A compatible product family. Product compatibility is the additional promise.

Two factories expose the same button and checkbox operations. render_form depends on that family interface. Strings keep the teaching example small; real products can be objects with behavior. Adding a family is localized, while adding a new product category affects every family.

What the function promises: Return matching string representations; this is not a UI framework implementation.

class TextFactory:
    def button(self, label):
        return f"[{label}]"
    def checkbox(self, checked):
        return "[x]" if checked else "[ ]"

class SymbolFactory:
    def button(self, label):
        return f"({label})"
    def checkbox(self, checked):
        return "☑" if checked else "☐"

def render_form(factory):
    return factory.button("Save") + " " + factory.checkbox(True)

assert render_form(TextFactory()) == "[Save] [x]"
assert render_form(SymbolFactory()) == "(Save) ☑"

Work and storage: O(output length) construction.

When to recognize it: Abstract Factory supplies related products together. If there is no family constraint, separate constructors may be enough.

Check before applying it: A new product category affects every family promising compatibility.

No. Extend the family interface and all concrete families. Abstract Factory favors adding families over adding new product categories.