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Error -> Defect for defects (#13908)

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* Error -> Defect for defects

The distinction between Error and Defect is subjective,
context-dependent and somewhat arbitrary, so when looking at an
exception, it's hard to guess what it is - this happens often when
looking at a `raises` list _without_ opening the corresponding
definition and digging through layers of inheritance.

With the help of a little consistency in naming, it's at least possible
to start disentangling the two error types and the standard lib can set
a good example here.
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Jacek Sieka 2020-04-28 19:56:01 +02:00 • committed by GitHub
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28
doc/manual.rst
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@ -113,7 +113,7 @@ pragmas_ for details.
Whether a panic results in an exception or in a fatal error is
implementation specific. Thus the following program is invalid; even though the
code purports to catch the `IndexError` from an out-of-bounds array access, the
code purports to catch the `IndexDefect` from an out-of-bounds array access, the
compiler may instead choose to allow the program to die with a fatal error.
.. code-block:: nim
@ -121,7 +121,7 @@ compiler may instead choose to allow the program to die with a fatal error.
let i = 5
try:
a[i] = 'N'
except IndexError:
except IndexDefect:
echo "invalid index"
The current implementation allows to switch between these different behaviors
@ -1033,10 +1033,10 @@ The IEEE standard defines five types of floating-point exceptions:
precision, for example, 2.0 / 3.0, log(1.1) and 0.1 in input.
The IEEE exceptions are either ignored during execution or mapped to the
Nim exceptions: `FloatInvalidOpError`:idx:, `FloatDivByZeroError`:idx:,
`FloatOverflowError`:idx:, `FloatUnderflowError`:idx:,
and `FloatInexactError`:idx:.
These exceptions inherit from the `FloatingPointError`:idx: base class.
Nim exceptions: `FloatInvalidOpDefect`:idx:, `FloatDivByZeroDefect`:idx:,
`FloatOverflowDefect`:idx:, `FloatUnderflowDefect`:idx:,
and `FloatInexactDefect`:idx:.
These exceptions inherit from the `FloatingPointDefect`:idx: base class.
Nim provides the pragmas `nanChecks`:idx: and `infChecks`:idx: to control
whether the IEEE exceptions are ignored or trap a Nim exception:
@ -1045,12 +1045,12 @@ whether the IEEE exceptions are ignored or trap a Nim exception:
{.nanChecks: on, infChecks: on.}
var a = 1.0
var b = 0.0
echo b / b # raises FloatInvalidOpError
echo a / b # raises FloatOverflowError
echo b / b # raises FloatInvalidOpDefect
echo a / b # raises FloatOverflowDefect
In the current implementation ``FloatDivByZeroError`` and ``FloatInexactError``
are never raised. ``FloatOverflowError`` is raised instead of
``FloatDivByZeroError``.
In the current implementation ``FloatDivByZeroDefect`` and ``FloatInexactDefect``
are never raised. ``FloatOverflowDefect`` is raised instead of
``FloatDivByZeroDefect``.
There is also a `floatChecks`:idx: pragma that is a short-cut for the
combination of ``nanChecks`` and ``infChecks`` pragmas. ``floatChecks`` are
turned off as default.
@ -1620,7 +1620,7 @@ An example:
# accessing n.thenPart is valid because the ``nkIf`` branch is active:
n.thenPart = Node(kind: nkFloat, floatVal: 2.0)
# the following statement raises an `FieldError` exception, because
# the following statement raises an `FieldDefect` exception, because
# n.kind's value does not fit and the ``nkString`` branch is not active:
n.strVal = ""
@ -4063,7 +4063,7 @@ Example:
var a = readLine(f)
var b = readLine(f)
echo "sum: " & $(parseInt(a) + parseInt(b))
except OverflowError:
except OverflowDefect:
echo "overflow!"
except ValueError:
echo "could not convert string to integer"
@ -4226,7 +4226,7 @@ the ``raise`` statement is the only way to raise an exception.
.. XXX document this better!
If no exception name is given, the current exception is `re-raised`:idx:. The
`ReraiseError`:idx: exception is raised if there is no exception to
`ReraiseDefect`:idx: exception is raised if there is no exception to
re-raise. It follows that the ``raise`` statement *always* raises an
exception.