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More than one way to do it...More than one way to do it...Posted Feb 9, 2008 16:56 UTC (Sat) by im14u2c (subscriber, #5246)In reply to: Oh, it's easy by rsidd Parent article: Interview: Mark "Markey" Kretschmann (Not the Gentoo Weekly News)
Let's ban C then... #include <stdio.h>
int times_two_a(int x) { return x * 2; }
int times_two_b(int x) { return x << 1; }
int times_two_c(int x) { return x + x; }
int main(void)
{
int i, j;
char buf[3];
for (i = 0; i < 10; i++)
printf("%d times two is %d\n", i, times_two_a(i));
i = 0;
while (i < 10)
{
j = times_two_b(i);
printf("%d times two is %d\n", i, j);
}
i = 0;
do
{
sprintf(buf, "%d", i);
fputs(buf, stdout);
fputs(" times two is ", stdout);
sprintf(buf, "%d", times_two_c(i));
fputs(buf, stdout);
} while (++i < 10);
return 0;
}
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More than one way to do it... Posted Feb 9, 2008 20:52 UTC (Sat) by tjc (subscriber, #137) [Link] The different ways of doing the same thing in your example arise in part from properties of arithmetic (addition and multiplication) and the binary representation of numbers (bit shifting). Granted, "for" loops are syntatic sugar, but a useful and common idiom.
More than one way to do it... Posted Feb 9, 2008 21:08 UTC (Sat) by im14u2c (subscriber, #5246) [Link] Surprised you didn't jump on the opportunity to point out that the latter two loops are flawed, in part because they aren't idiomatic... ;-) I was actually making two points: The first is that allowing for many ways to approach a problem can be valuable, and second is that mindlessly straying from idioms makes it easy to make mistakes and harder for others to understand your code. It's like goto: It is very easy to use it to turn your code into spaghetti. At the same time, it's probably a mistake to outright ban its use, as there are times when the alternative is less clear. (Escaping a nested loop comes to mind.)
It's not a mistake to ban goto... it's not a mistake to keep it... Posted Feb 10, 2008 7:53 UTC (Sun) by khim (subscriber, #9252) [Link] If there are two (or more) ways to do something (like for and while cycles in your samples) but they are used often in real programs - it's not a big deal: reader will remember both and it's easy to understood both. The constructs usable once per a blue moon must be rejected unless they are doing something which will be impossible or very-very hard to do otherwise. Now about goto: while it's not very useful it's still quite simple to understand because we have "goto in disguise": return. But of course plain old goto is so rare that ban makes sense. But any choice must be justified from reader's position, not from writer's one. This is not how perl chooses the constructs...
It's not a mistake to ban goto... it's not a mistake to keep it... Posted Feb 10, 2008 11:57 UTC (Sun) by filipjoelsson (subscriber, #2622) [Link] The last time I saw goto in serious use (where last is defined as most recent instance of coding - not last time I viewed ancient code), was in some DirectX example code (shipped with DirectX in ca 1999 - so it is a half way ancient, and it is MS being responsible). Anyway, the way they used it was to skip to a dtor-like section of a function. Not particularly elegant, not particularly object oriented, but not outright heresy either - which, since I thought it _was_ outright heresy confused me. Ever since, I have been trying to solve it in more elegant ways (using C++). Nested ifs, functors, exceptions, you name it - it's not very elegant either. Anybody know a better way to free resources in a C++ function when failing? (I tend to think the nested ifs are the least evil - but they do eat the line width at an alarming rate.) EORant ;)
It's not a mistake to ban goto... it's not a mistake to keep it... Posted Feb 10, 2008 13:48 UTC (Sun) by nix (subscriber, #2304) [Link] The Linux kernel uses goto in this manner all the time. It's useful if you can't do it by splitting the non-ctor-dtor stuff into a separate function.
freeing resources Posted Feb 11, 2008 3:26 UTC (Mon) by pflugstad (subscriber, #224) [Link] Are you looking for RAII?I use it quite often for things like mutexes, but it can be used in many other situations - any time you hold a resource in a function that must be cleaned up when the function exits, including when throwing an exception. It's a fairly common design pattern for C++ these days - I think I started seeing it a year or two ago...
freeing resources Posted Feb 11, 2008 8:19 UTC (Mon) by nix (subscriber, #2304) [Link] In C++ it's probably two decades old: I know it was landing in published textbooks ten years ago. I didn't see it in C outside the Linux kernel before about 2004.
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