tango.io.Stdout

Kris

Standard, global formatters for console output. If you don't need formatted output or unicode translation, consider using the module tango.io.Console directly. If you need to format, but not output to console, consider tango.text.convert.Format instead.

Stdout & Stderr expose this style of usage:

Stdout ("hello");                    // => hello
Stdout (1);                          // => 1
Stdout (3.14);                       // => 3.14
Stdout ('b');                        // => b
Stdout (1, 2, 3);                    // => 1, 2, 3
Stdout ("abc", 1, 2, 3);             // => abc, 1, 2, 3
Stdout ("abc", 1, 2) ("foo");        // => abc, 1, 2foo
Stdout ("abc") ("def") (3.14);       // => abcdef3.14

Stdout.format ("abc {}", 1);         // => abc 1
Stdout.format ("abc {}:{}", 1, 2);   // => abc 1:2
Stdout.format ("abc {1}:{0}", 1, 2); // => abc 2:1
Stdout.format ("abc ", 1);           // => abc

Note that the last example does not throw an exception. There are several use-cases where dropping an argument is legitimate, so we're currently not enforcing any particular trap mechanism.

Flushing the output is achieved through the flush() method, or via an empty pair of parens:

Stdout ("hello world") ();
Stdout ("hello world").flush;

Stdout.format ("hello {}", "world") ();
Stdout.format ("hello {}", "world").flush;

Special character sequences, such as "\n", are written directly to the output without any translation (though an output-filter could be inserted to perform translation as required). Platform-specific newlines are generated instead via the newline() method, which also flushes the output when configured to do so:

Stdout ("hello ") ("world").newline;
Stdout.format ("hello {}", "world").newline;
Stdout.formatln ("hello {}", "world");

The format() method of both Stderr and Stdout support the range of formatting options provided by tango.text.convert.Layout and extensions thereof; including the full I18N extensions where it has been configured in that manner. To enable a French Stdout, do the following:

import tango.text.locale.Locale;

Stdout.layout = new Locale (Culture.getCulture ("fr-FR"));

Note that Stdout is a shared entity, so every usage of it will be affected by the above example. For applications supporting multiple regions, create multiple Locale instances instead and cache them in an appropriate manner.

Stdout.layout can also be used for formatting without outputting to the console such as in the following example:

char[] str = Stdout.layout.convert("{} and {}", 42, "abc");
//str is "42 and abc"

This can be useful if you already have Stdout imported.

Note also that the output-stream in use is exposed by these global instances ~ this can be leveraged, for instance, to copy a file to the standard output:

Stdout.copy (new File ("myfile"));

Note that Stdout is *not* intended to be thread-safe. Use either tango.util.log.Trace or the standard logging facilities in order to enable atomic console I/O.