Module std
Lua Standard Libraries.
This module contains a selection of improved Lua core functions, among others.
Also, after requiring this module, simply referencing symbols in the submodule hierarchy will load the necessary modules on demand.
 By default there are no changes to any global symbols, or monkey
 patching of core module tables and metatables.  However, sometimes it's
 still convenient to do that: For example, when using stdlib from the
 REPL, or in a prototype where you want to throw caution to the wind and
 compatibility with other modules be damned. In that case, you can give
 stdlib permission to scribble all over your namespaces by using the
 various monkey_patch calls in the library.
Functions
| assert (expect[, f=""[, ...]]) | Enhance core assertto also allow formatted arguments. | 
| barrel ([namespace=_G]) | A barrel of monkey_patches. | 
| elems (t) | An iterator over all elements of a sequence. | 
| eval (s) | Evaluate a string as Lua code. | 
| getmetamethod (x, n) | Return named metamethod, if any, otherwise nil. | 
| ielems (t) | An iterator over the integer keyed elements of a sequence. | 
| ipairs (t) | An iterator over elements of a sequence, until the first nilvalue. | 
| ireverse (t) | Return a new table with element order reversed. | 
| monkey_patch ([namespace=_G]) | Overwrite core methods and metamethods with stdenhanced versions. | 
| npairs (t) | Ordered iterator for integer keyed values. | 
| pairs (t) | Enhance core pairsto respect__pairseven in Lua 5.1. | 
| require (module[, min[, too_big[, pattern]]]) | Enhance core requireto assert version number compatibility. | 
| ripairs (t) | An iterator like ipairs, but in reverse. | 
| rnpairs (t) | An iterator like npairs, but in reverse. | 
| tostring (x) | Enhance core tostringto render table contents as a string. | 
Tables
| std | Module table. | 
Metamethods
| __index (name) | Lazy loading of stdlib modules. | 
Functions
Methods- assert (expect[, f=""[, ...]])
- 
    Enhance core assertto also allow formatted arguments.Parameters:- expect expression, expected to be truthy
- f string format string (default "")
- ... arguments to format (optional)
 Returns:- 
        value of expect, if truthy
    
 Usage:std.assert (expected ~= nil, "100% unexpected!") std.assert (expected ~= nil, "%s unexpected!", expected) 
- barrel ([namespace=_G])
- 
    A barrel of monkey_patches. 
Apply all monkey_patchfunctions. Additionally, for backwards compatibility only, write a selection of sub-module functions into the given namespace.Parameters:- namespace table where to install global functions (default _G)
 Returns:- 
           table
        module table
    
 Usage:local std = require "std".barrel () 
- elems (t)
- 
    An iterator over all elements of a sequence.
 If t has a __pairsmetamethod, use that to iterate.Parameters:- t table a table
 Returns:- function iterator function
- table t, the table being iterated over
- key, the previous iteration key
 See also:Usage:for value in std.elems {a = 1, b = 2, c = 5} do process (value) end 
- eval (s)
- 
    Evaluate a string as Lua code.
    Parameters:- s string string of Lua code
 Returns:- 
        result of evaluating 
 sUsage:std.eval "math.min (2, 10)"
- getmetamethod (x, n)
- 
    Return named metamethod, if any, otherwise nil.Parameters:- x item to act on
- n string name of metamethod to lookup
 Returns:- 
           function or nil
        metamethod function, or 
 nilif no metamethodUsage:lookup = std.getmetamethod (require "std.object", "__index") 
- ielems (t)
- 
    An iterator over the integer keyed elements of a sequence.
 If t has a __lenmetamethod, iterate up to the index it returns.Parameters:- t table a table
 Returns:- function iterator function
- table t, the table being iterated over
- int index, the previous iteration index
 See also:Usage:for v in std.ielems {"a", "b", "c"} do process (v) end 
- ipairs (t)
- 
    An iterator over elements of a sequence, until the first nilvalue.Like Lua 5.1 and 5.3, but unlike Lua 5.2 (which looks for and uses the __ipairsmetamethod), this iterator returns successive key-value pairs with integer keys starting at 1, up to the firstnilvalued pair.Parameters:- t table a table
 Returns:- function iterator function
- table t, the table being iterated over
- int index, the previous iteration index
 See also:Usage:-- length of sequence args = {"first", "second", nil, "last"} --> 1=first --> 2=second for i, v in std.ipairs (args) do print (string.format ("%d=%s", i, v)) end 
- ireverse (t)
- 
    Return a new table with element order reversed.
 Apart from the order of the elments returned, this function follows
 the same rules as ipairs for determining first and last elements.
    Parameters:- t table a table
 Returns:- 
           table
        a new table with integer keyed elements in reverse
   order with respect to t
    
 See also:Usage:local rielems = std.functional.compose (std.ireverse, std.ielems) for e in rielems (l) do process (e) end 
- monkey_patch ([namespace=_G])
- 
    Overwrite core methods and metamethods with stdenhanced versions.Write all functions from this module, except std.barrelandstd.monkey_patch, into the given namespace.Parameters:- namespace table where to install global functions (default _G)
 Returns:- 
           table
        the module table
    
 Usage:local std = require "std".monkey_patch () 
- npairs (t)
- 
    Ordered iterator for integer keyed values.
 Like ipairs, but does not stop until the largest integer key.
    Parameters:- t table a table
 Returns:- function iterator function
- table t
 See also:Usage:for i,v in npairs {"one", nil, "three"} do ... end 
- pairs (t)
- 
    Enhance core pairsto respect__pairseven in Lua 5.1.Parameters:- t table a table
 Returns:- function iterator function
- table t, the table being iterated over
- key, the previous iteration key
 See also:Usage:for k, v in pairs {"a", b = "c", foo = 42} do process (k, v) end 
- require (module[, min[, too_big[, pattern]]])
- 
    Enhance core requireto assert version number compatibility. By default match against the last substring of (dot-delimited) digits in the module version string.Parameters:- module string module to require
- min string lowest acceptable version (optional)
- too_big string lowest version that is too big (optional)
- pattern
            string
         to match version in module.versionormodule._VERSION(default:"([%.%d]+)%D*$") (optional)
 Usage:-- posix.version == "posix library for Lua 5.2 / 32" posix = require ("posix", "29") 
- ripairs (t)
- 
    An iterator like ipairs, but in reverse.
 Apart from the order of the elments returned, this function follows
 the same rules as ipairs for determining first and last elements.
    Parameters:- t table any table
 Returns:- function iterator function
- table t
- 
           number
        #t + 1
 See also:Usage:for i, v = ripairs (t) do ... end 
- rnpairs (t)
- 
    An iterator like npairs, but in reverse.
 Apart from the order of the elments returned, this function follows
 the same rules as npairs for determining first and last elements.
    Parameters:- t table a table
 Returns:- function iterator function
- table t
 See also:Usage:for i,v in rnpairs {"one", nil, "three"} do ... end 
- tostring (x)
- 
    Enhance core tostringto render table contents as a string.Parameters:- x object to convert to string
 Returns:- 
           string
        compact string rendering of x
    
 Usage:-- {1=baz,foo=bar} print (std.tostring {foo="bar","baz"}) 
Tables
- std
- 
    Module table. 
In addition to the functions documented on this page, and a versionfield, references to other submodule functions will be loaded on demand.Fields:- version release version string
 
Metamethods
- __index (name)
- 
    Lazy loading of stdlib modules.
 Don't load everything on initial startup, wait until first attempt
 to access a submodule, and then load it on demand.
    Parameters:- name string submodule name
 Returns:- 
           table or nil
        the submodule that was loaded to satisfy the missing
   
 name, otherwisenilif nothing was foundUsage:local std = require "std" local prototype = std.object.prototype