This is not recent. Sage uses the preparser by default, so the choice to
print a^b as such is consistent with what is accepted at the prompt.
We have this:
sage: var("a,b")
(a, b)
sage: E = a^b
sage: bool(E == eval(preparse(str(E))))
True
or, if you prefer,
sage: sage_eval(str(E),globals())
a^b
Python is now much more well-known and accepted than when sage started out,
so perhaps the preparser is now less necessary for people to accept it as a
computer algebra language, but the legacy of having the preparser (and,
most importantly, "^" for exponentiation) is now set in sage and aligns it
with nearly all computer algebra systems. I don't think it will be doable
to abandon that in order to improve compatibility with the rest of python
(in notation).
By the way, the "%" operator is not the preferred way to format strings.
Using "{}".format(x) is now preferred in python. You have access to more
formatting features than through the "%" mechanism.
On Sunday, 16 February 2025 at 05:14:20 UTC-8 Emmanuel Charpentier wrote:
> The recent evolution of Sage seems to break the print(eval(read))
> equivalence :
> sage: var("a0, a1") (a0, a1) sage: "%s"%a0^a1 'a0^a1'
>
> So far so good. But :
> sage: eval("%s"%a0^a1)
> ---------------------------------------------------------------------------
> RuntimeError Traceback (most recent call last) Cell In[54], line 1 ----> 1
> eval("%s"%a0**a1) File <string>:1 File
> /usr/local/sage-10/local/var/lib/sage/venv-python3.12.5/lib/python3.12/site-packages/sage/structure/element.pyx:952,
>
> in sage.structure.element.Element.__xor__
> (build/cythonized/sage/structure/element.c:16917)() 950 951 def
> __xor__(self, right): --> 952 raise RuntimeError("Use ** for
> exponentiation, not '^', which means xor\n" 953 "in Python, and has the
> wrong precedence.") 954 RuntimeError: Use ** for exponentiation, not '^',
> which means xor in Python, and has the wrong precedence.
>
> But, inconsistently :
> sage: "%s"%a0**a1 'a0^a1'
>
> In other words, Sage insists for reading x**y and for printing x^y.
>
> Unless I’m missing something, *these choices are inconsistent*.
>
> Should I file an issue ?
>
>
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