• Gary Miller (35/35) Mar 30 2014 In a lot of my string manipulation functions I need the
• evilrat (7/11) Mar 30 2014 string.dup property does a copy of original array(! note that
• bearophile (9/19) Mar 30 2014 Here if you care for some efficiency you need to dup only

"Gary Miller" <aiguy roadrunner.com> writes:

In a lot of my string manipulation functions I need the 
flexibility of passing a string but other times I need to pass a 
char[] so that I can change the contents of the string in the 
function.  Because the string data type is immutable I get errors 
if I pass it as a parameter and try to change it in the function.

Can I overload a function to work for either a char[] or a string?

Many of the library functions that I need to call require string 
arguments such as the replace below.

I believe I can create a wrapper function for it like this to 
still get at the functionality. But this seems like a lot of work 
for every function.

I'm almost sorry that the the string datatype was created because 
then probably all the library string handling would have been 
written for char[].

Are there any alternate libraries for D that have a mutable 
string datatype or is there a way to override the immutable 
characteristic of the string datatype by reallocating it or 
something?

I realize that the reduced memory reallocation in string handling 
is probably a major reason that D is faster than other more 
dynamic languages like Python but

Maybe the functions in std.string could be overloaded into a 
std.mutablestring library at some point to eliminate emulate the 
functionality of more dynamic languages for those programs that 
need it.

	char[] ReplaceAllSubstrings(inout char[] Original,
                                     in char[] SearchString,
                                     in char[] Substring)
	{
	    string SOriginal = Original.dup;
	    string SSearchString = SearchString.dup;
	    string SSubstring = Substring.dup;
	    SOriginal.replace(SSearchString, SSubstring);
             return Original.dup;
         }

"evilrat" <evilrat666 gmail.com> writes:

On Sunday, 30 March 2014 at 15:58:52 UTC, Gary Miller wrote:

 Are there any alternate libraries for D that have a mutable 
 string datatype or is there a way to override the immutable 
 characteristic of the string datatype by reallocating it or 
 something?

string.dup property does a copy of original array(! note that 
this is array property and would work for any other arrays and 
slices).

you can have overloaded variant for strings but i think compiler 
would optimize to call everything as string variant, you can 
figure this out on your own.

"bearophile" <bearophileHUGS lycos.com> writes:

Gary Miller:

 	char[] ReplaceAllSubstrings(inout char[] Original,
                                     in char[] SearchString,
                                     in char[] Substring)
 	{
 	    string SOriginal = Original.dup;
 	    string SSearchString = SearchString.dup;
 	    string SSubstring = Substring.dup;
 	    SOriginal.replace(SSearchString, SSubstring);
             return Original.dup;
         }

Here if you care for some efficiency you need to dup only 
SOriginal. And at the end you can call assumeUnique if you want 
to return a string (or you can use a less efficient idup).

Note that in D string/function names start with a lowercase.

It's also better to use "auto" instead of "string" in that 
function, because the result of dup is not a string.

Bye,
bearophile