write a recognizer

[Klaus Neuner]

Hello,

I want to write a class Recognizer, like so:

class Recognizer(obje ct):

def is_of_category_ 1(self, token):
if token == 1:
return "1"
else:
return False

def is_of_category_ 2(self, token):
if token == 2:
return "2"
else:
return False

def recognize(self, token):
for fun in <?>:
result = apply(fun, token)
if result:
return result
return False

What do I have to write instead of <?>?
Or: How should I design the recognizer, if the above design is not good?

Klaus

[Peter Otten]

Re: write a recognizer

Klaus Neuner wrote:
[color=blue]
> Hello,
>
> I want to write a class Recognizer, like so:
>
> class Recognizer(obje ct):
>
> def is_of_category_ 1(self, token):
> if token == 1:
> return "1"
> else:
> return False
>
> def is_of_category_ 2(self, token):
> if token == 2:
> return "2"
> else:
> return False
>
> def recognize(self, token):
> for fun in <?>:
> result = apply(fun, token)
> if result:
> return result
> return False
>
> What do I have to write instead of <?>?
> Or: How should I design the recognizer, if the above design is not good?
>
> Klaus[/color]

The following assumes that all category checker method names start with a
common prefix. Those are automatically extracted in the __init__() method.
If you are interested in this technique, I stole it from cmd.py in the
library. IIRC, the implementation is more complete as it also inspects the
base classes.

class Recognizer(obje ct):
def __init__(self):
r = self.recognizer s = []
for n in dir(self.__clas s__):
if n.startswith("i s_"):
r.append(getatt r(self, n))

def is_of_category_ 1(self, token):
if token == 1:
return "1"

def is_of_category_ 2(self, token):
if token == 2:
return "2"

def recognize(self, token):
# would also work:
#for fun in [self.is_of_cate gory_1, self.is_of_cate gory_2]:

for fun in self.recognizer s:
result = fun(token)
if result:
return result
return False

if __name__ == "__main__":
r = Recognizer()
for t in "12341":
print r.recognize(int (t)),
print

Peter

[Chunming Luo]

Re: write a recognizer

Peter Otten wrote:
[color=blue]
>Klaus Neuner wrote:
>
>
>[color=green]
>>Hello,
>>
>>I want to write a class Recognizer, like so:
>>
>>class Recognizer(obje ct):
>>
>> def is_of_category_ 1(self, token):
>> if token == 1:
>> return "1"
>> else:
>> return False
>>
>> def is_of_category_ 2(self, token):
>> if token == 2:
>> return "2"
>> else:
>> return False
>>
>> def recognize(self, token):
>> for fun in <?>:
>> result = apply(fun, token)
>> if result:
>> return result
>> return False
>>
>>What do I have to write instead of <?>?
>>Or: How should I design the recognizer, if the above design is not good?
>>
>>Klaus
>>
>>[/color]
>
>The following assumes that all category checker method names start with a
>common prefix. Those are automatically extracted in the __init__() method.
>If you are interested in this technique, I stole it from cmd.py in the
>library. IIRC, the implementation is more complete as it also inspects the
>base classes.
>
>class Recognizer(obje ct):
> def __init__(self):
> r = self.recognizer s = []
> for n in dir(self.__clas s__):
> if n.startswith("i s_"):
> r.append(getatt r(self, n))
>
> def is_of_category_ 1(self, token):
> if token == 1:
> return "1"
>
> def is_of_category_ 2(self, token):
> if token == 2:
> return "2"
>
> def recognize(self, token):
> # would also work:
> #for fun in [self.is_of_cate gory_1, self.is_of_cate gory_2]:
>
> for fun in self.recognizer s:
> result = fun(token)
> if result:
> return result
> return False
>
>if __name__ == "__main__":
> r = Recognizer()
> for t in "12341":
> print r.recognize(int (t)),
> print
>
>Peter
>[/color]

Here is another solution:

def recongnize(self , token):
for item in self.__class__. __dict__.keys() :
method = self.__class__. __dict__[item]
if callable(method ) and method !=
self.__class__. __dict__["recongnize "]:
result = method(self, token)
if result:
return result
return false

-Chunming

[max khesin]

Re: write a recognizer

This is cool. Curious (my py object recall is a bit stale): would this
solution work for a class that derives from Recognizer (and implements
an 'is_' method)?

thanks,
max


Peter Otten wrote:
[color=blue]
> Klaus Neuner wrote:
>
>[color=green]
>>Hello,
>>
>>I want to write a class Recognizer, like so:
>>
>>class Recognizer(obje ct):
>>
>> def is_of_category_ 1(self, token):
>> if token == 1:
>> return "1"
>> else:
>> return False
>>
>> def is_of_category_ 2(self, token):
>> if token == 2:
>> return "2"
>> else:
>> return False
>>
>> def recognize(self, token):
>> for fun in <?>:
>> result = apply(fun, token)
>> if result:
>> return result
>> return False
>>
>>What do I have to write instead of <?>?
>>Or: How should I design the recognizer, if the above design is not good?
>>
>>Klaus[/color]
>
>
> The following assumes that all category checker method names start with a
> common prefix. Those are automatically extracted in the __init__() method.
> If you are interested in this technique, I stole it from cmd.py in the
> library. IIRC, the implementation is more complete as it also inspects the
> base classes.
>
> class Recognizer(obje ct):
> def __init__(self):
> r = self.recognizer s = []
> for n in dir(self.__clas s__):
> if n.startswith("i s_"):
> r.append(getatt r(self, n))
>
> def is_of_category_ 1(self, token):
> if token == 1:
> return "1"
>
> def is_of_category_ 2(self, token):
> if token == 2:
> return "2"
>
> def recognize(self, token):
> # would also work:
> #for fun in [self.is_of_cate gory_1, self.is_of_cate gory_2]:
>
> for fun in self.recognizer s:
> result = fun(token)
> if result:
> return result
> return False
>
> if __name__ == "__main__":
> r = Recognizer()
> for t in "12341":
> print r.recognize(int (t)),
> print
>
> Peter[/color]

[Peter Otten]

Re: write a recognizer

max khesin wrote:
[color=blue]
> This is cool. Curious (my py object recall is a bit stale): would this
> solution work for a class that derives from Recognizer (and implements
> an 'is_' method)?[/color]

No, but you can use the following instead of dir(...) in the for loop of
__init__():

(copied from cmd.py in the libarary)

def get_names(self) :
# Inheritance says we have to look in class and
# base classes; order is not important.
names = []
classes = [self.__class__]
while classes:
aclass = classes.pop(0)
if aclass.__bases_ _:
classes = classes + list(aclass.__b ases__)
names = names + dir(aclass)
return names

Peter

[Klaus Neuner]

Re: write a recognizer

Thanks to all who participated in this thread.