is strictly a
Type
operator
Summary
Evaluates to true if the actual type of value is the specified type.
Syntax
<value> is strictly { nothing | a boolean | a number | an integer | a real | a string | a name | a binary string | an array | a sequence | a dictionary }
Description
Use the is strictly a operator to determine the true type of a value. The true type of a value is the representation which the engine is currently holding for it, without performing any implicit type coercion. The true type of a value can be one of the following:
- nothing: no value, typically seen as < empty:::note[ boolean: either true or false, typically seen as the result of a comparison operator ]
number: a numeric value
- integer: a numeric value internally represented as an integer value
- real: a numeric value internally represented as a floating-point value
- string: a piece of text (sequence of characters)
- name: a string used as an array key or literal
- binary string: a sequence of bytes
- array: an associative array
- sequence: a sequence array which has not been explicitly marked as a dictionary
- dictionary: an array which has been marked to never be treated as a sequence even if it is a sequence
:::
The is strictly a operator differs from is a in that it does not
perform any type coercion. For example, x is a number would return
true if x currently holds a number or if it holds a string which can be parsed
as a number; whereas x is strictly a number only returns true if
x currently holds a number.
Arrays can be marked as a sequence or as a dictionary by using the as a operators.
Whether a numeric value is strictly an integer, or strictly a real
will depend on how it was generated. In particular, being strictly a real
does not mean the value has a fractional part.
Parameters
| Name | Type | Description |
|---|---|---|
value | The expression which will be tested for its type. |
Examples
"Hello World!" is strictly a string -- evaluates to true
1 + 200 is strictly a number -- evaluates to true
(100 is 100) is strictly a boolean -- evaluates to true
the compress of "Hello World!" is strictly a binary string -- evaluates to true
[ 1, 2 ] is strictly a sequence -- evaluates to true
([ 1, 2 ] as a dictionary) is strictly a sequence -- evaluates to false
Related
operator: is not strictly a, is a, is not a, as a
Compatibility and Support
Introduced
LiveCode 8.0
OS
mac
windows
linux
ios
android
Platforms
desktop
server
mobile