RGtk2 (version 2.8.8)

enums-and-flags: Enums and Flags

Description

Convenience functions and operators for operating on bitflags and enums

Usage

as.flag(x)
"[.flags"(x, value)
"|.flag"(x, y)
"&.flag"(x, y)
"!.flag"(x)
"==.flag"(x, y)
"==.enum"(x, y)

Arguments

x

Numeric value to coerce to a flag, an object of class flags, or the left hand operand

y

Right hand operand

value

The character id or index for a particular flag in a flags vector

Value

• A flag for as.flag, [.flags, and the bitwise operators. A logical value for the comparison operators.

Details

The libraries bound by RGtk2 often return numeric values that are either bitflags or enumerations. In order to facilitate operations on these types (especially bitflags), several methods have been defined corresponding to conventional operators for performing bitwise operations and comparisons.

Sometimes the API does not return a value specifically as a flag or enum. In this case, it is a generic numeric value and should be coerced with as.flag.

RGtk2 defines all of the enum and flag types from the API's as vectors of class flags or enums with their names corresponding to the character nicknames of the values. The [ operator on the flags class retrieves a value as a flag. This only necessary for the bitwise ops and thus is not necessary for enums.

The == operators compare a flag or enum with either a character or numeric representation. For a flag, it is also possible to compare against a logical to test whether it is non-zero, similar to C.