CLHS: Section 9.1.1

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## 9.1.1 Condition Types

The next figure lists the standardized condition types. Additional condition types can be defined by using define-condition.

    arithmetic-error                  floating-point-overflow   simple-type-error
    cell-error                        floating-point-underflow  simple-warning
    condition                         package-error             storage-condition
    control-error                     parse-error               stream-error
    division-by-zero                  print-not-readable        style-warning
    end-of-file                       program-error             type-error
    error                             reader-error              unbound-slot
    file-error                        serious-condition         unbound-variable
    floating-point-inexact            simple-condition          undefined-function
    floating-point-invalid-operation  simple-error              warning

Figure 9-1. Standardized Condition Types

All condition types are subtypes of type condition. That is,

     (typep c 'condition) =>  true

if and only if c is a condition.

Implementations must define all specified subtype relationships. Except where noted, all subtype relationships indicated in this document are not mutually exclusive. A condition inherits the structure of its supertypes.

The metaclass of the class condition is not specified. Names of condition types may be used to specify supertype relationships in define-condition, but the consequences are not specified if an attempt is made to use a condition type as a superclass in a defclass form.

The next figure shows operators that define condition types and creating conditions.

    define-condition  make-condition

Figure 9-2. Operators that define and create conditions.

The next figure shows operators that read the value of condition slots.

    arithmetic-error-operands   simple-condition-format-arguments
    arithmetic-error-operation  simple-condition-format-control
    cell-error-name             stream-error-stream
    file-error-pathname         type-error-datum
    package-error-package       type-error-expected-type
    print-not-readable-object   unbound-slot-instance

Figure 9-3. Operators that read condition slots.

## 9.1.1.1 Serious Conditions

The following X3J13 cleanup issues, not part of the specification, apply to this section:

- FORMAT-STRING-ARGUMENTS:SPECIFY
- COMPILER-DIAGNOSTICS:USE-HANDLER
- FLOATING-POINT-CONDITION-NAMES:X3J13-NOV-89
- READER-ERROR:NEW-TYPE
- ACCESS-ERROR-NAME
- PARSE-ERROR-STREAM:SPLIT-TYPES
- DATA-IO:ADD-SUPPORT
- UNDEFINED-VARIABLES-AND-FUNCTIONS:COMPROMISE

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