auto init & what the code means

[spir]

Hello,

I have a problem with D's auto-init feature. When reading in someone else's code
        int i;
there is no way, I guess, to know whether this means "i is initialised to 0" or 
"i is left undefined". For this reason, in the former case I do explicitely 
initialise. Thus,
        int i = 0;      // means initialised
        int i;          // means undefined _for me_
But, as _for me_ emphasizes, another reader still cannot guess the latter case.

I would enjoy having an idiom to express this clearly. Without it, a 
possibility may be to use a conventional comment like
        int i;  // undef
in public code (esp Phobos) and spread the word about it. (Then, variable 
declarations without init or comment are known to be by people who do not use 
this convention, and we know we need to search farther in code to interpret 
them.)

Note that this problem does not apply to floats or pointers/refs, for which 
.init is invalid for operating anyway. But there is a weird ambiguity about 
null/uninitialised arrays & strings which behave like empty in most cases. I 
would enjoy this to be clarified as well. For instance:
        int[] ints1 = [];
        ints1 ~= 1;             // ok
        int[] ints2;
        ints2 ~= 1;             // error
So that arrays behave like pointed/ref'ed thingies. (But I'm unsure about the 
best way.) (*)

Denis

(*) This is also related to the boolean / null-compare value os arrays and 
strings:
void main()
{
    writeln("array -- undef");
    int[] ints1;
    writeln('(',ints1,')');
    if (ints1) writeln("ints1");
    if (ints1 != null) writeln("ints1");
    if (ints1 !is null) writeln("ints1");
    ints1 ~= 1;
    writeln('(',ints1,')');
    
    writeln("array -- def");
    int[] ints2 = [];
    writeln('(',ints2,')');
    if (ints2) writeln("ints2");
    if (ints2 != null) writeln("ints2");
    if (ints2 !is null) writeln("ints2");
    ints2 ~= 1;
    writeln('(',ints2,')');
    
    writeln("string -- undef");
    string str1;
    writeln('(',str1,')');
    if (str1) writeln("str1");
    if (str1 != null) writeln("str1");
    if (str1 !is null) writeln("str1");
    str1 ~= '1';
    writeln('(',str1,')');
    
    writeln("string -- def");
    string str2 = "";
    writeln('(',str2,')');
    if (str2) writeln("str2");
    if (str2 != null) writeln("str2");
    if (str2 !is null) writeln("str2");
    str2 ~= '1';
    writeln('(',str2,')');
}  
==>
array -- undef
()
([1])
array -- def
()
([1])
string -- undef
()
(1)
string -- def
()
str2
str2
(1)
-- -- -- -- -- -- --
vit esse estrany ☣

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