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`three = 1` in the Linux sourcecode (2014)

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Re: `three = 1` in the Linux sourcecode (2014)

#41

Post by yoz-y »

hannasanarion wrote: post #39
CWuestefeld wrote: post #36

Many years ago in an age of klocs and flowcharts, at a large three-letter computer company, there were iron-clad coding rules that must be obeyed, no questions allowed. In general you could see their reasoning, but such bureaucratic reasoning doesn't pay off. One example of this was that all numeric values used in a program must be factored out as symbolic constants. The reason for doing this is obvious, but it faile…

Why is the reason for doing this obvious? I can't see any benefit. I get why you would prefer to name constants for their use, like `numIterations=3` or whatever, but renaming every integer seems senseless.

It's "obvious" if you take into account the corporate culture I guess. The rule of 'no magic numbers' is generally good, but then one has to remember that some numbers (like 0 and 1) are not magic.

Re: `three = 1` in the Linux sourcecode (2014)

#42

Post by function_seven »

hannasanarion wrote: post #39
CWuestefeld wrote: post #36

Many years ago in an age of klocs and flowcharts, at a large three-letter computer company, there were iron-clad coding rules that must be obeyed, no questions allowed. In general you could see their reasoning, but such bureaucratic reasoning doesn't pay off. One example of this was that all numeric values used in a program must be factored out as symbolic constants. The reason for doing this is obvious, but it faile…

Why is the reason for doing this obvious? I can't see any benefit. I get why you would prefer to name constants for their use, like `numIterations=3` or whatever, but renaming every integer seems senseless.

When formulating the rule, they didn't understand the point of it. They think "naked constants === bad" is equivalent to "no numbers in source".

Which, of course, is wrong. They're not the same. Same bastardization happened to Hungarian Notation, IIRC. It was meant to add some information to variables, like `iterN` for a counter, or `lenX` for a length, but someone somewhere decided that you were meant to prefix with the most primitive of type info, so you get stupid shit like `intN` and `intX`, and aren't much more informed. (Especially with an IDE showing the type info)

Re: `three = 1` in the Linux sourcecode (2014)

#43

Post by marcosdumay »

tremon wrote: post #31
scotty79 wrote: post #12

Earlier quoted context omitted.

Not really. Nobody sane would think other sane developer with any expeirience would call a simple variable according to what it initially contains. You'd expect either name related to what is the meaning of the contents, or meaningless name.

When unsigned three = 1; is accompanied by unsigned five = 5; unsigned seven = 7; what would be the sane conclusion?

That the code was edited more than once on its lifetime, and in one of those times (not the last one), by someone with pretty bad naming habits.

Re: `three = 1` in the Linux sourcecode (2014)

#45

Post by de6u99er »

ben_w wrote: post #29
kortex wrote: post #26

Earlier quoted context omitted.

unsigned three = 1; To me, that is a 20 foot tall neon orange flashing Chesterton's fence. I think, "surely there is a very strong reason for this." Maybe not a good reason, but definitely a compelling one.

If I was code reviewing this, I would almost certainly insist on a different name to make the WTF go away. I’m not going to suggest one here despite having read the other code comment, as doing so would be bikeshedding — not my codebase and I have no skin in this — the only point I will insist on is that I cannot believe that “three” is a sensible choice of name for whatever it does. Not even what the comment implies…

Or at least require a comment explaining it, before someone needs to dig through the code.

Powers of three, five, and seven sounds a little bit like Totvald's very own little FizzBuzz game hidden in ext4's file-system source code.

Re: `three = 1` in the Linux sourcecode (2014)

#46

Post by [deleted] »

hannasanarion wrote: post #39
CWuestefeld wrote: post #36

Many years ago in an age of klocs and flowcharts, at a large three-letter computer company, there were iron-clad coding rules that must be obeyed, no questions allowed. In general you could see their reasoning, but such bureaucratic reasoning doesn't pay off. One example of this was that all numeric values used in a program must be factored out as symbolic constants. The reason for doing this is obvious, but it faile…

Why is the reason for doing this obvious? I can't see any benefit. I get why you would prefer to name constants for their use, like `numIterations=3` or whatever, but renaming every integer seems senseless.

[deleted]

Re: `three = 1` in the Linux sourcecode (2014)

#47

Post by hyperman1 »

CWuestefeld wrote: post #36

Many years ago in an age of klocs and flowcharts, at a large three-letter computer company, there were iron-clad coding rules that must be obeyed, no questions allowed. In general you could see their reasoning, but such bureaucratic reasoning doesn't pay off. One example of this was that all numeric values used in a program must be factored out as symbolic constants. The reason for doing this is obvious, but it faile…

An application I touched a few weeks ago has a DB column named 'type' with values 1,2,3. So on to the source code we go:

  enum RecordType {TypeOne(1),TypeTwo(2),TypeThree(3); RecordType(int dbValue) ...}
As it happens, I know an end user of this particular beast, so I show her some record IDs of each type and ask in what way they differ. She looks a few seconds, then says: 'This is clearly a type one record, the next is a type two, and here you have a type three'. After a little back an forth, it turns out even our internal course for new personnel talks about 'records' with different rules to follow for 'type one/two/three'. The end users have no other word to describe these entities than 'records' each with its own numbered type, and think about it as completely natural. The application is based on an older COBOL application, and the terminology just stuck around.

Clearly, the application is well-written: The enum uses the terminology used by the business. Another of my flabbers just got ghasted.

Re: `three = 1` in the Linux sourcecode (2014)

#48

Post by inetknght »

hannasanarion wrote: post #39
CWuestefeld wrote: post #36

Many years ago in an age of klocs and flowcharts, at a large three-letter computer company, there were iron-clad coding rules that must be obeyed, no questions allowed. In general you could see their reasoning, but such bureaucratic reasoning doesn't pay off. One example of this was that all numeric values used in a program must be factored out as symbolic constants. The reason for doing this is obvious, but it faile…

Why is the reason for doing this obvious? I can't see any benefit. I get why you would prefer to name constants for their use, like `numIterations=3` or whatever, but renaming every integer seems senseless.

> but renaming every integer seems senseless.

When the integer itself is self-explainatory but you can't just assign the integer as a name.

For example:

   constexpr int 42 = 42; // compiler error
So instead:

   constexpr int fourtytwo = 42; // yay!
However the obviousness of what 42 means is debatable.

   int universe = fourtytwo; // why?
   int sum = fourtytwo; // sum... of what?
   int magic = fourtytwo / 7;

Re: `three = 1` in the Linux sourcecode (2014)

#49

Post by scotty79 »

forgottenlogin9 wrote: post #30
scotty79 wrote: post #27

Earlier quoted context omitted.

True. But the intention of writing int three = 3; is insane. I would never ascribe to previous programmer (unless he just learned what variables are) the intention of creating variable (not even constant, which wouldn't make it any better) named 'three' and assigning actual value 3 to it.

If that is insane, you may not have issue with this specific line but you surely have issue with the 2 “insane” lines that follow it?

If something looks insane, but probablu sane person made it and it works then that's usually good indicator that you are missing part of the picture and should look around. It still might be bad, but probably not insane.

Re: `three = 1` in the Linux sourcecode (2014)

#50

Post by scotty79 »

tremon wrote: post #31
scotty79 wrote: post #12

Earlier quoted context omitted.

Not really. Nobody sane would think other sane developer with any expeirience would call a simple variable according to what it initially contains. You'd expect either name related to what is the meaning of the contents, or meaningless name.

When unsigned three = 1; is accompanied by unsigned five = 5; unsigned seven = 7; what would be the sane conclusion?

That there are some entities (maybe ordered, maybe related to numbers three, five and seven in some way) and there are some values associated with those entities, two of which (accidentally or not) need to be initially set to corresponding number, but the third one possibly not, but better look around in the comments or code to understand and make sure the code is correct.

Then maybe leave a comment right after `= 1;` why this variable shouldn't be initialized with 3 that would clear up confusion for you if it was there.

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