Metadata-Version: 1.1
Name: whatwhen
Version: 0.1
Summary: A higher-level topological sort.
Home-page: UNKNOWN
Author: Stijn Debrouwere
Author-email: stijn@stdout.be
License: MIT
Download-URL: http://www.github.com/newslynx/python-whatwhen/tarball/master
Description: `whatwhen` is a higher-level topological sort, a useful algorithm to resolve dependencies and calculate a workable execution order for functions and other things.
        
        Basic topological sorting:
        
            tasks = [
                {
                    'name: 'drive', 
                    'dependencies': ['car'], 
                }, {
                    'name': 'car', 
                    'dependencies': ['wheels', 'gas'], 
                }, {
                    'name': 'wheels', 
                    'dependencies': 'rubber', 
                }, {
                    'name': 'gas', 
                }, {
                    'name': 'rubber', 
                }, 
            ]
        
            whatwhen.sort(items)
        
        Topological sorting using contracts (needs and provisions):
        
            tasks = [
                {
                    'name': 'drive', 
                    'needs': ['car', 'gas'], 
                }, {
                    'name': 'fill tank', 
                    'provides': ['gas'], 
                }, {
                    'name': 'rent a car', 
                    'provides': ['car'], 
                    'dependencies': ['money'],
                }, {
                    'name': 'money'
                }
            ]
        
            whatwhen.sort(items)
        
        Needs and provisions are useful when you don't know exactly what function (or system or module or whatever) is going to provide the necessary data or preconditions, but you do know what that data or those preconditions are. This might happen in large systems or systems over which you don't have full control.
        
        In addition to dictionaries, the metadata on tasks can also be added to functions:
        
            def one():
                pass
        
            def two():
                pass
        
            one.dependencies = ['two']
        
            whatwhen.sort([one, two])
        
        WhatWhen will return the original functions (or dictionaries) in sorted order, rather than just a sorted list of node names, so it's slightly easier to work with than a raw topological sort.
        
        WhatWhen lets the [tarjan](https://github.com/bwesterb/py-tarjan) module do most of the heavy lifting, so there's really only about 40 lines of wrapper code to this module. It's up to you to decide whether you'd rather build on top of WhatWhen or plain Tarjan.
Keywords: topological sort toposort topsort dependencies dependency resolver
Platform: UNKNOWN
Classifier: Development Status :: 4 - Beta
Classifier: Intended Audience :: Developers
Classifier: License :: OSI Approved :: MIT License
Classifier: Operating System :: OS Independent
Classifier: Programming Language :: Python
Classifier: Topic :: Utilities
