Hi,
I ran across the following behavior in sage-3.4.1 and sage-4.0 (I don't
have 4.0.1 yet), and I find it fairly disturbing.
sage: d = {'a': 1} # Create some object
sage: d
{'a': 1}
sage: type(d) = type({}) # Attempt to check the type but
# foolishly use = instead of ==
TypeError: cannot coerce type '<type 'type'>' into a
SymbolicExpression. # An error is expected
sage: d # But now my data is gone!
d
sage: type(d) # Replaced by a symbolic variable
<class 'sage.calculus.calculus.SymbolicVariable'>
This is not 'dictionary' specific; the same problem of data loss occurs
with any object at all.
sage: type(Integer) = type(2) # Admittedly a silly thing to do...
TypeError: ...
sage: 1
DeprecationWarning: Substitution using function-call syntax and
unnamed arguments is deprecated and will be removed from a future
release of Sage; you can use named arguments instead, like
EXPR(x=..., y=...)
My feeling is that coercion is being a little too aggressive here. I
understand that coercion sees the '=' and tries its best to make sense
out of the expression, but I would hope that when it fails, nothing in
the expression would be changed.
Best,
Jason Bandlow
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