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C#: Search cleanup, add InternalError exception.

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Added an InternalError class to explicitly indicate
that an exception occurs due to an internal assertion
failure inside Astronomy Engine. Any InternalError
should be considered a bug in Astronomy Engine, not
a bug in calling code.

Upon reviewing the code for searching moon phases,
I discovered that there was inconsistent behavior
in SearchMoonPhase. It was sometimes returning null,
other times throwing an exception. Because the caller
passes in `limitDays`, it makes sense to simply
return `null` in any case where the search fails.
This is to support callers that intentionally want
to find whether or not a moon phase occurs in a given
small window of time.

Updated internal callers of SearchMoonPhase to throw
an InternalError when they know they should always
find an event.

Internal function FindSeasonChange did not check to
make sure SearchSunLongitude succeeded. There is no
known case where this failure happens, but if it did,
a null AstroTime would have been stored in SeasonsInfo.
It is better to fail early with an explicit InternalError.

Other miscellaneous C# code cleanup.

In the Python code, I found a couple of `raise Error`
that needed to be changed to `raise InternalError`.
This commit is contained in:
Don Cross
2022-04-05 12:30:13 -04:00
parent 9d6294d7fe
commit d7e86fae52
6 changed files with 166 additions and 135 deletions
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10
source/python/astronomy/astronomy.py
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@@ -378,7 +378,7 @@ class InternalError(Error):
Astronomy Engine for everyone! (Thank you in advance from the author.)
"""
def __init__(self):
Error.__init__(self, 'Internal error - please report issue at https://github.com/cosinekitty/astronomy/issues')
Error.__init__(self, 'Internal error - please report issue, including stack trace, at https://github.com/cosinekitty/astronomy/issues')
class NoConvergeError(Error):
"""A numeric solver did not converge.
@@ -8667,7 +8667,7 @@ def SearchLunarEclipse(startTime):
# Search for the next full moon. Any eclipse will be near it.
fullmoon = SearchMoonPhase(180, fmtime, 40)
if fullmoon is None:
raise Error('Cannot find full moon.')
raise InternalError() # should have always found the next full moon
# Pruning: if the full Moon's ecliptic latitude is too large,
# a lunar eclipse is not possible. Avoid needless work searching for
@@ -8751,7 +8751,7 @@ def SearchGlobalSolarEclipse(startTime):
# Search for the next new moon. Any eclipse will be near it.
newmoon = SearchMoonPhase(0.0, nmtime, 40.0)
if newmoon is None:
raise Error('Cannot find new moon')
raise InternalError() # should always find the next new moon
# Pruning: if the new moon's ecliptic latitude is too large, a solar eclipse is not possible.
eclip_lat = _MoonEclipticLatitudeDegrees(newmoon)
@@ -8826,6 +8826,8 @@ def SearchLocalSolarEclipse(startTime, observer):
while True:
# Search for the next new moon. Any eclipse will be near it.
newmoon = SearchMoonPhase(0.0, nmtime, 40.0)
if newmoon is None:
raise InternalError() # should always find the next new moon
# Pruning: if the new moon's ecliptic latitude is too large, a solar eclipse is not possible.
eclip_lat = _MoonEclipticLatitudeDegrees(newmoon)
@@ -9080,7 +9082,7 @@ def SearchMoonNode(startTime):
kind = NodeEventKind.Ascending if (eclip2.lat > eclip1.lat) else NodeEventKind.Descending
result = Search(_MoonNodeSearchFunc, kind.value, time1, time2, 1.0)
if result is None:
raise InternalError()
raise InternalError() # should always find the next lunar node
return NodeEventInfo(kind, result)
time1 = time2
eclip1 = eclip2