +31,8 @@ def from_ewkb_body(cls, reader, srid=None):
 
     @property
     def wkt_coords(self):
-        fmt = '{}' if self.SUBCLASS == Point else '({})' 
-        return ', '.join(fmt.format(g.wkt_coords) for g in self)
+        fmt = "{}" if self.SUBCLASS == Point else "({})"
+        return ", ".join(fmt.format(g.wkt_coords) for g in self)
 
     def write_ewkb_body(self, writer):
         writer.write_int(len(self.geoms))

postgis/point.py

@@ -6,7 +6,7 @@ class Point(Geometry):
     __slots__ = ['x', 'y', 'z', 'm', 'srid']
     TYPE = 1
 
-    def __init__(self, x, y=None, z=None, m=None, srid=None):
+    def __init__(self, x, y=None, z=None, m=None, srid=0):
         if y is None and isinstance(x, (tuple, list)):
             x, y, *extra = x
             if extra:
@@ -17,8 +17,7 @@ def __init__(self, x, y=None, z=None, m=None, srid=None):
         self.y = float(y)
         self.z = float(z) if z is not None else None
         self.m = float(m) if m is not None else None
-        if srid is not None:
-            self.srid = srid
+        self.srid = srid
 
     def __getitem__(self, item):
         if item in (0, 'x'):

tests/test_linestring.py

@@ -21,3 +21,13 @@ def test_geom_should_compare_with_coords():
 def test_linestring_get_item():
     line = LineString(((30, 10), (10, 30), (40, 40)))
     assert line[0] == (30, 10)
+
+
+def test_linestring_is_hashable():
+    l1 = LineString(((1, 2), (3, 4)))
+    l2 = LineString(((1, 2), (3, 4)))
+    l3 = LineString(((3, 4), (5, 6)))
+    assert {l1, l2, l3} == {l1, l3}
+    l1 = LineString(((1, 2), (3, 4)), srid=4326)
+    l2 = LineString(((1, 2), (3, 4)), srid=3857)
+    assert len({l1, l2}) == 2

tests/test_point.py

@@ -98,3 +98,13 @@ def test_0_as_m_is_considered():
     assert point.y == 2.0
     assert point.z == 3
     assert point.m == 0
+
+
+def test_point_is_hashable():
+    p1 = Point(1, 1)
+    p2 = Point(1, 1)
+    p3 = Point(2, 2)
+    assert {p1, p2, p3} == {p1, p3}
+    p1 = Point(1, 1, srid=4326)
+    p2 = Point(1, 1, srid=3857)
+    assert len({p1, p2}) == 2

tests/test_polygon.py

@@ -2,18 +2,38 @@
 
 
 def test_geom_should_compare_with_coords():
-    assert (((35, 10), (45, 45), (15, 40), (10, 20), (35, 10)), ((20, 30), (35, 35), (30, 20), (20, 30))) == Polygon((((35, 10), (45, 45), (15, 40), (10, 20), (35, 10)), ((20, 30), (35, 35), (30, 20), (20, 30))))  # noqa
+    assert (
+        ((35, 10), (45, 45), (15, 40), (10, 20), (35, 10)),
+        ((20, 30), (35, 35), (30, 20), (20, 30)),
+    ) == Polygon(
+        (
+            ((35, 10), (45, 45), (15, 40), (10, 20), (35, 10)),
+            ((20, 30), (35, 35), (30, 20), (20, 30)),
+        )
+    )  # noqa
 
 
 def test_polygon_geojson():
     poly = Polygon((((1, 2), (3, 4), (5, 6), (1, 2)),))
-    assert poly.geojson == {"type": "Polygon",
-                            "coordinates": (((1, 2), (3, 4), (5, 6), (1, 2)),)}
+    assert poly.geojson == {
+        "type": "Polygon",
+        "coordinates": (((1, 2), (3, 4), (5, 6), (1, 2)),),
+    }
 
 
 def test_polygon_wkt():
     poly = Polygon((((1, 2), (3, 4), (5, 6), (1, 2)),))
     wkt = poly.wkt
-    wkt = wkt.replace('.0','')
-    wkt = wkt.replace(', ',',')
-    assert wkt == 'POLYGON((1 2,3 4,5 6,1 2))'
+    wkt = wkt.replace(".0", "")
+    wkt = wkt.replace(", ", ",")
+    assert wkt == "POLYGON((1 2,3 4,5 6,1 2))"
+
+
+def test_polygon_is_hashable():
+    p1 = Polygon((((1, 2), (3, 4), (5, 6), (1, 2)),))
+    p2 = Polygon((((1, 2), (3, 4), (5, 6), (1, 2)),))
+    p3 = Polygon((((1, 2), (3, 4), (6, 7), (1, 2)),))
+    assert {p1, p2, p3} == {p1, p3}
+    p1 = Polygon((((1, 2), (3, 4), (5, 6), (1, 2)),), srid=4326)
+    p2 = Polygon((((1, 2), (3, 4), (5, 6), (1, 2)),), srid=3857)
+    assert len({p1, p2}) == 2