Just a different way to extract desired data from an xml code string.

Edited 3 Years Ago by vegaseat: if isinstance(xml_code, str):

Comments
always good examples
''' xml_extract_data1.py
read an xml string and extract needed data
modified to work with Python27 and Python33
'''

try:
    # Python2
    from urllib2 import urlopen
    import urllib
except ImportError:
    # Python3
    from urllib.request import urlopen
    import urllib.parse as urllib 

def extract_between(text, sub1, sub2):
    """
    extract a substring from text between two given substrings
    sub1 (first occurrence) and sub2 (first occurrence)
    arguments are case sensitive
    """
    # prevent sub2 from being ignored if it's not there
    if sub2 not in text.partition(sub1)[-1]:
            return None
    return text.partition(sub1)[2].partition(sub2)[0]

address = "Lowell Observatory, Flagstaff, AZ"
url1 = "http://maps.googleapis.com/maps/api/geocode/xml?address="
url2 = url1 + urllib.quote(address.encode('utf-8')) + "&sensor=false"

xml_code = urlopen(url2).read()

print(type(xml_code))

#if type(xml_code) == str:
if isinstance(xml_code, str):
    print("using Python2 string")
else:
    print("decoding Python3 bytes to string")
    xml_code = xml_code.decode()

print(type(xml_code))
#print(xml_code)
print('-'*50)

print("extracting address:")
sub1 = "<formatted_address>"
sub2 = "</formatted_address>"
address2 = extract_between(xml_code, sub1, sub2)
print(address2)

''' result ...

<class 'bytes'>
decoding Python3 bytes to string
<class 'str'>
--------------------------------------------------
extracting address:
Lowell Observatory, 1400 West Mars Hill Road, Flagstaff, AZ 86001, USA

'''

When I was researching on how to get the type of an object everything I read said "don't do type(), use isinstance() instead".

Videos from people like Guido van Rossum, or others with a high standing in the python community always drop little comments like:

"type() would work here, but you should be using isinstance() for that anyway"

They drop little lines like this in their talks, without going into a lot of detail as to why. I wish I had a direct quote, I know I've heard it more than once.

What I'm asking is, in something as simple as what you've done there with if type(xml_code) == str: , which is really similar to what I was trying to do. Just basic types, nothing fancy. Is it okay to do that? Or is it still better to do a if isinstance(xml_code, str):? I don't know everyone here at daniweb but I know vegaseat and pyTony know their stuff, and I'm sure a lot of others do too. So I'm asking you, what do you think?

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