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- sizeof lambda - 2 Updates
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| "AP" <unixpronospam@verizon.net>: Sep 18 04:39PM -0400 http://www.open-std.org/JTC1/SC22/WG21/docs/papers/2009/n2927.pdf says that "In addition, this rewrite adds the restriction that lambda expressions cannot be used in the operand of a sizeof operator, alignof operator, or decltype specifier. That restriction— suggested by Doug Gregor and John Spicer—avoids severe implementation difficulties with template argument deduction (e.g., this avoids the need to encode arbitrary statement sequences in mangled names)." And yet this snippet compiles and runs just fine : #include <iostream> int main() { auto lambda=[](){ return nullptr;}; std::cout << sizeof lambda << std::endl; return 0; } Is it wrong to read the open-std papers ? --- This email is free from viruses and malware because avast! Antivirus protection is active. http://www.avast.com --- news://freenews.netfront.net/ - complaints: news@netfront.net --- |
| Victor Bazarov <v.bazarov@comcast.invalid>: Sep 18 07:20PM -0400 On 9/18/2014 4:39 PM, AP wrote: > return 0; > } > Is it wrong to read the open-std papers ? In your code 'lambda' is an object, the lambda-expression is the expression between the '=' and the semicolon that ends the declaration statement. What you're not supposed to do is to write .... sizeof []() { return nullptr; } ^^^^^^^^^^^^^^^^^^^^^^^^^ That is a lambda-expression. It cannot appear as an argument of 'sizeof'. It's pretty much useless there, if you ask me... V -- I do not respond to top-posted replies, please don't ask |
| "AP" <unixpronospam@verizon.net>: Sep 18 04:33PM -0400 What is wrong with it ? I'm trying to digest Exceptional C++ on the subject and can't get it ... --- This email is free from viruses and malware because avast! Antivirus protection is active. http://www.avast.com --- news://freenews.netfront.net/ - complaints: news@netfront.net --- |
| "AP" <unixpronospam@verizon.net>: Sep 18 04:31PM -0400 And then people wonder why the obesity in trolls ... --- This email is free from viruses and malware because avast! Antivirus protection is active. http://www.avast.com --- news://freenews.netfront.net/ - complaints: news@netfront.net --- |
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