Closures & evaluate

Orbit is happiest when configuration can be either a value or a small function. evaluate() is the shared switch: if it’s callable, call it; otherwise return it as-is.

from almasix.orbit.support.evaluate import evaluate

evaluate("static")                         # "static"
evaluate(lambda record=None, **_: record["title"], record={"title": "Hi"})
# "Hi"

Resolution order

When the candidate is callable, evaluate tries:

1. candidate(**ctx)
2. candidate(*args) (if positional args were passed)
3. candidate(*args, **ctx)
4. candidate()
5. If all raise TypeError, returns the callable unchanged

That means you can write lambda record=None, **_: or a zero-arg function or something that only accepts record — Orbit will meet you halfway.

Where callables show up

On almost every fluent component (Component and friends):

Method	Callable?	Notes
.label(...)	yes	Falls back to title-cased name
.helper_text(...) / .hint(...) / .hint_icon(...)	yes
.default(...)	yes	Evaluated via get_default(**ctx)
.visible(...) / .disabled(...)	yes	Bool result
.extra_attributes({...})	values yes	Each value is evaluated
Field .placeholder(...) / .required(...) / .options(...)	yes
Action .url(...) / .color(...) / .icon(...) / .authorize(...)	yes
Column .color(...) / .url(...)	yes	Often get record + state

from almasix.orbit.forms import TextInput
from almasix.orbit.tables import TextColumn
from almasix.orbit.actions import Action

TextInput.make("slug")
    .label(lambda record=None, **_: "Slug" if record else "New slug")
    .helper_text(lambda **ctx: "Locked" if ctx.get("published") else "Editable")
    .disabled(lambda record=None, **_: bool(record and record.get("published")))
    .default(lambda **_: "untitled")
    .extra_attributes({"data-id": lambda record=None, **_: record and record.get("id")})

TextColumn.make("status").color(
    lambda record=None, state=None, **_: "success" if state == "published" else "gray"
)

Action.make("publish").authorize(lambda user=None, **_: user and user.is_editor)

Passing context

Render / resolve methods take **ctx — pass what your callables need:

field.render(state, record=post, user=request.user, published=post.is_published)
column.render_cell(record, user=request.user)
action.render(record=record, user=request.user)

Invisible components return empty HTML. Disabled ones still render, but won’t take input.

Mental model

Think of closures as stage directions, not a second schema language. Same field tree; manners that depend on who’s in the room. For form-focused examples see Form closures.