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Sunday, October 23, 2016

Using text file with python 2.7 .

This simple tutorial is about text file. The text file come with txt extension.
It is a file containing text that can be used and further processing by functions and modules python.
I used Tkinter python module. The reason I chose this python mpodule is:
  • old python module;
  • rapidly developing graphical interfaces.
First step is to import the python module and then to put all of dir command into one text file.
The name of this file is: Tkinter_funct.txt
Open your python and try this source code:
C:\Python27>python.exe
Python 2.7.8 (default, Jun 30 2014, 16:08:48) [MSC v.1500 64 bit (AMD64)] on win32
Type "help", "copyright", "credits" or "license" for more information.
>>> import Tkinter
>>> from Tkinter import *
>>> Tkinter_all=dir(Tkinter)
>>> Tkinter_file=open('Tkinter_funct.txt','w')
>>> Tkinter_file.write(str(Tkinter_all))
>>> print Tkinter_all

You will see the content of dir python module.
The text file is also have this text output.
To read the file is need to open the file with open function, to put position for read by using seek function and to read with read function.
This example will show you how is working:
>>> test=open('Tkinter_funct.txt','r+')
>>> test.seek(1)
>>> test.read()

Will open the file named Tkinter_funct.txt and r+ access to file.
The position it is set to 1.
The read function make all with full content output.
Now let's see the next steps, by change the read and seek values.

>>> test.read(1)
''
>>> test.read(2)
''
>>> test.read(10)
''
>>> test.seek(2)
>>> test.read(1)
'A'
>>> test.read(10)
"CTIVE', 'A"
>>> test.read(20)
"LL', 'ANCHOR', 'ARC'"

This outputs come with parts of all content and show you how it's working.

Monday, October 3, 2016

The python CacheControl module - part 002.

Today was a hard day and this is the reason I make this short tutorial.
Teory of HTTP:
HTTP specifies four response cache headers that you can set to enable caching:
  • Cache-Control
  • Expires
  • ETag
  • Last-Modified
These four headers are used to help cache your responses into two different models:
  • Expiration Caching - used to cache your entire response for a specific amount of time (e.g. 24 hours), simple, but cache invalidation is more difficult;
  • Validation Caching - this is more complex and used to cache your response, but allows you to dynamically invalidate it as soon as your content changes.
First you need to know about this code is a raw example about how we can access cache of the page.
Come with a simple class named DictCache. You can named with any name and is a BaseCache class.
The next step I make is to show you how can access it.
One simpe way is to see the page - first session.
The complex come when you need to access for example data and info like:
 'adapters', 'auth', 'cert', 'close', 'cookies', 'delete', 'get', 'get_adapter', 'head', 'headers', 'hooks', 'max_redirects', 'merge_environment_settings', 'mount', 'options', 'params', 'patch', 'post', 'prepare_request', 'proxies', 'put', 'rebuild_auth', 'rebuild_method', 'rebuild_proxies', 'redirect_cache', 'request', 'resolve_redirects', 'send', 'stream', 'trust_env', 'verify'
And this is come with teh second session from this source code:

import requests
from cachecontrol import CacheControl
from cachecontrol.cache import BaseCache

class DictCache(BaseCache):

    def __init__(self, init_dict=None):
        self.data = init_dict or {}

    def get(self, key):
        return self.data.get(key, None)

    def set(self, key, value):
        self.data.update({key: value})

    def delete(self, key):
        self.data.pop(key)

print "first session requests"
sess = requests.session()
cached_sess = CacheControl(sess)
response = cached_sess.get('http://google.com')
print '=================='
print 'see page by add this: print response.text'
print '=================='
print "second session BaseCache"
sess2 = requests.session()
base=DictCache(sess2)
print '=================='
print "dir(base)"
print dir(base)
print '=================='
print"dir(base.data)"
print dir(base.data)
print '=================='
print"base.data.max_redirects"
print base.data.max_redirects
print '=================='