Is it bad practice to have a long initialization method?

Asked 2010-04-12T13:20:16.073

Many people have argued about function size. They say that functions in general should be pretty short. Opinions vary from something like 15 lines to "about one screen", which today is probably about 40-80 lines.
Also, functions should always fulfill one task only.

However, there is one kind of function that frequently fails in both criteria in my code: Initialization functions.

For example in an audio application, the audio hardware/API has to be set up, audio data has to be converted to a suitable format and the object state has to properly initialized. These are clearly three different tasks and depending on the API this can easily span more than 50 lines.

The thing with init-functions is that they are generally only called once, so there is no need to re-use any of the components. Would you still break them up into several smaller functions would you consider big initialization functions to be ok?

function initialization code-size

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2 Answers

If you have a lot of components the need to be plugged into each other, it can certainly be reasonably natural to have a large method - even if the creation of each component is refactored into a separate method where feasible.

One alternative to this is to use a Dependency Injection framework (e.g. Spring, Castle Windsor, Guice etc). That has definite pros and cons... while working your way through one big method can be quite painful, you at least have a good idea of where everything is initialized, and there's no need to worry about what "magic" might be going on. Then again, the initialization can't be changed after deployment (as it can with an XML file for Spring, for example).

I think it makes sense to design the main body of your code so that it can be injected - but whether that injection is via a framework or just a hard-coded (and potentially long) list of initialization calls is a choice which may well change for different projects. In both cases the results are hard to test other than by just running the application.

answered 2010-04-12T13:24:39.240

Function length is, as you tagged, a very subjective matter. However, a standard best-practice is to isolate code that is often repeated and/or can function as its own entity. For instance, if your initialization function is loading library files or objects that will be used by a specific library, that block of code should be modularized.

With that said, it's not bad to have an initialization method that's long, as long as it's not long because of lots of repeated code or other snippets that can be abstracted away.

Hope that helps,
Carlos Nunez

answered 2010-04-12T14:22:27.337

Is it bad practice to have a long initialization method?

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