Handling of const strings/char arrays, e.g. with KActionCollection

[Thiago Macieira]

On Tuesday 22 April 2008 18:58:35 Friedrich W. H. Kossebau wrote:
> Now I could go and wrap all strings with QLatin1String on the caller side.
> Another, perhaps more simple fix would be to overload all functions with
> their const-char* equivalents as convenience functions, which internally
> call the old one using QLatin1String.
> What is to be preferred? How costly are the additional symbols in the
> library against all the explicit QLatin1String calls in the binary code,
> which are also making the source code harder to read? Any idea?
> Should I prepare such a patch for KActionCollection?

There's no gain in performance or memory allocation. You shouldn't keep 
objects of type QLatin1String around, since they don't do deep copies. The 
QLatin1String class is just there so you can easily mark your code for "this 
is Latin 1" and avoid using QString::fromLatin1(). It's meant to be converted 
to QString later.

In some operations, like indexOf, replace, endsWith, etc., QString has a 
QLatin1String overload. In that case, there is a gain in performance since no 
extra QString is allocated. I.e., you invoke the Latin 1 comparison functions 
(where they exist), which are cheaper.

-- 
  Thiago Macieira  -  thiago (AT) macieira.info - thiago (AT) kde.org
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