Hypothesis support for custom post types (rough draft)

hypothesis.php

<?php 

    $posttypes = apply_filters('hypothesis_supported_posttypes', array(
			'post' => 'posts',
			'page' => 'pages'
		) );

		foreach ( $posttypes as $posttype => $name ) {
			add_settings_field(
				"allow-on-$posttype",
				"Allow on $name",
				array( $this, 'allow_on_posttype_callback' ),
				'hypothesis-setting-admin',
				'setting_section_id',
				array(
					$posttype,
					$name
				)
			);
		}

// then in sanitize…

		foreach ( $posttypes as $posttype => $name ) {
			if( isset( $input["allow-on-$name"] ) )
				$new_input["allow-on-$name"] = absint($input["allow-on-$name"]);
		}

// callback…

	public function allow_on_posttype_callback( $args )
	{
		$slug = sanitize_title($args[1]);
		printf(
			'<input type="checkbox" id="allow-on-' . $slug . '" name="wp_hypothesis_options[allow-on-' . $slug . ']" value="1"
			'.checked( isset($this->options["allow-on-" . $slug]) ? $this->options["allow-on-" . $slug]: null, 1, false ).' />',
			isset( $this->options['allow-on-' . $slug] ) ? esc_attr( $this->options['allow-on-' . $slug]) : 0
		);
	}