Re: Number of times I've used goto in Perl

I found goto useful in C.

char *p1 = alloc();
if (p1 == NULL) goto ERROR;

char *p2 = alloc();
if (p2 == NULL) goto ERROR2;

char *p3 = alloc();
if (p3 == NULL) goto ERROR3;

...

return 1;

ERROR3: free(p2);
ERROR2: free(p1);
ERROR:  return 0
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But with Perl's reference counting and destructors, this model isn't necessary.

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Re^2: Number of times I've used goto in Perl by Anonymous Monk on May 06, 2018 at 13:55 UTC
In C, any time you use the `switch` statement, you're really using (forward) `goto` in disguise.	[reply] [d/l] [select]
Re^3: Number of times I've used goto in Perl by ikegami (Patriarch) on May 06, 2018 at 18:51 UTC
`for`, `while`, `if`, and more can also be implemented using a jump. That doesn't matter. The problem with goto isn't that it's a jump instruction; the problem is the resulting lack of code structure. For code to readable, it you should composed of "blocks". Prematures exits (next, last, return, die, and goto as used in my C example) are an exception as they can actually improve readability. This is why they don't necessarily have the same problem as goto.	[reply] [d/l] [select]
Re^4: Number of times I've used goto in Perl by Anonymous Monk on May 07, 2018 at 09:04 UTC
Just one example what you can do with `switch`: Duff's device. Switch cases have the fallthrough property, so those blocks can have multiple entry edges. Besides that, `switch` and `goto` have the same problem that they can enter a scope at the middle. (For instance, C prohibits bypassing the declaration of variably modified type, e.g. `int foo[n];` where `n` is a variable too — this is more or less the same as `alloca()`.) The main benefit of `goto` is that it can be used to set up a simple FSM without using a state variable. Which is also the main problem with `goto`, in case the simple turns out to be "simple".	[reply] [d/l] [select]