.LIF File Format

Introduction

Some .lif files have the layout of Life 1.05 but no #Life line. They hold a pattern drawn with . and *, sometimes with a #P line to say where it goes, a comment, or nothing else. The 33 patterns in PATTERNS.ZIP that came with Dave Crawford’s Windows program Get a Life (version 1.0, 1993), and the logo file GETALIFE.LIF that the program shows when it starts, are of this kind.

Get a Life’s own help says only that its pattern files are text “in which empty squares are represented by ‘.’ and filled squares by ‘*’”, with the default extension .LIF, and that a loaded pattern is centred on the screen. Which of the lines below the program reads is not in its documents, so what follows is what the files contain.

A file dropped on this page opens in the explorer as a picture of the pattern with its live cells, bounding box and density, and the pattern written out as text. Each cell is linked to its byte.

Lines

The other directives of Life 1.05, #D, #N and #R, may appear and are read as in Life 1.05, but no file here has one.

Rows

In the 33 patterns the rows are all as wide as the pattern: shorter rows are padded with dots, so each is a full line of the picture (50 characters is the widest). The explorer does not need that: a row that stops early has dead cells after it. A line of no characters is ignored and does not move the next row down, as in Life 1.05. No file has one.

With no #P line, the file says nothing about where its pattern goes. Get a Life centres it. The explorer draws it with its upper-left cell at 0, 0 and says that the file gives no position.

A worked example

GLIDER.LIF from PATTERNS.ZIP (Old Zips, 1993): 25 bytes.

00000000  23 50 20 2D 31 20 2D 31 0D 0A 2E 2E 2A 0D 0A 2A  #P -1 -1....*..*
00000010  2E 2A 0D 0A 2E 2A 2A 0D 0A                       .*...**..

A glider: five cells, a 3 × 3 box around the origin.

How the explorer takes a file

A file is read as this format when it does not begin with #Life, every line is empty, starts with # or is made of . and * only, and there is at least one row. Anything else is another variant or damaged. A #P line that is not followed by two numbers, or a character other than . and * in a row, makes the file damaged rather than another variant. The 34 different files on the Mac, GETALIFE.LIF and the 33 patterns, are all read without a note.

This reference is partial: what the files contain is described, but no document that describes the format itself is on the Mac, so how each program reads the lines, especially the absence of a position, is not checked.

Not described

This is what the reference leaves out and what the viewer does not do.

• Reference: no document describes this layout. Which lines Get a Life reads, how it treats a missing #P line beyond centring, and where the layout came from are not known.
• Reference: #D, #N and #R in a file with no version line are assumed to mean what they mean in Life 1.05; no file here has one.
• Viewer: it draws only the first generation and does not run the rules.
• Viewer: with no #P line it draws the pattern with its corner at 0, 0, not centred as Get a Life does.

Variants

• Life 1.05 pattern – a version line, description, rules and cell blocks of dots and stars
• Life 1.06 pattern – a version line and one live cell a line, as two numbers
• Life pattern without a version line – the Life 1.05 layout with no first line, and bare grids of dots and stars
• Life pattern (x grid) – rows of x and spaces with no header

Links