{diff}
Shows what changed between two texts - word by word in the flow of the text, or line by line in one column or side by side.
Syntax
{diff $old, $new}
{diff $old, $new, lines, from='Monday', to='Friday'}
{diff $old, $new, side, from='before', to='after'}Parameters
-
old - The old text.
-
new - The new text.
Options
-
lines - Bare option: compare line by line - a table with the old and the new line number, a sign and the line.
-
side - Bare option: the lines side by side, a changed line beside its counterpart, line numbers on both sides.
-
from - The name of the old version - a column head side by side, a caption in one column.
-
to - The name of the new version.
Description
{diff $old, $new} compares two texts and writes the new one with what changed marked: the words that went out as <del>, the words that came in as <ins>. The differences are found by Myers' algorithm, the shortest edit script, as git diff finds them. In a run of changes the deletions come before the insertions, and the space between two changed words joins the change, so a rewritten phrase reads as one change instead of a patchwork.
lines compares line by line, in one column: the old and the new line number, a sign and the line. side puts the two versions next to each other, a changed line beside its counterpart. In both a changed line that has a counterpart marks the words that changed within it; a line without one is struck or added whole. from= and to= name the two versions.
Everything of both texts is escaped. A screen reader hears where each deletion and insertion starts and ends, from words in pseudo-elements that are hidden from the eye. The colours are custom properties on .pad-diff - --pad-diff-del, --pad-diff-ins and their -mark forms, -text, -muted, -line - with light-dark() defaults written once a page. A {diff} without the second text is a strict error.
Examples
Two versions of a sentence
Word by word in the flow of the text - struck what went, marked what came.
{diff $draft, $final}<?php
$draft = 'PAD templates drive the application: a page is a template, and the template asks for its data.';
$final = 'PAD templates drive the application: every page is a template, and the template asks for the data it needs.';
?>Line by line
A shopping list in one column - the old and the new line number, a sign, the line.
{diff $monday, $friday, lines, from='Monday', to='Friday'}<?php
$monday = "Milk\nEggs\nBread\nButter\nCoffee";
$friday = "Milk\nEggs\nSourdough bread\nCoffee\nPears";
?>| 1 | 1 | Milk | |
| 2 | 2 | Eggs | |
| 3 | - |
|
|
| 3 | + | Sourdough bread | |
| 4 | - |
|
|
| 5 | 4 | Coffee | |
| 5 | + | Pears |
Side by side
Two versions of a function next to each other, the changed words marked within each changed line.
{diff $before, $after, side, from='before', to='after'}<?php
$before = "function total ( \$rows ) {\n \$sum = 0;\n foreach ( \$rows as \$row )\n \$sum += \$row ['price'];\n return \$sum;\n}";
$after = "function total ( \$rows, \$tax = 0.21 ) {\n \$sum = 0;\n foreach ( \$rows as \$row )\n \$sum += \$row ['price'] * \$row ['quantity'];\n return round ( \$sum * ( 1 + \$tax ), 2 );\n}";
?>| before | after | ||
|---|---|---|---|
| 1 | function total ( $rows ) { | 1 | function total ( $rows, $tax = 0.21 ) { |
| 2 | $sum = 0; | 2 | $sum = 0; |
| 3 | foreach ( $rows as $row ) | 3 | foreach ( $rows as $row ) |
| 4 | $sum += $row ['price']; | 4 | $sum += $row ['price'] * $row ['quantity']; |
| 5 | return $sum; | 5 | return round ( $sum * ( 1 + $tax ), 2 ); |
| 6 | } | 6 | } |
See also
- {excerpt} Cuts a long text to whole words with an ellipsis, centred on the first match of search words, every match marked.
- {highlight} Colours source code on the server - PAD, PHP, HTML, CSS, JavaScript, JSON, YAML, SQL or shell - with optional line numbers and marked lines.
- {markdown} Renders its content, or the value of its parameter, as Markdown and writes the HTML.