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digitalmars.D - Enum AA with classes not allowed anymore?

reply bauss <jj_1337 live.dk> writes:
I'm aware that the following has always been illegal:

enum a = new Foo();

However the following were used to work in older versions of DMD:

enum aa = [0 : new Foo("0"), 1 : new Foo("1")];

When did that change happen and what was the reason for the 
change? I were depending on AA's created like that to use them at 
compile-time.

It happens to break my following project:
https://github.com/bausshf/Diamond

More specifically:
https://github.com/bausshf/Diamond/blob/master/src/templates/parser.d#L13

The change has happened somewhere between 2.072.2 and the current 
version.
Oct 07 2017
next sibling parent reply Daniel Kozak <kozzi11 gmail.com> writes:
Up to      2.062  : Failure with output:
-----
onlineapp.d(10): Error: cannot evaluate new Foo("0") at compile time
onlineapp.d(10): Error: cannot evaluate new Foo("1") at compile time
-----

2.063   to 2.072.2: Success with output: Hello D
Since      2.073.2: Failure with output: onlineapp.d(10): Error: variable
onlineapp.aa : Unable to initialize enum with class or pointer to struct.
Use static const variable instead.

https://run.dlang.io/is/mJqayC

On Sun, Oct 8, 2017 at 4:29 AM, bauss via Digitalmars-d <
digitalmars-d puremagic.com> wrote:


 I'm aware that the following has always been illegal:

 enum a = new Foo();

 However the following were used to work in older versions of DMD:

 enum aa = [0 : new Foo("0"), 1 : new Foo("1")];

 When did that change happen and what was the reason for the change? I were
 depending on AA's created like that to use them at compile-time.

 It happens to break my following project:
 https://github.com/bausshf/Diamond

 More specifically:
 https://github.com/bausshf/Diamond/blob/master/src/templates/parser.d#L13

 The change has happened somewhere between 2.072.2 and the current version.
Oct 07 2017
parent reply bauss <jj_1337 live.dk> writes:
On Sunday, 8 October 2017 at 04:40:59 UTC, Daniel Kozak wrote:

 Up to      2.062  : Failure with output:
 -----
 onlineapp.d(10): Error: cannot evaluate new Foo("0") at compile 
 time
 onlineapp.d(10): Error: cannot evaluate new Foo("1") at compile 
 time
 -----

 2.063   to 2.072.2: Success with output: Hello D
 Since      2.073.2: Failure with output: onlineapp.d(10): 
 Error: variable
 onlineapp.aa : Unable to initialize enum with class or pointer 
 to struct.
 Use static const variable instead.

 https://run.dlang.io/is/mJqayC

 On Sun, Oct 8, 2017 at 4:29 AM, bauss via Digitalmars-d < 
 digitalmars-d puremagic.com> wrote:


 [...]




Do you know what the reason for the change is and are there any 
workarounds to actually declare AA's with classes that can be 
used at compile-time then?
Oct 11 2017
next sibling parent Daniel Kozak <kozzi11 gmail.com> writes:
Not sure, but I belive this could be one of reasons:
https://issues.dlang.org/show_bug.cgi?id=15989

On Wed, Oct 11, 2017 at 4:54 PM, bauss via Digitalmars-d <
digitalmars-d puremagic.com> wrote:


 On Sunday, 8 October 2017 at 04:40:59 UTC, Daniel Kozak wrote:


 Up to      2.062  : Failure with output:
 -----
 onlineapp.d(10): Error: cannot evaluate new Foo("0") at compile time
 onlineapp.d(10): Error: cannot evaluate new Foo("1") at compile time
 -----

 2.063   to 2.072.2: Success with output: Hello D
 Since      2.073.2: Failure with output: onlineapp.d(10): Error: variable
 onlineapp.aa : Unable to initialize enum with class or pointer to struct.
 Use static const variable instead.

 https://run.dlang.io/is/mJqayC

 On Sun, Oct 8, 2017 at 4:29 AM, bauss via Digitalmars-d <
 digitalmars-d puremagic.com> wrote:

 [...]




 Do you know what the reason for the change is and are there any
 workarounds to actually declare AA's with classes that can be used at
 compile-time then?





 Oct 11 2017



prev sibling  parent  Daniel Kozak <kozzi11 gmail.com>  writes:


so you can try to use static immutable insted of enum

On Wed, Oct 11, 2017 at 5:04 PM, Daniel Kozak <kozzi11 gmail.com> wrote:


 Not sure, but I belive this could be one of reasons:
 https://issues.dlang.org/show_bug.cgi?id=15989

 On Wed, Oct 11, 2017 at 4:54 PM, bauss via Digitalmars-d <
 digitalmars-d puremagic.com> wrote:


 On Sunday, 8 October 2017 at 04:40:59 UTC, Daniel Kozak wrote:


 Up to      2.062  : Failure with output:
 -----
 onlineapp.d(10): Error: cannot evaluate new Foo("0") at compile time
 onlineapp.d(10): Error: cannot evaluate new Foo("1") at compile time
 -----

 2.063   to 2.072.2: Success with output: Hello D
 Since      2.073.2: Failure with output: onlineapp.d(10): Error: variable
 onlineapp.aa : Unable to initialize enum with class or pointer to struct.
 Use static const variable instead.

 https://run.dlang.io/is/mJqayC

 On Sun, Oct 8, 2017 at 4:29 AM, bauss via Digitalmars-d <
 digitalmars-d puremagic.com> wrote:

 [...]




 Do you know what the reason for the change is and are there any
 workarounds to actually declare AA's with classes that can be used at
 compile-time then?







 Oct 11 2017



prev sibling  parent reply Jonathan M Davis <newsgroup.d jmdavisprog.com>  writes:


On Wednesday, October 11, 2017 17:05:19 Daniel Kozak via Digitalmars-d 
wrote:

 so you can try to use static immutable insted of enum


Yeah. Similarly, you could just have a regular function that you call at
compile time that returns what you want (assuming that it's not being
assigned to an enum) - then if it's just being used to generate something
that you actually want to keep around after compiling, you're not stuck with
the AA continuing to exist past compile time.

I don't know that it will ever happen, but there has been talk of
disallowing enums of anything that will allocate, because you pretty much
never want that (since it will allocate every time it's used), and it's easy
to do accidentally.

- Jonathan M Davis



 Oct 11 2017



  parent  bauss <jj_1337 live.dk>  writes:


On Wednesday, 11 October 2017 at 17:40:15 UTC, Jonathan M Davis 
wrote:

 On Wednesday, October 11, 2017 17:05:19 Daniel Kozak via 
 Digitalmars-d wrote:

 so you can try to use static immutable insted of enum


 Yeah. Similarly, you could just have a regular function that 
 you call at compile time that returns what you want (assuming 
 that it's not being assigned to an enum) - then if it's just 
 being used to generate something that you actually want to keep 
 around after compiling, you're not stuck with the AA continuing 
 to exist past compile time.

 I don't know that it will ever happen, but there has been talk 
 of disallowing enums of anything that will allocate, because 
 you pretty much never want that (since it will allocate every 
 time it's used), and it's easy to do accidentally.

 - Jonathan M Davis


Yeah I ended up making property functions that returns the AA's 
with what I want.

Ex.

 property string[string] myAA() {
     string[string] aa;

     // ... populate aa

     return aa;
}

Because then I didn't have to change any places it was used. 
Since it's compile-time it shouldn't matter too much that it 
might be called multiple times and generate a new AA. There seem 
to be no better way to cache it other than local variables where 
it's used.

I did have one enum AA I could change to a static AA since it 
wasn't called during compile-time, so I guess there were some 
advantages by not being able to compile with latest version; like 
I wouldn't have caught that mistake if I didn't come by this.



 Oct 12 2017