Overloading the ">>" operator in Python 2.2.1
tjreedy at udel.edu
Thu Sep 12 08:57:26 EDT 2002
"Andy Elvey" <andy.elvey at paradise.net.nz> wrote in message
news:fhYf9.1418$b5.128061 at news02.tsnz.net...
> Hi all .
> I'm using Python 2.2.1 under Win98. I'm doing some experimenting
> parsing, and as part of that, I'm trying to overload the right-shift
> operator (>>) so that I can use it as follows (testing against a
> that I read in) -
> a >> b would mean "a is followed by b" .
> So, you could have a function like seqtest("string_to_test" ,
> "foo">>"bar" ) , and that function would return true or false,
> whether foo was followed by bar.
> ( I know it's possible to use regexes for this, but being able to
> a sequence-testing operator like this would be useful .)
> Many thanks in advance ......
You did not explicitly ask a question, but here's a possible answer
>>> class wierd(str):
... def __rshift__(self,other):
... print self, 'followed by', other
>>> foo = wierd('foo')
>>> bar = wierd('bar')
foo followed by bar
You cannot add attributes to built-in types. You can only subclass
them (in 2.2+).
Terry J. Reedy
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