[Issue 3813] Bad writeln of string arrays

[d-bugmail at puremagic.com]

http://d.puremagic.com/issues/show_bug.cgi?id=3813



--- Comment #3 from bearophile_hugs at eml.cc 2010-08-09 07:31:25 PDT ---
In dmd 2.048beta the situation is improved, but it's not good enough yet. This
D2 program:


import std.stdio, std.typetuple, std.typecons;
void main() {
    auto a1 = ["10", "20"];
    writeln(a1);
    auto a2 = [10, 20];
    writeln(a2);
    char[] a3 = ['5', '7', '9'];
    writeln(a3);
    auto t1 = TypeTuple!(10, "20", '7');
    writeln(t1);
    auto t2 = tuple(10, "20");
    writeln(t2);
}


Prints:

[10, 20]
[10, 20]
579
10207
Tuple!(int,string)(10, 20)

>From that output there is now way, in both the array and the TypeTuple, to tell
apart strings, numbers and chars. This doesn't help D2 debugging, and it
doesn't help all when you write quick scripts that often use a simple writeln()
for their output. In both cases being able to tell apart numbers and strings in
the output is quite important.

So my warm suggestion is to put "" around strings, '' around chars when they
are printed inside collections (Inside string literals special chars need to be
escaped).

So my expected output is:

["10", "20"]
[10, 20]
579
10"20"'7'
Tuple!(int,string)(10, "20")


A possible alternative output:

["10", "20"]
[10, 20]
['5', '7', '9']
10"20"'7'
Tuple!(int, string)(10, "20")



A similar Python 2.7 program:

from collections import namedtuple
a1 = ["10", "20"]
print a1
a2 = [10, 20]
print a2
a3 = ['5', '7', '9']
print a3
t1 = (10, "20", '7')
print t1
t2 = namedtuple('Two', 'a b')(10, "20")
print t2



Prints:

['10', '20']
[10, 20]
['5', '7', '9']
(10, '20', '7')
Two(a=10, b='20')

(In Python strings can be delimited by '' too.)


In D I presume writeln() can't tell that the input is a TypeTuple, so it can't
print something like the () as in Python.

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