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kabaret.flow contextual dict

Project description

kabaret.flow_contextual_dict

This package provide the ContextualView class and the get_contextual_dict function.

Together, they give your flow users the ability to use defined value anywhere in the branch underneeth and override those values where you see fit in the branches.

Everything is explained here, but if your of the kind that prefers to read and execute code, there is a demo flow in the package for that. Install the package an create a new project with the type kabaret.flow_contextual_dict.demo_flow.DemoFlow.

Concept

Here is a quick example with this classic structure where settings are ContextualView Objects:

Project
    settings
    episodes
        ep001
            settings
            sequences
                seq001
                    settings
                    shots
                        shot001
                            settings
                            anim
                                settings
                                init_action
                                bake_action
                            lighting
                                settings
                                init_action
                                render_action
                            comp
                                settings
                                init_action
                                render_action
                        shot002
                seq002
                    ...
        ep002
            ...

Let's say in the Project.settings defines fps=24 and a pool="ANY". Every object in the episodes branch can call get_contextual_dict() to receive a dict like {fps:24, pool:"ANY"}. Most likely, action of every step/department of every shot will use this.

Now let's say the sequence seq002 is in a hurry and you want to dispatch all actions on your farm's "SUPER_COMPUTERS" pool. All you need is to "override" with pool="SUPER_COMPUTERS" in ep002.settings.

You can do this in each settings in the flow, and you can also "add" values in each of them (those "overrides" and "adds" are called "edits").

In a nutshell, it's a cascading dict, or as some call it: a contextual dict.

Install

pip install kabaret.flow_contextual_dict

Please use a virtual env, it is good for you and your karma ^^

Usage

Defining Contexts

In order to add a contextual dict in your flow, you just need to add a Child relation to a ContextualView:

class Shot(flow.Object):

    settings = flow.Child(contextualView)
    ...

The name of the relation is very important:

  • Overrides stacking is based on this name so you need to use the same name along your branch in order for overrides to work as expected.
  • It defines the "context_name" argument to use for get_contextual_dict() calls.

So this will not work:

Project
    settings
    episodes
        ep001
            episode_settings

But this will:

Project 
    settings
    episodes
        ep001
            settings

Note that you can use Child().ui(label="Episode Settings") if you really want to display a different name in the GUI.

This gives the ability to use several contexts in the same flow. In this structure, all * marked item are ContextualView. There is two context defined: settings and config. The first one drives values by sequences and shots, the second one only affects episodes.

Project
    settings *
    config *
    episodes
        ep001
        config *
        sequences
            seq001
                settings *
                shots
                    shot001
                        settings *

Editing Context Values

Once your flow is salted with ContextualView, the user will be able to add value using the "Add" action and to edit values by double clicking on them.

If you want, for debug or inquiry, you can inspect the edits done thru a ContectualView by using its "Show Edits" actions. It will bring you to a page showing only values defined here. Double-clicking one of those items will show you more information, especially the history of modification for this value (what changed, who did it, and when). You will also be able to change the override value, as well as disable/enable it.

You can also programatically edit the context by defining get_default_contextual_edits(context_name) methods returning a dict of value to use if no override exists for them.

In other words: user edits made with ContextualView actions will override values returned by a local or upstream get_default_contextual_edits() method.

Using Context Values

In order to get a context dict, you just need to call get_contextual_dict(leaf, context_name). The leaf is the point in the branch where you want the value to be evaluated. It will most of the time be self.

Here is an example in an Action.run():

class SubmitRender(flow.Action):

    render_settings = flow.Child(ContextualView)

    def run(self, button):
        if button == 'Confirm':
            context = get_contextual_dict(
                self, 'render_settings'
            )
            my_dispatcher.submit(
                scene=self.get_scene_path(),
                fps=context.get('fps', 24),
                pool=context.get('pool', 'ANY'),
            )

Note that the second arg of the get_contextual_dict() call must match the name of each ContextualView to evaluate in the upstream branch.

Also note that using a ContextualView as the Action Child has drawbacks in term of UX. We're waiting for a update of kabaret to fix this.

Default Value

At the base of your context, you will probably want to have a set of default values.

You will do this by adding a 'get_default_contextual_edits()` method returning the default value.

Let's say your Project is the first level for you settings. You would do something like:

class Project(flow.Object):

    settings = flow.Child(ContextualView)
    episodes = flow.Child(Episodes)

    def get_default_contextual_edits(self, context_name):
        if context_name == 'settings':
            return dict(
                fps=30,
                pool="ANY"
            )

Special Case

Sometimes, you will want to put the visualisation/edition of the contextual values aside from the branch it affect.

An example would be the settings of a project. They affect the WHOLE UNIVERSE so maybe you wouldn't want them to show on the first page all users land to...

A classic aproach is to use an admin group and shove all geeky stuff in it:

Project
    word_of_the_day
    episodes
        ...
    admin
        settings
        config
        preferences

In this case, the settings object is not inside the episodes branch so it does not affect it. This is a fail at being usefull :/

To fix this, you can define inside Project a get_contextual_view method that returns a ContextView to consider as if it was its Child:

class Project(flow.Object):
    
    word_of_the_day = flow.Chid(WOTD)
    episodes = flow.Child(Episodes)
    admin = flow.Child(ProjectAdmin)

    def get_contextual_view(self, context_name):
        if context_name == 'settings':
            return self.admin.settings
        elif context_name == 'config'
            return self.admin.config

    def get_default_contextual_edits(self, context_name):
        if context_name == 'settings':
            return dict(
                fps=30,
                pool="ANY"
            )

Note that the default value must still be provided by the Project class !

Project details


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