scope guards

[Manu via Digitalmars-d]

On 4 August 2014 13:44, Dicebot via Digitalmars-d <
digitalmars-d at puremagic.com> wrote:

> On Monday, 4 August 2014 at 03:15:32 UTC, Manu via Digitalmars-d wrote:
>
>> Well, then they're not particularly useful in practise. I'm finding that I
>> can rarely blanket an operation across all exceptions.
>> The nature of exceptions is that they are of a particular type, so why
>> have
>> no access to that concept when trying to respond to them...
>>
>
> You may have coding style particularly alien to scope guards :) Those are
> very convenient to use as a simple an generic alternative to RAII,
> especially when interfacing with C libraries.


Sure, scope() may be useful for this, but it seems in my experience that
destructors almost always perform this without any additional code at the
callsite. C libraries are exactly the only case where I've managed to use
scope() successfully.
This seems like a waste. A key talking point of the language finds use
almost exclusively when used in conjunction with another language... :/

I find that most often one wants to catch majority of exceptions only in
> somewhat high level parts of code (i.e. main loop) and rest is just cleanup
> code - perfect fit for scope guards.
>

I can't think of many instances where I would want to catch an exception at
the main loop unless it was completely unexpected, like out of memory or
something.

Almost all exceptions I throw are in relation to bad input data, and they
are to be caught at a slightly higher level of input processing. My code
has become try/catch-tastic, and I really don't like looking at it. It
rather sickens me and reminds me of Java, and I'm strongly tempted to just
abandon my experiment and return to C-style error handling with sentinel
values.

So... why not make scope guards more useful? It wouldn't be hard.
scope(failure, MyException e) is completely non-destructive, and adds
significant power to the concept.

scope(success) is probably one I don't see use case case for though
>

Yeah, I can't imagine a use for it either.
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