Formal Review of std.process

[Lars T. Kyllingstad]

On Thursday, 11 April 2013 at 15:43:18 UTC, Steven Schveighoffer 
wrote:
> A couple minor comments:
>
> 1. I have two issues with Error being used.  One is that we 
> should have a specific type that is thrown, not raw Error type.
>  Second is that I think in situations where the error is due to 
> an incorrect parameter, it should be an exception not an error 
> (and not a straight Exception either!).

Let's go through the places where an Error or Exception is thrown:

spawnProcess() throws RangeError when args[] is empty, but this 
is just the normal behaviour of arrays, and with 
-release/-noboundscheck it just segfaults.  As such, there is 
little point in specifying this in the documentation.  I'll 
remove it.  (Honestly, I don't know why I put it in there in the 
first place.  It may have had something to do with me being 
thoroughly annoyed over other the lack of exception 
specifications in Phobos documentation at large.  I used to like 
enforce(), but now I think it has given D programmers a way too 
lax attitude towards error handling.)

kill() throws Error if the code/signal is negative.  I suspect 
the cases where this number comes directly from user input are so 
few and far between that it is reasonable to expect the 
programmer to ensure that it is nonnegative.  In principle, on 
POSIX we don't need the check, because POSIX kill() will return 
an "invalid signal" error if you try to give it a negative 
number.  On Windows, however, TerminateProcess() takes an 
unsigned integer (which is why I added the check in the first 
place), and I think we should strive to have the same behaviour 
on all platforms to the extent possible.  I would not be strongly 
opposed to making this an Exception of some kind, though, if you 
think there is a good reason to do so.

pipeProcess throws Error on an invalid combination of Redirect 
flags, and ProcessPipes does the same on an attempt to access a 
non-redirected stream.  Are we in agreement that these two are 
always programming errors?

escapeShellCommand() throws Error if the input contains \0, \r or 
\n.  Here, it is very likely that the arguments are user input, 
but it would be very strange application code that somehow 
allowed those three characters to enter the input.  Even so, it 
may be better to make it an Exception, just to be safe.

Lars