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.\"
.IX Title "Imager::Probe 3pm"
.TH Imager::Probe 3pm "2012-04-29" "perl v5.14.2" "User Contributed Perl Documentation"
.\" For nroff, turn off justification.  Always turn off hyphenation; it makes
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.SH "NAME"
Imager::Probe \- hot needle of inquiry for libraries
.SH "SYNOPSIS"
.IX Header "SYNOPSIS"
.Vb 1
\&  require Imager::Probe;
\&
\&  my %probe = 
\&    (
\&     # short name of what we\*(Aqre looking for (displayed to user)
\&     name => "FOO",
\&     # pkg\-config lookup
\&     pkg => [ qw/name1 name2 name3/ ],
\&     # perl subs that probe for the library
\&     code => [ \e&foo_probe1, \e&foo_probe2 ],
\&     # or just: code => \e&foo_probe,
\&     inccheck => sub { ... },
\&     libcheck => sub { ... },
\&     # search for this library if libcheck not supplied
\&     libbase => "foo",
\&     # library link time options, uses libbase to build options otherwise
\&     libopts => "\-lfoo",
\&     # C code to check the library is sane
\&     testcode => "...",
\&     # header files needed
\&     testcodeheaders => [ "stdio.h", "foo.h" ],
\&    );
\&  my $result = Imager::Probe\->probe(\e%probe)
\&    or print "Foo library not found: ",Imager::Probe\->error;
.Ve
.SH "DESCRIPTION"
.IX Header "DESCRIPTION"
Does the probes that were hidden in Imager's \fIMakefile.PL\fR, pulled
out so the file format libraries can be externalized.
.PP
The return value is either nothing if the probe fails, or a hash
containing:
.IP "\(bu" 4
\&\f(CW\*(C`INC\*(C'\fR \- \f(CW\*(C`\-I\*(C'\fR and other C options
.IP "\(bu" 4
\&\f(CW\*(C`LIBS\*(C'\fR \- \f(CW\*(C`\-L\*(C'\fR, \f(CW\*(C`\-l\*(C'\fR and other link-time options
.IP "\(bu" 4
\&\f(CW\*(C`DEFINE\*(C'\fR \- \f(CW\*(C`\-D\*(C'\fR options, if any.
.PP
The possible values for the hash supplied to the \fIprobe()\fR method are:
.IP "\(bu" 4
\&\f(CW\*(C`pkg\*(C'\fR \- an array of \fIpkg-config\fR names to probe for.  If the
\&\fIpkg-config\fR checks pass, \f(CW\*(C`inccheck\*(C'\fR and \f(CW\*(C`libcheck\*(C'\fR aren't used.
.IP "\(bu" 4
\&\f(CW\*(C`inccheck\*(C'\fR \- a code reference that checks if the supplied include
directory contains the required header files.
.IP "\(bu" 4
\&\f(CW\*(C`libcheck\*(C'\fR \- a code reference that checks if the supplied library
directory contains the required library files.  Note: the
\&\fIMakefile.PL\fR version of this was supplied all of the library file
names instead.  \f(CW\*(C`libcheck\*(C'\fR can also be an arrayref of library check
code references, all of which must find a match for the library to be
considered \*(L"found\*(R".
.IP "\(bu" 4
\&\f(CW\*(C`libbase\*(C'\fR \- if \f(CW\*(C`inccheck\*(C'\fR is supplied, but \f(CW\*(C`libcheck\*(C'\fR isn't, then a
\&\f(CW\*(C`libcheck\*(C'\fR that checks for \f(CW\*(C`lib\*(C'\fR\fIlibbase\fR\fI\f(CI$Config\fI{_a}\fR and
\&\f(CW\*(C`lib\*(C'\fR\fIlibbase\fR.\fI\f(CI$Config\fI{so}\fR is created.  If \f(CW\*(C`libopts\*(C'\fR isn't
supplied then that can be synthesized as \f(CW\*(C`\-l\f(CIlibbase\f(CW\*(C'\fR. \f(CW\*(C`libbase\*(C'\fR can also be an arrayref of library base names to search
for, in which case all of the libraries mentioned must be found for
the probe to succeed.
.IP "\(bu" 4
\&\f(CW\*(C`libopts\*(C'\fR \- if the libraries are found via \f(CW\*(C`inccheck\*(C'\fR/\f(CW\*(C`libcheck\*(C'\fR,
these are the \f(CW\*(C`\-l\*(C'\fR options to supply during the link phase.
.IP "\(bu" 4
\&\f(CW\*(C`code\*(C'\fR \- a code reference to perform custom checks.  Returns the
probe result directly.  Can also be an array ref of functions to call.
.IP "\(bu" 4
\&\f(CW\*(C`testcode\*(C'\fR \- test C code that is run with Devel::CheckLib.  You also
need to set \f(CW\*(C`testcodeheaders\*(C'\fR.
.IP "\(bu" 4
\&\f(CW\*(C`testcodeprologue\*(C'\fR \- C code to insert between the headers and the
main function.
.IP "\(bu" 4
\&\f(CW\*(C`incpath\*(C'\fR \- \f(CW$Config{path_sep}\fR separated list of header file
directories to check, or a reference to an array of such.
.IP "\(bu" 4
\&\f(CW\*(C`libpath\*(C'\fR \- \f(CW$Config{path_sep}\fR separated list of library file
directories to check, or a reference to an array of such.
.IP "\(bu" 4
\&\f(CW\*(C`alternatives\*(C'\fR \- an optional array reference of alternate
configurations (as hash references) to test if the primary
configuration isn't successful.  Each alternative should include an
\&\f(CW\*(C`altname\*(C'\fR key describing the alternative.  Any key not mentioned in
an alternative defaults to the value from the main configuration.