How to determine whether a property or a method is more appropriate

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How to determine whether a property or a method is more appropriate

published 11 months, 18 days ago, submitted by manovich 11 months, 19 days ago

dotnettipoftheday.org — Guidelines for choosing between implementing a class member as a property or a method.

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Comments:

"Calling the member twice in succession produces different results."

Not necessarily, DateTime.Now and Random.Next are examples of a valid propertys that produce different results when called in succession.

[)amien

posted by

DamienG 11 months, 18 days ago

Minor correction: System.Random.Next is not a property.

Discussing DateTime.Now is a rather moot, academic exercise as it follows "Use a property when the member is a logical data member" [1] ;)

-- bg

[1] http://msdn2.microsoft.com/en-us/library/bzwdh01d(VS.71).aspx#cpconpropertyusageguidelinesanchor1

posted by

boki 11 months, 18 days ago

Yeah sorry Random.Next isn't... but Stopwatch.Elapsed is ;-)

Perhaps it should be worded "Calling the member twice in succession produces different results with the exception of time-based activities"

[)amien

posted by

DamienG 11 months, 18 days ago

Biggest one that is missed: The operation may throw an exception. You should never have to wrap property accesses within try/catch blocks.

Biggest one that's complete bullshit: If it returns an array. Why? Because you cannot guarantee callers won't change the state of the array.

1) How is this different than any property that exposes an object via a getter?
2) Have you seen the framework? Collections are regularly exposed via properties.

This "hint" is full of fail and ugly. NO KICK FOR U.

posted by

yesthatmcgurk 11 months, 18 days ago

Yeah, I must agree that the arrays one I just ignored thinking Collections get returned in the framework. :)

On the bonus side, there is the link in the article to MS's Design Guidelines for Class Library Developers.

posted by

powerrush 11 months, 18 days ago

Common sense should be used when applying any guidelines. These are guidelines not strict rules.

Regarding returning array: IMHO if by desing it is acceptable that array/collection will be modified by external code, then I think member can be implemented as property (every rule has an exception).

posted by Sirko 11 months, 18 days ago