Less than is more than ?

[Dave Brueck]

On Fri, 20 Dec 2002, Andrew Thompson wrote:

> I just got bitten by  100 < '10' returning 1 -- or true.
>
> Obviously I meant to use string.atoi() here,

.. or just int(x) or float(x) or whatever ...

> but problem is that my program compiled and ran happily!

And it should! This also works:

class Foo: pass
f = Foo()
f < '5'

> 100.__cmp__('foo') raises an Exception, as expected.

Yeah, but the Exception is a syntax error exception, right? ;-)

>>> 100.__cmp__('foo')
  File "<stdin>", line 1
    100.__cmp__('foo')
              ^

SyntaxError: invalid syntax

If you tried:

100 .__cmp__('foo')

then you would get a TypError, but you would also get a TypeError for

100 .__cmp__('10')

too.

> Have I missed something here?

Just the documentation :) :

5.6 Comparing Sequences and Other Types

"Note that comparing objects of different types is legal. The outcome is
deterministic but arbitrary: the types are ordered by their name. ...
Mixed numeric types are compared according to their numeric value, so 0
equals 0.0, etc."

Note that __cmp__ gets called only if the class specifically implements it
and an appropriate rich comparison operator (e.g. __gt__) is not defined.

HTH,
Dave