Custom renderer

Create a renderer when parsed Markdown should become something other than standard HTML.

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Renderers inherit from BaseRenderer and dispatch handlers by node type. Use class-level registration when a renderer type should always have a handler. Use instance-level registration when only one configured renderer should be changed.

Class-level handlers

Register handlers on a renderer subclass when the behavior belongs to that renderer type. Every new instance of the subclass receives the registered handler.

from wenmode import Wenmode
from wenmode.nodes import Text
from wenmode.renderers import BaseRenderer, RenderContext


class UpperRenderer(BaseRenderer):
    pass


@UpperRenderer.register('text')
def render_text(renderer: UpperRenderer, node: Text, context: RenderContext) -> str:
    return node.value.upper()


wen = Wenmode(renderer=UpperRenderer())
source = 'Hello *there*'

text = wen.render(source)

assert text == 'HELLO THERE'

Use this pattern when the output format is application-specific and should be reused across the application.

Instance-level handlers

Register handlers on a renderer instance when the behavior should be local to one configured Wenmode object.

from wenmode import HTMLRenderer, Wenmode
from wenmode.nodes import Text
from wenmode.renderers import RenderContext


def render_text(renderer: HTMLRenderer, node: Text, context: RenderContext) -> str:
    return renderer.escape_html(node.value.upper())


renderer = HTMLRenderer()
renderer.register_handler('text', render_text)

wen = Wenmode(renderer=renderer)
html = wen.render('Hello **there**')

assert html == '<p>HELLO <strong>THERE</strong></p>\n'
assert Wenmode().render('Hello **there**') == '<p>Hello <strong>there</strong></p>\n'

Use instance-level handlers for one-off presentation changes, tests, or local application wiring. For reusable syntax extensions, package parser rules and renderer handlers together in a plugin; see Custom Plugins.