Factor out error generation for function calls with wrong nargs.

... matching the wording for standard functions.

Note that nargs_error returns the exception without raising it itself to
make the control flow clearer on the caller side.

Author: anntzer

lib/matplotlib/_api/__init__.py

@@ -334,6 +334,12 @@ def my_func(*args, **kwargs):
                 raise
 
 
+def nargs_error(name, takes, given):
+    """Generate a TypeError to be raised by function calls with wrong arity."""
+    return TypeError(f"{name}() takes {takes} positional arguments but "
+                     f"{given} were given")
+
+
 def recursive_subclasses(cls):
     """Yield *cls* and direct and indirect subclasses of *cls*."""
     yield cls

lib/matplotlib/axes/_axes.py

@@ -5695,8 +5695,7 @@ def _pcolorargs(self, funcname, *args, shading='auto', **kwargs):
                     Y = Y.data
             nrows, ncols = C.shape
         else:
-            raise TypeError(f'{funcname}() takes 1 or 3 positional arguments '
-                            f'but {len(args)} were given')
+            raise _api.nargs_error(funcname, takes="1 or 3", given=len(args))
 
         Nx = X.shape[-1]
         Ny = Y.shape[0]

lib/matplotlib/contour.py

@@ -1444,17 +1444,16 @@ def _contour_args(self, args, kwargs):
             fn = 'contourf'
         else:
             fn = 'contour'
-        Nargs = len(args)
-        if Nargs <= 2:
+        nargs = len(args)
+        if nargs <= 2:
             z = ma.asarray(args[0], dtype=np.float64)
             x, y = self._initialize_x_y(z)
             args = args[1:]
-        elif Nargs <= 4:
+        elif nargs <= 4:
             x, y, z = self._check_xyz(args[:3], kwargs)
             args = args[3:]
         else:
-            raise TypeError("Too many arguments to %s; see help(%s)" %
-                            (fn, fn))
+            raise _api.nargs_error(fn, takes="from 1 to 4", given=nargs)
         z = ma.masked_invalid(z, copy=False)
         self.zmax = float(z.max())
         self.zmin = float(z.min())

lib/matplotlib/gridspec.py

@@ -587,8 +587,7 @@ def _from_subplot_args(figure, args):
         elif len(args) == 3:
             rows, cols, num = args
         else:
-            raise TypeError(f"subplot() takes 1 or 3 positional arguments but "
-                            f"{len(args)} were given")
+            raise _api.nargs_error("subplot", takes="1 or 3", given=len(args))
 
         gs = GridSpec._check_gridspec_exists(figure, rows, cols)
         if gs is None:

lib/matplotlib/quiver.py

@@ -406,20 +406,19 @@ def _parse_args(*args, caller_name='function'):
     """
     X = Y = C = None
 
-    len_args = len(args)
-    if len_args == 2:
+    nargs = len(args)
+    if nargs == 2:
         # The use of atleast_1d allows for handling scalar arguments while also
         # keeping masked arrays
         U, V = np.atleast_1d(*args)
-    elif len_args == 3:
+    elif nargs == 3:
         U, V, C = np.atleast_1d(*args)
-    elif len_args == 4:
+    elif nargs == 4:
         X, Y, U, V = np.atleast_1d(*args)
-    elif len_args == 5:
+    elif nargs == 5:
         X, Y, U, V, C = np.atleast_1d(*args)
     else:
-        raise TypeError(f'{caller_name} takes 2-5 positional arguments but '
-                        f'{len_args} were given')
+        raise _api.nargs_error(caller_name, takes="from 2 to 5", given=nargs)
 
     nr, nc = (1, U.shape[0]) if U.ndim == 1 else U.shape
 
@@ -476,7 +475,7 @@ def __init__(self, ax, *args,
         %s
         """
         self._axes = ax  # The attr actually set by the Artist.axes property.
-        X, Y, U, V, C = _parse_args(*args, caller_name='quiver()')
+        X, Y, U, V, C = _parse_args(*args, caller_name='quiver')
         self.X = X
         self.Y = Y
         self.XY = np.column_stack((X, Y))
@@ -928,7 +927,7 @@ def __init__(self, ax, *args,
             kwargs['linewidth'] = 1
 
         # Parse out the data arrays from the various configurations supported
-        x, y, u, v, c = _parse_args(*args, caller_name='barbs()')
+        x, y, u, v, c = _parse_args(*args, caller_name='barbs')
         self.x = x
         self.y = y
         xy = np.column_stack((x, y))

lib/matplotlib/tests/test_quiver.py

@@ -51,11 +51,11 @@ def test_quiver_number_of_args():
     X = [1, 2]
     with pytest.raises(
             TypeError,
-            match='takes 2-5 positional arguments but 1 were given'):
+            match='takes from 2 to 5 positional arguments but 1 were given'):
         plt.quiver(X)
     with pytest.raises(
             TypeError,
-            match='takes 2-5 positional arguments but 6 were given'):
+            match='takes from 2 to 5 positional arguments but 6 were given'):
         plt.quiver(X, X, X, X, X, X)