11.3.161 print_message/2 [hookable]

Synopsis

print_message(+Severity, +MessageTerm)

Print a Message of a given Severity. The behavior can be customized using the hooks user:portray_message/2, user:generate_message_hook/3 and user:message_hook/3.

Arguments

Severity
atom, must be nonvar

Unless the default system portrayal is overidden with user:message_hook/3, Severity must be one of:

Value
Prefix
informational
`% '
warning
`* '
error
`! '
help
query
silent
no prefix

MessageTerm
term

Description

First print_message/2 calls user:portray_message/2 with the same arguments. If this does not succeed, the message is processed in the following phases:

An unhandled exception message E calls print_message(error, E) before returning to the top level. The convention is that an error message is the result of an unhandled exception. Thus, an error message should only be printed if raise_exception/1 does not find a handler and unwinds to the top-level.

All messages from the system are printed using this predicate. Means of intercepting these messages before they are printed are provided.

print_message/2 always prints to user_error. Messages can be redirected to other streams using user:message_hook/3 and print_message_lines/3

Silent messages do not get translated or printed, but they can be intercepted with user:portray_message/2 and user:message_hook/3.

Exceptions

instantiation_error
type_error
domain_error
in Severity

See Also

ref-msg.


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