Object Diff

An object diff framework in Pharo.

Motivation

Assertions failing in SUnit are sometimes difficult to dig into. In particular, those comparing two long and almost identical strings.

Design

Object Diff injects extension methods into certain classes to compute the differences with arbitrary instances. It uses double-dispatch to properly compare classes according to their semantics. As last resort, it relies on instVar comparisions.

Usage

First, load it with Metacello:

Metacello new repository: 'github://rydnr/object-diff:main'; baseline: 'ObjectDiff'; load

Afterwards, just call yourInstance odDiff: anotherInstance. It will return a specific instance of the classes of the package Object-Diff. You'll be able to ask if they are identical, incompatible, or to display the differences in a custom format.

Customization

By default Object-Diff uses wildcards to compare objects. For example,

'abc' odDiff: '<ANYTHING>' identical

returns true. You can disable this feature with ODWildcards disable, or add your own wildcards with

ODWildcards matches at: '*' put: true

Work in progress

• Add Glamorous Toolkit visualization.
• Support for file diffs.
• Improve String vs String differences.

Credits

• Background of the Pharo image by JoBischPeuchet from Pixabay.