Can the return type of the function be obtained from within the function?

Multi tool use
Multi tool use

The name of the pictureThe name of the pictureThe name of the pictureClash Royale CLAN TAG#URR8PPP











up vote
38
down vote

favorite
3












Can the return type of a function be obtained in a simple way within the function?



For example, given:



template <typename P>
static inline auto foo(P p) -> typename std::remove_reference<decltype(*p)>::type 
 typename std::remove_reference<decltype(*p)>::type f; // <-- here

 ...



In C++11 can I refer to the big nasty return type of foo, within foo itself, without repeating it, at the line marked // <-- here?






c++ c++11 trailing-return-type







share|improve this question



















  • 1




    In C++14, you can remove the trailing return type instead, and use return f; to deduce the return type.
    – jingyu9575
    Sep 6 at 4:42














up vote
38
down vote

favorite
3












Can the return type of a function be obtained in a simple way within the function?



For example, given:



template <typename P>
static inline auto foo(P p) -> typename std::remove_reference<decltype(*p)>::type 
 typename std::remove_reference<decltype(*p)>::type f; // <-- here

 ...



In C++11 can I refer to the big nasty return type of foo, within foo itself, without repeating it, at the line marked // <-- here?






c++ c++11 trailing-return-type







share|improve this question



















  • 1




    In C++14, you can remove the trailing return type instead, and use return f; to deduce the return type.
    – jingyu9575
    Sep 6 at 4:42












up vote
38
down vote

favorite
3









up vote
38
down vote

favorite
3






3





Can the return type of a function be obtained in a simple way within the function?



For example, given:



template <typename P>
static inline auto foo(P p) -> typename std::remove_reference<decltype(*p)>::type 
 typename std::remove_reference<decltype(*p)>::type f; // <-- here

 ...



In C++11 can I refer to the big nasty return type of foo, within foo itself, without repeating it, at the line marked // <-- here?






c++ c++11 trailing-return-type







share|improve this question















Can the return type of a function be obtained in a simple way within the function?



For example, given:



template <typename P>
static inline auto foo(P p) -> typename std::remove_reference<decltype(*p)>::type 
 typename std::remove_reference<decltype(*p)>::type f; // <-- here

 ...



In C++11 can I refer to the big nasty return type of foo, within foo itself, without repeating it, at the line marked // <-- here?






c++ c++11 trailing-return-type




c++ c++11 trailing-return-type






share|improve this question















share|improve this question













share|improve this question




share|improve this question








edited Sep 5 at 18:24

























asked Sep 5 at 17:33









BeeOnRope

24k873162




24k873162







  • 1




    In C++14, you can remove the trailing return type instead, and use return f; to deduce the return type.
    – jingyu9575
    Sep 6 at 4:42












  • 1




    In C++14, you can remove the trailing return type instead, and use return f; to deduce the return type.
    – jingyu9575
    Sep 6 at 4:42







1




1




In C++14, you can remove the trailing return type instead, and use return f; to deduce the return type.
– jingyu9575
Sep 6 at 4:42




In C++14, you can remove the trailing return type instead, and use return f; to deduce the return type.
– jingyu9575
Sep 6 at 4:42












1 Answer
1






active

oldest

votes

















up vote
50
down vote



accepted










Call the function with a decltype.



decltype(foo(p)) f;





share|improve this answer
















  • 6




    life made easy by decltype ;)
    – JeJo
    Sep 5 at 18:18










  • Works well in this case where there are few parameters...
    – Max Langhof
    Sep 6 at 8:01










  • @MaxLanghof Yes. The more general solution would be to define an alias and use that. :)
    – Rakete1111
    Sep 6 at 8:02










Your Answer





StackExchange.ifUsing("editor", function ()
StackExchange.using("externalEditor", function ()
StackExchange.using("snippets", function ()
StackExchange.snippets.init();
);
);
, "code-snippets");

StackExchange.ready(function()
var channelOptions =
tags: "".split(" "),
id: "1"
;
initTagRenderer("".split(" "), "".split(" "), channelOptions);

StackExchange.using("externalEditor", function()
// Have to fire editor after snippets, if snippets enabled
if (StackExchange.settings.snippets.snippetsEnabled)
StackExchange.using("snippets", function()
createEditor();
);

else
createEditor();

);

function createEditor()
StackExchange.prepareEditor(
heartbeatType: 'answer',
convertImagesToLinks: true,
noModals: false,
showLowRepImageUploadWarning: true,
reputationToPostImages: 10,
bindNavPrevention: true,
postfix: "",
onDemand: true,
discardSelector: ".discard-answer"
,immediatelyShowMarkdownHelp:true
);



);













 

draft saved


draft discarded


















StackExchange.ready(
function ()
StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2fstackoverflow.com%2fquestions%2f52190625%2fcan-the-return-type-of-the-function-be-obtained-from-within-the-function%23new-answer', 'question_page');

);

Post as a guest

















1 Answer
1






active

oldest

votes








1 Answer
1






active

oldest

votes









active

oldest

votes






active

oldest

votes








up vote
50
down vote



accepted










Call the function with a decltype.



decltype(foo(p)) f;





share|improve this answer
















  • 6




    life made easy by decltype ;)
    – JeJo
    Sep 5 at 18:18










  • Works well in this case where there are few parameters...
    – Max Langhof
    Sep 6 at 8:01










  • @MaxLanghof Yes. The more general solution would be to define an alias and use that. :)
    – Rakete1111
    Sep 6 at 8:02














up vote
50
down vote



accepted










Call the function with a decltype.



decltype(foo(p)) f;





share|improve this answer
















  • 6




    life made easy by decltype ;)
    – JeJo
    Sep 5 at 18:18










  • Works well in this case where there are few parameters...
    – Max Langhof
    Sep 6 at 8:01










  • @MaxLanghof Yes. The more general solution would be to define an alias and use that. :)
    – Rakete1111
    Sep 6 at 8:02












up vote
50
down vote



accepted







up vote
50
down vote



accepted






Call the function with a decltype.



decltype(foo(p)) f;





share|improve this answer












Call the function with a decltype.



decltype(foo(p)) f;






share|improve this answer












share|improve this answer



share|improve this answer










answered Sep 5 at 17:35









Rakete1111

32.7k975110




32.7k975110







  • 6




    life made easy by decltype ;)
    – JeJo
    Sep 5 at 18:18










  • Works well in this case where there are few parameters...
    – Max Langhof
    Sep 6 at 8:01










  • @MaxLanghof Yes. The more general solution would be to define an alias and use that. :)
    – Rakete1111
    Sep 6 at 8:02












  • 6




    life made easy by decltype ;)
    – JeJo
    Sep 5 at 18:18










  • Works well in this case where there are few parameters...
    – Max Langhof
    Sep 6 at 8:01










  • @MaxLanghof Yes. The more general solution would be to define an alias and use that. :)
    – Rakete1111
    Sep 6 at 8:02







6




6




life made easy by decltype ;)
– JeJo
Sep 5 at 18:18




life made easy by decltype ;)
– JeJo
Sep 5 at 18:18












Works well in this case where there are few parameters...
– Max Langhof
Sep 6 at 8:01




Works well in this case where there are few parameters...
– Max Langhof
Sep 6 at 8:01












@MaxLanghof Yes. The more general solution would be to define an alias and use that. :)
– Rakete1111
Sep 6 at 8:02




@MaxLanghof Yes. The more general solution would be to define an alias and use that. :)
– Rakete1111
Sep 6 at 8:02

















 

draft saved


draft discarded















































 


draft saved


draft discarded














StackExchange.ready(
function ()
StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2fstackoverflow.com%2fquestions%2f52190625%2fcan-the-return-type-of-the-function-be-obtained-from-within-the-function%23new-answer', 'question_page');

);

Post as a guest
































































jSxK8VTA64fllFH,H1B,REN,8zI,gV V4ld,J3Q6DdUWT1vGo8PBjZjUD
-
oNrKZuj7l,f00zbMyqjwNC,n 2oJJfO K5uF,s2T0DMWwjQRvR,M3 GVRypCM

Popular posts from this blog

How to check contact read email or not when send email to Individual?

Image
Clash Royale CLAN TAG #URR8PPP up vote 1 down vote favorite I'm using WordPress 4.9.8, CiviCRM to 5.5.1, I usually send email to contact by Search> Find contacts View contact details Action> Send email Send email ok, Contact received mail ok like picture But status only Email sent though contact read email or not. So, can CiviCRM can change status to Email read when contact read email? wordpress email share | improve this question asked Sep 26 at 0:12 ToanLuong 49 9 add a comment  |  up vote 1 down vote favorite I'm using WordPress 4.9.8, CiviCRM to 5.5.1, I usually send email to contact by Search> Find contacts View contact details Action> Send email Send email ok, Contact received mail ok like picture But status only Email sent though contact read email or not. So, can CiviCRM can change status to Email read when contact read email? wordpress email share | improve this questi...
Read more

How many registers does an x86_64 CPU actually have?

Image
Clash Royale CLAN TAG #URR8PPP up vote 2 down vote favorite I am currently learning reverse engineering and am studying the flags register. I had in my mind that rflags was just another name for one of the 16 general purpose registers, for example rax or rbx . But it looks like rflags is actually an additional register. So that makes 17 registers in total... how many more could there be? I have spent at least an hour on this and found numerous different answers. The best answer so far is this, which says that there are 40 registers in total. 16 General Purpose Registers 2 Status Registers 6 Code Segment Registers 16 SSE Registers 8 FPU/MMX Registers But if I add that up, I get 48. Could anybody provide an official answer on how many registers an x86_64 CPU has (e.g. an Intel i7). Additionally, I have seen references to 'hardware' and 'architectural' registers. What are those registers and how many are there? register x86-64 share | improve this...
Read more

Displaying single band from multi-band raster using QGIS

Image
Clash Royale CLAN TAG #URR8PPP 1 How can I extract a single band from multi-band raster in QGIS? I have an remote sensed image which has 6 bands (including NDVI band), I want to display each band separately, but have no idea how to do. I have seen some questions similar here but none worked for me. The original image (has 6 bands) is: I want to display the band 6 which should be like this: But I tried gdal_translate, and couldn't get the correct result. What I have got is: qgis raster multi-band share | improve this question edited Mar 5 at 0:53 Summer asked Mar 4 at 6:42 Summer Summer 23 6 Is this any help gis.stackexchange.com/questions/220658/… ? if not gis.stackexchange.com/questions/62133/… might help. – Michael Stimson Mar 4 at 6:46 Thanks for answering but when I used gdal_translate, qgis showed that 'Error 4: Kayena.tif: No such file or directory". Would you know how to fi...
Read more