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Clarify what signalling an error means.

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Richard M. Stallman 2002-05-12 17:04:51 +00:00
parent 850ed7b3a7
commit 1e0c9c1870
1 changed files with 11 additions and 4 deletions
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15
lispref/control.texi
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@ -733,6 +733,12 @@ instead. @xref{Catch and Throw}.
@subsubsection How to Signal an Error
@cindex signaling errors
@dfn{Signalling} an error means beginning error processing. Error
processing normally aborts all or part of the running program and
returns to a point that is set up to handle the error
(@pxref{Processing of Errors}). Here we describe how to signal an
error.
Most errors are signaled ``automatically'' within Lisp primitives
which you call for other purposes, such as if you try to take the
@sc{car} of an integer or move forward a character at the end of the
@ -743,10 +749,11 @@ buffer. You can also signal errors explicitly with the functions
considered an error, but it is handled almost like an error.
@xref{Quitting}.
The error message should state what is wrong (``File does not
exist''), not how things ought to be (``File must exist''). The
convention in Emacs Lisp is that error messages should start with a
capital letter, but should not end with any sort of punctuation.
Every error specifies an error message, one way or another. The
message should state what is wrong (``File does not exist''), not how
things ought to be (``File must exist''). The convention in Emacs
Lisp is that error messages should start with a capital letter, but
should not end with any sort of punctuation.
@defun error format-string &rest args
This function signals an error with an error message constructed by