inspect.lua/README.textile
2011-12-05 19:51:36 +01:00

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h1. inspect.lua
This function transform any Lua table into a human-readable representation of that table.
The objective here is human understanding (i.e. for debugging), not serialization or compactness.
h1. Examples of use
"Array-like" tables are rendered horizontally:
<pre>inspect({1,2,3,4}) == "<1>{ 1, 2, 3, 4 }"</pre>
"dictionary-like" tables are rendered with one element per line:
<pre>inspect({a=1,b=2}) == [[<1>{
a = 1,
b = 2
}]]</pre>
The keys will be sorted alphanumerically when possible.
"Hybrid" tables will have the array part on the first line, and the dictionary part just below them:
<pre>
inspect({1,2,3,a=1,b=2}) == [[<1>{ 1, 2, 3,
a = 1,
b = 2
}]]
</pre>
Tables can be nested, and will be indented with two spaces per level.
<pre>
inspect({a={b=2}}) = [[<1>{
a = <2>{
b = 2
}
}]]
</pre>
By default, @inspect@ will stop rendering at a depth of 4 levels. When that point is reached, it will just return @{...}@ :
<pre>
local t5 = {a = {b = {c = {d = {e = 5}}}}}
inspect(t5) == [[<1>{
a = <2>{
b = <3>{
c = <4>{
d = {...}
}
}
}
}]]
</pre>
You can increase/decrease the max depth with the second parameter:
<pre>
inspect(t5, 2) == [[<1>{
a = <2>{
b = {...}
}
}]])
inspect(t5, 7) == [[<1>{
a = <2>{
b = <3>{
c = <4>{
d = <5>{
e = 5
}
}
}
}
}]])
</pre>
Functions, userdata and threads are simply rendered as @<function x>@, @<userdata x>@ and @<thread x>@ respectively:
<pre>
inspect({ f = print, ud = some_user_data, thread = a_thread} ) == [[{
f = <function 1>,
u = <userdata 1>,
thread = <thread 1>
}]])
</pre>
If the table has a metatable, inspect will include it at the end, in a special field called @<metatable>@:
<pre>
inspect(setmetatable({a=1}, {b=2}) == [[<1>{
a = 1
<metatable> = <2>{
b = 2
}
}]])
</pre>
You may have noticed that all tables are preceded by an @<id>@ string. If a table has already been printed out, @inspect@ will just print @<table id>@ the second time it finds it. This will prevent infinite loops.
<pre>
a = {1,2}
b = {3,4,a}
a[3] = b
inspect(a) = "<1>{ 1, 2, <2>{ 3, 4, <table 1> } }"
</pre>
Notice how the second appearance of @a@ was replaced by @<table 1>@ in the string above.
h1. Gotchas / Warnings
This method is *not* appropiate for saving/restoring tables. It is ment to be used by the programmer mainly while debugging a program.
h1. Installation
Just copy the inspect.lua file somewhere in your projects (maybe inside a /lib/ folder) and require it accordingly.
Remember to store the value returned by require somewhere! (I suggest a local variable named inspect, altough others might like table.inspect)
<pre>
local inspect = require 'inspect'
-- or --
table.inspect = require 'inspect'
</pre>
Also, make sure to read the license file; the text of that license file must appear somewhere in your projects' files.
h1. Specs
This project uses "telescope":https://github.com/norman/telescope for its specs. If you want to run the specs, you will have to install telescope first. Then just execute the following from the root inspect folder:
<pre>
tsc -f spec/*
</pre>