www.digitalmars.com         C & C++   DMDScript  

digitalmars.D.bugs - [Issue 4716] New: std.stdio.input() or similar

reply d-bugmail puremagic.com writes:
http://d.puremagic.com/issues/show_bug.cgi?id=4716

           Summary: std.stdio.input() or similar
           Product: D
           Version: D2
          Platform: All
        OS/Version: All
            Status: NEW
          Severity: enhancement
          Priority: P2
         Component: Phobos
        AssignedTo: nobody puremagic.com
        ReportedBy: bearophile_hugs eml.cc



If not already present, a function template similar to this one may be useful
for the std.stdio module. Similar functions are present in Basic and Python
languages:


T input(T)(string msg) {
    write(msg);
    auto read = readln();
    static if (!is(T == string) && !is(T == dstring) &&!is(T == wstring))
        read = read.strip();
    return to!T(read);
}


To be used mostly in scripts, as:

double x = input!double("Enter value x: ");

Its name may be changed if there is collision with something different, but it
needs to be simple, given its purpose.

This function may be made much more refined, but I suggest to keep it simple.
Even the static if it contains is more complex than originally thought.

-- 
Configure issuemail: http://d.puremagic.com/issues/userprefs.cgi?tab=email
------- You are receiving this mail because: -------
Aug 22 2010
next sibling parent d-bugmail puremagic.com writes:
http://d.puremagic.com/issues/show_bug.cgi?id=4716




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, "<");
}

-- 
Configure issuemail: http://d.puremagic.com/issues/userprefs.cgi?tab=email
------- You are receiving this mail because: -------
Aug 23 2010
prev sibling next sibling parent d-bugmail puremagic.com writes:
http://d.puremagic.com/issues/show_bug.cgi?id=4716




Adam Ruppe has suggested:


 I'd say make it do a combination of writef though, so you can do more
 complex prompts.

 auto number = ask!int("Enter a number, %s", name);


-- 
Configure issuemail: http://d.puremagic.com/issues/userprefs.cgi?tab=email
------- You are receiving this mail because: -------
Feb 08 2011
prev sibling parent d-bugmail puremagic.com writes:
http://d.puremagic.com/issues/show_bug.cgi?id=4716




A D2 program that reads a string from the keyboard:


import std.stdio;
void main() {
    string s = readln();
    writeln(">", s, "<");
}


Running it it shows that the newline is left inside the string s:

...>test
123

123


<


I don't know other languages where the command line input function leaves the
newline at the end of the input string. This is why in input() I have used
chomp().

-- 
Configure issuemail: http://d.puremagic.com/issues/userprefs.cgi?tab=email
------- You are receiving this mail because: -------
Oct 28 2011