elisp: Warning Variables
37.5.2 Warning Variables
------------------------
Programs can customize how their warnings appear by binding the
variables described in this section.
-- Variable: warning-levels
This list defines the meaning and severity order of the warning
severity levels. Each element defines one severity level, and they
are arranged in order of decreasing severity.
Each element has the form ‘(LEVEL STRING FUNCTION)’, where LEVEL is
the severity level it defines. STRING specifies the textual
description of this level. STRING should use ‘%s’ to specify where
to put the warning type information, or it can omit the ‘%s’ so as
not to include that information.
The optional FUNCTION, if non-‘nil’, is a function to call with no
arguments, to get the user’s attention.
Normally you should not change the value of this variable.
-- Variable: warning-prefix-function
If non-‘nil’, the value is a function to generate prefix text for
warnings. Programs can bind the variable to a suitable function.
‘display-warning’ calls this function with the warnings buffer
current, and the function can insert text in it. That text becomes
the beginning of the warning message.
The function is called with two arguments, the severity level and
its entry in ‘warning-levels’. It should return a list to use as
the entry (this value need not be an actual member of
‘warning-levels’). By constructing this value, the function can
change the severity of the warning, or specify different handling
for a given severity level.
If the variable’s value is ‘nil’ then there is no function to call.
-- Variable: warning-series
Programs can bind this variable to ‘t’ to say that the next warning
should begin a series. When several warnings form a series, that
means to leave point on the first warning of the series, rather
than keep moving it for each warning so that it appears on the last
one. The series ends when the local binding is unbound and
‘warning-series’ becomes ‘nil’ again.
The value can also be a symbol with a function definition. That is
equivalent to ‘t’, except that the next warning will also call the
function with no arguments with the warnings buffer current. The
function can insert text which will serve as a header for the
series of warnings.
Once a series has begun, the value is a marker which points to the
buffer position in the warnings buffer of the start of the series.
The variable’s normal value is ‘nil’, which means to handle each
warning separately.
-- Variable: warning-fill-prefix
When this variable is non-‘nil’, it specifies a fill prefix to use
for filling each warning’s text.
-- Variable: warning-type-format
This variable specifies the format for displaying the warning type
in the warning message. The result of formatting the type this way
gets included in the message under the control of the string in the
entry in ‘warning-levels’. The default value is ‘" (%s)"’. If you
bind it to ‘""’ then the warning type won’t appear at all.
Info Catalog
elisp: Warning Basics
elisp: Warnings
elisp: Warning Options