Language Specific Class Checklists

Thomas Kennedy

Contents:

We will start by revisiting the C++ class checklist, mapping its parts into Java and Python 3.

1 Language Specific Class Checklists

Every semester I draw a table on the whiteboard. I last drew this table on 16 October 2018, and discussed the C++ class checklist and how each item compares to Java and Python 3.

It was obvious that the potato used to take the photo was not properly calibrated. Consider the following table…

C++	Java	Python 3
Default Constructor	Default Constructor	`__init__`
Copy Constructor	Clone and/or Copy Constructor	`__deepcopy__`
Destructor
	finalize (deprecated/discouraged)	`__del__`
Assignment Operator (=)
Accessors (Getters)	Accessors (Getters)	Accessors (consider `@property`)
Mutators (Setters)	Mutators (Setters)	Setter (consider `@attribute.setter`)
Swap
Logical Equivalence Operator (==)	equals	`__eq__`
Less-Than / Comes-Before Operator (<)	hashCode	`__hash__`
Stream Insertion Operator (<<)	toString	`__str__`
		`__repr__`
`begin()` and `end()`	`iterator`	`__iter__`

You should recall from your previous coursework that not all accessors are getters and not all mutators are setters. The accessor and mutator rows deal with getters and setters, respectively.

Let us expand the table to include one more language… Rust.

C++	Java	Python 3	Rust
Default Constructor	Default Constructor	`__init__`	`new()` or Default trait
Copy Constructor	Clone and/or Copy Constructor	`__deepcopy__`	Clone trait
Destructor
	finalize (deprecated/discouraged)	`__del__`	Drop trait
Assignment Operator (=)
Accessors (Getters)	Accessors (Getters)	Accessors (`@property`)	Accessors (Getters)
Mutators (Setters)	Mutators (Setters)	Setter (`@attribute.setter`)	Mutators (setters)
Swap
Logical Equivalence Operator (==)	equals	`__eq__`	std::cmp::PartialEq trait
Less-Than / Comes-Before Operator (<)	hashCode	`__hash__`	std::cmp::PartialOrd trait
Stream Insertion Operator (<<)	toString	`__str__`	std::fmt::Display trait
		`__repr__`	std::fmt::Debug trait
`begin()` and `end()`	`iterator`	`__iter__`	`iter()` and `iter_mut()`

The Python __str__ method generates human readable output (much like the Java toString method).
There is no analogue in C++ or Java to Python’s __repr__. The __repr__ method is used for debugging. It, by definition, should generate an unambiguous string representation.

We are not going to look in Java or Python in detail… Yet!