CODEWITHSUNDEEP
error-handlingcommon-lisp
Sim
Sim

Reputation: 4184

How to take advantage of format control supplied by a subclass of simple-error

I am currently developing using the cxml-stp framework, but while parsing I do get a cxml-stp:stp-error, which is a subclass of simple-error, which is documented to be a kind of error where a format-control is supplied.

How can I print the error message? As neither API supplies any specific functions and a simple FORMAT just results in the object being printed but not using the supplied FORMAT string.

e.g.

(SB-KERNEL:CASE-FAILURE
 ETYPECASE
 #<CXML-STP:STP-ERROR "text includes characters that cannot be ~
                represented in XML at all: ~S"
   {1007814951}>
 (STRING SIMPLE-STRING))

Upvotes: 1

Views: 215

Answers (2)

user797257
user797257

Reputation: 

(defun try-handle-error (err)
  (handler-case
      (error err)
    (serious-condition (condition)
      (apply #'format
         (nconc (list t)
            (cons (simple-condition-format-control condition)
              (simple-condition-format-arguments condition)))))))

(try-handle-error (make-condition
        'simple-error
        :format-control "say something ~s~&"
        :format-arguments '(42)))

This would be an example. Basically, format-control and format-arguments are slot-readers declared on simple-error class. When you handle an error, you can call them on that error to get the values it received during creation.

Upvotes: 1

Rainer Joswig
Rainer Joswig

Reputation: 139311

Simply write the condition object without escaping:

(write condition :escape nil)

Upvotes: 3

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