COMPSCI 61A Lecture Notes - Lecture 17: Init, Message Passing, Return Ratio

• School: Berkeley
• Department: Computer Science
• Course: COMPSCI 61A
• Professor: De Nero John

Document Summary

Object value should behave like the kind of data it is meant to represent. For instance, by producing string representation of itself. Strings are important: they represent language and programs. In python, all objects produce two string representations: Str and repr strings are often the smae, but not always. Repr func returns a python expression (a string) that evaluates to an equal object. Returns canonical string representation of the obejct, for most object types, eval(repr(object)) == object. Result of calling repr on a value is what python prints in an interactive session. Some objects do not have a simple python readable string. Human interpretable strings are useful as well: Gives back value that is human interpretable representation of string. Result calling str on value of an expressino is what python prints using the print fucntino: Polymorphic function:function that applies to many )poly) different forms(morph) of data. Str and repr are both polymorphic; they apply to any object.