there is a
Type
operator
Summary
Evaluates to true if the specified object, file, folder, or process exists, false otherwise.
Syntax
there is a {<object> | file <filePath> | folder <folderPath> | process <procName>}
Description
Use the there is a operator to make sure an object or file exists before working with it, or to find out whether there are any objects of a specified type.
The there is a operator is the logical inverse of the there is no operator. When one is true, the other is false.
The expression there is a stack stackName evaluates to true if the stack is open, if it is closed but loaded into memory, or if it appears in the stackFiles property of any open stack.
To find out whether a stack is open, check its mode property. A stack that is loaded into memory but is not open has a mode of zero.
The there is a operator is implemented internally as a function, and therefore has lower precedence than other operators.
Parameters
| Name | Type | Description |
|---|---|---|
object | Any object reference. | |
filePath | The filePath specifies the name and location of a file you want to check. If you specify a name but not a location, LiveCode looks for the file in the defaultFolder. | |
folderPath | The folderPath specifies the name and location of a folder you want to check. If you specify a name but not a location, LiveCode looks for the folder in the defaultFolder. | |
procName | The name of any process that LiveCode started. |
Examples
there is a card button 1 -- evaluates to true if any card buttons exist
if there is a card ID 3445 then go card ID 3445
put (there is a file it) into fileIsThere
Related
control structure: function
function: exists
glossary: property, loaded into memory, operator, precedence, folder, evaluate, process, object
keyword: file
object: stack
operator: there is no
property: stackFiles, mode
Compatibility and Support
Introduced
LiveCode 1.0
OS
mac
windows
linux
ios
android
Platforms
desktop
server
mobile