6.4.1 – Patterns Patterns in Lua are described by regular strings, which are interpreted as patterns by the pattern-matching functions string.find, string.gmatch, string.gsub, and string.match. This section describes the syntax and the meaning (that is, what they match) of these strings. Character Class: A character class is used to represent a set of characters. The following combinations are allowed in describing a character class: x: (where x is not one of the magic characters ^$()%.[]

pairs (t) If t has a metamethod __pairs, calls it with t as argument and returns the first three results from the call. Otherwise, returns three values: the next function, the table t, and nil, so that the construction for k,v in pairs(t) do body end will iterate over all key–value pairs of table t. See function next for the caveats of modifying the table during its traversal.

package.searchpath (name, path [, sep [, rep]]) Searches for the given name in the given path. A path is a string containing a sequence of templates separated by semicolons. For each template, the function replaces each interrogation mark (if any) in the template with a copy of name wherein all occurrences of sep (a dot, by default) were replaced by rep (the system's directory separator, by default), and then tries to open the resulting file name. For instance, if the path is the string

package.searchers A table used by require to control how to load modules. Each entry in this table is a searcher function. When looking for a module, require calls each of these searchers in ascending order, with the module name (the argument given to require) as its sole parameter. The function can return another function (the module loader) plus an extra value that will be passed to that loader, or a string explaining why it did not find that module (or nil if it has nothing to say). Lu

package.preload A table to store loaders for specific modules (see require). This variable is only a reference to the real table; assignments to this variable do not change the table used by require.

package.path The path used by require to search for a Lua loader. At start-up, Lua initializes this variable with the value of the environment variable LUA_PATH_5_3 or the environment variable LUA_PATH or with a default path defined in luaconf.h, if those environment variables are not defined. Any ";;" in the value of the environment variable is replaced by the default path.

package.loadlib (libname, funcname) Dynamically links the host program with the C library libname. If funcname is "*", then it only links with the library, making the symbols exported by the library available to other dynamically linked libraries. Otherwise, it looks for a function funcname inside the library and returns this function as a C function. So, funcname must follow the lua_CFunction prototype (see lua_CFunction). This is a low-level function. It completely bypasses the package

package.loaded A table used by require to control which modules are already loaded. When you require a module modname and package.loaded[modname] is not false, require simply returns the value stored there. This variable is only a reference to the real table; assignments to this variable do not change the table used by require.

package.cpath The path used by require to search for a C loader. Lua initializes the C path package.cpath in the same way it initializes the Lua path package.path, using the environment variable LUA_CPATH_5_3, or the environment variable LUA_CPATH, or a default path defined in luaconf.h.

package.config A string describing some compile-time configurations for packages. This string is a sequence of lines: The first line is the directory separator string. Default is '\' for Windows and '/' for all other systems. The second line is the character that separates templates in a path. Default is ';'. The third line is the string that marks the substitution points in a template. Default is '?'. The fourth line is a string that, in a path in Windows, is replaced by the executable's di