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107 condition-call-if
(condition-call 0 ... )
condition-cali And :no-error
As a special case, predicate-m (the last one) can be the special symbol
:no-error. If form is evaluated and no error is signalled during the evaluation,
condition-case executes the :no-error clause instead of returning the
values returned by form. The variables vars are bouna to the values
produced by form, in the style of multiple-value-bind, so that they can be
. accessed by the body of the :no-error case. Any extra variables are bound
to nil.
Some limitations on predicates:
• Predicates must not have side effects. The number of times that the
signalling mechanism chooses to invoke the predicates and the order
in which it invokes them are not defined. For side effects in the
dynamic environment of the signal, use condition-bind.
• The predicates are not lexical closures and therefore cannot access
variables of the lexically containing form, unless those variables are
declared special.
• Lambda-expression predicates are not compiled.
The conditional variant of condition-call is the form:
condi tion-calI-if
For a table of related items: See the section "Basic Forms for Bound
Handlers" in Symbolics Common Lisp: Language Concepts.
I
condition-call-if cond-form (&rest varlist) form &body clauses Special Form
condition-call-if binds its handlers conditionally. In all other respects, it is
just like condition-call. Its format includes cond-form, the subform that
controls binding handlers:
(condi t i on-call-i f cond-form (var)
form
(predicate-I form-I-I form-I-2 ... form-I-n)
(predicate-2 form-2-I form-2-2 ... form-2-n)
(predicate-m form-m-l form-m-2 ... form-m-n))
condition-call-if iust evaluates cond-form. If the result is nil, it does not
set up any handlers; it just evaluates the form. If the result is not nil, it
continues just like condition-call, binding the handlers and evaluating the
form.
The :no-error clause applies whether or not cond-form is nil.