Elegant way to distinct Path or Entry key - regex

Question

I have an application loading CAD data (Custom format), either from the local filesystem specifing an absolute path to a drawing or from a database.
Database access is realized through a library function taking the drawings identifier as a parameter.
the identifiers have a format like ABC 01234T56-T, while my paths a typical windows Paths (eg x:\Data\cadfiles\cadfile001.bin).
I would like to write a wrapper function Taking a String as an argument which can be either a path or an identifier which calls the appropriate functions to load my data.
Like this:
Function CadLoader(nameOrPath : String):TCadData;
My Question: How can I elegantly decide wether my string is an idnetifier or a Path to a file?
Use A regexp? Or just search for '\' and ':', which are not appearing in the Identifiers?

Answer 1

Try this one
Function CadLoader(nameOrPath : String):TCadData;
begin
if FileExists(nameOrPath) then
<Load from file>
else
<Load from database>
end;

Answer 2

I would do something like this:
function CadLoader(nameOrPath : String) : TCadData;
begin
if ((Pos('\\',NameOrPath) = 1) {UNC} or (Pos(':\',NameOrPath) = 2) { Path })
and FileExists(NameOrPath) then
begin
// Load from File
end
else
begin
// Load From Name
end;
end;
The RegEx To do the same thing would be: \\\\|.:\\ I think the first one is more readable.

Answer 3

In my opinion, the K.I.S.S. principle applies (or Keep It Simple Stupid!). Sounds harsh, but if you're absolutely certain that the combination :\ will never be in your identifiers, I'd just look for it on the 2nd position of the string. Keeps things understandable and readable. Also, one more quote:
Some people, when confronted with a
problem, think "I know, I'll use
regular expressions." Now they have
two problems. - Jamie Zawinski

Answer 4

You should pass in an additional parameter that says exactly what the identifier actually represents, ie:
type
CadLoadType = (CadFromPath, CadFromDatabase);
Function CadLoader(aType: CadLoadType; const aIdentifier: String): TCadData;
begin
case aType of
CadFromPath: begin
// aIdentifier is a file path...
end;
CadFromDatabase: begin
// aIdentifier is a database ID ...
end;
end;
end;
Then you can do this:
Cad := CadLoader(CadFromFile, 'x:\Data\cadfiles\cadfile001.bin');
Cad := CadLoader(CadFromDatabase, 'ABC 01234T56-T');