Hi!

I wonder where there is no const counterpart to the existing version.
I recently stumbled on that problem when writing a getValue(Key)
Function that I declared as const. I couldnt use operator[] to get the
value but had to use find().

Is there any harm in adding this function?

thx for any insights,

Christoph

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Christoph Rabel wrote:
> Hi!
>
> I wonder where there is no const counterpart to the existing version.
> I recently stumbled on that problem when writing a getValue(Key)
> Function that I declared as const. I couldnt use operator[] to get the
> value but had to use find().
>
> Is there any harm in adding this function?
>
> thx for any insights,

This has been covered a number of times in the past;
a search of the archives through Google Groups might
well dig up repeated discussions.

In a nutshell:
(a) There is none because the convenience of having
operator[] automatically add values if they are absent
was chosen
(b) It is unacceptable to many for a const version to
behave differently than a non-const version, except in
const-ness, so a const operator[] cannot be added.

You can write a function to get an element from a map,
but you'll need to decide what it should do if the element
is absent.  You'll just have to choose a name for the
function: the name operator[] has already been taken for
a function with different semantics.

-- James.

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