8.42 diagnostics (Perl in a Nutshell)

8.42 diagnostics

Provides more descriptive diagnostics than those generated by the Perl compiler and interpreter. Uses the longer, more explanatory error messages found in the perldiag manpage. Can be used as a pragma or as a standalone program, splain . When used as a pragma, diagnostics affects the compilation phase of your program as well as the execution phase. As a standalone module, it is used to post-process errors after execution has completed.

The splain program links to diagnostics.pm to act on the standard error output of a Perl program. The program's output can be sent to a file, which is then used as input to splain , or it can be piped directly to splain . Output from splain is directed to STDOUT.

8.42.1 Options

-p: Sets the variable $diagnostics::PRETTY to true.
-v: Prints the perldiag manpage introduction, then any diagnostic messages.

As a pragma:

use diagnostics [-verbose]

enables the use of


diagnostics

in your program (and enables Perl's -w flag). Compilation is then subject to the enhanced diagnostics, which are issued to STDERR. Set the


diagnostics::PRETTY

variable in a BEGIN block to provide nicer escape sequences for pagers, so your output looks better. The


-verbose

option prints the perldiag manpage introduction, then any diagnostic messages. Functions are:

enable: Turns diagnostics on at runtime.
disable: Turns diagnostics off at runtime.