File: flymake.el.html

Flymake is a minor Emacs mode performing on-the-fly syntax checks.

Flymake collects diagnostic information for multiple sources, called backends, and visually annotates the relevant portions in the buffer.

This file contains the UI for displaying and interacting with the results produced by these backends, as well as entry points for backends to hook on to.

The main interactive entry point is the flymake-mode(var)/flymake-mode(fun) minor mode, which periodically and automatically initiates checks as the user is editing the buffer. The variables flymake-no-changes-timeout, flymake-start-on-flymake-mode give finer control over the events
triggering a check, as does the interactive command flymake-start,
which immediately starts a check.

Shortly after each check, a summary of collected diagnostics should appear in the mode-line. If it doesn't, there might not be a suitable Flymake backend for the current buffer's major mode, in which case Flymake will indicate this in the mode-line. The indicator will be ! (exclamation mark), if all the configured backends errored (or decided to disable themselves) and ?
(question mark) if no backends were even configured.

For programmers interested in writing a new Flymake backend, the docstring of flymake-diagnostic-functions, the Flymake manual, and the code of existing backends are probably good starting points.

The user wishing to customize the appearance of error types should set properties on the symbols associated with each diagnostic type. The standard diagnostic symbols are :error, :warning and
:note (though a specific backend may define and use more). The
following properties can be set:

* flymake-bitmap, an image displayed in the fringe according to
flymake-fringe-indicator-position. The value actually follows the syntax of flymake-error-bitmap (which see). It is overridden by any before-string overlay property.

* flymake-severity, a non-negative integer specifying the
diagnostic's severity. The higher, the more serious. If the overlay property priority is not specified, severity is used to set it and help sort overlapping overlays.

* flymake-overlay-control, an alist ((OVPROP . VALUE) ...) of
further properties used to affect the appearance of Flymake annotations. With the exception of category and evaporate, these properties are applied directly to the created overlay. See Info Node (elisp)Overlay Properties.

* flymake-category, a symbol whose property list is considered a
default for missing values of any other properties. This is useful to backend authors when creating new diagnostic types that differ from an existing type by only a few properties. The category symbols flymake-error, flymake-warning and flymake-note make good candidates for values of this property.

For instance, to omit the fringe bitmap displayed for the standard
:note type, set its flymake-bitmap property to nil:

  (put :note 'flymake-bitmap nil)

To change the face for :note type, add a face entry to its flymake-overlay-control property.

  (push '(face . highlight) (get :note 'flymake-overlay-control))

If you push another alist entry in front, it overrides the previous one. So this effectively removes the face from :note diagnostics.

  (push '(face . nil) (get :note 'flymake-overlay-control))

To erase customizations and go back to the original look for
:note types:

  (cl-remf (symbol-plist :note) 'flymake-overlay-control) (cl-remf (symbol-plist :note) 'flymake-bitmap)

Defined variables (45)

Defined functions (122)

Defined faces (13)