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Goto (2007)

beej.us

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Re: Goto (2007)

#111

Post by recursive »

gwbas1c wrote: post #67

In the past 20 years I've used a goto a few times, and then refactored it out once I was able to look at the problem with a clear head. I remember that, every time, I replaced the goto by breaking up a large method into smaller methods, and then replacing the goto with either return statements or logic that would essentially return. Yes, a goto is part of our programmers' toolbox. But, now even I consider a "good got…

Often this is true, but those smaller methods might need to share so much local state that the solution is worse than the problem.

Re: Goto (2007)

#112

Post by 0xffff2 »

bodyfour wrote: post #99

Probably coming too late to the discussion, but commenting anyway... The issue I think is that people today read "GOTO Considered Harmful" without really understanding the world at the time. Other than simple integer FOR loops, basically all control-flow in the FORTRAN of those days was accomplished with GOTO -- and to numbered lines, not labels. Things we take for granted in all languages today like { code blocks }…

Can you give an example of where you've used goto in C or a C-like language? Or a rough estimate of the number of times you've found goto to be the best solution?

I agree with your post in principle, but in practice I can't think of a single example where I've used a goto that wasn't eventually refactored to something better that didn't have the goto.

Edit: Probably the most common example (and one given early in the article) is deeply nested loops. This is a good example of where I'm very unlikely to use goto. Almost certainly, I will prefer to hide one or more of the inner loops inside of a function call.

Re: Goto (2007)

#113

Post by mumblemumble »

0xffff2 wrote: post #112
bodyfour wrote: post #99

Probably coming too late to the discussion, but commenting anyway... The issue I think is that people today read "GOTO Considered Harmful" without really understanding the world at the time. Other than simple integer FOR loops, basically all control-flow in the FORTRAN of those days was accomplished with GOTO -- and to numbered lines, not labels. Things we take for granted in all languages today like { code blocks }…

Can you give an example of where you've used goto in C or a C-like language? Or a rough estimate of the number of times you've found goto to be the best solution? I agree with your post in principle, but in practice I can't think of a single example where I've used a goto that wasn't eventually refactored to something better that didn't have the goto. Edit: Probably the most common example (and one given early in the…

What's wrong with the examples in the article?

Re: Goto (2007)

#115

Post by codr7 »

0xffff2 wrote: post #112
bodyfour wrote: post #99

Probably coming too late to the discussion, but commenting anyway... The issue I think is that people today read "GOTO Considered Harmful" without really understanding the world at the time. Other than simple integer FOR loops, basically all control-flow in the FORTRAN of those days was accomplished with GOTO -- and to numbered lines, not labels. Things we take for granted in all languages today like { code blocks }…

Can you give an example of where you've used goto in C or a C-like language? Or a rough estimate of the number of times you've found goto to be the best solution? I agree with your post in principle, but in practice I can't think of a single example where I've used a goto that wasn't eventually refactored to something better that didn't have the goto. Edit: Probably the most common example (and one given early in the…

https://github.com/codr7/ampl/blob/main/src/ampl/eval.cpp

Re: Goto (2007)

#117

Post by 0xFACEFEED »

dragonwriter wrote: post #95
srott wrote: post #61

Earlier quoted context omitted.

> There is no need to use GOTO when a language has functions/procedures and exceptions. ... and defer

> and defer Which “defer”? The go panic/defer pair is, while structured differently, functionally equivalent to exceptions.

You use exceptions to clean up resources even when there are no errors? Why?

Re: Goto (2007)

#118

Post by Jtsummers »

recursive wrote: post #111
gwbas1c wrote: post #67

In the past 20 years I've used a goto a few times, and then refactored it out once I was able to look at the problem with a clear head. I remember that, every time, I replaced the goto by breaking up a large method into smaller methods, and then replacing the goto with either return statements or logic that would essentially return. Yes, a goto is part of our programmers' toolbox. But, now even I consider a "good got…

Often this is true, but those smaller methods might need to share so much local state that the solution is worse than the problem.

This is where languages that permit nested functions come in handy. You can locally factor out new functions while preserving access to variables in the lexical scope without needing to pass them in as parameters or lift them into a higher level scope (object, class, global, file, etc.).

Re: Goto (2007)

#119

Post by beej71 »

userbinator wrote: post #65

Another good use of goto is to implement state machines --- "goto state_x" is clearer and simpler than the loop-switch that people often use. I can certainly say that over the years I've encountered code which was more difficult to understand and less efficient because either the author didn't want to use goto, or the language didn't have it. While it's true that you can always rewrite code to remove goto statements,…

Oh, that's an interesting use I hadn't considered!

Re: Goto (2007)

#120

Post by InfiniteRand »

0xffff2 wrote: post #112
bodyfour wrote: post #99

Probably coming too late to the discussion, but commenting anyway... The issue I think is that people today read "GOTO Considered Harmful" without really understanding the world at the time. Other than simple integer FOR loops, basically all control-flow in the FORTRAN of those days was accomplished with GOTO -- and to numbered lines, not labels. Things we take for granted in all languages today like { code blocks }…

Can you give an example of where you've used goto in C or a C-like language? Or a rough estimate of the number of times you've found goto to be the best solution? I agree with your post in principle, but in practice I can't think of a single example where I've used a goto that wasn't eventually refactored to something better that didn't have the goto. Edit: Probably the most common example (and one given early in the…

It's good for a simplified version of exception handling for C (granted C does have setjmp/longjmp but that's more like the complicated version of exception handling)

If you hit an error condition in deeply nested logic and need to go to common error handling code or go to a recovery point, then goto makes sense.

Often times in these scenarios simplifying the logic is also an option, but that isn't always the case, especially when dealing with external interfaces that have a lot of potential error conditions that cannot be dealt with easily from the immediate caller (I'm thinking primarily of system interfaces, but also potentially library interfaces).

From what I've seen this is the only really good scenario for goto and I think the examples in the article more or less fall into this category of escaping from deeply nested error cases.

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