Node:Argp Help Filtering, Previous:Argp Children, Up:Argp Parsers
The help_filter
field in a struct argp
is a pointer to a
function to filter the text of help messages before displaying them.
They have a function signature like:
char *help-filter (int key, const char *text, void *input)where key is either a key from an option, in which case text is that option's help text (see Argp Option Vectors), or one of the special keys with names beginning with
ARGP_KEY_HELP_
, describing
which other help text text is (see Argp Help Filter Keys).
The function should return either text, if it should be used
as-is, a replacement string, which should be allocated using
malloc
, and will be freed by argp, or zero, meaning `print
nothing'. The value of text supplied is after any
translation has been done, so if any of the replacement text also needs
translation, that should be done by the filter function. input is
either the input supplied to argp_parse
, or zero, if
argp_help
was called directly by the user.