Unexpected deprecation warning

[David Lucas]

When running these statements :

        sage: F = GF(11)
        sage: n, k = 10 , 5
        sage: C = GeneralizedReedSolomonCode(F.list()[:n], k)
        sage: E = EncoderGRSEvaluationPolynomial(C)
        sage: p = x^2 + 3*x + 10
        sage: E.encode(p)

I receive that for the last line :

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=...) See http://trac.sagemath.org/5930 for details.

Must be checked.

[Johan Rosenkilde]

I think it's because x is a symbolic expression in the above; you didn't introduce PolynomialRing(F,'x').

[Johan Rosenkilde]

Thus in the encoder when it calls p(alpha), this is application of alpha to a non-specified variable in a symbolic expression.

[Daniel Augot]

What do you mean in your second comment ? Did you mean an application of p instead of an application alpha ?

[Johan Rosenkilde]

When p(alpha) is executed then alpha should replace some variable in p. The intention of the code is that it replaces x. But since p is a SymbolicExpression, which could contain any number of variables with no canonical ordering, Sage doesn't really know which variable to replace. That's the reason for the deprecation warning (since early versions of Sage would consider x a "special" variable which was to be replaced whenever it was left unspecified).

[David Lucas]

Resolved issue #89

→ <<cset 4084c8810395>>

[Johan Rosenkilde]

I don't like the way you resolved this. In my opinion, it is good that the user is warned that he didn't supply a polynomial but a SymbolicExpression. The "fix" should be in the example you provided at the top, where F[x] should be declared.

[David Lucas]

Indeed, if we use :

    sage: F = GF(11)
    sage: n, k = 10 , 5
    sage: C = GeneralizedReedSolomonCode(F.list()[:n], k)
    sage: E = EncoderGRSEvaluationPolynomial(C)
    sage: K.<x> = F[]
    sage: p = x^2 + 3*x + 10
    sage: E.encode(p)

instead, it works just fine. I remove the change.