| ================================= | |
| MEP13: Use properties for Artists | |
| ================================= | |
| .. contents:: | |
| :local: | |
| Status | |
| ====== | |
| - **Discussion** | |
| Branches and Pull requests | |
| ========================== | |
| None | |
| Abstract | |
| ======== | |
| Wrap all of the matplotlib getter and setter methods with python | |
| `properties | |
| <https://docs.python.org/3/library/functions.html#property>`_, allowing | |
| them to be read and written like class attributes. | |
| Detailed description | |
| ==================== | |
| Currently matplotlib uses getter and setter functions (usually | |
| prefixed with get\_ and set\_, respectively) for reading and writing | |
| data related to classes. However, since 2.6 python supports | |
| properties, which allow such setter and getter functions to be | |
| accessed as though they were attributes. This proposal would | |
| implement all existing setter and getter methods as properties. | |
| Implementation | |
| ============== | |
| 1. All existing getter and setter methods will need to have two | |
| aliases, one with the get\_ or set\_ prefix and one without. | |
| Getter methods that currently lack prefixes should be recording in | |
| a text file. | |
| 2. Classes should be reorganized so setter and getter methods are | |
| sequential in the code, with getter methods first. | |
| 3. Getter and setter methods that provide additional optional arguments should | |
| have those arguments accessible in another manner, either as additional | |
| getter or setter methods or attributes of other classes. If those classes | |
| are not accessible, getters for them should be added. | |
| 4. Property decorators will be added to the setter and getter methods | |
| without the prefix. Those with the prefix will be marked as | |
| deprecated. | |
| 5. Docstrings will need to be rewritten so the getter with the prefix | |
| has the current docstring and the getter without the prefix has a | |
| generic docstring appropriate for an attribute. | |
| 6. Automatic alias generation will need to be modified so it will also | |
| create aliases for the properties. | |
| 7. All instances of getter and setter method calls will need to be | |
| changed to attribute access. | |
| 8. All setter and getter aliases with prefixes will be removed | |
| The following steps can be done simultaneously: 1, 2, and 3; 4 and 5; | |
| 6 and 7. | |
| Only the following steps must be done in the same release: 4, 5, | |
| and 6. All other changes can be done in separate releases. 8 should | |
| be done several major releases after everything else. | |
| Backward compatibility | |
| ====================== | |
| All existing getter methods that do not have a prefix (such as get\_) | |
| will need to be changed from function calls to attribute access. In | |
| most cases this will only require removing the parenthesis. | |
| setter and getter methods that have additional optional arguments will | |
| need to have those arguments implemented in another way, either as a | |
| separate property in the same class or as attributes or properties of | |
| another class. | |
| Cases where the setter returns a value will need to be changed to | |
| using the setter followed by the getter. | |
| Cases where there are set_ATTR_on() and set_ATTR_off() methods will be | |
| changed to ATTR_on properties. | |
| Examples | |
| ======== | |
| axes.Axes.set_axis_off/set_axis_on | |
| ---------------------------------- | |
| Current implementation: :: | |
| axes.Axes.set_axis_off() | |
| axes.Axes.set_axis_on() | |
| New implementation: :: | |
| True = axes.Axes.axis_on | |
| False = axes.Axes.axis_on | |
| axes.Axes.axis_on = True | |
| axes.Axes.axis_on = False | |
| axes.Axes.get_xlim/set_xlim and get_autoscalex_on/set_autoscalex_on | |
| ------------------------------------------------------------------- | |
| Current implementation: :: | |
| [left, right] = axes.Axes.get_xlim() | |
| auto = axes.Axes.get_autoscalex_on() | |
| [left, right] = axes.Axes.set_xlim(left=left, right=right, emit=emit, auto=auto) | |
| [left, right] = axes.Axes.set_xlim(left=left, right=None, emit=emit, auto=auto) | |
| [left, right] = axes.Axes.set_xlim(left=None, right=right, emit=emit, auto=auto) | |
| [left, right] = axes.Axes.set_xlim(left=left, emit=emit, auto=auto) | |
| [left, right] = axes.Axes.set_xlim(right=right, emit=emit, auto=auto) | |
| axes.Axes.set_autoscalex_on(auto) | |
| New implementation: :: | |
| [left, right] = axes.Axes.axes_xlim | |
| auto = axes.Axes.autoscalex_on | |
| axes.Axes.axes_xlim = [left, right] | |
| axes.Axes.axes_xlim = [left, None] | |
| axes.Axes.axes_xlim = [None, right] | |
| axes.Axes.axes_xlim[0] = left | |
| axes.Axes.axes_xlim[1] = right | |
| axes.Axes.autoscalex_on = auto | |
| axes.Axes.emit_xlim = emit | |
| axes.Axes.get_title/set_title | |
| ----------------------------- | |
| Current implementation: :: | |
| string = axes.Axes.get_title() | |
| axes.Axes.set_title(string, fontdict=fontdict, **kwargs) | |
| New implementation: :: | |
| string = axes.Axes.title | |
| string = axes.Axes.title_text.text | |
| text.Text = axes.Axes.title_text | |
| text.Text.<attribute> = attribute | |
| text.Text.fontdict = fontdict | |
| axes.Axes.title = string | |
| axes.Axes.title = text.Text | |
| axes.Axes.title_text = string | |
| axes.Axes.title_text = text.Text | |
| axes.Axes.get_xticklabels/set_xticklabels | |
| ----------------------------------------- | |
| Current implementation: :: | |
| [text.Text] = axes.Axes.get_xticklabels() | |
| [text.Text] = axes.Axes.get_xticklabels(minor=False) | |
| [text.Text] = axes.Axes.get_xticklabels(minor=True) | |
| [text.Text] = axes.Axes.([string], fontdict=None, **kwargs) | |
| [text.Text] = axes.Axes.([string], fontdict=None, minor=False, **kwargs) | |
| [text.Text] = axes.Axes.([string], fontdict=None, minor=True, **kwargs) | |
| New implementation: :: | |
| [text.Text] = axes.Axes.xticklabels | |
| [text.Text] = axes.Axes.xminorticklabels | |
| axes.Axes.xticklabels = [string] | |
| axes.Axes.xminorticklabels = [string] | |
| axes.Axes.xticklabels = [text.Text] | |
| axes.Axes.xminorticklabels = [text.Text] | |
| Alternatives | |
| ============ | |
| Instead of using decorators, it is also possible to use the property | |
| function. This would change the procedure so that all getter methods | |
| that lack a prefix will need to be renamed or removed. This makes | |
| handling docstrings more difficult and harder to read. | |
| It is not necessary to deprecate the setter and getter methods, but | |
| leaving them in will complicate the code. | |
| This could also serve as an opportunity to rewrite or even remove | |
| automatic alias generation. | |
| Another alternate proposal: | |
| Convert ``set_xlim``, ``set_xlabel``, ``set_title``, etc. to ``xlim``, | |
| ``xlabel``, ``title``,... to make the transition from ``plt`` | |
| functions to ``axes`` methods significantly simpler. These would still | |
| be methods, not properties, but it's still a great usability | |
| enhancement while retaining the interface. | |