On 2017-12-14 03:16:11 +0000, Wolf K said:

On 2017-12-13 19:37, Your Name wrote:
On 2017-12-13 22:13:44 +0000, Tim Streater said:
In article , nospam
wrote:
[...]
The type of a file and which app you'd like it to open with are items
of file metadata and have no business being part of the filename.

It is useful and sensible to have the file type as part of the
filename. Otherwise you'd get a pile of files which neither you nor the
OS having any idea whether they are images, sounds, text, etc. You
would then have to try to open the file in every app you own until you
found one that could open it

Many files have such type-identifiers included. E.g., a JPG file begins
with JFIF, a WordPerfect file includes WPC in the first line, an MS
.doc includes "Microsoft Word Document" in plain text in the header,
and so on. Some image viewers will even tell you that the extension
doesn't match the file type, if that happens to be the case.

But then you actually have to open the file to see that. The filename
extension, or Classic Mac OS's type and creator codes, don't need the
file to be opened to find out what it is ... or at least supposedly is
since those can be easily fooled.



... you can't rely on the OS to do that since a JPEG image file can
actually be opened in a text editor as the file's data, even if it's
rarely useful to do so.

That's what Open With is for.

Open With is near useless if you don't know what the file actually is.
You'd have to Open With with every app you have until you found one
that could open it properly.