assertions {RGtk2} | R Documentation

## RGtk2 Type Assertion

### Description

Assert that an object is of a particular type

### Usage

    checkPtrType(w, klass = "GtkWidget", nullOk = FALSE, critical = TRUE)
    implements(obj, interface)

### Arguments

`w` | An object whose type is to be verified.
`klass` | The type the object is expected to be.
`nullOk` | Whether the object is allowed to be `NULL`.
`critical` | Whether to stop if the object is not of the specified type. If this is a character vector, then the function will stop on mismatch and report that string as the error message.
`obj` | A GObject.
`interface` | The interface that `obj` is expected to implement.

### Details

All RGtk2 functions check that the arguments are of the correct type, if possible. The `checkPtrType` function is most useful to the user when it is not known if an object is of the required type. A good example is the user data argument of a callback function. To see if a `GObject` implements a certain interface, use `implements`.

### Author(s)

Michael Lawrence and Duncan Temple Lang

[Package RGtk2 version 2.20.40 Index]