Commit b75fb81e authored by Lars Ingebrigtsen's avatar Lars Ingebrigtsen

Extend button.el to take callback data

* doc/lispref/display.texi (Button Buffer Commands)
(Button Buffer Commands): Document this.
* lisp/button.el (backward-button, forward-button): Accept a
NO-ERROR parameter.
(button-activate): Make it possible to have specific data in the
callback action.
parent 99156a03
......@@ -6473,7 +6473,9 @@ that is the value of that property, passing it the single argument
@var{button}). If @var{use-mouse-action} is non-@code{nil}, try to
invoke the button's @code{mouse-action} property instead of
@code{action}; if the button has no @code{mouse-action} property, use
@code{action} as normal.
@code{action} as normal. If the @code{button-data} property is
present in @var{button}, use that as the argument for the
@code{action} function instead of @var{button}.
@end defun
@defun button-label button
......@@ -6541,14 +6543,16 @@ event's position is used. If there's no button at @var{pos}, do
nothing and return @code{nil}, otherwise return @code{t}.
@end deffn
@deffn Command forward-button n &optional wrap display-message
@deffn Command forward-button n &optional wrap display-message no-error
Move to the @var{n}th next button, or @var{n}th previous button if
@var{n} is negative. If @var{n} is zero, move to the start of any
button at point. If @var{wrap} is non-@code{nil}, moving past either
end of the buffer continues from the other end. If
@var{display-message} is non-@code{nil}, the button's help-echo string
is displayed. Any button with a non-@code{nil} @code{skip} property
is skipped over. Returns the button found.
is skipped over. Returns the button found, and signals an error if no
buttons can be found. If @var{no-error} in non-@code{nil}, return nil
instead of signalling the error.
@end deffn
@deffn Command backward-button n &optional wrap display-message
......@@ -6558,7 +6562,9 @@ button at point. If @var{wrap} is non-@code{nil}, moving past either
end of the buffer continues from the other end. If
@var{display-message} is non-@code{nil}, the button's help-echo string
is displayed. Any button with a non-@code{nil} @code{skip} property
is skipped over. Returns the button found.
is skipped over. Returns the button found, and signals an error if no
buttons can be found. If @var{no-error} in non-@code{nil}, return nil
instead of signalling the error.
@end deffn
@defun next-button pos &optional count-current
......
......@@ -1968,6 +1968,12 @@ valid event type.
* Lisp Changes in Emacs 27.1
+++
** Buttons (created with 'make-button' and related functions) can
now use the 'button-data' property. If present, the data in this
property will be passed on to the 'action' function instead of the
button itself in 'button-activate'.
** 'defcustom' now takes a ':local' keyword that can be either t or
'permanent', which mean that the variable should be automatically
buffer-local. 'permanent' also sets the variable's 'permanent-local'
......
......@@ -235,15 +235,19 @@ The action can either be a marker or a function. If it's a
marker then goto it. Otherwise if it is a function then it is
called with BUTTON as only argument. BUTTON is either an
overlay, a buffer position, or (for buttons in the mode-line or
header-line) a string."
header-line) a string.
If BUTTON has a `button-data' value, call the function with this
value instad of BUTTON."
(let ((action (or (and use-mouse-action (button-get button 'mouse-action))
(button-get button 'action))))
(button-get button 'action)))
(data (button-get button 'button-data)))
(if (markerp action)
(save-selected-window
(select-window (display-buffer (marker-buffer action)))
(goto-char action)
(recenter 0))
(funcall action button))))
(funcall action (or data button)))))
(defun button-label (button)
"Return BUTTON's text label."
......@@ -324,6 +328,10 @@ using `make-text-button'. Note, however, that if there is an existing
face property at the site of the button, the button face may not be visible.
You may want to use `make-button' in that case.
If the property `button-data' is present, it will later be used
as the argument for the `action' callback function instead of the
default argument, which is the button itself.
BEG can also be a string, in which case it is made into a button.
Also see `insert-text-button'."
......@@ -462,13 +470,17 @@ return t."
(button-activate button use-mouse-action)
t))))
(defun forward-button (n &optional wrap display-message)
(defun forward-button (n &optional wrap display-message no-error)
"Move to the Nth next button, or Nth previous button if N is negative.
If N is 0, move to the start of any button at point.
If WRAP is non-nil, moving past either end of the buffer continues from the
other end.
If DISPLAY-MESSAGE is non-nil, the button's help-echo string is displayed.
Any button with a non-nil `skip' property is skipped over.
If NO-ERROR, return nil if no further buttons could be found
instead of erroring out.
Returns the button found."
(interactive "p\nd\nd")
(let (button)
......@@ -497,22 +509,28 @@ Returns the button found."
(unless (button-get button 'skip)
(setq n (1- n)))))))
(if (null button)
(user-error (if wrap "No buttons!" "No more buttons"))
(if no-error
nil
(user-error (if wrap "No buttons!" "No more buttons")))
(let ((msg (and display-message (button-get button 'help-echo))))
(when msg
(message "%s" msg)))
button)))
(defun backward-button (n &optional wrap display-message)
(defun backward-button (n &optional wrap display-message no-error)
"Move to the Nth previous button, or Nth next button if N is negative.
If N is 0, move to the start of any button at point.
If WRAP is non-nil, moving past either end of the buffer continues from the
other end.
If DISPLAY-MESSAGE is non-nil, the button's help-echo string is displayed.
Any button with a non-nil `skip' property is skipped over.
If NO-ERROR, return nil if no further buttons could be found
instead of erroring out.
Returns the button found."
(interactive "p\nd\nd")
(forward-button (- n) wrap display-message))
(forward-button (- n) wrap display-message no-error))
(provide 'button)
......
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