win32utils devel - Oct 2007 - Getting an actual system error

Heya all,

I don''t think I''ve been paying attention. When a Windows API
function
fails, I could have been doing this:

raise SystemCallError(GetLastError())

Instead of this:

# Where ''Error'' is nested under the current class.
raise Error, get_last_error

I''m not sure how big of a deal this is in practice, however, or if
it''s
even preferred for our purposes.

Regards,

Dan


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Berger, Daniel wrote:
> Heya all,
> 
> I don''t think I''ve been paying attention. When a Windows
API function
> fails, I could have been doing this:
> 
> raise SystemCallError(GetLastError())
Whoops, that should have been SystemCallError.new(GetLastError())
> Instead of this:
> 
> # Where ''Error'' is nested under the current class.
> raise Error, get_last_error
> 
> I''m not sure how big of a deal this is in practice, however, or if
it''s
> even preferred for our purposes.
A bit more research indicates that the error messages don''t always
match
up if you do this. For example, if you do:

unless RemoveDirectory(bogus)
    raise SystemCallError.new(GetLastError()) # GetLastError returns 3
end

The result is Errno::ESRCH (errno 3), whereas Ruby would raise 
Errno::ENOENT, which is errno 2. Looking at win32.c I now see why - 
they''ve got certain errors specifically mapped to certain codes. Take a
look at the errmap struct.

Regards,

Dan