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Explain use of `declare'.

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Richard M. Stallman 2002-04-19 00:17:47 +00:00
parent 11713b6daf
commit f9350c5cef
1 changed files with 30 additions and 18 deletions
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48
lispref/edebug.texi
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@ -1063,32 +1063,44 @@ macro call are forms to be evaluated. (Evaluation may occur explicitly
in the macro body, or when the resulting expansion is evaluated, or any
time later.)
Therefore, you must define an Edebug specification for each macro that
Edebug will encounter, to explain the format of calls to that macro. To
do this, use @code{def-edebug-spec}.
Therefore, you must define an Edebug specification for each macro
that Edebug will encounter, to explain the format of calls to that
macro. To do this, add an @code{edebug} declaration to the macro
definition. Here is a simple example that shows the specification for
the @code{for} example macro (@pxref{Argument Evaluation}).
@example
(defmacro for (var from init to final do &rest body)
"Execute a simple \"for\" loop.
For example, (for i from 1 to 10 do (print i))."
(declare (edebug symbolp "from" form "to" form "do" &rest form))
...)
@end example
@defspec declare (edebug @var{specification})
Specify which expressions of a call to the macro in which the
declaration appears are forms to be evaluated. For simple macros, the
@var{specification} often looks very similar to the formal argument list
of the macro definition, but specifications are much more general than
macro arguments.
@end defspec
You can also define an edebug specification for a macro separately
from the macro definition with @code{def-edebug-spec}. Adding
@code{edebug} declarations is preferred, and more convenient, for
macro definitions in Lisp, but @code{def-edebug-spec} makes it
possible to define Edebug specifications for special forms implemented
in C.
@deffn Macro def-edebug-spec macro specification
Specify which expressions of a call to macro @var{macro} are forms to be
evaluated. For simple macros, the @var{specification} often looks very
similar to the formal argument list of the macro definition, but
specifications are much more general than macro arguments.
evaluated. @var{specification} should be the edebug specification.
It is not evaluated.
The @var{macro} argument can actually be any symbol, not just a macro
name.
@end deffn
Here is a simple example that defines the specification for the
@code{for} example macro (@pxref{Argument Evaluation}), followed by an
alternative, equivalent specification.
@example
(def-edebug-spec for
(symbolp "from" form "to" form "do" &rest form))
(def-edebug-spec for
(symbolp ['from form] ['to form] ['do body]))
@end example
Here is a table of the possibilities for @var{specification} and how each
directs processing of arguments.