MILLISEC_PER_SEC is never needed
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I put it to you that a variable, constant or define named "MILLISEC_PER_SEC" is never, ever, ever needed.
cheers Chris Maunder
But what about ONE_SECOND_MS ?
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Surely that's a constant?
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I put it to you that a variable, constant or define named "MILLISEC_PER_SEC" is never, ever, ever needed.
cheers Chris Maunder
But you wouldn't believe how many people talk about 'kWh per hour' Sure, it could be meaningful if the power varies, but then 'kWh per hour' might vary, too, and cannot be treated as a single value. And lots of people refer to kWh/hour even when the power is constant.
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I put it to you that a variable, constant or define named "MILLISEC_PER_SEC" is never, ever, ever needed.
cheers Chris Maunder
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Or, perhaps it's needed to differentiate in regions where they use an Imperial Second instead of a regular one.
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Like a dueling second?
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Is that a leading question?
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Is that a leading question?
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I suppose that's the long and short of it.
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I actually disagree; I often deal with code using second, milliseconds, microseconds and even nanoseconds, sometimes with more than one unit in a function. Having a const (of some sort) declares what conversion was intended.
A counterargument. Excellent. My counter-counter argument, and the reason my brain popped: I would always prefer to have something like
var timeInSeconds = X;
var timeInMilliseconds = timeInSeconds / 1000;My point is that the 1000 is always 1000. The variables surrounding that should be the ones clearly named. The "1000" can never be anything other than 1000. At least that's what I think.
cheers Chris Maunder
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But you wouldn't believe how many people talk about 'kWh per hour' Sure, it could be meaningful if the power varies, but then 'kWh per hour' might vary, too, and cannot be treated as a single value. And lots of people refer to kWh/hour even when the power is constant.
So: What if you then had
var kiloWattPerHourPerHour = X;
var kiloWattPerHourPerMinute = kiloWattPerHourPerHour / 60;Should the 60 be a constant or a literal?
cheers Chris Maunder
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A counterargument. Excellent. My counter-counter argument, and the reason my brain popped: I would always prefer to have something like
var timeInSeconds = X;
var timeInMilliseconds = timeInSeconds / 1000;My point is that the 1000 is always 1000. The variables surrounding that should be the ones clearly named. The "1000" can never be anything other than 1000. At least that's what I think.
cheers Chris Maunder
Aaaaggghhhh, Magic Number..... "It's supposed to be microseconds? Shit." (Near accurate quote.)
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I blame the Brits for that one.
cheers Chris Maunder
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Aaaaggghhhh, Magic Number..... "It's supposed to be microseconds? Shit." (Near accurate quote.)
<small pause> OK. That argument I will accept in that the number may appear in more than one place, making refactoring painful. Except, except, except: the calculation should only be done in one place:
var variable = ConvertToMilliFurlongs(X);
...
function ConvertToMilliFurlongs(furlongs)
{
return furlongs / 1000;
}So if it's "Dammit, Janet. It should be microFurlongs" then you rename
ConvertToMilliFurlongstoConvertToMicroFurlongsand change the 1000 to 1000000. Everything's still clear.cheers Chris Maunder
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<small pause> OK. That argument I will accept in that the number may appear in more than one place, making refactoring painful. Except, except, except: the calculation should only be done in one place:
var variable = ConvertToMilliFurlongs(X);
...
function ConvertToMilliFurlongs(furlongs)
{
return furlongs / 1000;
}So if it's "Dammit, Janet. It should be microFurlongs" then you rename
ConvertToMilliFurlongstoConvertToMicroFurlongsand change the 1000 to 1000000. Everything's still clear.cheers Chris Maunder
I thought you preferred cubits. Here's a webpage for you: Furlongs to Cubits | Kyle's Converter[^]
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Damn. I was hoping you knew of one! ;)
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I put it to you that a variable, constant or define named "MILLISEC_PER_SEC" is never, ever, ever needed.
cheers Chris Maunder
It depends on what it is used for. It could be set to other values to speed up or slow down the time counting without changing other modules. If you develop PLC virtualizations, emulators or firmware that value may be fundamental instead of useless.
GCS d-- s-/++ a- C++++ U+++ P- L+@ E-- W++ N+ o+ K- w+++ O? M-- V? PS+ PE- Y+ PGP t+ 5? X R+++ tv-- b+(+++) DI+++ D++ G e++ h--- ++>+++ y+++* Weapons extension: ma- k++ F+2 X
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I blame the Brits for that one.
cheers Chris Maunder
You'd better blame the french, and the long scale was the original.
Wrong is evil and must be defeated. - Jeff Ello
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A counterargument. Excellent. My counter-counter argument, and the reason my brain popped: I would always prefer to have something like
var timeInSeconds = X;
var timeInMilliseconds = timeInSeconds / 1000;My point is that the 1000 is always 1000. The variables surrounding that should be the ones clearly named. The "1000" can never be anything other than 1000. At least that's what I think.
cheers Chris Maunder
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So: What if you then had
var kiloWattPerHourPerHour = X;
var kiloWattPerHourPerMinute = kiloWattPerHourPerHour / 60;Should the 60 be a constant or a literal?
cheers Chris Maunder
Eeeeh... kW per hour per hour? In which situations does that unit occur? When does kW per hour occur? A constantly rising (or falling) power, at a rate of x kW/h? And then you want to a unit for how much, in kW, the power has risen in one hour. You don't want to simply call it kW, these are not 'absolute' kilowatts, but a change in power, and that is a change per hour over a period of an hour, which is a different kind of kW unit. Then you want the unit of the increase in power for each minute, right? You come across the strangest units if you look around :-) When I was a student, we did some filter calculations where I (after years of wondering) saw how a frequency correction could be given by a time value (European FM pre-emphashis is 50 us, US radios use 75 us - or is it the other way around?), but I never got it under my skin; it is just a strange artifact of unit arithmetics! If you change that 60 to NumberOfMinutesPerHour, the question is: Are these really the same MinutesPerHour as when you measure 'absolute' time progression? Or, do these MinutesPerHour have a slightly different semantics from the wall clock's minutes per hour (similar to a kW value indicating a change in kiloWattPerHourPerHour is different from an instantaneous, or constant, power kilowatt value)? Maybe it should be called NumberOfMinutesPerHourWhenCalculatingChangesInPowerOverTime? When we updated our programming guidelines, the project leader of our project immediately granted an exception from the 80 char maximum line length: Our rules for how to construct 'const' names (this was K&R C) led to serveral cases of identifiers of length >80. Finally, there is the famous Xerox Fortran manual quote:
"The primary purpose of the DATA statement is to give names to constants; instead of referring to pi as 3.141592653589793 at every appearance, the variable pi can be given that value with a DATA statement and used instead of the longer form of the constant. This also simplifies modifying the program, should the value of pi change."
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It depends on what it is used for. It could be set to other values to speed up or slow down the time counting without changing other modules. If you develop PLC virtualizations, emulators or firmware that value may be fundamental instead of useless.
GCS d-- s-/++ a- C++++ U+++ P- L+@ E-- W++ N+ o+ K- w+++ O? M-- V? PS+ PE- Y+ PGP t+ 5? X R+++ tv-- b+(+++) DI+++ D++ G e++ h--- ++>+++ y+++* Weapons extension: ma- k++ F+2 X
In such a situation, the constant is badly mis-named. Calling it a constant, if you intend to vary it, is a small detail. Setting MILLISECONDS_PER_SEC to 2000? Seriously? Which time-dependent operations would that affect - those where milliseconds are used, those where other milliseconds are used? Or all? Would it double or half the speed? A properly named semi-constant value would be something like SLOWDOWN_FACTOR or VIRTUAL_TIME_TO_REAL_TIME. And while I am at it: I really hate this C style CONSTANTS_IN_ALL_UPPER_CASE rule - much because I have seen too many cases where functional extensions requiring the symbol defintion to be changed to a a variable to adapt to other situations - but the old UC name was used in so many source files and documentation that it cost too much to change it, and the old UC name was retained for the variable. (I also had my first serious programming training in Pascal, and when switching to C, I really missed the option to replace a semi-const/variable definition with a (parameterless) function call - parentheses were not required in Pascal, but in C you have to go through every use and add () to every use of the symbol.)
