Search results
Results from the WOW.Com Content Network
Python sets are very much like mathematical sets, and support operations like set intersection and union. Python also features a frozenset class for immutable sets, see Collection types. Dictionaries (class dict) are mutable mappings tying keys and corresponding values. Python has special syntax to create dictionaries ({key: value})
In Python, if a name is intended to be "private", it is prefixed by one or two underscores. Private variables are enforced in Python only by convention. Names can also be suffixed with an underscore to prevent conflict with Python keywords. Prefixing with double underscores changes behaviour in classes with regard to name mangling.
A reference variable, once declared and bound, behaves as an alias of the original variable, but it can also be rebounded to another variable by using the reference assignment operator = ref. The variable itself can be of any type, including value types and reference types, i.e. by passing a variable of a reference type by reference (alias) to ...
Monty Python references appear frequently in Python code and culture; [190] for example, the metasyntactic variables often used in Python literature are spam and eggs instead of the traditional foo and bar. [190] [191] The official Python documentation also contains various references to Monty Python routines.
Spam, ham, and eggs are the principal metasyntactic variables used in the Python programming language. [10] This is a reference to the famous comedy sketch, "Spam", by Monty Python, the eponym of the language. [11] In the following example spam, ham, and eggs are metasyntactic variables and lines beginning with # are comments.
The reference to the object is passed as a hidden argument, usually accessible from within the method as this. A parameter called by reference is syntactic sugar for technically passing a pointer as the parameter, but syntactically handling it as the variable itself, to avoid constant pointer de-referencing in the code inside the function.
For variables, Python has function scope, module scope, and global scope. Names enter context at the start of a scope (function, module, or global scope), and exit context when a non-nested function is called or the scope ends. If a name is used prior to variable initialization, this raises a runtime exception.
The identifier list is bound to a variable in the first line; in the second, an object (a linked list of strings) is assigned to the variable. The linked list referenced by the variable is then mutated, adding a string to the list. Next, the variable is assigned the constant null. In the last line, the identifier is rebound for the scope of the ...