<?php
/**
 * Plugin Name: YOUR PLUGIN NAME
 */

include( dirname( __FILE__ ) . '/lib/requirements-check.php' );

$your_plugin_requirements_check = new YOUR_PREFIX_Requirements_Check( array(
	'title' => 'YOUR PLUGIN NAME',
	'php'   => '5.4',
	'wp'    => '4.8',
	'file'  => __FILE__,
));

if ( $your_plugin_requirements_check->passes() ) {
  // 1. Load classes or define an autoloader.
  // 2. Initialize your plugin.
}

unset( $your_plugin_requirements_check );

<?php

class YOUR_PREFIX_Requirements_Check {
	private $title = '';
	private $php = '5.2.4';
	private $wp = '3.8';
	private $file;

	public function __construct( $args ) {
		foreach ( array( 'title', 'php', 'wp', 'file' ) as $setting ) {
			if ( isset( $args[$setting] ) ) {
				$this->$setting = $args[$setting];
			}
		}
	}

	public function passes() {
		$passes = $this->php_passes() && $this->wp_passes();
		if ( ! $passes ) {
			add_action( 'admin_notices', array( $this, 'deactivate' ) );
		}
		return $passes;
	}

	public function deactivate() {
		if ( isset( $this->file ) ) {
			deactivate_plugins( plugin_basename( $this->file ) );
		}
	}

	private function php_passes() {
		if ( $this->__php_at_least( $this->php ) ) {
			return true;
		} else {
			add_action( 'admin_notices', array( $this, 'php_version_notice' ) );
			return false;
		}
	}

	private static function __php_at_least( $min_version ) {
		return version_compare( phpversion(), $min_version, '>=' );
	}

	public function php_version_notice() {
		echo '<div class="error">';
		echo "<p>The &#8220;" . esc_html( $this->title ) . "&#8221; plugin cannot run on PHP versions older than " . $this->php . '. Please contact your host and ask them to upgrade.</p>';
		echo '</div>';
	}

	private function wp_passes() {
		if ( $this->__wp_at_least( $this->wp ) ) {
			return true;
		} else {
			add_action( 'admin_notices', array( $this, 'wp_version_notice' ) );
			return false;
		}
	}

	private static function __wp_at_least( $min_version ) {
		return version_compare( get_bloginfo( 'version' ), $min_version, '>=' );
	}

	public function wp_version_notice() {
		echo '<div class="error">';
		echo "<p>The &#8220;" . esc_html( $this->title ) . "&#8221; plugin cannot run on WordPress versions older than " . $this->wp . '. Please update WordPress.</p>';
		echo '</div>';
	}
}