[Level 2] Implement with syntax in Python. 

#!/bin/env python
class myOpen(object):
    def __init__(self, filename, readwrite):
        self.__filename = filename
        self.__readwrite = readwrite
        self.__fd = None

    def __enter__(self):
        self.__fd = open(self.__filename, self.__readwrite)
        return self.__fd

    def __exit__(self, *args):
        self.__fd.close()

with myOpen('/tmp/my.txt', 'r') as f:
    print f.readlines()

with myOpen('/tmp/hello.txt', 'w') as f:
    f.write('hello world!\n')

$ ./test.py 
['-rwxr--r-- 1 stanley stanley   846 2012-12-26 13:07 ./c.py\n', '-rwxr--r-- 1 stanley stanley   486 2013-01-08 17:54 ./test.py\n']
$ cat ./my.txt 
-rwxr--r-- 1 stanley stanley   846 2012-12-26 13:07 ./c.py
-rwxr--r-- 1 stanley stanley   486 2013-01-08 17:54 ./test.py
$ cat ./hello.txt 
hello world!

Wish this helps.

regards,
Stanley Huang

Comments

Post a Comment

Popular posts from this blog

[Level 1] Rar tool for Solaris.

Sometimes we will got a rar compressed file from our friends, but there is no default tool in OpenSolaris to decompress the rar filess. We can got a Solaris Intel version from rarlab . The steps as the following: 1. down load the rar tools from rarlab. http://www.rarlab.com/rar_add.htm 2. uncompressed the source. # gunzip ./unrar-sol-intel.gz 3. move it to the location you used to. # mv /unrar-sol-intel.gz /usr/bin/unrar 4. try to decomprss # unrar x ./test.rar Wish this helps. regards, Stanley Huang
Read more

[Level 2] iif in Python

If you want to implement iif in Python, please refer to the following sample code: #!/bin/env python def iif(b): return 'It\'s True' if b else 'It\'s False' print iif(True) print iif(False) And the following sample, guess what will you get! #!/bin/env python b = True print 'b: %s' % 'Ture' if b else 'False' b = False print 'b: %s' % 'Ture' if b else 'False' Result: $ ./iif.py b: Ture False The second result is "False", not "b: False". Why??? Because the prededence of string concatenation is higher than if. Therefore you need to use () to make it correct. #!/bin/env python b = True print 'b: %s' % 'Ture' if b else 'False' b = False print 'b: %s' % ('Ture' if b else 'False') Wish this helps. regards, Stanley Huang
Read more