Re: dircat vs. path_concat

["Klaus Schmid" <klaus.schmid@xxxxxxx>]

> Joerg Sommer <joerg@xxxxxxxxxxxx> wrote:
[...]
>But I would write it a little bit different:
[...]
> I don't know the syntax of VMS paths and I don't know what is valid, but
> dircat("d:foo.bar", "") brings "d:foo.bar]"

For dircat I think a few syntax rules are sufficient.
Very roughly:
x:a + b  --> undefined
a + b  -->  []a + b
x]a + b  -->  x.a]b

I think dircat works (or should work) the same way as path_concat.
An obvious difference is the expand_filename() at the end of dircat;
I don't know why this was introduced into dircat.

Personally I would prefer to have one set of path-functions to
match all. First a set of functions to split an input-string into
two substrings, realized dependant on os-type:
(dir,base)= split_file( file)
(core,extv)= split_base( base)
(ext,v)= split_extv( extv)

Then two basic functions to navigate through the directory tree,
realized os-type-dependant:
(d,b)= dir_up( dir)
dir= dir_down( d,b)

e.g.:
split_file( "a:[b]c.txt") --> "a:[b]", "c.txt"
dir_down( "a:[b]", "c.dir") --> "a:[b.c]"
dir_up( "a:[b.c]") --> "a:[b]", "c.dir"

For compatibiliy, the existing functions could be rewritten
in SLang or C by referring to this basic functions.

One UNIX-detail I am almost sure cannot be transposed to VMS:
"a" == "a/."  == "a/b/.."
Obviously dirname may output a dot, but does not respect these
'free' dots at input very well -- are they important/useful anyway?

-- Klaus











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