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Source for wiki StandardConditionPredicatesCowan version 4
author
cowan
comment
ipnr
198.185.18.207
name
StandardConditionPredicatesCowan
readonly
0
text
= Standard condition predicates and accessors =
Conditions created by an implementation are opaque objects as far as
this standard is concerned; they may be any Scheme object such as a list, a vector, or a
record. However, a variety of predicates and accessors
are provided in order to help programs
examine implementation-specific conditions.
If a predicate returns `#t` on a particular condition, the related accessor(s)
will return information, hopefully meaningful and useful. Otherwise, calling the accessors
has undefined effect.
It is common for more than one predicate to return `#t` on a particular condition.
* `(message-condition? `''condition''`)`
Returns `#t` iff ''condition'' contains a string message describing the condition to humans, otherwise `#f`.
* `(condition-message `''message-condition''`)`
Returns the message associated with ''message-condition''.
* `(who-condition? `''condition''`)`
Returns `#t` iff ''condition'' contains a string or symbol describing the object which is the
source of the exception, otherwise `#f`.
* `(condition-who `''who-condition''`)`
Returns the ''who'' object associated with ''who-condition''.
* `(irritants-condition? `''condition''`)`
Returns `#t` iff ''condition'' contains a list of objects providing additional information
about the condition, otherwise `#f`.
* `(condition-irritants `''irritants-condition''`)`
Returns the list of irritants (possibly empty) associated with ''message-condition''.
* `(warning-condition? `''condition''`)`
Returns `#t` iff ''condition'' describes an exceptional situation that does not,
in principle, prohibit immediate continued execution of the program,
but may interfere with the program’s execution later, otherwise `#f`.
* `(serious-condition? `''condition''`)`
Returns `#t` iff ''condition'' describes an exceptional situation that is
serious enough that it cannot safely be ignored, otherwise `#f`.
* `(external-condition? `''condition''`)`
Returns `#t` iff ''condition'' describes an exceptional situation that is
caused by something that has gone wrong in the interaction
of the program with the external world or the user, otherwise `#f`.
* `(violation-condition? `''condition''`)`
Returns `#t` iff ''condition'' describes an exceptional situation that is
a violation of the language standard or a library standard,
typically caused by a programming error, otherwise `#f`.
* `(invocation-condition? `''condition''`)`
Returns `#t` iff ''condition'' describes an invalid call to a procedure,
such as passing an invalid number of arguments or passing an argument of the wrong type, otherwise `#f`.
* `(implementation-restriction-condition? `''condition''`)`
Returns `#t` iff ''condition'' describes a violation of an implementation restriction
that is allowed by the specification, otherwise `#f`.
* `(storage-exhausted-condition? `''condition''`)`
Returns `#t` iff ''condition'' is reporting that storage is exhausted, otherwise `#f`.
* `(parse-condition? `''condition''`)`
Returns `#t` iff ''condition'' describes a lexical syntax error
or an error in parsing a datum, otherwise `#f`.
* `(condition-parse-string `''parse-condition''`)`
Returns the string which could not be parsed.
* `(syntax-condition? `''condition''`)`
Returns `#t` iff ''condition'' describes a syntax error, otherwise `#f`.
* `(condition-form `''syntax-condition''`)`
Returns the form containing a syntax error.
* `(condition-subform `''syntax-condition''`)`
Returns the subform which more precisely locates the syntax error.
* `(identifier-condition? `''condition''`)`
Returns `#t` iff ''condition'' describes an undefined identifier, otherwise `#f`.
* `(condition-identifier `''identifier-condition''`)`
Returns the identifier which is undefined as a symbol.
* `(port-condition? `''condition''`)`
Returns `#t` iff ''condition'' describes a problem with a port, otherwise `#f`.
* `(condition-port `''port-condition''`)`
Returns the port associated with ''port-condition''.
* `(i/o-condition? `''condition''`)`
Returns `#t` iff ''condition'' describes an exceptional situation with I/O, otherwise `#f`.
* `(read-condition? `''condition''`)`
Returns `#t` iff ''condition'' describes an exceptional situation with input, otherwise `#f`.
* `(write-condition? `''condition''`)`
Returns `#t` iff ''condition'' describes an exceptional situation with output, otherwise `#f`.
* `(position-condition? `''condition''`)`
Returns `#t` iff ''condition'' describes an attempt
to set a port's position invalidly, otherwise `#f`.
* `(condition-position `''position-condition''`)`
Returns the position specified by the user.
* `(filename-condition? `''condition''`)`
Returns `#t` iff ''condition'' has a filename associated with it, otherwise `#f`.
* `(condition-filename `''filename-condition''`)`
Returns the filename associated with ''filename-condition'' as a string.
* `(file-protection-condition? `''condition''`)`
Returns `#t` iff ''condition'' describes a file protection violation, otherwise `#f`.
* `(file-existence-condition? `''condition''`)`
Returns `#t` iff ''condition'' describes the existence or nonexistence of a file, otherwise `#f`.
* `(condition-file-exists? `''file-existence-condition''`)`
Returns `#t` if the filename associated with ''file-existence-condition'' exists but should not,
or `#f` if it does not exist but should.
time
2010-07-09 22:23:57
version
4