Bug in ManyToOneReplacer about matchpy

[arihantparsoya]

Here is my Constraint class (cons()):

from matchpy import Constraint, substitute
from sympy import sympify

class cons(Constraint):
    def __init__(self, expr, vars):
        self.expr = expr
        self.vars = frozenset(v.name for v in vars)

    def __call__(self, substitution):
        sub = substitute(self.expr, substitution)
        try:
            return sympify(str(sub))
        except:
            print(('Unable to sympify: {}').format(sub))
            return False

    @property
    def variables(self):
        return self.vars

    def with_renamed_vars(self, renaming):
        copy = cons(self.expr, [])
        copy.vars = frozenset(renaming.get(v, v) for v in self.vars)
        return copy

    def __eq__(self, other):
        return isinstance(other, cons) and other.vars == self.vars and other.expr == self.expr

    def __hash__(self):
        return hash((self.vars, self.expr))

I figured out that self.vars are getting changed in with_renamed_vars from frozenset({'m', 'x'}) to frozenset({'i1', 'i2'}) and stays the same when __call__ is called.

[wheerd]

You will have to rename the variables in the expression as well:

    def with_renamed_vars(self, renaming):
        new_expr = self.expr.with_renamed_vars(renaming)
        new_vars = [renaming.get(v, v) for v in self.vars]
        return cons(new_expr, new_vars)

Unfortunately, this will only work if the expression consists of Expression instances, i.e. no ints etc. I want to get rid of the requirement for renaming. I hope I can get to that next week, but I can't promise it.

[arihantparsoya]

Thanks!