help with class

[tekion]

Hello,
I am playing with class. Below is the code snippet:
#!/usr/bin/python
2
3 class test_class:
4 #import gzip
5 def __init__(self,file):
6 self.file = file
7 def open_file(self):
8 try:
9 print "file: %s" % self.file
10 self.xml_file = gzip.GzipFile(self.file,'r')
11 except:
12 print "an exception has occured"
13 for line in self.xml_file:
14 print "line: %s" % line
15 self.xml_file.close()
16
17
18 if __name__ == '__main__':
19 import gzip
20 import sys
21 t = test_class( sys.argv[1] )
22 t.open_file()

My question are:
1. Why do I need to use "import gzip" on main section to get it the
script to work? I would assume you need the import of gzip in the
class section.
2. What is the proper way of using module in a class you are creating?

 

[Arnaud Delobelle]

Hello,
I am playing with class. Below is the code snippet:
#!/usr/bin/python
2
3 class test_class:
4 #import gzip
5 def __init__(self,file):
6 self.file = file
7 def open_file(self):
8 try:
9 print "file: %s" % self.file
10 self.xml_file = gzip.GzipFile(self.file,'r')
11 except:
12 print "an exception has occured"
13 for line in self.xml_file:
14 print "line: %s" % line
15 self.xml_file.close()
16
17
18 if __name__ == '__main__':
19 import gzip
20 import sys
21 t = test_class( sys.argv[1] )
22 t.open_file()

My question are:
1. Why do I need to use "import gzip" on main section to get it the
script to work? I would assume you need the import of gzip in the
class section.

This is how Python works. Here is the relevant extract from the
Reference Manual:

A scope defines the visibility of a name within a block. If a local
variable is defined in a block, its scope includes that block. If
the definition occurs in a function block, the scope extends to any
blocks contained within the defining one, unless a contained block
introduces a different binding for the name. The scope of names
defined in a class block is limited to the class block; it does not
extend to the code blocks of methods – this includes generator
expressions since they are implemented using a function scope.

(Quoted from http://docs.python.org/reference/executionmodel.html)

2. What is the proper way of using module in a class you are creating?

import it into the global namespace of the module in which you are
defining your class.

 

[r]

Hello,
I am playing with class.  Below is the code snippet:
#!/usr/bin/python
      2
      3 class test_class:
      4    #import gzip
      5    def __init__(self,file):
      6       self.file = file
      7    def open_file(self):
      8       try:
      9          print "file: %s" % self.file
     10          self.xml_file = gzip.GzipFile(self.file,'r')
     11       except:
     12          print "an exception has occured"
     13       for line in self.xml_file:
     14          print "line: %s" % line
     15       self.xml_file.close()
     16
     17
     18 if __name__ == '__main__':
     19    import gzip
     20    import sys
     21    t = test_class( sys.argv[1] )
     22    t.open_file()

My question are:
1.  Why do I need to use "import gzip" on main section to get it the
script to work?  I would assume you need the import of gzip in the
class section.

This is how Python works.  Here is the relevant extract from the
Reference Manual:

    A scope defines the visibility of a name within a block. If a local
    variable is defined in a block, its scope includes that block. If
    the definition occurs in a function block, the scope extends to any
    blocks contained within the defining one, unless a contained block
    introduces a different binding for the name. The scope of names
    defined in a class block is limited to the class block; it does not
    extend to the code blocks of methods – this includes generator
    expressions since they are implemented using a function scope.

(Quoted fromhttp://docs.python.org/reference/executionmodel.html)

2.  What is the proper way of using module in a class you are creating?

import it into the global namespace of the module in which you are
defining your class.

That's funny...this same question was asked at 11:30 this morning

see thread:
http://groups.google.com/group/comp.lang.python/browse_thread/thread/a42bf1e9504c3c3f?hl=en#

 

[tekion]

Hi,
so I am assuming global name space refers to the location of where the
module is imported, for example my previous example where I call the
gzip module from test_class class, like so:

class test_class:
import gzip

did not work because of scoping. So global name space in this case is
declaring the import outside of test_class like so:

import gzip
class test_class:
etc..

Is my assumption correct? Thanks.

 

[Chris Rebert]

Hi,
so I am assuming global name space refers to the location of where the
module is imported, for example my previous example where I call the
gzip module from test_class class, like so:

class test_class:
import gzip

did not work because of scoping. So global name space in this case is
declaring the import outside of test_class like so:

import gzip
class test_class:
etc..

Is my assumption correct? Thanks.

Yes. Global == module-level.

Cheers,
Chris[/QUOTE]