update fibonacci

Author: dham

doc/source/6_exceptions.rst

@@ -44,9 +44,9 @@ error:
 .. code-block:: ipython3
 
     In [3]: 0./0.
-    ---------------------------------------------------------------------------
-    ZeroDivisionError                         Traceback (most recent call last)
-    <ipython-input-3-4e5c12397e23> in <module>
+    --------------------------------------------------------------------------
+    ZeroDivisionError                        Traceback (most recent call last)
+    Cell In [3], line 1
     ----> 1 0./0.
 
     ZeroDivisionError: float division by zero
@@ -71,7 +71,7 @@ Now consider the case of an expression that doesn't make mathematical sense:
 .. code-block:: ipython3
 
     In [5]: 3 * %
-      File "<ipython-input-5-442f22cdc61f>", line 1
+    Cell In [5], line 1
         3 * %
             ^
     SyntaxError: invalid syntax
@@ -164,9 +164,9 @@ of exception built in. For example, if we attempt to access the number
 .. code-block:: ipython3
 
     In [1]: (0, 1)[2]
-    ---------------------------------------------------------------------------
-    IndexError                                Traceback (most recent call last)
-    <ipython-input-1-def0bb43ba85> in <module>
+    --------------------------------------------------------------------------
+    IndexError                               Traceback (most recent call last)
+    Cell In [1], line 1
     ----> 1 (0, 1)[2]
 
     IndexError: tuple index out of range
@@ -202,7 +202,7 @@ the :class:`~polynomial.Polynomial` class from
 
 .. code-block:: ipython3
 
-    In [1]: from polynomial import Polynomial
+    In [1]: from example_code.polynomial import Polynomial
 
     In [2]: p = Polynomial(("a", "b"))
 
@@ -217,22 +217,24 @@ trouble:
 .. code-block:: ipython3
 
     In [4]: print(1 + p)
-    ---------------------------------------------------------------------------
-    TypeError                                 Traceback (most recent call last)
-    <ipython-input-5-141816221609> in <module>
+    --------------------------------------------------------------------------
+    TypeError                                Traceback (most recent call last)
+    Cell In [4], line 1
     ----> 1 print(1 + p)
 
-    ~/docs/object-oriented-programming/src/polynomial.py in __radd__(self, other)
-         57     def __radd__(self, other):
-         58
-    ---> 59         return self + other
+    File ~/docs/principles_of_programming/object-oriented-programming/example_code/polynomial.py:59, in Polynomial.__radd__(self, other)
+        58 def __radd__(self, other):
+    ---> 59     return self + other
 
-    ~/docs/object-oriented-programming/src/polynomial.py in __add__(self, other)
-         38
-         39         if isinstance(other, Number):
-    ---> 40             return Polynomial((self.coefficients[0] + other,) + self.coefficients[1:])
-         41
-         42         elif isinstance(other, Polynomial):
+    File ~/docs/principles_of_programming/object-oriented-programming/example_code/polynomial.py:38, in Polynomial.__add__(self, other)
+        36 def __add__(self, other):
+        37     if isinstance(other, Number):
+    ---> 38         return Polynomial((self.coefficients[0] + other,)
+        39                           + self.coefficients[1:])
+        41     elif isinstance(other, Polynomial):
+        42         # Work out how many coefficient places the two polynomials have in
+        43         # common.
+        44         common = min(self.degree(), other.degree()) + 1
 
     TypeError: can only concatenate str (not "int") to str
 
@@ -304,22 +306,24 @@ Let's return to the traceback for our erroneous polynomial addition:
 .. code-block:: ipython3
 
     In [4]: print(1 + p)
-    ---------------------------------------------------------------------------
-    TypeError                                 Traceback (most recent call last)
-    <ipython-input-5-141816221609> in <module>
+    --------------------------------------------------------------------------
+    TypeError                                Traceback (most recent call last)
+    Cell In [4], line 1
     ----> 1 print(1 + p)
 
-    ~/docs/object-oriented-programming/src/polynomial.py in __radd__(self, other)
-         57     def __radd__(self, other):
-         58
-    ---> 59         return self + other
+    File ~/docs/principles_of_programming/object-oriented-programming/example_code/polynomial.py:59, in Polynomial.__radd__(self, other)
+        58 def __radd__(self, other):
+    ---> 59     return self + other
 
-    ~/docs/object-oriented-programming/src/polynomial.py in __add__(self, other)
-         38
-         39         if isinstance(other, Number):
-    ---> 40             return Polynomial((self.coefficients[0] + other,) + self.coefficients[1:])
-         41
-         42         elif isinstance(other, Polynomial):
+    File ~/docs/principles_of_programming/object-oriented-programming/example_code/polynomial.py:38, in Polynomial.__add__(self, other)
+        36 def __add__(self, other):
+        37     if isinstance(other, Number):
+    ---> 38         return Polynomial((self.coefficients[0] + other,)
+        39                           + self.coefficients[1:])
+        41     elif isinstance(other, Polynomial):
+        42         # Work out how many coefficient places the two polynomials have in
+        43         # common.
+        44         common = min(self.degree(), other.degree()) + 1
 
     TypeError: can only concatenate str (not "int") to str
 
@@ -330,34 +334,32 @@ occurred. The traceback for this frame starts:
 
 .. code-block:: ipython3
 
-    ~/docs/object-oriented-programming/src/polynomial.py in __add__(self, other)
-
-This indicates that the frame describes code in the file
-`polynomial.py` (which, on the author's computer, is located in the
-folder `~~/docs/object-oriented-programming/src/`). Specifically, the
-stack frame describes the execution of the :meth:`__add__` method,
-which is the :term:`special method` responsible for polynomial
-addition. The lines below this show the line on which execution
-stopped (line 40, in this case) and a couple of lines on either side,
-for context.
-
-The stack frame above this shows the function from which the
-:meth:`__add__` method was called. In this case, this is the reverse
-addition :term:`special method`, :meth:`__radd__`. On line 59 :meth:`__radd__` calls
-:meth:`__add__` through the addition of `self` and `other`.
-
-Finally, the top stack frame corresponds to the command that the user
-typed in iPython. This stack frame looks a little different from the
-others. For starters, instead of the file name there is the string
-`<ipython-input-5-141816221609>`. This is simply the :term:`Python
-interpreter`'s internal name for a notional "file" containing one line
-of iPython input. Similarly, because the line the user typed is not in
-any function, the interpreter treats it as code written in the top
-level of an unnamed module called `<module>`. Finally, because the
-interpreter treats every line of input as a separate file, the call to
-:meth:`__radd__` implementing the reverse addition of the number 1 to
-the polynomial `p` occurs on line 1 even though we are on the fourth
-line of the iPython session.
+    File ~/docs/principles_of_programming/object-oriented-programming/example_code/polynomial.py:38, in Polynomial.__add__(self, other)
+
+This indicates that the frame describes code in the file `polynomial.py`
+(which, on the author's computer, is located in the folder
+`~~/principles_of_programming/object-oriented-programming/example_code/`).
+Specifically, the stack frame describes the execution of the :meth:`__add__`
+method, which is the :term:`special method` responsible for polynomial
+addition. The lines below this show the line on which execution stopped (line
+38, in this case) and a couple of lines on either side, for context.
+
+The stack frame above this shows the function from which the :meth:`__add__`
+method was called. In this case, this is the reverse addition :term:`special
+method`, :meth:`__radd__`. On line 59 :meth:`__radd__` calls :meth:`__add__`
+through the addition of `self` and `other`.
+
+Finally, the top stack frame corresponds to the command that the user typed in
+iPython. This stack frame looks a little different from the others. Instead of
+a file name there and a function name there is `Cell In [4], line 1`. This
+indicates that the exception was raised on line 1 of the IPython cell `In [4]`.
+
+.. hint::
+
+    Older versions of Python display less helpful location information for the
+    top stack frame, so in that case you might see something like
+    `<ipython-input-2-c3aeb16193d4> in <module>` rather than
+    `Cell In [4], line 1`.
 
 .. hint::
 
@@ -399,24 +401,32 @@ take a string argument, which is the error message to be printed. In
 :numref:`typesafe_fib`, we inform the user that we were expecting an
 integer rather than the type actually provided.
 
+.. only:: book
+
+    .. raw:: latex
+
+        \clearpage
+
+
 .. _typesafe_fib:
 
 .. code-block:: python3
-    :emphasize-lines: 6,7,8
+    :emphasize-lines: 8,9,10
     :caption: A version of the Fibonacci function which raises an
              exception if a non-integer type is passed as the
              argument.
     :linenos:
 
-
     from numbers import Integral
 
+
     def typesafe_fib(n):
         """Return the n-th Fibonacci number, raising an exception if a
         non-integer is passed as n."""
         if not isinstance(n, Integral):
                 raise TypeError(
-                        f"fib expects an integer, not a {type(n).__name__}")
+                    f"fib expects an integer, not a {type(n).__name__}"
+                )
         if n == 0:
             return 0
         elif n == 1:
@@ -429,19 +439,22 @@ If we now pass a non-integer value to this function, we observe the following:
 
 .. code-block:: ipython3
 
-    In [1]: from fibonacci import typesafe_fib
+    In [1]: from fibonacci.typesafe_fibonacci import typesafe_fib
     In [2]: typesafe_fib(1.5)
-    ---------------------------------------------------------------------------
-    TypeError                                 Traceback (most recent call last)
-    <ipython-input-2-c3aeb16193d4> in <module>
+    --------------------------------------------------------------------------
+    TypeError                                Traceback (most recent call last)
+    Cell In [2], line 1
     ----> 1 typesafe_fib(1.5)
 
-    ~/docs/object-oriented-programming/fibonacci/fibonacci.py in typesafe_fib(n)
-         14        non-integer is passed as n."""
-         15        if not isinstance(n, Integral):
-    ---> 16               raise TypeError(
-         17                      f"fib expects an integer, not a {type(n).__name__}")
-         18        if n == 0:
+    File ~/docs/principles_of_programming/object-oriented-programming/fibonacci/typesafe_fibonacci.py:8, in typesafe_fib(n)
+        5 """Return the n-th Fibonacci number, raising an exception if a
+        6 non-integer is passed as n."""
+        7 if not isinstance(n, Integral):
+    ----> 8     raise TypeError(
+        9         f"fib expects an integer, not a {type(n).__name__}"
+        10     )
+        11 if n == 0:
+        12     return 0
 
     TypeError: fib expects an integer, not a float
 

fibonacci/fibonacci.py

@@ -1,6 +1,3 @@
-from numbers import Integral
-
-
 def fib(n):
     """Return the n-th Fibonacci number."""
     if n == 0:
@@ -9,16 +6,3 @@ def fib(n):
         return 1
     else:
         return fib(n-2) + fib(n-1)
-
-
-def typesafe_fib(n):
-    """Return the n-th Fibonacci number, raising an exception if a
-    non-integer is passed as n."""
-    if not isinstance(n, Integral):
-        raise TypeError(f"fib expects an integer, not a {type(n).__name__}")
-    if n == 0:
-        return 0
-    elif n == 1:
-        return 1
-    else:
-        return fib(n-2) + fib(n-1)

fibonacci/typesafe_fibonacci.py

@@ -0,0 +1,16 @@
+from numbers import Integral
+
+
+def typesafe_fib(n):
+    """Return the n-th Fibonacci number, raising an exception if a
+    non-integer is passed as n."""
+    if not isinstance(n, Integral):
+        raise TypeError(
+            f"fib expects an integer, not a {type(n).__name__}"
+        )
+    if n == 0:
+        return 0
+    elif n == 1:
+        return 1
+    else:
+        return fib(n-2) + fib(n-1)