• Amex (5/5) Jun 02 2019 A.B
• Paul Backus (15/20) Jun 02 2019 The "optional" package on dub [1] has a .dispatch method that
• Amex (2/26) Jun 02 2019 thanks.
• Basile B. (3/8) Jun 02 2019 safeAccess from iz does this :

Amex <Amex gmail.com> writes:

A.B

If A is null, crash.

A?.B : writeln("HAHA");

No crash, ignored, equivalent to

if (A is null) writeln("HAHA"); else A.B;

Paul Backus <snarwin gmail.com> writes:

On Sunday, 2 June 2019 at 07:55:27 UTC, Amex wrote:
 A.B

 If A is null, crash.

 A?.B : writeln("HAHA");

 No crash, ignored, equivalent to

 if (A is null) writeln("HAHA"); else A.B;

The "optional" package on dub [1] has a .dispatch method that 
does this:

     auto d = some(A());

     // Dispatch to one of its methods

     d.dispatch.f(); // calls a.f, returns some(4)
     d.dispatch.inner.g(); // calls a.inner.g, returns some(7)

     // Use on a pointer or reference type as well
     A* e = null;

     // If there's no value in the reference type, dispatching
     // works, and produces an optional
     assert(e.dispatch.f() == none);
     assert(e.dispatch.inner.g() == none);


Full example: https://run.dlang.io/is/SmsGQu

[1] https://code.dlang.org/packages/optional

Amex <Amex gmail.com> writes:

On Sunday, 2 June 2019 at 14:37:48 UTC, Paul Backus wrote:
 On Sunday, 2 June 2019 at 07:55:27 UTC, Amex wrote:
 A.B

 If A is null, crash.

 A?.B : writeln("HAHA");

 No crash, ignored, equivalent to

 if (A is null) writeln("HAHA"); else A.B;

 The "optional" package on dub [1] has a .dispatch method that 
 does this:

     auto d = some(A());

     // Dispatch to one of its methods

     d.dispatch.f(); // calls a.f, returns some(4)
     d.dispatch.inner.g(); // calls a.inner.g, returns some(7)

     // Use on a pointer or reference type as well
     A* e = null;

     // If there's no value in the reference type, dispatching
     // works, and produces an optional
     assert(e.dispatch.f() == none);
     assert(e.dispatch.inner.g() == none);


 Full example: https://run.dlang.io/is/SmsGQu

 [1] https://code.dlang.org/packages/optional

thanks.

Basile B. <b2.temp gmx.com> writes:

On Sunday, 2 June 2019 at 07:55:27 UTC, Amex wrote:
 A.B

 If A is null, crash.

 A?.B : writeln("HAHA");

 No crash, ignored, equivalent to

 if (A is null) writeln("HAHA"); else A.B;

safeAccess from iz does this : 
https://github.com/Basile-z/iz/blob/master/import/iz/sugar.d#L1666