Merge lp:~stefanor/ibid/math-dos-382549 into lp:~ibid-core/ibid/old-trunk-pack-0.92

[Stefano Rivera]

[lp:~stefanor/ibid/math-dos-382549]

647. By Stefano Rivera on 2009-06-02

factorial shouldn't allow floating point values

[Michael Gorven (mgorven)]

 review approve

review: Approve

[Stefano Rivera (stefanor)]

Vhata: be aware that there is one extra revision, post-diff

[Jonathan Hitchcock (vhata)]

review: Approve

=== modified file 'ibid/plugins/math.py'
--- ibid/plugins/math.py	2009-05-30 16:15:04 +0000
+++ ibid/plugins/math.py	2009-06-02 09:10:54 +0000
@@ -71,7 +71,7 @@
             error = unicode_output(error.strip())
             raise Exception("BC Error: %s" % error)
 
-help['calc'] = u'Returns the anwser to mathematical expressions'
+help['calc'] = u'Returns the anwser to mathematical expressions. Uses Python syntax and semantics (i.e. radians)'
 class LimitException(Exception):
     pass
 
@@ -81,6 +81,17 @@
             raise LimitException
     return pow(*args)
 
+# Factorial is only available in 2.6:
+try:
+    from math import factorial
+except ImportError:
+    factorial = lambda x: x == 0 and 1 or reduce(lambda a, b: a * b, xrange(1, x + 1))
+
+def limited_factorial(x):
+    if x >= 500:
+        raise LimitException
+    return factorial(x)
+
 # ast method
 class PowSubstitutionTransformer(NodeTransformer):
     def visit_BinOp(self, node):
@@ -119,6 +130,7 @@
     for function in extras:
         safe[function] = eval(function)
     safe['pow'] = limited_pow
+    safe['factorial'] = limited_factorial
 
     @match(r'^(?:calc\s+)?(.+?)$')
     def calculate(self, event, expression):