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Articles by Rajendra Dharmkar
Page 15 of 16
How do you compare Python objects with .NET objects?
By default, all .NET objects are reference types and their equality and hash code is determined by their memory address. Additionally, assigning a variable to an existing object just makes it point to that address in memory, so there is no costly copying occurring. It appears that this is true for python objects as well to certain extent.Properties of Python objects: All python objects havea unique identity (an integer, returned by id(x)); a type (returned by type(x))You cannot change the identity; You cannot change the type.Some objects allow you to change their content (without changing the identity or the type, that is).Some ...
Read MoreHow to compress Python objects before saving to cache?
We need sometimes to compress Python objects (list, dictionary, string, etc) before saving them to cache and decompress after reading from cache.Firstly we need to be sure we need to compress the objects. We should check if the data structures/objects are too big just to fit uncompressed in the cache. There is going to be an overhead for compression/decompression, that we have to tradeoff with the gains made by caching in the first place.If we really need compression, then we probably want to use zlib.If we are going to use zlib, we might want to experiment with the different compression ...
Read MoreWhen are python objects candidates for garbage collection?
A python object or variable will be eligible for garbage collection as soon as all references to it go out of scope or are manually deleted (del x). We would have to presume there were no references to the object anywhere else for it to be garbage collected.
Read MoreWhat are repeating character classes used in Python regular expression?
A character class followed by operators like '?', '*' or '+' are called repeating character classes.If you repeat a character class by using the '?', '*' or '+' operators, you will repeat the entire character class, and not just the character that it matched. The regex '[0-9]+' can match '579' as well as '333'. If you want to repeat the matched character, rather than the class, you will need to use backreferences. '([0- 9])\1+' will match '333' but not “579”. When applied to the string “922226”, it will match '2222' in the middle of this string. If you do not ...
Read MoreWhat Content-type is required to write Python CGI program?
If we run simple scripts like hello.py, its output is written on the STDOUT file, i.e., screen. There is one important and extra feature available which is the first line to be printed Content-type:text/html\r\r. This line is sent back to the browser and it specifies the content type to be displayed on the browser screen.We can write advanced CGI programs using Python. This script can interact with any other external system and even exchange information with RDBMS.
Read MoreHow do cookies work in Python CGI Programming?
Using Cookies in CGIHTTP protocol is a stateless protocol. For a commercial website, it is required to maintain session information among different pages. For example, one user registration ends after completing many pages. How to maintain user's session information across all the web pages?In many situations, using cookies is the most efficient method of remembering and tracking preferences, purchases, commissions, and other information required for better visitor experience or site statistics.How Cookies workYour server sends some data to the visitor's browser in the form of a cookie. The browser may accept the cookie. If it does, it is stored as ...
Read MoreWhat is the difference between time.clock() and time.time()?
The function time.time() returns the time in seconds since the epoch, i.e., the point where the time starts.For Unix, the epoch is January 1, 1970. For Windows, the epoch is January 1, 1601.time.time() is used for benchmarking on Windows. time.time() behaves the same on both UNIX and Windows but time.clock() has different meanings.On UNIX, time.clock returns the current processor time expressed in seconds, i.e., the CPU time it takes to execute the current thread so far. While on Windows, it returns the wall-clock time expressed in seconds elapsed since the first call to this function, based on the Win32 function ...
Read MoreHow to use Python modules over Paramiko (SSH)?
You connect and use a python module on the remote computer over SSH, as SSH only provides limited functionality so calling the module isn't possible.You can call a script on the remote server and run that as a way of getting around this problem. To get a result from the script, you can look at it by reading the lines from stdout if you're logging your result. Alternatively, you can write the result to a file and then read the file once the result has been generated and written to the file.If you want to do this over the network ...
Read MoreIs it possible to use Python modules in Octave?
There is no straightforward way to do this. But it is possible to run a Python program and parse the output. You can execute any shell command using the function system (cmd, flag). The second argument is optional. If it is present, the output of the command is returned by system as a string. If it is not supplied, any output from the command is printed, with the standard output filtered through the pager. For example,output = system ("python /path/to/your/python/script.py", 1)
Read MoreHow to prohibit a Python module from calling other modules?
You can use "Sandboxed Python". A "Sandboxed Python" would let you permit or forbid modules, limit execution slices, permit or deny network traffic, constrain filesystem access to a particular directory (floated as "/"), and so on. It is also referred to as RestrictedExecution. There are many ways to implement sandboxing on Python. You could Modify the CPython Runtime, Use Another Runtime, Use Operating System Support, etc to implement such a sandbox. You can read more about sandboxing at: https://wiki.python.org/moin/SandboxedPythonPypi has a package called RestrictedPython(https://pypi.python.org/pypi/RestrictedPython) that is a defined subset of the Python language which allows to provide a program input ...
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