Reduce code complexity: Guard clauses

[Kent Sharkey]

Rock and Null[^]:

Almost every software engineer fights a never-ending fight: we strive to make our codebase simpler and thus more readable every day.

If you don't guard your clauses, who knows what may happen to them

Yeah, very lame. It's Sunday, and my brain isn't working right now.

[David ONeil]

Guard clauses cause clustering complexity collapse. Claus that's the way they roll! :rimshot: - followed by deathly silence.

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[Greg Utas]

It's brief and recommends putting guards in their own if statements. It will trigger those who cleave to the shibboleth that a function should only have one return statement.

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The fox knows many things, but the hedgehog knows one big thing.

[realJSOP]

I cleave to that shibboleth.

".45 ACP - because shooting twice is just silly" - JSOP, 2010
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You can never have too much ammo - unless you're swimming, or on fire. - JSOP, 2010
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When you pry the gun from my cold dead hands, be careful - the barrel will be very hot. - JSOP, 2013

[den2k88]

Like PC-Lint and MISRA standards.

GCS d--(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--- r+++ y+++*      Weapons extension: ma- k++ F+2 X

[Richard Deeming]

Quis custodes custodit? :-D

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"These people looked deep within my soul and assigned me a number based on the order in which I joined." - Homer

[Gary Wheeler]

A completely stupid idea. It adds a thrown exception that functions solely as a goto.

Software Zen: delete this;

[Gary Wheeler]

Agreed.

Software Zen: delete this;

[Marc Clifton]

It's so sad that other programmers that I may end up working with at some point read that drivel and adopt it.

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[Kent Sharkey]

At least with a GOTO you can get back to where you were - much more difficult with exceptions. :sigh:

TTFN - Kent

[Gary Wheeler]

True, but then I'm a purist. I haven't used a goto statement in over 20 years. I will admit I use break and continue, but they are 'structured' to my way of thinking.

Software Zen: delete this;

[Greg Utas]

Did I miss something? An exception is more than a goto, because it can jump outside of the current scope. This is very useful for aborting work that has run into a serious error, when it is appropriate to exit a chain of function calls and recover from a known point well down the stack. That's actually the only thing I use exceptions for. In most cases, such as a bad argument, the function should simply return a failure result instead. EDIT: It looks like the code could well be overusing exceptions when returning a failure result would be more appropriate, so that's probably what I missed.

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The fox knows many things, but the hedgehog knows one big thing.

[Gary Wheeler]

The 'guard' code from the article was this:

fun guard() {
if (!condition1) {
throw Exception1()
}
doThings1()

if (!condition2) {
    throw Exception2()
}
doThings2()

if (!condition3) {
    throw Exception3()
}
doThings3()

}

This call needs to be surrounded by a try...catch in order to exactly reproduce the functionality of the original. I'm not sure which language is used for the original code; I think it may be Javascript, but the fun keyword is odd. In any case, throwing an exception in lieu of nested conditionals or a goto is overly complicated and error-inducing. Imagine debugging this sort of nonsense when the catch misses one of the exceptions thrown.

Software Zen: delete this;

[Daniel Pfeffer]

:omg:

Freedom is the freedom to say that two plus two make four. If that is granted, all else follows. -- 6079 Smith W.

[BillWoodruff]

Hi Marc, Perhaps my memory is flawed, but, I seem to recall eyeballing code of yours that used preventive filters in this way. I'd appreciate your comments on my post below !

«The mind is not a vessel to be filled but a fire to be kindled» Plutarch

[BillWoodruff]

I believe in anticipating/handling errors in parameter data before you get to the juicy parts, and I think guard clauses are a good example of a strategy for that. I also think liberal use of Try/Catch for things like file-ops is a good thing. Guard clauses' "virtual isolation" at the start of a method is, imho, "separation of concerns." You can easily comment them out, remove them, as conditions/state management require. However, there are other strategies. What I'd like to see is a radical extension of Attributes in C# that do AOP-like transformations, and, internally generate the equivalent of guard clauses: there's already an example of that in the semantics of the Nullable attributes: [^]. A "wedding" of unit-tests and attributes :)

«The mind is not a vessel to be filled but a fire to be kindled» Plutarch

[Richard Andrew x64]

BillWoodruff wrote:

What I'd like to see is a radical extension of Attributes in C#

You always did strike me as a radical!

The difficult we do right away... ...the impossible takes slightly longer.