View Issue Details [ Jump to Notes ]

[ Print ]

Project

Category

View Status

Date Submitted

Last Update

0012455

Insight Software Consortium

(No Category)

public

2011-09-13 16:03

Reporter

Benjamin Schwartz

Assigned To

Priority

normal

Severity

minor

Reproducibility

have not tried

Status

new

Resolution

open

Platform

OS Version

Summary

0012455: WrapITK Python is not idiomatic

Description

An uninformed opinion:

According to [1], a goal for ITK 4 wrapping is: "Have ITK behaves in the different languages as close to the native code as possible"

The python example at [2] has the code:

"""
reader = readerType.New()
writer = writerType.New()
reader.SetFileName( argv[1] )
writer.SetFileName( argv[2] )
writer.SetInput( reader.GetOutput() )
writer.Update()
"""

IMHO this is unpythonic. In idiomatic python the interface would be

"""
reader = readerType()
writer = writerType()
reader.fileName = argv[1]
writer.fileName = argv[2]
writer.input = reader.output
writer.update()
"""

The specific issues are:
1. Factory methods (i.e. New()) are uncommon in Python. Instead, the name of the type is called directly as a constructor to instantiate and initialize a new object. This is semantic sugar over the __new__ and __init__ methods.

This pattern is used by list(), set(), dict(), str(), int(), file(), and also the complex types in the standard library.

2. Explicit Setters and Getters are discouraged in Python. Instead properties should be accessed directly. When the object needs a setter or getter to maintain internal state, it should be hidden behind a property() abstraction [3].

[1] http://cmake.org/Wiki/ITK_Release_4/Wrapping [^]
[2] http://cmake.org/Wiki/ITK_Release_4/Wrapping/Examples [^]
[3] http://docs.python.org/library/functions.html#property [^]

Issue History
Date Modified	Username	Field	Change
2011-09-13 16:03	Benjamin Schwartz	New Issue

Relationships

Notes
There are no notes attached to this issue.