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From: nagler@olsen.UUCP (Rob Nagler)
Newsgroups: comp.lang.perl
Subject: Re: MS Perl Questions
Summary: Yet another DOS workaround
Message-ID: <220@munz.UUCP>
Date: 7 Mar 91 19:06:46 GMT
References: <1991Mar1.041441.4810@ccu1.aukuni.ac.nz> <1991Mar4.165742.12909@holos0.uucp> <4657@eastapps.East.Sun.COM>
Reply-To: nagler@olsen.ch (Rob Nagler)
Organization: Olsen & Associates, Zurich, Switzerland
Lines: 55

Len Read writes:
>>@REM=("
>>@perl 0%.bat ...
>>@end=")
> This often won't work, and it didn't really work in patch level 18 
> when d.d.s. suggested doing it....
> I could not find a general solution to this problem.

The following works ok with pl18 and pl44.  Keep your industrial
strength barf bags handy.

Create a file (in your path) called _#perl.bat which contains:
    @perl %1 %2 %3 %4 %5 %6 %7

The top of your perl file should have.
    @_#perl -S %0.bat %1 %2 %3 %4 %5 %6 %7
    ;

This works because batch files under DOS do not nest, they chain.
You could do something fancier, e.g. rename perl.exe to _#perl.exe
and have an empty batch file called _#exit (or whatever) and have
    @_#perl -S %0.bat %1 %2 %3 %4 %5 %6 %7 %8 %9
    ;@_#exit
    ;
at the top, but this seems a lot more work for the benefit of 2 extra
args.

One minor problem with DOS perl, it doesn't automatically seach the
current directory with the -S option.  You can either put "." in your
path.  Of course, don't put any batch files in "\", because it won't
find 'em; "." doesn't exist in the root directory.

Tom Dinger writes:
> If you are using a DOS version before 3.30, you have some problems, as the
> '@' character is not recognised as suppressing echo of the command

The above scheme will work for earlier DOS, but you'll have to name
the _#perl.bat to be @_#perl.bat.

> Limitations of the above:
> 1. This will only work if you type the batch file name without an extension:
>    If you enter the command "t.bat" to DOS, perl will look for "t.bat.BAT"

Technically, @_#perl.bat or _#perl.bat could really be a perl program
that seaches for your perl file and then calls "do".  However, there
may be problems with DOS perl expanding args before you are ready,
i.e. you can't call "exec" because the line is greater than 128
characters after the expansion.  You could write a non-perl program
that would do this work with the expansion problems.  In practice,
"can't execute foo.bat" doesn't occur very often and I don't pass
very many "words" to my perl scripts anyway.  Stick with the above.

Flames to Bill Gates.

Rob nagler@olsen.ch