created October 17, 2001 · complexity advanced · author Benoit Cerrina · version 6.0
When writing scripts using the embedded interpreter available if Vim has the +perl ore +perl/dyn on gives you access to this powerfull and FAST scripting language (especially fast compared to vim scripts) there are some gotchas.
First:
never embed complex perl command in the body of a Vim function this will be recompiled and evaled each time for a tremendous loss of time.instead to it like this
perl << EOF
sub mySub
{
#some usefull perl stuff
}
EOF
function! MyFunction
perl mySub "an argument", "another"
endfunction
to pass computed argument to your perl sub use the Vim exec command
function! MyFunction exec "perl mySub " . aLocalVar . ", " b:aBufferLocalVar endfunction
It may be very hard to debug your perl sub since the output of the perl compiler is somehow lost in the middle of nowhere and the debugger is not available.
When a compilation error occurs in your sub definition you'll get an error message when you try to call it saying that the sub does not exists.
One thing which I have found very usefull is to write a fake VIM module with stub methods which will allow you to use the command line perl interpretor to at least compile your program. You could make your stub smart enough to fake a Vim and use the debugger. Here is a sample for such a fake module defining just those method which I was using.
package VIM;
use diagnostics;
use strict;
sub VIM::Eval
{
$_ = shift;
print "Eval $_\n";
{
return '^(?!!)([^\t]*)\t[^\t]*\t(.*);"\t([^\t]*)\tline:(\d*).*$' if (/g:TagsBase_pattern/);
return $ARGV[0] if (/b:fileName/);
return '$3' if (/g:TagsBase_typePar/);
return '$1' if (/g:TagsBase_namePar/);
return '$4' if (/g:TagsBase_linePar/);
return 'Ta&gs' if (/s:menu_name/);
return $ARGV[1] if (/g:TagsBase_groupByType/);
die "unknown eval $_";
}
}
sub VIM::Msg
{
my $msg = shift;
print "MSG $msg\n";
}
sub VIM::DoCommand
{
my $package;
my $filename;
my $line;
($package, $filename, $line) = caller;
my $command = shift;
print "at $filename $line\n";
print "DoCommand $command\n";
}
1;
Then you can copy other your perl code in a separate file and add a use VIM; at the top and your set to debug.
Comments
For an example of the techniques described see script#100.
little changes to the tip
perl << EOF
sub mySub
{
#some usefull perl stuff
}
EOF
function! MyFunction()
perl mySub "an argument", "another"
endfunction
to pass computed argument to your perl sub use the Vim exec command
function! MyFunction() exec "perl mySub " . aLocalVar . ", " b:aBufferLocalVar endfunction
another way to do this is to get the arguments from within the perl function
perl << EOF
sub mySub
{
my $anArg=VIM::Eval("a:anArg");
#some usefull perl stuff
}
EOF
function! MyFunction(anArg)
perl mySub
endfunction
finally to be able to return something from perl
perl << EOF
sub mySub
{
my $anArg=VIM::Eval("a:anArg");
#some usefull perl stuff
VIM::DoCommand "let retVal=". aMeaningfullThingToReturn;
}
EOF
function! MyFunction(anArg)
perl mySub
if exists('retVal')
return retVal
endif
endfunction