- Available C++ Libraries FAQ - 1 Update
- Hashing for unordered containers? - 1 Update
- C++20 Designated initializers + struct member initializer - 2 Updates
| Nikki Locke <nikki@trumphurst.com>: Oct 14 10:23PM Available C++ Libraries FAQ URL: http://www.trumphurst.com/cpplibs/ This is a searchable list of libraries and utilities (both free and commercial) available to C++ programmers. If you know of a library which is not in the list, why not fill in the form at http://www.trumphurst.com/cpplibs/cppsub.php Maintainer: Nikki Locke - if you wish to contact me, please use the form on the website. |
| Jorgen Grahn <grahn+nntp@snipabacken.se>: Oct 14 08:05PM On Sun, 2020-10-11, Öö Tiib wrote: > own issues. > Program is put together of patterns and it is business of compiler > to reduce it to minimal binary code. It's not how I see it, but I couldn't come up with a good explanation of how I /do/ see it. >> types. > May be it is indeed better to use unordered_map<std::string, Photo>. > I think of such idiom as "dictionary idiom" as it is rather common. For me, anything that discourages use of domain-specific types is a bad thing. I use them a lot to (the way I see it) make my designs clearer; it's one of the main benefits of C++ IMO. > That does compile when <string> is included. What you search > for photo in your set of photos with? Without file name in > external interface? Dummy photo? In this application, a (name of a) photo isn't just a string: it's either a file name matching a certain pattern, or it's invalid. I establish that at the external interface, before this set or map gets involved. Then it makes sense to represent it as a type, to show that this invariant holds. [snip] /Jorgen -- // Jorgen Grahn <grahn@ Oo o. . . \X/ snipabacken.se> O o . |
| Thiago Adams <thiago.adams@gmail.com>: Oct 14 11:01AM -0700 This sample prints: https://godbolt.org/z/3f13vW #include <stdio.h> struct Point { const char* name = ""; int x = 1, y = 2; }; struct Line { struct Point pt1 = { .name = "pt1" }; }; int main() { struct Line line = {}; printf(".pt1 = {.name='%s' .x=%d .y=%d}\n", line.pt1.name, line.pt1.x , line.pt1.y); struct Line line2 = { .pt1 = {.x = 3} }; printf(".pt1 = {.name='%s' .x=%d .y=%d}\n", line2.pt1.name, line2.pt1.x , line2.pt1.y); } .pt1 = {.name='pt1' .x=1 .y=2} .pt1 = {.name='' .x=3 .y=2} I was expecting this for the last print: .pt1 = {.name='pt1' .x=3 .y=2} basically the designated initializers does not care about the defaults of line. I was expecting the designed initializer something that could override the defaults but not ignore then. What do you think? What is the rationale for this? |
| Thiago Adams <thiago.adams@gmail.com>: Oct 14 11:04AM -0700 On Wednesday, October 14, 2020 at 3:02:07 PM UTC-3, Thiago Adams wrote: > What is the rationale for this? Some references: http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2016/p0329r0.pdf http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2017/p0329r3.pdf http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2017/p0329r4.pdf |
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