To an extent transients can be customized interactively, see Enabling and Disabling Suffixes. This section explains how existing transients can be further modified non-interactively.
The following functions share a few arguments:
define-transient-command. Note that an infix is a special kind of suffix. Depending on context "suffixes" means "suffixes (including infixes)" or "non-infix suffixes". Here it means the former. See Suffix Specifications.
These functions operate on the information stored in the
transient--layout property of the PREFIX symbol. Suffix entries in
that tree are not objects but have the form
(LEVEL CLASS PLIST), where
plist should set at least
This function inserts SUFFIX into PREFIX before LOC.
This function inserts SUFFIX into PREFIX after LOC.
This function replaces the suffix at LOC in PREFIX with SUFFIX.
This function removes the suffix at LOC in PREFIX.
This function returns the suffix at LOC in PREFIX. The returned value has the form mentioned above.
This function edits the suffix at LOC in PREFIX, by setting the PROP of its plist to VALUE.
Most of these functions do not signal an error if they cannot perform
the requested modification. The functions that insert new suffixes
show a warning if LOC cannot be found in PREFIX, without signaling an
error. The reason for doing it like this is that establishing a key
binding (and that is what we essentially are trying to do here) should
not prevent the rest of the configuration from loading. Among these
signal an error.