On 2:59 PM, Roelof Wobben wrote:
Hello,
Fine that you are in a arque
But can we come back to my problem.
How can I take care that test2 can be initialized.
Roelof
You had this code, and got the following error:
class zoeken() :
pass
def __len__(self):
return 0
def __str__(self):
return test2
def find(self, strng, ch, start, stop):
index = start
while index< len(strng) and index< stop:
if strng[index] == ch:
return index
index += 1
return -1
test = zoeken()
test.woord = "tamara"
test2 = zoeken.find(test, "a", 1,5)
print test(test2)
But now I get this message :
Traceback (most recent call last):
File "C:\Users\wobben\workspace\oefeningen\src\test.py", line 20, in<module>
test2 = zoeken.find(test, "a", 1,5)
TypeError: find() takes exactly 5 arguments (4 given)
The immediate answer is that
1) you are calling the find method with the class as the first
argument, while it was declared with 'self'.
2) you never pass a string to be searched, so there's nothing useful
to be passed to strng.
It's the second problem that causes the error, but the first one is
tied with it. You can fix the immediate syntax error by passing the
string explicitly.
test2 = test.find("tamara", "a", 1, 5)
The real problem though is one of design, or intent. You're assigning
that "tamara" to an attribute of a particular instance of zoeken(). So
did you mean that find() would look there for it? If that were the
case, the find declaration should change to:
def find(self, ch, start, stop):
and naturally, the reference to strng[index] should change to
self.woord[index]
There are several things wrong with the find() method, and with the
__str__() method, but the first question that needs answering is What
does a zoeken (please capitalize it, to follow Python conventions)
object represent? What are its data attributes going to mean? Since
it's not English, I don't get a clue from the name, but normally I'd get
one from the __init__() method, which you omitted. My convention is to
initialize all attributes in the __init__() method, even if they're not
always used. But if that's undesirable for some reason, then at least
comment on them there.
DaveA
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