Evan Simpson wrote:
Guido van Rossum wrote:
IMO TALES should solve this for itself by introducing an if/then/else expression form rather than depending on Python. If you can have a "not:.." expression, surely you can have an "if:..:then:..:else:.." expression.
Now that you point it out, it's not even hard. Here's a proof-of-concept, with really awful parsing (it obviously breaks on nested if: then: else:), that actually works:
class IfExpr: def __init__(self, name, expr, compiler): self._s = expr = expr.lstrip() m = re.match('(.*) then:(.*) else:(.*)', expr) if m is not None: condexpr, thenexpr, elseexpr = m.groups() self._cond = compiler.compile(condexpr) self._then = compiler.compile(thenexpr) self._else = compiler.compile(elseexpr)
def __call__(self, econtext): if econtext.evaluateBoolean(self._cond): return econtext.evaluate(self._then) return econtext.evaluate(self._else)
(Tested with <div tal:replace="if:options/x then:string:yes else:string:no">)
Is this worth a robust implementation, ZPT folks?
I think so. Iam much too often using "python:test(...." just for simple condition testing.
Cheers,
Evan @ 4-am