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In Python, functions are first-class objects, just like strings, numbers, lists etc. This feature eliminates the need to write a function object in many cases. Any object with a __call__() method can be called using function-call syntax. An example is this accumulator class (based on Paul Graham's study on programming language syntax and ...
Python supports a wide variety of string operations. Strings in Python are immutable, so a string operation such as a substitution of characters, that in other programming languages might alter the string in place, returns a new string in Python. Performance considerations sometimes push for using special techniques in programs that modify ...
The following REBOL/Red code demonstrates callback use. As alert requires a string, form produces a string from the result of calculate; The get-word! values (i.e., :calc-product and :calc-sum) trigger the interpreter to return the code of the function rather than evaluate with the function. The datatype! references in a block!
In Python, constructors are defined by one or both of __new__ and __init__ methods. A new instance is created by calling the class as if it were a function, which calls the __new__ and __init__ methods. If a constructor method is not defined in the class, the next one found in the class's Method Resolution Order will be called. [14]
Parse tree of Python code with inset tokenization. The syntax of textual programming languages is usually defined using a combination of regular expressions (for lexical structure) and Backus–Naur form (a metalanguage for grammatical structure) to inductively specify syntactic categories (nonterminal) and terminal symbols. [7]
There are subtle differences and distinctions in the use of the terms "generator" and "iterator", which vary between authors and languages. [5] In Python, a generator is an iterator constructor: a function that returns an iterator. An example of a Python generator returning an iterator for the Fibonacci numbers using Python's yield statement ...
A built-in function, or builtin function, or intrinsic function, is a function for which the compiler generates code at compile time or provides in a way other than for other functions. [23] A built-in function does not need to be defined like other functions since it is built in to the programming language. [24]
Anonymous functions are often arguments being passed to higher-order functions or used for constructing the result of a higher-order function that needs to return a function. [1] If the function is only used once, or a limited number of times, an anonymous function may be syntactically lighter than using a named function.