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A snippet of Python code with keywords highlighted in bold yellow font. The syntax of the Python programming language is the set of rules that defines how a Python program will be written and interpreted (by both the runtime system and by human readers). The Python language has many similarities to Perl, C, and Java. However, there are some ...
Iterator pattern – defines a traversal principle like the visitor pattern, without making a type differentiation within the traversed objects Church encoding – a related concept from functional programming, in which tagged union/sum types may be modeled using the behaviors of "visitors" on such types, and which enables the visitor pattern ...
In Python, returning self in the instance method is one way to implement the fluent pattern. It is however discouraged by the language’s creator, Guido van Rossum, [3] and therefore considered unpythonic (not idiomatic) for operations that do not return new values. Van Rossum provides string processing operations as example where he sees the ...
Python hides essentially all of the details using the iterator protocol. Confusingly, Design Patterns uses "aggregate" to refer to the blank in the code for x in ___: which is unrelated to the term "aggregation". [1]
The patterns generally have the form of either sequences or tree structures. Uses of pattern matching include outputting the locations (if any) of a pattern within a token sequence, to output some component of the matched pattern, and to substitute the matching pattern with some other token sequence (i.e., search and replace).
In Python 3.x the range() function [28] returns a generator which computes elements of the list on demand. Elements are only generated when they are needed (e.g., when print(r[3]) is evaluated in the following example), so this is an example of lazy or deferred evaluation: >>>
A regex pattern matches a target string. The pattern is composed of a sequence of atoms. An atom is a single point within the regex pattern which it tries to match to the target string. The simplest atom is a literal, but grouping parts of the pattern to match an atom will require using ( ) as metacharacters.
Python has a glob module in the standard library which performs wildcard pattern matching on filenames, [28] and an fnmatch module with functions for matching strings or filtering lists based on these same wildcard patterns. [17] Guido van Rossum, author of the Python programming language, wrote and contributed a glob routine to BSD Unix in ...