NostalgiaPHP

Understanding functions.php

One of the most important files in NostalgiaPHP is functions.php. It holds the core helper functions that make the whole system work — from rendering templates to parsing Markdown. This post walks through each function and explains what it does.

Path and URL Helpers

normalize_path($path)

Cleans up filesystem paths so they always use forward slashes. This makes things consistent across Windows, macOS, and Linux.

config($key, $default)

Fetches a configuration value from your global settings. Handy for site‑wide options like the site name or base_url.

site($key, $default)

Shortcut to grab site‑specific config keys (name, description, etc.).

path($key, $extra)

Builds an absolute path inside the project. For example, path('templates') points to the templates folder.

url($path)

Generates a site URL. Useful for links inside templates so you don’t hard‑code the domain.

request_path()

Returns the current request path (e.g. /about). Used by the router to figure out what content to load.

Content Helpers

is_collection($dir)

Checks if a directory looks like a collection (e.g. blog/ with multiple Markdown items).

read_file($file)

Reads a file into a string. A thin wrapper, but useful for consistency.

parse_front_matter($text)

Splits the front matter (the --- metadata block at the top of a Markdown file) from the body content.

markdown_to_html($markdown)

Turns Markdown into HTML. This is what lets you write posts in .md files and see them rendered on your site.

load_page($slug)

Loads a page by slug, looking in the content/pages directory. Returns both the front matter and the rendered HTML body.

sanitize_rel_path($path)

Ensures a relative path doesn’t contain ../ tricks. Prevents directory traversal vulnerabilities.

load_page_path($file)

Loads a page from a known file path instead of a slug. Similar output to load_page.

load_collection_item($collection, $slug)

Loads a single item from a collection (e.g. one blog post).

list_collection($collection)

Lists all items in a collection, sorted and parsed. This powers your collection index pages.

excerpt_from_html($html, $length)

Creates a text excerpt from HTML content, useful for previews on cards or lists.

Templating Helpers

nav_link($href, $label, $path)

Builds a navigation link. Automatically adds an active class when the current page matches.

is_active($href, $current_path, $prefix)

Check if a navigation link should be marked "active."

active_class($href, $current_path, $prefix, $class)

Return a CSS class if a link should be marked "active."

render($view, $vars)

Renders a template from the templates/ folder. Variables like $title and $content are extracted for use inside the template.

Tags (how NostalgiaPHP reads them)

NostalgiaPHP treats tags as plain front-matter. You can write them as a CSV string:

---
title: Example
tags: php, simplicity, retro
---

Internally, the tag pages scan Markdown files and read front matter via parse_front_matter(). They’re tolerant to:

  • tags: or tag: (either works)
  • casing (Tags, TAG, etc.)
  • CSV strings or arrays
  • an optional fallback key: keywords:

Why keep these in one file?

functions.php is small, fast, and easy to read. Every helper is:

  • Global: Available everywhere in the project.
  • Focused: Each does one simple job.
  • Composable: You can combine them to build routes, load content, and render pages.

This file is the glue that holds NostalgiaPHP together — tiny, clear functions instead of a heavy framework.

Next Steps

  • Skim through functions.php yourself — it’s less than a couple hundred lines.
  • Try adding your own helper if you need something site‑wide.
  • Use the Dox collection to extend your own project documentation.

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