Re: [MacPerl-Porters] Re: File::Spec catfile etc.

On Sat, Sep 15, 2001 at 09:01:04AM -0700, Peter Prymmer wrote:
> 
> Then what value has adding the warning to:
> 
>      $path = "C:\foo" ;
>      $fullpath = File::Spec->catfile( $path, "bar" ) ;

Here you're asking for portability.

> added to File::Spec?  If I am on win32 and I want to concatenate names
> into a valid win32 file spec I no longer can without specifying:
> 
>      $fullpath = File::Spec::Win32->catfile( $path, "bar" ) ;

There you're telling us that you're manipulating Win32 paths.

If you need to put volume names in, then catpath() is needed.

> Is it not the case that the former implies that I have at least given some
> thought to portability.

Exactly.  The former example is blighted by the (mistyped)

   $path = "C:\\foo" ;

; what I meant to show was that if $path contains a volume spec or a
dirsep, then a warning should be delivered.

> Note that it would have been much easier for
> me to specify:
> 
>      $path = "C:\\foo" ;
>      $fullpath = "$path\\bar" ;
> 
> Rather than using the File::Spec lib module(s).

Yup.

> The problem with the "portability" goal is that on non rooted file systems
> (basically most non-Unix) that there can be no agreeing on full path names
> anyway.

File::Spec's primary goal is portability.  It'll never be 100%, but we
can keep nudging it towards the asymtote.

> Sure I might very well expect to see these on win32:
>
>      A:\
>      C:\
>      D:\
> 
> And I might very well see these on VMS:
> 
>      _SATURN::DKA100:
>      _SATURN::DKA200:
>      _SATURN::DKA300:
> 

See them where?  Passed in to catdir() and/or catfile()?  Or catpath()?

> but why would perl need to remind me that the two sets are different? 

It's not reminding you that they're different; it's warning you when you
use them in a context that is supposed to be portable.  If you're
writing a program on Win32, and a C: or "\\" or even "/" sneaks in,
File::Spec can do you the favor of warning you that you've got some
platform specific bits sneaking in.

> I think that the annoyance of the warnings detracts from the desirablity
> to even use File::Spec to begin with.  My worry is that folks will start
> avoiding it rather than getting to know it.  E.g. look at the
> non-portability of the installperl script.  It currently works only on
> Unix, Windows, and VMS (perhaps other POSIXly oriented environs).  It
> won't work on MacOS at all and ought to use the build
> directorie's copy of File::Spec.
> 
> I suspect, although I have not attempted to code it, that adding the
> various warnings will fill up File/Spec.pm and/or the various
> lib/File/Spec/$osname.pm files with a lot of extra regular expession
> parsing and whatnot that will slow File::Spec down.

There will definitely be a few extra m// ops.  Not sure how important
they are, since actually using a path for anything goes out to the FS
and is therefore likely to be so slow that a few extra m// ops won't be
noticed.  In theory anyway.

The whole idea is for File::Spec to help people use it portably; if you
don't need portability, just hack the paths manually (as you point out)
or use File::Spec::Foo directly.  If we think the warnings are too much
"help", I'm not too worried about adding them.

> Thanks for the help you've given thus far.  Even pulling it out of
> MakeMaker was a challenging task for which I am grateful.

Alas, that was before my time...

- Barrie