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The Zen of Python is a collection of 19 "guiding principles" for writing computer programs that influence the design of the Python programming language. [1] Python code that aligns with these principles is often referred to as "Pythonic". [2] Software engineer Tim Peters wrote this set of principles and posted it on the Python mailing list in ...
Elements in a set must be hashable. Thus, for example, a frozenset can be an element of a regular set whereas the opposite is not true. Python also provides extensive collection manipulating abilities such as built in containment checking and a generic iteration protocol.
In Raku, a sister language to Perl, for must be used to traverse elements of a list (foreach is not allowed). The expression which denotes the collection to loop over is evaluated in list-context, but not flattened by default, and each item of the resulting list is, in turn, aliased to the loop variable(s). List literal example:
Python's is operator may be used to compare object identities (comparison by reference), and comparisons may be chained—for example, a <= b <= c. Python uses and, or, and not as Boolean operators. Python has a type of expression named a list comprehension, and a more general expression named a generator expression. [78] Anonymous functions ...
Like the unstructured if, only one statement can be specified so in many cases a GOTO is needed to decide where flow of control should resume. Unfortunately, some implementations had a substantial overhead in both space and time (especially SUBSCRIPTRANGE), so many programmers tried to avoid using conditions. Common Syntax examples:
Machine code is generally different from bytecode (also known as p-code), which is either executed by an interpreter or itself compiled into machine code for faster (direct) execution. An exception is when a processor is designed to use a particular bytecode directly as its machine code, such as is the case with Java processors .
For example, i = arr[i] = f() is equivalent to arr[i] = f(); i = arr[i]. In C++ they are also available for values of class types by declaring the appropriate return type for the assignment operator. In Python, assignment statements are not expressions and thus do not have a value. Instead, chained assignments are a series of statements with ...
For example, a programmer may write a function in source code that is compiled to machine code that implements similar semantics. There is a callable unit in the source code and an associated one in the machine code, but they are different kinds of callable units – with different implications and features.