Hi, i would like to get some view points on the use of properties within
classes. My belief is that properties should generally be used to return
values of private members. They should not do anything that is likely to
return an error and they should not instantiate or return any big objects
etc.
My company seems to be using them for everything which is starting to cause
me concern. Any comments or other viewpoints is appreciated.
Oct 24 '06
39  1953 
"Jon Skeet [C# MVP]" <sk***@pobox.co mwrote in message
news:MP******** *************** *@msnews.micros oft.com...
On the other hand, it can cause problem if you *later* want any of the
above - you break both source and binary compatibility.
If binary compatibility is necessary, then you have to make up-front
decisions that would otherwise be better deferred. That's not the case
for
most code, at least in my experience.
Would the source compatibility part apply only to ref arguments?
Yes, unless reflection is being used.
Okay, now I'm a little lost I think. I must be reading "source
compatibility" differently than intended, since I got the exact opposite
answer to the question than you did. :)
My interpretation:
"binary compatibility" -- you don't need to recompile
"source compatibility" -- you don't need to change the source code
In other words, if you have a public field, and decide to make that private
to support some desired behavior that using a property gives you, you have
to go modify the code. That breaks what I know as "source compatibility".
So, clue me in...what ARE you guys talking about, and why does it only
affect "ref arguments"? (which I read to mean "arguments using the 'ref'
keyword"...that is, arguments passed by reference).
Thanks,
Pete
"Peter Duniho" <Np*********@Nn OwSlPiAnMk.coms chrieb im Newsbeitrag
news:12******** *****@corp.supe rnews.com...
"Jon Skeet [C# MVP]" <sk***@pobox.co mwrote in message
news:MP******** *************** *@msnews.micros oft.com...
>On the other hand, it can cause problem if you *later* want any of the
above - you break both source and binary compatibility.
If binary compatibility is necessary, then you have to make up-front
decisions that would otherwise be better deferred. That's not the case
for
most code, at least in my experience.
Would the source compatibility part apply only to ref arguments?
Yes, unless reflection is being used.
Okay, now I'm a little lost I think. I must be reading "source
compatibility" differently than intended, since I got the exact opposite
answer to the question than you did. :)
My interpretation:
"binary compatibility" -- you don't need to recompile
"source compatibility" -- you don't need to change the source code
In other words, if you have a public field, and decide to make that
private to support some desired behavior that using a property gives you,
you have to go modify the code. That breaks what I know as "source
compatibility".
This surely would break source compatibility as well as binary comptability.
What they meant is replacing the public Field with property of the same
name, with a field with another name. Since access to fields an properties
are same in C# but different in IL that wouldn't break source compatibility
but binary compatability.
>
So, clue me in...what ARE you guys talking about, and why does it only
affect "ref arguments"? (which I read to mean "arguments using the 'ref'
keyword"...that is, arguments passed by reference).
Fields can by passed as ref/out parameters while properties can't.
>
Thanks,
Pete
It would also trash any reflective usage that explicetely looks for a
field... so you'd need to look for the field/property name as a string.
Not that I condone reflection as the first answer to a problem, but it has a
few uses...
Marc
>Using properties is not a problem and indeed it looks rather neat.
>Writing and maintaining your own properties does give some headache.
Where, for example, do you store them in the source file? I put fields at
top, then the constructor(s) followed by the methods, in alphabetical
order. Properties landed between the fields and the constructor, were
hard to find, were hard to maintain.
Switch from notepad to an IDE.
:-) no, I stick with vim. Working with properties became cumbersome when I
had to decide how to address fields within the class itself. Private,
protected or public is not an issue there, but some of the validation was
stored in the property-accessor. So I had two different outlooks on the same
internal data. My methods, that are usually very short and concise, became
difficult to interpret because raw data access was mingled with
property-based access. One day I decided to kick all home-grown properties
out and that cleared things up a lot (although they seem to be creeping
back)
"Peter Duniho" <Np*********@Nn OwSlPiAnMk.comw rote in message
news:12******** *****@corp.supe rnews.com...
>
No. If you want to later encapsulate the behavior of what was previously
a public field, you will require any user of the class to be modified and
recompiled.
I'm talking about converting public fields to public getter/setters. I don't
see how client source would need to be modified (unless the fields were
passed as ref arguments). The client would need to be recompiled (which is
important if and only if binary compatibility is required).
///ark
"Jon Skeet [C# MVP]" <sk***@pobox.co mwrote in message
news:MP******** *************** *@msnews.micros oft.com...
>
Of course, using fields means you can't use an interface to define the
contract of the class (or at least, you can't include the field in the
contract, whereas you can include a property).
Again, this is a no-brainer. -IF- you need to do this, then of course you
will use properties. My comment is whether one should just automatically use
getter/setters to wrap fields instead of using public properties when it
is -possible- to do so.
And, again, I feel that getter/setter property pairs are in general a bad
idea anyway.
///ark
Mark Wilden <mw*****@commun itymtm.comwrote :
Of course, using fields means you can't use an interface to define the
contract of the class (or at least, you can't include the field in the
contract, whereas you can include a property).
Again, this is a no-brainer. -IF- you need to do this, then of course you
will use properties. My comment is whether one should just automatically use
getter/setters to wrap fields instead of using public properties when it
is -possible- to do so.
And, again, I feel that getter/setter property pairs are in general a bad
idea anyway.
When are they a bad idea but public fields are a *good* idea?
--
Jon Skeet - <sk***@pobox.co m> http://www.pobox.com/~skeet Blog: http://www.msmvps.com/jon.skeet
If replying to the group, please do not mail me too
"Mark Wilden" <mw*****@commun itymtm.comwrote in message
news:%2******** **********@TK2M SFTNGP05.phx.gb l...
>No. If you want to later encapsulate the behavior of what was previously
a public field, you will require any user of the class to be modified and
recompiled.
I'm talking about converting public fields to public getter/setters. I
don't see how client source would need to be modified (unless the fields
were passed as ref arguments).
Ahh...I guess for some reason I just assumed that in the process, the public
field would be renamed. On reflection, I see that was a dumb assumption.
:)
Not sure why I made that assumption...I mean, I use fairly strict naming
conventions in which the names of fields and the names of properties would
never be the same, but then I would never make a public field anyway, so my
own personal preferences obviously have nothing to do with the way someone
else might do it. :)
Thanks...
Pete
"Jon Skeet [C# MVP]" <sk***@pobox.co mwrote in message
news:MP******** *************** *@msnews.micros oft.com...
>And, again, I feel that getter/setter property pairs are in general a bad
idea anyway.
When are they a bad idea but public fields are a *good* idea?
What I was saying is that they are both code smells. "Encapsulat ing" full
access to one's innards simply by wrapping those innards in properties is
usually just a band-aid.
Peter Duniho wrote:
"Jon Skeet [C# MVP]" <sk***@pobox.co mwrote in message
news:MP******** *************** *@msnews.micros oft.com...
On the other hand, it can cause problem if you *later* want any of the
above - you break both source and binary compatibility.
If binary compatibility is necessary, then you have to make up-front
decisions that would otherwise be better deferred. That's not the case
for
most code, at least in my experience.
Would the source compatibility part apply only to ref arguments?
Yes, unless reflection is being used.
Okay, now I'm a little lost I think. I must be reading "source
compatibility" differently than intended, since I got the exact opposite
answer to the question than you did. :)
My interpretation:
"binary compatibility" -- you don't need to recompile
"source compatibility" -- you don't need to change the source code
I think that you need to narrow what you mean by "source code".
"binary compatibility" -- you don't need to recompile _client_
applications for changes in the library code.
"source compatibility" -- you don't need to change the code of _client_
applications for changes in the library code.
In all cases, of course, you have to change the source code for the
class in question, and recompile.
So if you make a public field private and make a public property for
it, you of course have to recompile the code for that class.
Compatibility just asks whether you have to recompile / modify any of
the code _using_ the changed class. This thread has been closed and replies have been disabled. Please start a new discussion. Similar topics | |
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