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.
NOTE: this function is imported from utils.is_type.
Parameters:
- obj An object to check
- tp The expected type
See also:
- type (obj)
-
a string representation of a type.
For tables and userdata with metatables, we assume that the metatable has a
_name
field. If the field is not present it will return 'unknown table' or 'unknown userdata'. Lua file objects return the type 'file'.Parameters:
- obj an object
Returns:
-
a string like 'number', 'table', 'file' or 'List'
- is_integer (x)
-
is this number an integer?
Parameters:
- x a number
Returns:
-
boolean
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)
- a string with no content ("")
- not a nil/table/string
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 if it only contains spaces.
Returns:
true
if the object is empty, otherwise a falsy value. - is_indexable (val)
-
is an object 'array-like'?
An object is array like if:
- it is a table, or
- it has a metatable with
__len
and__index
methods
NOTE: since
__len
is 5.2+, on 5.1 is usually returnsfalse
for userdataParameters:
- val any value.
Returns:
true
if the object is array-like, otherwise a falsy value. - is_iterable (val)
-
can an object be iterated over with pairs?
An object is iterable if:
- it is a table, or
- it has a metatable with a
__pairs
meta method
NOTE: since
__pairs
is 5.2+, on 5.1 is usually returnsfalse
for userdataParameters:
- val any value.
Returns:
true
if the object is iterable, otherwise a falsy value. - is_writeable (val)
-
can an object accept new key/pair values? An object is iterable if:
- it is a table, or
- it has a metatable with a
__newindex
meta method
Parameters:
- val any value.
Returns:
true
if the object is writeable, otherwise a falsy 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. - everything else: Is not
nil
andcheck_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. (optional)
Returns:
-
true if the input evaluates to true, otherwise false.