Platform-specific file path delimiters

[Mark Waddingham]

On 2015-09-23 21:02, Richard Gaskin wrote:
> It's nice when it works like that.  I started using MC on Mac Classic,
> and I ran into path issues early on because IIRC no such accommodation
> was made for the Mac-specific ":" delimiter.   Rather than read the
> docs I wrote to Dr. Raney, who referred me to the docs.

As I said, the fact it worked on Windows is entirely down to the Win32 
APIs being lax - not by explicit design:

i.e. Win32 API calls happily treat / the same as \ in many instances - 
this was not the case in Mac Classic API calls.

If it had been me doing the Windows port I would have made the attempt 
to use such paths on Windows an error -as my personal opinion is that 
explicitly delimited strictness is always better than undocumented 
laxness in an environment where you intend things to be 'easy to use'.

> So it looks like we're covered:  anyone looking for cross-platform
> info can find what they need, and Windows-specific work is still
> supported using Windows-specific path delimiters.

Again, sorry to beat the drum again here - Windows-specific path 
delimiters are supported for backwards-compatibility and no more than 
that, please avoid using them for new code.

> Why would that be necessary if Windows-specific paths are supported,
> as Mark just described above?

I realize I didn't explain why it is a bad idea to use \ in your paths - 
I shall now attempt to do so.

On UNIX systems '\' is nothing special - it can be part of a filename. 
This means that LiveCode has to treat it as part of a filename lest you 
want strange reports from users of your software when choosing certain 
filenames in an open/save dialog causes odd breakage. Now, fortunately, 
'/' *is* reserved on all platforms we support - thus this is the path 
separator that LiveCode understands.

Now, at the moment, we do not have much if any syntax which directly 
allows you to process file paths. However, it is not beyond the realm of 
possibility that (at some point) we will add syntax which allows easier 
manipulation. e.g.
   put the filename of filepath "foo/bar/zee.txt"
   put the folder of filepath "foo/bar/zee.txt"

This syntax would be predicated on using '/' uniformly as the path 
separator for all platforms. We can't make it work for both '\' and '/' 
as then it would mean you would not be able to access some valid paths 
on UNIX derived systems. Thus any application which does use the 
Windows-specific platform separator on Windows would find that they 
would not be able to use any new syntax that might appear in the future 
in this regard.

I should perhaps also point out that there are numerous places in the 
engine where it computes the leaf of a filepath - these will not work 
with '\' separated paths correctly for exactly the same reason.

Warmest Regards,

Mark.

-- 
Mark Waddingham ~ mark at livecode.com ~ http://www.livecode.com/
LiveCode: Everyone can create apps