VipsArgumentFlags

Flags we associate with each object argument.

Have separate input & output flags. Both set is an error; neither set is OK.

Input gobjects are automatically reffed, output gobjects automatically ref us. We also automatically watch for “destroy” and unlink.

VIPS_ARGUMENT_SET_ALWAYS is handy for arguments which are set from C. For example, VipsImage::width is a property that gives access to the Xsize member of struct _VipsImage. We default its ‘assigned’ to TRUE since the field is always set directly by C.

VIPS_ARGUMENT_DEPRECATED arguments are not shown in help text, are not looked for if required, are not checked for “have-been-set”. You can deprecate a required argument, but you must obviously add a new required argument if you do.

Input args with VIPS_ARGUMENT_MODIFY will be modified by the operation. This is used for things like the in-place drawing operations.

VIPS_ARGUMENT_NON_HASHABLE stops the argument being used in hash and equality tests. It’s useful for arguments like revalidate which control the behaviour of the operator cache.