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digitalmars.D.announce - concepts v0.0.1

reply Atila Neves <atila.neves gmail.com> writes:
Since my phobos PR for better static assertions was clearly never 
getting merged (https://github.com/dlang/phobos/pull/3677), I 
moved the code to dub instead:

http://code.dlang.org/packages/concepts

Basically, as long as you pair up your template constraints (e.g. 
isFoo) with a suitably named function that should compile (e.g. 
checkFoo, not a lambda), then you can write this:

 models!(Foo, isFoo)
struct Foo {
     //...
}

And in the case that isFoo is false, you'll get to know _why_ it 
didn't compile instead of an AssertError that leaves you confused.

At least it used to and the unit tests pass so I'm assuming it 
still does :P

Atila
Dec 16 2016
next sibling parent =?UTF-8?B?Tm9yZGzDtnc=?= <per.nordlow gmail.com> writes:
On Friday, 16 December 2016 at 20:51:19 UTC, Atila Neves wrote:

 Atila


Surprisingly little code. Thx.
Dec 16 2016
prev sibling next sibling parent reply Nicholas Wilson <iamthewilsonator hotmail.com> writes:
On Friday, 16 December 2016 at 20:51:19 UTC, Atila Neves wrote:

  models!(Foo, isFoo)



What happened to the __UDA_ATTACHMENT__ proposal?
Dec 16 2016
parent reply Nicholas Wilson <iamthewilsonator hotmail.com> writes:
On Friday, 16 December 2016 at 23:49:18 UTC, Nicholas Wilson 
wrote:

 On Friday, 16 December 2016 at 20:51:19 UTC, Atila Neves wrote:

  models!(Foo, isFoo)



 What happened to the __UDA_ATTACHMENT__ proposal?


Also are UDAs legal after the symbol? i.e. with 
__UDA_ATTACHMENT__ could you do struct Foo  models!isFoo
{
     void foo();
}

  ?
Dec 16 2016
parent Atila Neves <atila.neves gmail.com> writes:
On Saturday, 17 December 2016 at 04:00:32 UTC, Nicholas Wilson 
wrote:

 On Friday, 16 December 2016 at 23:49:18 UTC, Nicholas Wilson 
 wrote:

 On Friday, 16 December 2016 at 20:51:19 UTC, Atila Neves wrote:

  models!(Foo, isFoo)



 What happened to the __UDA_ATTACHMENT__ proposal?




Nothing AFAIK.


 Also are UDAs legal after the symbol? i.e. with 
 __UDA_ATTACHMENT__ could you do struct Foo  models!isFoo
 {
     void foo();
 }

  ?


Nope.
Dec 19 2016
prev sibling parent reply Jacob Carlborg <doob me.com> writes:
On 2016-12-16 21:51, Atila Neves wrote:

 Since my phobos PR for better static assertions was clearly never
 getting merged (https://github.com/dlang/phobos/pull/3677), I moved the
 code to dub instead:

 http://code.dlang.org/packages/concepts

 Basically, as long as you pair up your template constraints (e.g. isFoo)
 with a suitably named function that should compile (e.g. checkFoo, not a
 lambda), then you can write this:

  models!(Foo, isFoo)
 struct Foo {
     //...
 }

 And in the case that isFoo is false, you'll get to know _why_ it didn't
 compile instead of an AssertError that leaves you confused.

 At least it used to and the unit tests pass so I'm assuming it still
 does :P


It's not very well tested ;). When a check fails I get this error:

Error: can only import from a module, not from package 
std.algorithm.searching.countUntil

After fixing that to a proper selective import I get:

Error: template instance moduleName!P template 'moduleName' is not defined

Adding an import for std.traits will fix that. Then after fixing all 
that it seems to work properly :)

Asserting that something does not compile is very risky because it does 
not tell you why it didn't compile. One should always first compile 
without __traits(compiles) to verify that the correct error is reported.

-- 
/Jacob Carlborg
Dec 17 2016
parent Atila Neves <atila.neves gmail.com> writes:
On Saturday, 17 December 2016 at 14:58:24 UTC, Jacob Carlborg 
wrote:

 On 2016-12-16 21:51, Atila Neves wrote:

 [...]


 It's not very well tested ;). When a check fails I get this 
 error:


Oops!

Fixed it now. Look, now it's version 0.0.2! :P

Atila
Dec 19 2016