• Venkat (19/19) Jul 28 2018 struct SomeStruct {
• Venkat (13/31) Jul 28 2018 Session session = req.session;
• Steven Schveighoffer (13/40) Aug 02 2018 What is happening is the session storage is complaining it can't store
• Venkat (1/1) Aug 05 2018 Thankyou.

Venkat <venkatram.akkineni gmail.com> writes:

struct SomeStruct {
	string p;
	string q;
	string[] pq;
}

ErrorMessage[] pq;
session.set("registerBody", pq);

/home/venkat/.dub/packages/vibe-d-0.8.4/vibe-d/http/vibe/http/session.d(83,3):
Error: static assert:  "Type SomeStruct contains references, which is not
supported for session storage."


vibe.d session won't let me put in a simple struct with an array 
or an associative array. session.put calls std.traits.hasAliasing 
which is returning true when I have either an array or an 
associative array. I looked through the std.traits.hasAliasing 
code. I can't make a whole lot of sense there.

The hasAliasing function documentation says as long as the array 
or associative array are not immutable it should return true. 
Since session.put does !hasAliasing I changed string[] to 
immutable, that throws a whole lot of other compilation error 
messages.

What is hasAliasing doing ?

Venkat <venkatram.akkineni gmail.com> writes:

On Sunday, 29 July 2018 at 01:05:19 UTC, Venkat wrote:
 struct SomeStruct {
 	string p;
 	string q;
 	string[] pq;
 }

Session session = req.session;
session.get!SomeStruct("registerBody");
 /home/venkat/.dub/packages/vibe-d-0.8.4/vibe-d/http/vibe/http/session.d(83,3):
Error: static assert:  "Type SomeStruct contains references, which is not
supported for session storage."


 vibe.d session won't let me put in a simple struct with an 
 array or an associative array. session.put calls 
 std.traits.hasAliasing which is returning true when I have 
 either an array or an associative array. I looked through the 
 std.traits.hasAliasing code. I can't make a whole lot of sense 
 there.

 The hasAliasing function documentation says as long as the 
 array or associative array are not immutable it should return 
 true. Since session.put does !hasAliasing I changed string[] to 
 immutable, that throws a whole lot of other compilation error 
 messages.

 What is hasAliasing doing ?

Posted the wrong code. Fixed it above. Reposting below for 
clarity. For the record both session.get and session.put call 
hasAliasing.

struct SomeStruct {
	string p;
	string q;
	string[] pq;
}

Session session = req.session;
session.get!SomeStruct("registerBody");

Steven Schveighoffer <schveiguy gmail.com> writes:

On 7/28/18 9:21 PM, Venkat wrote:
 On Sunday, 29 July 2018 at 01:05:19 UTC, Venkat wrote:
 struct SomeStruct {
     string p;
     string q;
     string[] pq;
 }

 Session session = req.session;
 session.get!SomeStruct("registerBody");
 /home/venkat/.dub/packages/vibe-d-0.8.4/vibe-d/http/vibe/http/session.d(83,3): 
 Error: static assert:  "Type SomeStruct contains references, which is 
 not supported for session storage."


What is happening is the session storage is complaining it can't store 
the array. I think because the array data could change without the 
struct itself changing.

Even though string has a pointer, the data is immutable, so it is allowed.

 vibe.d session won't let me put in a simple struct with an array or an 
 associative array. session.put calls std.traits.hasAliasing which is 
 returning true when I have either an array or an associative array. I 
 looked through the std.traits.hasAliasing code. I can't make a whole 
 lot of sense there.

 The hasAliasing function documentation says as long as the array or 
 associative array are not immutable it should return true. Since 
 session.put does !hasAliasing I changed string[] to immutable, that 
 throws a whole lot of other compilation error messages.

 What is hasAliasing doing ?


hasAliasing means there are references to mutable data somewhere in your 
struct. In this case, the array pq is a reference to mutable data (yes, 
the strings inside are immutable, but they can be changed).

The qualifications are listed here:
https://dlang.org/library/std/traits/has_aliasing.html

"an array U[] and U is not immutable"

Try immutable(string)[] pq.

-Steve

Venkat <venkatram.akkineni gmail.com> writes:

Thankyou.