Server Side Programming Articles

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How to compress Python objects before saving to cache?

Rajendra Dharmkar
Rajendra Dharmkar
Updated on 30-Jul-2019 452 Views

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 ...

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How do cookies work in Python CGI Programming?

Rajendra Dharmkar
Rajendra Dharmkar
Updated on 30-Jul-2019 639 Views

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 ...

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Why the use of "using namespace std' considered bad practice?

Abhinaya
Abhinaya
Updated on 30-Jul-2019 507 Views

C++ has a standard library that contains common functionality you use in building your applications like containers, algorithms, etc. If names used by these were out in the open, for example, if they defined a queue class globally, you'd never be able to use the same name again without conflicts. So they created a namespace, std to contain this change.The using namespace statement just means that in the scope it is present, make all the things under the std namespace available without having to prefix std:: before each of them.While this practice is okay for example code, pulling in the ...

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What is object slicing in C++ or Java?

Ankitha Reddy
Ankitha Reddy
Updated on 30-Jul-2019 3K+ Views

Object slicing is used to describe the situation when you assign an object of a derived class to an instance of a base class. This causes a loss of methods and member variables for the derived class object. This is termed as information being sliced away. For example, class Foo { int a; }; class Bar : public Foo { int b; }; Since Bar extends Foo, it now has 2 member variables, a and b. So if you create a variable bar of type Bar and then create ...

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Difference between undefined, unspecified, and implementation-defined behavior in C and C++?

Abhinanda Shri
Abhinanda Shri
Updated on 30-Jul-2019 619 Views

Undefined behavior is simply behavior that is not defined by the C++ specification. For example, if you have multiple unary increment/decrement operations in an expression like i++ + ++i, they result in behavior that is not defined. This is simply due to the fact that some language constructs are syntactically valid but you can't predict the behavior when the code is run. Another example is the expression: u = (u++);Implementation-defined behavior is behavior unspecified by the specification and left for the implementor to decide and document how the choice is made. In this case, the choice that is made must ...

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The auto storage class in C++

Jennifer Nicholas
Jennifer Nicholas
Updated on 30-Jul-2019 285 Views

In C, The auto storage class specifier lets you explicitly declare a variable with automatic storage. The auto storage class is the default for variables declared inside a block. A variable x that has automatic storage is deleted when the block in which x was declared exits.You can only apply the auto storage class specifier to names of variables declared in a block or to names of function parameters. However, these names by default have automatic storage. Therefore the storage class specifier auto is usually redundant in a data declaration.It was initially carried over to C++ for syntactical compatibility only, ...

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Why there is not do...while loop in Python?

Pythonista
Pythonista
Updated on 30-Jul-2019 1K+ Views

PEP 315 (Python Enhancement Proposal) to include do..while statement has been rejected because it doen't fit in the general format of indented block statement: indented block used by every other Python compound statement. In words of Guido Van Rossum -  "Please reject the PEP. More variations along these lines won't make the language more elegant or easier to learn. They'd just save a few hasty folks some typing while making others who have to read/maintain their code wonder what it means".

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What is the max length of a Python string?

Rajendra Dharmkar
Rajendra Dharmkar
Updated on 30-Jul-2019 4K+ Views

With a 64-bit Python installation, and 64 GB of memory, a Python 2 string of around 63 GB should be quite feasible. If you can upgrade your memory much beyond that, your maximum feasible strings should get proportionally longer. But this comes with a hit to the runtimes.With a typical 32-bit Python installation, of course, the total memory you can use in your application is limited to something like 2 or 3 GB (depending on OS and configuration), so the longest strings you can use will be much smaller than in 64-bit installations with very high amounts of RAM.

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Is it possible to use Python modules in Octave?

Rajendra Dharmkar
Rajendra Dharmkar
Updated on 30-Jul-2019 370 Views

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)

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How to use Python modules over Paramiko (SSH)?

Rajendra Dharmkar
Rajendra Dharmkar
Updated on 30-Jul-2019 658 Views

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 ...

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