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>> O (3) ( Solaris man: Библиотечные вызовы ) O (3) ( Разные man: Библиотечные вызовы )
O - Generic interface to Perl Compiler backends
perl -MO=Backend[,OPTIONS] foo.pl
This is the module that is used as a frontend to the Perl
Most compiler backends use the following conventions:
OPTIONS consists of a comma-separated list of words (no
white-space). The `-v' option usually puts the backend into
verbose mode. The `-ofile' option generates output to file
instead of stdout. The `-D' option followed by various
letters turns on various internal debugging flags. See the
documentation for the desired backend (named `B::Backend'
for the example above) to find out about that backend.
This section is only necessary for those who want to write a
compiler backend module that can be used via this module.
The command-line mentioned in the SYNOPSIS section
corresponds to the Perl code
use O ("Backend", OPTIONS);
The `import' function which that calls loads in the
appropriate `B::Backend' module and calls the `compile'
function in that package, passing it OPTIONS. That function
is expected to return a sub reference which we'll call
CALLBACK. Next, the "compile-only" flag is switched on
(equivalent to the command-line option `-c') and a CHECK
block is registered which calls CALLBACK. Thus the main Perl
program mentioned on the command-line is read in, parsed and
compiled into internal syntax tree form. Since the `-c' flag
is set, the program does not start running (excepting BEGIN
blocks of course) but the CALLBACK function registered by
the compiler backend is called.
In summary, a compiler backend module should be called
"B::Foo" for some foo and live in the appropriate directory
for that name. It should define a function called
`compile'. When the user types
perl -MO=Foo,OPTIONS foo.pl
that function is called and is passed those OPTIONS (split
on commas). It should return a sub ref to the main
compilation function. After the user's program is loaded
and parsed, that returned sub ref is invoked which can then
go ahead and do the compilation, usually by making use of
the `B' module's functionality.
Malcolm Beattie, `firstname.lastname@example.org'