FB_ONE_OR_NONE(hello, world) expands to hello and FB_ONE_OR_NONE(hello) expands to nothing. This macro is used to insert or eliminate text based on the presence of another argument.
Synopsis
Declared in <folly/Preprocessor.h>
#define FB_ONE_OR_NONE(a, …)Parameters
Name |
Description |
a |
The token emitted when a second argument is present. |
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