test | ||
analyze_structure.lua | ||
function.lua | ||
init.lua | ||
library.lua | ||
LICENSE.txt | ||
number.lua | ||
pretty.lua | ||
README.md | ||
table_type.lua |
Pretty
pretty
is an advanced pretty printer for Lua aiming primarily for
human readability. It does this by looking for patterns in the input data, and
creating an output string utilizing and highlighting those patterns. Thus it's
a primarily a debugging tool, not a speedy serialization tool.
Code Example
Setup is simple, just pretty = require 'pretty'
, and you're good to go.
> print(pretty( { 1, 2, 3 } ))
{ 1, 2, 3 }
> print(pretty( { hello = 'world', num = 42 } ))
{
num = 42
hello = 'world'
}
> print(pretty( { abs = math.abs, max = math.max, some = function() end } ))
{
abs = builtin function (x) ... end
max = builtin function (x, ...) ... end
some = function () ... end
}
> print(pretty( math.abs ))
builtin function (x)
-- math.abs
-- Returns the absolute value of x
...
end
Motivation
This project is the outcome of my frustration with existing pretty printers, and
a desire to expand upon the pretty printer I developed for
Xenoterm. The original Xenoterm pretty
printer was much simpler than pretty
- and the current is even simpler - but
the enhancements I make, when compared to other pretty printers, inspired me to
create pretty
.
pretty
sorts it's priorities like so:
- Human readability.
- Lua-compatible output.
- Customization.
I'd rather have good defaults than provide a ton of customization options. And if some structure cannot be represented in Lua, I will rather extend the syntax, than lose the info.
Another aspect where pretty
shines is in exploratory programming, when
attempting to avoid reliance on outside documentation. The amount of information
pretty
exposes varies by the data you are inspecting. If you're inspecting
a list of functions, their function signatures are visible, but if you're
inspecting a single function, documentation and source location may appear if
available.
Features
- Written in good-old pureblood Lua, with support for PUC Lua 5.0+ and LuaJIT 2.0+.
- Redefining what it means to be "human readable":
- Is multi-line centric, to aid readablitiy.
- Indention and alignment of keys-value pairs.
- Keys-value pairs are properly sorted by key type and thereafter alphabetically.
- The format and structure of output changes depending upon the input. Maps appear differently to deeply nested tables to long sequences with short strings to short lists.
- Uses the standard
debug
library to gain information about functions and other advanced structures.
Installation
TODO
API Documentation
TODO
Tests
TODO
Performance
As specified in the introduction, pretty
is not a performance oriented
library. Expected usage is in error conditions and debugging, not in tight
inner loops.
Don't use pretty.lua
if you want fast serialization. Use one of the pretty
printers specified below.
TODO
I'm looking into implementing following features:
- Improve display of medium-long lists with short elements. One option is
something analog to the default results of
ls
on Linux. - Add support for
setmetatable
, and exploring the values accessible through it. - Provide nice formatting for
cdata
datatype in LuaJIT. - Expand on the comment output in output, for
__tostring
methods, and global namespaces likeio
ormath
. - Look into using concat operation to improve appearance of overly long non-breaking strings. Attempt to break near whitespace.
- Attempt to fit output within a predefined width limit. Default to 80.
- Find a better name than
pretty
. - Add option for colored output. Primarily syntax highlighting, but also BlueJ-style scope highlighting, with some faint background colors.
- Look more into
string.dump
in the core library. - Better support upvalues for in functions. Complete support is impossible without traversing the original code or inspecting the intermediate representation, due to lexical scoping. (Pluto does it, but it's written in C.)
Other pretty printers
pretty
is large, slow, and requires the debug library to work. It's not
designed for serialization purposes, nor is it concerned with offering the same
level of customization as other libraries do.
If you want a sleek, fast, customizable or embeddable library, there are other options. Lua has a large library of pretty printers and serialization libraries:
- inspect.lua: One of the classic debugging pretty printers.
- pprint.lua: Reimplementation of
inspect.lua
- serpent: Advanced and fast pretty printer.
- pluto: Can serialize arbitrary parts of Lua, including functions, upvalues, and proper lexical scoping. Not written in native Lua.
- binser: Library for special purpose serialization.
Find others at the lua-users wiki.
Contact
The author is available at jonjmaa (at) gmail.com
. Be sure to send an email if
you have ideas for improvements, find an issue, or even an unintuitive result.
License
This project is licensed under the BeerWare license - Please see the LICENSE.txt file for details.