• Nick Sabalausky (3/3) May 22 2014 I know there's been a lot of chatter about scope vars needing work, what...
• Andrej Mitrovic (3/6) May 22 2014 Example nastiness of scoped!():
• Dicebot (10/13) May 22 2014 You speak about scope storage class (aka scope classes as in D1).
• Nick Sabalausky (4/16) May 22 2014 Is phobos scoped at least good enough for real-world use in the meantime...
• Dicebot (10/38) May 22 2014 First question - don't now for sure. It worked for me few times I
• Nick Sabalausky (9/14) May 22 2014 Ooh, looking at the docs for phobos scoped now, I see it's mainly just
• Jonathan M Davis via Digitalmars-d (8/50) May 22 2014 AFAIK, scope is only implemented for delegates (and I'm not even sure

Nick Sabalausky <SeeWebsiteToContactMe semitwist.com> writes:

I know there's been a lot of chatter about scope vars needing work, what 
exactly is the deal with that? Isn't there a lib version of scoped? Are 
there current problems with that?

"Andrej Mitrovic" <andrej.mitrovich gmail.com> writes:

On Thursday, 22 May 2014 at 19:08:53 UTC, Nick Sabalausky wrote:
 I know there's been a lot of chatter about scope vars needing 
 work, what exactly is the deal with that? Isn't there a lib 
 version of scoped? Are there current problems with that?

Example nastiness of scoped!():
https://issues.dlang.org/show_bug.cgi?id=10921

"Dicebot" <public dicebot.lv> writes:

On Thursday, 22 May 2014 at 19:08:53 UTC, Nick Sabalausky wrote:
 I know there's been a lot of chatter about scope vars needing 
 work, what exactly is the deal with that? Isn't there a lib 
 version of scoped? Are there current problems with that?

You speak about scope storage class (aka scope classes as in D1). 
It has been deprecated and replaced by Phobos scoped.

Recent chatter is about scope type qualifier which is supposed to 
prohibit escaping references to variable making it only available 
in current and nested scopes. There are many possible 
applications for that - safe casting away for shared, safe rvalue 
references, efficient reference counting and so on. It is 
currently present in the language but has no actual 
implementation, being effectively a NO-OP.

Nick Sabalausky <SeeWebsiteToContactMe semitwist.com> writes:

On 5/22/2014 3:31 PM, Dicebot wrote:
 On Thursday, 22 May 2014 at 19:08:53 UTC, Nick Sabalausky wrote:
 I know there's been a lot of chatter about scope vars needing work,
 what exactly is the deal with that? Isn't there a lib version of
 scoped? Are there current problems with that?

 You speak about scope storage class (aka scope classes as in D1). It has
 been deprecated and replaced by Phobos scoped.

 Recent chatter is about scope type qualifier which is supposed to
 prohibit escaping references to variable making it only available in
 current and nested scopes. There are many possible applications for that
 - safe casting away for shared, safe rvalue references, efficient
 reference counting and so on. It is currently present in the language
 but has no actual implementation, being effectively a NO-OP.

Is phobos scoped at least good enough for real-world use in the meantime?

Also, is this unimplemented scope type qualifier you speak of going to 
basically replace phobos scoped?

"Dicebot" <public dicebot.lv> writes:

On Thursday, 22 May 2014 at 19:36:06 UTC, Nick Sabalausky wrote:
 On 5/22/2014 3:31 PM, Dicebot wrote:
 On Thursday, 22 May 2014 at 19:08:53 UTC, Nick Sabalausky 
 wrote:
 I know there's been a lot of chatter about scope vars needing 
 work,
 what exactly is the deal with that? Isn't there a lib version 
 of
 scoped? Are there current problems with that?

 You speak about scope storage class (aka scope classes as in 
 D1). It has
 been deprecated and replaced by Phobos scoped.

 Recent chatter is about scope type qualifier which is supposed 
 to
 prohibit escaping references to variable making it only 
 available in
 current and nested scopes. There are many possible 
 applications for that
 - safe casting away for shared, safe rvalue references, 
 efficient
 reference counting and so on. It is currently present in the 
 language
 but has no actual implementation, being effectively a NO-OP.

 Is phobos scoped at least good enough for real-world use in the 
 meantime?

 Also, is this unimplemented scope type qualifier you speak of 
 going to basically replace phobos scoped?

First question - don't now for sure. It worked for me few times I 
have used it but there several bug reports in bugzilla with some 
nastiness.

Second question - that is something yet to investigate. Natural 
relation between those is that value captured by `scoped` should 
be qualified as `scope` to be reliably memory safe. Does that 
also mean that you can skip `scoped` altogether and release all 
scope variables at the end of scope automatically? Something yet 
to investigate.

Nick Sabalausky <SeeWebsiteToContactMe semitwist.com> writes:

On 5/22/2014 3:39 PM, Dicebot wrote:
 Second question - that is something yet to investigate. Natural relation
 between those is that value captured by `scoped` should be qualified as
 `scope` to be reliably memory safe. Does that also mean that you can
 skip `scoped` altogether and release all scope variables at the end of
 scope automatically? Something yet to investigate.

Ooh, looking at the docs for phobos scoped now, I see it's mainly just 
for emplacing a class on the stack, and doesn't prevent escaping at all. 
I'm understanding it better now.

I had thought there was something in phobos that worked for structs, 
preventing escaping by disabling postblit and then guaranteeing 
destruction at the end of the defining scope - or something vaguely like 
that anyway. But I think I was confusing several different things such 
as scoped, emplace and RefCOunted.

Jonathan M Davis via Digitalmars-d <digitalmars-d puremagic.com> writes:

On Thu, 22 May 2014 19:39:58 +0000
Dicebot via Digitalmars-d <digitalmars-d puremagic.com> wrote:

 On Thursday, 22 May 2014 at 19:36:06 UTC, Nick Sabalausky wrote:
 On 5/22/2014 3:31 PM, Dicebot wrote:
 On Thursday, 22 May 2014 at 19:08:53 UTC, Nick Sabalausky 
 wrote:
 I know there's been a lot of chatter about scope vars needing 
 work,
 what exactly is the deal with that? Isn't there a lib version 
 of
 scoped? Are there current problems with that?

 You speak about scope storage class (aka scope classes as in 
 D1). It has
 been deprecated and replaced by Phobos scoped.

 Recent chatter is about scope type qualifier which is supposed 
 to
 prohibit escaping references to variable making it only 
 available in
 current and nested scopes. There are many possible 
 applications for that
 - safe casting away for shared, safe rvalue references, 
 efficient
 reference counting and so on. It is currently present in the 
 language
 but has no actual implementation, being effectively a NO-OP.

 Is phobos scoped at least good enough for real-world use in the 
 meantime?

 Also, is this unimplemented scope type qualifier you speak of 
 going to basically replace phobos scoped?

 
 First question - don't now for sure. It worked for me few times I 
 have used it but there several bug reports in bugzilla with some 
 nastiness.
 
 Second question - that is something yet to investigate. Natural 
 relation between those is that value captured by `scoped` should 
 be qualified as `scope` to be reliably memory safe. Does that 
 also mean that you can skip `scoped` altogether and release all 
 scope variables at the end of scope automatically? Something yet 
 to investigate.

AFAIK, scope is only implemented for delegates (and I'm not even sure
that that fully works). For all other types, it does nothing (which is
part of why using in makes no sense). So, on the whole, scope is
currently ill-defined and mostly unimplemented.

- Jonathan M Davis

- Jonathan M Davis