Re: [MacPerl] FindFolder puzzler

[Ronald J Kimball <rjk@linguist.dartmouth.edu>]

On Wed, Feb 23, 2000 at 01:06:23AM +0800, robinmcf@altern.org wrote:
> The script below is an attempt at writing a generic handler script for
> getting the paths to standard folders. Though logic says by passing the
> name of the folder to FindFolder() it should yield the path to the folder,
> yet I get
> 
> # Use of uninitialized value.
> File 'Untitled'; Line 37 # (#1)
> 
> What gives?

The usual problem: failure to check return values.

> #! perl -w
> 
> use diagnostics-verbose;
> use strict;
> 
> 
> #-=-=-=-=-=Declare Includes-=-=-=-=-=-=-=-=-=-=-=
> use Mac::Files;
> use File::Find;
> #-=-=-=-=-=Declare Variables-=-=-=-=-=-=-=-=-=-=
> 
> my ($path,$folder,$file,@StdFolders,);
> 
> #-=-=-=-=-=Script Body-=-=-=-=-=-=-=-=-=-=-=-=-=
> 
> $path = FindFolder(kOnSystemDisk(),kDesktopFolderType()); #typing the
> folder name like this
> 
> #  works
> print "path to desktop folder is> $path\n";
> 
> @StdFolders= q(kAppleMenuFolderType() #load the standard folders into an array

An array of one element...  I assume you meant qw().  And that comment is
part of the string.

That's only half the problem, though.  Consider the difference between
these two lines of code:

$path = FindFolder(kOnSystemDisk(),kDesktopFolderType());
$path = FindFolder(kOnSystemDisk(),"kDesktopFolderType()");

> kShutdownFolderType()
> kControlPanelFolderType()
> kStartupFolderType()
> kDesktopFolderType()
> kSystemFolderType()
> kExtensionFolderType()
> kTemporaryFolderType()
> kFontsFolderType()
> kTrashFolderType()
> kPreferencesFolderType()
> );
> 
> 
> foreach $file (@StdFolders) {
>     $path=(FindFolder(kOnSystemDisk(),$file));

FindFolder() is returning undef because its second argument does not
specify an existing file.  Unfortunately, instead of checking the return
value from FindFolder, you just go ahead and print it:

>     print "$path\n";
>     print "$file\n";
> 
> 	 }
> _END_


Ronald

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