[xsd-users] Feature request: Explicit constructors

[Benjamin Schindler]

Hi


On 11/19/2010 01:59 PM, Ray Lischner wrote:
> Benjamin Schindler <bschindler at inf.ethz.ch> writes:
>> In C++, implicit type conversions are usually not recommended due to the
>> difficult predictability of performance. Using explicit as much as
>> possible is recommended, see i.e.
>> http://www.doc.ic.ac.uk/lab/cplus/c++.rules/chap13.html
> 
>> I know they are useful - but they are only useful until you get hit by a
>> type conversion you didn't expect causing weird bugs, at which point you
>> usually stop using them for 99% percent of the code. For a generic
>> library such as xsd doubly so
> 
> The MyClass constructors that are already defined rely on implicit construction of std::string from char const*.
> My recommendation is to add a constructor to bypass that implicit construction and to be explicit about the construction of MyClass from char const*.

There are a few problems here:
- the implicit conversion from const char* to std::string is required by
the standard (I thought) and natural because you're basically converting
a string to a string
- Converting a string to an enum by implicit conversion is a very
suspicious operation at best (Is the value defined? If not, exception?
Error?). If you really want it, make it explicit by calling
FrameKind("myString") - I'm not trying to disable that. This also makes
you aware that this constructor might throw etc. I consider this a lot
more clean tells the developer clearly what's happening.
- The bypass doesn't really work, see the example below:

void someFunction(const char* arg);

std::string myString = "someValue";
someFunction(myString); // does not compile, but I require that

I know, there is c_str(), but now we're really working around a problem.

Cheers
Benjamin


> 
> Ray Lischner,
> Senior Member of Technical Staff
> 133 National Business Pkwy, Ste 150     t. 443.539.3448
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> rlischner at proteuseng.com                     f. 443.539.3370
> 
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