Kawa, the Java-based Scheme system

Node:Dynamic records, Next:Mangling, Previous:Record types, Up:Objects Classes and Modules

### Creating New Record Types On-the-fly

Calling the `make-record-type` procedure creates a new record data type at run-time, without any compile-time support. It is primarily provided for compatibility; in most cases it is better to use the `define-record-type` form (see Record types).

make-record-type type-name field-names | Function

Returns a record-type descriptor, a value representing a new data type disjoint from all others. The type-name argument must be a string, but is only used for debugging purposes (such as the printed representation of a record of the new type). The field-names argument is a list of symbols naming the fields of a record of the new type. It is an error if the list contains any duplicates.

record-constructor rtd [field-names] | Function

Returns a procedure for constructing new members of the type represented by rtd. The returned procedure accepts exactly as many arguments as there are symbols in the given list, field-names; these are used, in order, as the initial values of those fields in a new record, which is returned by the constructor procedure. The values of any fields not named in that list are unspecified. The field-names argument defaults to the list of field names in the call to `make-record-type` that created the type represented by rtd; if the field-names argument is provided, it is an error if it contains any duplicates or any symbols not in the default list.

record-predicate rtd | Function

Returns a procedure for testing membership in the type represented by rtd. The returned procedure accepts exactly one argument and returns a true value if the argument is a member of the indicated record type; it returns a false value otherwise.

record-accessor rtd field-name | Function

Returns a procedure for reading the value of a particular field of a member of the type represented by rtd. The returned procedure accepts exactly one argument which must be a record of the appropriate type; it returns the current value of the field named by the symbol field-name in that record. The symbol field-name must be a member of the list of field-names in the call to `make-record-type` that created the type represented by rtd.

record-modifier rtd field-name | Function

Returns a procedure for writing the value of a particular field of a member of the type represented by rtd. The returned procedure accepts exactly two arguments: first, a record of the appropriate type, and second, an arbitrary Scheme value; it modifies the field named by the symbol field-name in that record to contain the given value. The returned value of the modifier procedure is unspecified. The symbol field-name must be a member of the list of field-names in the call to `make-record-type` that created the type represented by rtd.

record? obj | Function

Returns a true value if obj is a record of any type and a false value otherwise.

record-type-descriptor record | Function

Returns a record-type descriptor representing the type of the given record. That is, for example, if the returned descriptor were passed to `record-predicate`, the resulting predicate would return a true value when passed the given record.

record-type-name rtd | Function

Returns the type-name associated with the type represented by rtd. The returned value is `eqv?` to the type-name argument given in the call to `make-record-type` that created the type represented by rtd.

record-type-field-names rtd | Function

Returns a list of the symbols naming the fields in members of the type represented by rtd. The returned value is `equal?` to the field-names argument given in the call to `make-record-type` that created the type represented by rtd.

Records are extensions of the class `Record`. These procedures use the Java 1.1 reflection facility.