The Big Programming Thread - Page 462

On April 01 2014 19:48 Manit0u wrote:


There wasn't any. Didn't want to bother with doing it for such a small project that I was working alone with. Came back to bite me in the ass in the end.

On April 01 2014 23:21 nunez wrote:
put some time aside to get gcc-4.9.0 up and running with -std=c++1y.
return type deduction with decltype(auto) seems very sweet.

Difference from decltype

Unfortunately, there is no way to get the effect of decltype with an auto return type; plain auto never deduces to a reference, and auto&& always deduces to a reference. This is a significant problem, as it means that forwarding functions can't use auto. We could consider using decltype semantics instead of the existing auto semantics, but that would mean giving different deduction semantics to auto depending on whether the declaration is of a variable or a function, and making auto functions different from lambdas.

Therefore, I propose to also allow decltype(auto) to get the decltype semantics without having to repeat the expression. For simplicity of specification and orthogonality I propose to allow it everywhere that plain auto is allowed, except for introducing a trailing-return-type. It occurs to me that the difference in meaning of decltype depending on the form of the expression (e.g. parenthesized or not) might be more surprising in this context, but I think it would be even more surprising if this worked differently from C++11 decltype.

On April 01 2014 06:18 Cyx. wrote:

Or you could compile with warnings as errors, then you get the best of both worlds - compiler error when you typo, and you don't have to make your code awkward to read ^^

On April 04 2014 01:47 Blisse wrote:
My main problem with books is that you can't CTRL+F through them, and I don't really have the time nor need to go step-by-step through any textbook. Maybe if you have a lot more time on your hands then they would be useful, but online references have usually been good. A pdf version of the book would be better too, but I don't absolutely buy the idea that books are easier to learn from unless you're actually going through the book page by page.

On April 04 2014 09:53 darkness wrote:
I've been reading a bit of that "Clean Code" book. One of the suggestions is not to return null but to throw an exception or return a special case object. Is that how you guys do it as well? I've recently got annoyed at some bits of my code that are if (object == null).

But then, do you have to catch those exceptions? Can't they go silently like "return" in a void method? What about int/boolean methods though? "return" is insufficient there, but if you write "return -1", then whether you check for (object == null) or (object != -1) kind of has the same purpose.

On April 04 2014 06:44 Fawkes wrote:
Guess I'll slowly work through MSDN and stuff.

Need help with a SQL query, trying to update 2 columns on rows in a table that match a certain criteria. Assuming I have a userid column that starts with '13%', and I want to change every userid that starts like that to '14%'...so something like

13Fawkes would be turned into 14Fawkes, is this possible?

mySQL

update 'tablename'
set 'user_id' = CONCAT('14', SUBSTRING('user_id', 3)), 'user_id_clone' = CONCAT('14', SUBSTRING('user_id', 3))
where 'user_id' LIKE '13%'

Would this work?

On April 04 2014 09:22 Manit0u wrote:


That's why you have numerous indexes in the book, you can search through them too, you just have to know how

Also, it's easier to learn from a book because it's a physical object that gives you more references to the information you seek. Stuff you don't normally notice, like how far it is from the beginning/end of the book judging by how much paper you feel under your fingers, where is it located on the page etc. That's how our brain memorizes stuff.

As an example: It is easier to learn about numerous characters in the book, their names, appearance, history etc. than it is to memorize a 30 digit number even though the amount of data is vastly greater in the first case. It's all because of this roadmaps with waypoints that your brain creates when reading an actual book. That's also why in the memory-enhancing classes they teach you to make stories when you have to memorize something so that instead of having to commit a long number to the memory you remember stuff like 5 elephants bought 3 apples but monkeys stole 2 of them and sold them for 4 pennies. Even though at first it seems that memorizing a story is harder since it's more data it's actually easier for your brain to process because that's how it's built.

You don't necessarily have to read through the entire textbook too. Just pick it up if you need something, go through the index and try to find it. If you ever need that info again you'll be surprised how fast you can find it again (usually even faster than searching on the net). The added benefit is that after you read it in the book there's a greater chance that it'll stay with you and you won't have to look for it again.

On April 04 2014 13:17 CatNzHat wrote:

recent example I ran into was an accessor method for a signed cookie. If it successfully unsigns the cookie then it will return the value, otherwise it will return nil (which could be caused by bad cookie value or no cookie at all). This creates a clean encapsulation for accessing the signed cookie values that is easy to test.