[Issue 4716] std.stdio.input() or similar

[d-bugmail at puremagic.com]

http://d.puremagic.com/issues/show_bug.cgi?id=4716



--- Comment #1 from bearophile_hugs at eml.cc 2010-08-23 05:14:22 PDT ---
Improved code. Both IsType() and IsString() may be useful to add to std.traits,
if something similar is not already present.


import std.string: chomp;
import std.stdio: write, readln;
import std.conv: to;

// true is T is one of the successive types
template IsType(T, Types...) {
    static if (Types.length)
        enum bool IsType = is(T == Types[0]) || IsType!(T, Types[1..$]);
    else
        enum bool IsType = true;
}

// true if T is string, wstring, or dstring
template IsString(T) {
    enum bool IsString = IsType!(T, string, wstring, dstring);
}

T input(T)(string msg) {
    write(msg);
    auto read = readln();
    static if (IsString!T)
        return to!T(read.chomp());
    else
        return to!T(read.strip());
}

// usage demo --------------
import std.stdio: writeln;
void main() {
    //auto x = input!string("Enter value x: ");
    auto x = input!double("Enter value x: ");
    writeln(">", x, "<");
}

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