Meaning

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3 total messages Started by Shannon Peterson Wed, 16 Mar 2005 15:51

#45

Author: Shannon Peterson
Date: Wed, 16 Mar 2005 15:51

14 lines
1329 bytes

I have a chunck of code and it uses code like:

AnsiString mystring = ::func(stuff() + "string");

all over the place and I was wondering if the :: is just allocating 
space for data returned by the function call?

is it the same as void::Func()?

if my assumption is wrong could you please correct me.

thanks

Shannon

Re: Meaning

#46

Author: Thomas Maeder [TeamB]
Date: Wed, 16 Mar 2005 16:08

44 lines
2321 bytes

Shannon Peterson <speterson@ae-solutions.com> writes:

> AnsiString mystring = ::func(stuff() + "string");
>
> all over the place and I was wondering if the :: is just allocating
> space for data returned by the function call?

Not at all.

The expression

func("string")

means that a function named func() is to be called, and "string" is to
be passed as argument.

This sounds simple, but it's not. Because in C++, we have
overloading.

The compiler thus first has to look for functions named func in a
sequence of namespaces. As soon as one or more functions named func
have been found in a namespace, this search stops. Among the functions
found, those that can't take "string" as an argument are discarded
from the candidate functions. If this process ends up with exactly one
function, that function is called.

Prefixing func with :: changes the sequence of namespace where the
search for func is performed: func() is only looked for the global
namespace.

> is it the same as void::Func()?

No.

void::Func()

is a sytax error, while

AnsiString mystring = ::func(stuff() + "string");

is syntactically correct.

Re: Meaning

#47

Author: Shannon Peterson
Date: Wed, 16 Mar 2005 16:17

54 lines
2437 bytes

Thanks, it all makes sense now.

Shannon

Thomas Maeder [TeamB] wrote:

> Shannon Peterson <speterson@ae-solutions.com> writes:
> 
> 
>>AnsiString mystring = ::func(stuff() + "string");
>>
>>all over the place and I was wondering if the :: is just allocating
>>space for data returned by the function call?
> 
> 
> Not at all.
> 
> 
> The expression
> 
> func("string")
> 
> means that a function named func() is to be called, and "string" is to
> be passed as argument.
> 
> 
> This sounds simple, but it's not. Because in C++, we have
> overloading.
> 
> The compiler thus first has to look for functions named func in a
> sequence of namespaces. As soon as one or more functions named func
> have been found in a namespace, this search stops. Among the functions
> found, those that can't take "string" as an argument are discarded
> from the candidate functions. If this process ends up with exactly one
> function, that function is called.
> 
> Prefixing func with :: changes the sequence of namespace where the
> search for func is performed: func() is only looked for the global
> namespace.
> 
> 
> 
>>is it the same as void::Func()?
> 
> 
> No.
> 
> void::Func()
> 
> is a sytax error, while
> 
> AnsiString mystring = ::func(stuff() + "string");
> 
> is syntactically correct.

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