Other operations implicitly set $_, so knowing the behaviour of a Perl script can mean knowing the behaviour of Perl, not understanding the instructions in the script. In fact it is more likely to be a dig at a design choice in Perl, where unary functions (one argument) also have a nullary (zero-argument) form: chomp $foo strips trailing whitespace from $foo, while chomp acts on the $_ variable. This can be read as a preference for configuration over convention: do things I say, and only things I say.

We are considering not just the practicality of programming with this tool, but the experience of using the tool, too. Well, this is clearly subjective, but still important: we are taking subjective principles into account. There are only 19 lines, we may as well go through each one! Beautiful is better than ugly.

This sort of information is priceless: knowing how your programming language was designed will help you understand how to read code written in it, and write your own code. This document is published as PEP 20 - The Zen of Python. Type import this into the Python interpreter and you will get a short collection of aphorisms that each summarise a design principle of the Python language (or really of Guido van Rossum). This month, we are going to read an Easter egg in a programming language. A good programmer’s library (I will let you decide whether that is a good library owned by a programmer, or a library belonging to a good programmer) includes essays, scholarly articles, videos, magazines, blog posts, podcast episodes, and more. > print('It is good to meet you, '.Not everything that is worth reading is a book. > print('What is your name?') # ask for their name Please note the two spaces in front of the comment. _spam should not be used again in the code. Variable name starting with an underscore ( _ ) are considered as 'unuseful`. It can use only letters, numbers, and the underscore ( _ ) character.3. You can name a variable anything as long as it obeys the following rules:ġ. Note: Avoid + operator for string concatenation. String Concatenation and ReplicationString Concatenation and Replication OperatorsOperators OperationOperation ExampleExampleĮxamples of expressions in the interactive shell:įloating-point numbers -1.25, -1.0, -0.5, 0.0, 0.5, 1.0, 1.25 Namespaces are one honking great idea - let's do more of those!įrom HighestHighest to LowestLowest precedence: If the implementation is easy to explain, it may be a good idea.

If the implementation is hard to explain, it's a bad idea. There should be one- and preferably only one -obvious way to do it.Īlthough that way may not be obvious at first unless you're Dutch.Īlthough never is often better than *right* now.

In the face of ambiguity, refuse the temptation to guess. Special cases aren't special enough to break the rules. Long time Pythoneer Tim Peters succinctly channels the BDFL's guiding principles for Python's design into 20 aphorisms, only 19 of which have been writtendown. Namespaces are one honking great idea - let's do more of those! Python Basics Python Basics Math Operators Math Operators From Highest Highest to Lowest Lowest precedence: Operators Operators Operation Operation Example Example ** Exponent 2 ** 3 = 8 % Modulus/Remainder 22 % 8 = 6 // Integer division 22 // 8 = 2 / Division 22 / 8 = 2.75 * Multiplication 3 * 3 = 9 - Subtraction 5 - 2 = 3 + Addition 2 + 2 = 4 Examples of expressions in the interactive shell: > 2 + 3 * 6 20 > (2 + 3) * 6 30 > 2 ** 8 256 Although never is often better than *right* now. Although that way may not be obvious at first unless you're Dutch. There should be one- and preferably only one -obvious way to do it. > import this The Zen of Python, by Tim Peters Beautiful is better than ugly. The Zen of Python The Zen of Python From the PEP 20 - The Zen of Python : Long time Pythoneer Tim Peters succinctly channels the BDFL's guiding principles for Python's design into 20 aphorisms, only 19 of which have been written down.

Pep20 zen of python