Penlight

• Index

Contents

• Functions

Libraries

• pl
• pl.Set
• pl.app
• pl.array2d
• pl.class
• pl.compat
• pl.comprehension
• pl.config
• pl.data
• pl.dir
• pl.file
• pl.func
• pl.import_into
• pl.input
• pl.lapp
• pl.lexer
• pl.luabalanced
• pl.operator
• pl.path
• pl.permute
• pl.pretty
• pl.seq
• pl.sip
• pl.strict
• pl.stringio
• pl.stringx
• pl.tablex
• pl.template
• pl.test
• pl.text
• pl.types
• pl.url
• pl.utils
• pl.xml

Classes

• pl.Date
• pl.List
• pl.Map
• pl.MultiMap
• pl.OrderedMap

Manual

• Introduction
• Tables and Arrays
• Strings. Higher-level operations on strings.
• Paths and Directories
• Date and Time
• Data
• Functional Programming
• Additional Libraries
• Technical Choices

Examples

• seesubst.lua
• sipscan.lua
• symbols.lua
• test-cmp.lua
• test-data.lua
• test-listcallbacks.lua
• test-pretty.lua
• test-symbols.lua
• testapp.lua
• testclone.lua
• testconfig.lua
• testglobal.lua
• testinputfields.lua
• testinputfields2.lua
• testxml.lua
• which.lua

Module pl.types

Dealing with Detailed Type Information

Functions

is_callable (obj)	is the object either a function or a callable object?.
is_type (obj, tp)	is the object of the specified type?.
type (obj)	a string representation of a type.
is_integer (x)	is this number an integer?
is_empty (o, ignore_spaces)	Check if the object is “empty”.
is_indexable (val)	is an object ‘array-like’?
is_iterable (val)	can an object be iterated over with pairs?
is_writeable (val)	can an object accept new key/pair values?
to_bool (o[, true_strs[, check_objs]])	Convert to a boolean value.

Functions

is_callable (obj)

is the object either a function or a callable object?.

Parameters:

• obj Object to check.

is_type (obj, tp)

is the object of the specified type?. If the type is a string, then use type, otherwise compare with metatable

Parameters:

• obj An object to check
• tp String of what type it should be

type (obj)

a string representation of a type. For tables with metatables, we assume that the metatable has a _name field. Knows about Lua file objects.

Parameters:

• obj an object

Returns:

a string like ‘number’, ‘table’ or ‘List’

is_integer (x)

is this number an integer?

Parameters:

• x a number

Raises:

error if x is not a number

is_empty (o, ignore_spaces)

Check if the object is “empty”. An object is considered empty if it is nil, a table with out any items (key, value pairs or indexes), or a string with no content (“”).

Parameters:

• o The object to check if it is empty.
• ignore_spaces If the object is a string and this is true the string is considered empty is it only contains spaces.

Returns:

true if the object is empty, otherwise false.

is_indexable (val)

is an object ‘array-like’?

Parameters:

• val any value.

is_iterable (val)

can an object be iterated over with pairs?

Parameters:

• val any value.

is_writeable (val)

can an object accept new key/pair values?

Parameters:

• val any value.

to_bool (o[, true_strs[, check_objs]])

Convert to a boolean value. True values are:

• boolean: true.
• string: ‘yes’, ‘y’, ‘true’, ’t', ‘1’ or additional strings specified by true_strs.
• number: Any non-zero value.
• table: Is not empty and check_objs is true.
• object: Is not nil and check_objs is true.

Parameters:

• o The object to evaluate.
• true_strs optional Additional strings that when matched should evaluate to true. Comparison is case insensitive. This should be a List of strings. E.g. “ja” to support German. (optional)
• check_objs True if objects should be evaluated. Default is to evaluate objects as true if not nil or if it is a table and it is not empty. (optional)

Returns:

true if the input evaluates to true, otherwise false.