digitalmars.D.learn - Strange casting error when using lamdas
- =?iso-8859-1?Q?Robert_M._M=FCnch?= (24/26) Dec 03 2019 I have very strange casting error I don't understand:
- =?iso-8859-1?Q?Robert_M._M=FCnch?= (13/44) Dec 03 2019 The first three lines are on module level, the second two lines are
- Steven Schveighoffer (4/21) Dec 04 2019 Is one a delegate and one a function pointer? This can easily happen for...
- =?iso-8859-1?Q?Robert_M._M=FCnch?= (11/13) Dec 05 2019 That's a very good point and hint. A function pointer will be 8LU and a
- Steven Schveighoffer (5/19) Dec 05 2019 Use std.functional.toDelegate. If it's already a delegate, it just
- =?iso-8859-1?Q?Robert_M._M=FCnch?= (32/34) Dec 05 2019 Not sure if the code-snippets already give an explanation but the
- =?iso-8859-1?Q?Robert_M._M=FCnch?= (7/36) Dec 04 2019 So, it all boils down to a breaking change in the RX framework... which
I have very strange casting error I don't understand: alias typeof(windows_message_streams[WM_MOUSEMOVE].filter!(win => (win.wParam & MK_LBUTTON))) WM_MOUSEMOVE_LBUTTON_TYPE; WM_MOUSEMOVE_LBUTTON_TYPE WM_MOUSEMOVE_LBUTTON_STREAM; pragma(msg,typeof(WM_MOUSEMOVE_LBUTTON_STREAM));WM_MOUSEMOVE_LBUTTON_STREAM = cast(WM_MOUSEMOVE_LBUTTON_TYPE)(windows_message_streams[WM_MO SEMOVE].filter!(win => (win.wParam & MK_LBUTTON))); pragma(msg,typeof(wstreams[WM_MOUSEMOVE].filter!(win => (win.wParam & MK_LBUTTON))));FilterObservable!(__lambda39, SubjectObject!(OS_State))..\..\gui.d(317,104): Error: cannot cast expression filter(windows_message_streams[512u]) of type FilterObservable!(__lambda6, SubjectObject!(OS_State)) to FilterObservable!(__lambda39, SubjectObject!(OS_State)) because of different sizes FilterObservable!(__lambda7, SubjectObject!(OS_State)) My code worked in the past but now it doesn't and I don't know why. I don't understand the "because of different sizes" message. It looks like I have to explicitly create a lambda and re-use it. But how to do that? -- Robert M. Münch http://www.saphirion.com smarter | better | fasterFilterObservable!(__lambda7, SubjectObject!(OS_State))
Dec 03 2019
On 2019-12-03 16:34:43 +0000, Robert M. Münch said:I have very strange casting error I don't understand: alias typeof(windows_message_streams[WM_MOUSEMOVE].filter!(win => (win.wParam & MK_LBUTTON))) WM_MOUSEMOVE_LBUTTON_TYPE; WM_MOUSEMOVE_LBUTTON_TYPE WM_MOUSEMOVE_LBUTTON_STREAM; pragma(msg,typeof(WM_MOUSEMOVE_LBUTTON_STREAM));The first three lines are on module level, the second two lines are inside a class member function. pragma(msg,WM_MOUSEMOVE_LBUTTON_STREAM.sizeof);WM_MOUSEMOVE_LBUTTON_STREAM = cast(WM_MOUSEMOVE_LBUTTON_TYPE)(windows_message_streams[WM_MO SEMOVE].filter!(win => (win.wParam & MK_LBUTTON))); pragma(msg,typeof(wstreams[WM_MOUSEMOVE].filter!(win => (win.wParam & MK_LBUTTON))));FilterObservable!(__lambda39, SubjectObject!(OS_State))..\..\gui.d(317,104): Error: cannot cast expression filter(windows_message_streams[512u]) of type FilterObservable!(__lambda6, SubjectObject!(OS_State)) to FilterObservable!(__lambda39, SubjectObject!(OS_State)) because of different sizes FilterObservable!(__lambda7, SubjectObject!(OS_State)) My code worked in the past but now it doesn't and I don't know why. I don't understand the "because of different sizes" message. It looks like I have to explicitly create a lambda and re-use it. But how to do that?FilterObservable!(__lambda7, SubjectObject!(OS_State))but pragma(msg,windows_message_streams[WM_MOUSEMOVE].filter!(win => (win.wParam & MK_LBUTTON)).sizeof);8LUWhy do these two things have different sizes even the declaration is exactly the same? -- Robert M. Münch http://www.saphirion.com smarter | better | faster16LU
Dec 03 2019
On 12/3/19 12:35 PM, Robert M. Münch wrote:The first three lines are on module level, the second two lines are inside a class member function. pragma(msg,WM_MOUSEMOVE_LBUTTON_STREAM.sizeof);Is one a delegate and one a function pointer? This can easily happen for untyped lambdas. -Stevebut pragma(msg,windows_message_streams[WM_MOUSEMOVE].filter!(win => (win.wParam & MK_LBUTTON)).sizeof);8LUWhy do these two things have different sizes even the declaration is exactly the same?16LU
Dec 04 2019
On 2019-12-04 19:23:07 +0000, Steven Schveighoffer said:Is one a delegate and one a function pointer? This can easily happen for untyped lambdas.That's a very good point and hint. A function pointer will be 8LU and a delegate 16LU, right? This is a strong argument that this is really the problem. How can I find out? That's why I used a pragma to get the type of the alias. So, the alias needs to become a delegate. No clue how to write this down. -- Robert M. Münch http://www.saphirion.com smarter | better | faster
Dec 05 2019
Steven Schveighoffer <schveiguy gmail.com> On 12/5/19 3:57 AM, Robert M. Münch wrote:On 2019-12-04 19:23:07 +0000, Steven Schveighoffer said:Use std.functional.toDelegate. If it's already a delegate, it just returns the delegate, otherwise it makes a delegate out of a function pointer. -SteveIs one a delegate and one a function pointer? This can easily happen for untyped lambdas.That's a very good point and hint. A function pointer will be 8LU and a delegate 16LU, right? This is a strong argument that this is really the problem. How can I find out? That's why I used a pragma to get the type of the alias. So, the alias needs to become a delegate. No clue how to write this down.
Dec 05 2019
On 2019-12-04 19:23:07 +0000, Steven Schveighoffer said:Is one a delegate and one a function pointer? This can easily happen for untyped lambdas.Not sure if the code-snippets already give an explanation but the differences I have are: 1. Working case template filter(alias pred) { auto filter(TObservable)(auto ref TObservable observable) { static struct FilterObservable { ... } return FilterObservable(observable); } } 2. Non-Working case template filter(alias pred) { auto filter(TObservable)(auto ref TObservable observable) { return FilterObservable!(pred, TObservable)(observable); } } struct FilterObservable(alias pred, TObservable) { ... } The constructor has the same implementaion in both cases. -- Robert M. Münch http://www.saphirion.com smarter | better | faster
Dec 05 2019
On 2019-12-03 16:34:43 +0000, Robert M. Münch said:I have very strange casting error I don't understand: alias typeof(windows_message_streams[WM_MOUSEMOVE].filter!(win => (win.wParam & MK_LBUTTON))) WM_MOUSEMOVE_LBUTTON_TYPE; WM_MOUSEMOVE_LBUTTON_TYPE WM_MOUSEMOVE_LBUTTON_STREAM; pragma(msg,typeof(WM_MOUSEMOVE_LBUTTON_STREAM));So, it all boils down to a breaking change in the RX framework... which I still don't understand... -- Robert M. Münch http://www.saphirion.com smarter | better | fasterWM_MOUSEMOVE_LBUTTON_STREAM = cast(WM_MOUSEMOVE_LBUTTON_TYPE)(windows_message_streams[WM_MO SEMOVE].filter!(win => (win.wParam & MK_LBUTTON))); pragma(msg,typeof(wstreams[WM_MOUSEMOVE].filter!(win => (win.wParam & MK_LBUTTON))));FilterObservable!(__lambda39, SubjectObject!(OS_State))..\..\gui.d(317,104): Error: cannot cast expression filter(windows_message_streams[512u]) of type FilterObservable!(__lambda6, SubjectObject!(OS_State)) to FilterObservable!(__lambda39, SubjectObject!(OS_State)) because of different sizes FilterObservable!(__lambda7, SubjectObject!(OS_State)) My code worked in the past but now it doesn't and I don't know why. I don't understand the "because of different sizes" message. It looks like I have to explicitly create a lambda and re-use it. But how to do that?FilterObservable!(__lambda7, SubjectObject!(OS_State))
Dec 04 2019