enum str = "abc"; vs string str = "abc";

[H. S. Teoh]

On Wed, Jan 16, 2019 at 06:21:29PM +0000, Victor Porton via Digitalmars-d wrote:
> What is more space efficient:
> 
> enum str = "safjkdfjksdlfkdsj";
> 
> or
> 
> string str = "safjkdfjksdlfkdsj";
> 
> ?
> 
> with the first code fragment, won't the string be re-created and
> re-inserted into the object file one time whenever str is used, rather
> than once?

Strings are a bit special, in that the compiler automatically stores
them in a string table and emits them only once.  However, you're quite
right that using enum with arrays in general is not a good idea
space-wise.


> What of the two you would recommend?

Use:
	immutable str = "...";

in module-global scope. Or if this is inside a function,

	static immutable str = "...";

This places it in the data section of the object file and elides the
extra pointer/size pair of `str` if it were mutable.


OTOH, if `str` is only referenced at compile-time, then it's more
efficient to use the enum, because then it won't even appear in the
object file. :-)  Also, you may have no choice but to use an enum if
`str` is referenced by compile-time code, since static globals would not
be readable at compile-time.


T

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