Patch¶

class pyhf.patchset.Patch(spec)[source]¶

Bases: jsonpatch.JsonPatch

A way to store a patch definition as part of a patchset (PatchSet).

It contains metadata about the Patch itself:

a descriptive name

a list of the values for each dimension in the phase-space the associated PatchSet is defined for, see labels

In addition to the above metadata, the Patch object behaves like the underlying jsonpatch.JsonPatch.

Attributes

metadata¶: The metadata of the patch

name¶: The name of the patch

operations = mappingproxy({'remove': <class 'jsonpatch.RemoveOperation'>, 'add': <class 'jsonpatch.AddOperation'>, 'replace': <class 'jsonpatch.ReplaceOperation'>, 'move': <class 'jsonpatch.MoveOperation'>, 'test': <class 'jsonpatch.TestOperation'>, 'copy': <class 'jsonpatch.CopyOperation'>})¶

A JSON Patch is a list of Patch Operations.

>>> patch = JsonPatch([
...     {'op': 'add', 'path': '/foo', 'value': 'bar'},
...     {'op': 'add', 'path': '/baz', 'value': [1, 2, 3]},
...     {'op': 'remove', 'path': '/baz/1'},
...     {'op': 'test', 'path': '/baz', 'value': [1, 3]},
...     {'op': 'replace', 'path': '/baz/0', 'value': 42},
...     {'op': 'remove', 'path': '/baz/1'},
... ])
>>> doc = {}
>>> result = patch.apply(doc)
>>> expected = {'foo': 'bar', 'baz': [42]}
>>> result == expected
True

JsonPatch object is iterable, so you can easily access each patch statement in a loop:

>>> lpatch = list(patch)
>>> expected = {'op': 'add', 'path': '/foo', 'value': 'bar'}
>>> lpatch[0] == expected
True
>>> lpatch == patch.patch
True

Also JsonPatch could be converted directly to bool if it contains any operation statements:

>>> bool(patch)
True
>>> bool(JsonPatch([]))
False

This behavior is very handy with make_patch() to write more readable code:

>>> old = {'foo': 'bar', 'numbers': [1, 3, 4, 8]}
>>> new = {'baz': 'qux', 'numbers': [1, 4, 7]}
>>> patch = make_patch(old, new)
>>> if patch:
...     # document have changed, do something useful
...     patch.apply(old)    
{...}

values¶: The values of the associated labels for the patch

Methods

__init__(spec)[source]¶

Construct a Patch.

Parameters: spec (jsonable) – The patch JSON specification
Returns: The Patch instance.
Return type: patch (Patch)