From: Steven Kah Hien Wong <steven@...>
Date: 2008-05-10T12:21:57+09:00
Subject: Do strings from rb_str_new and friends need to be free'd?

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Hi,

I have some C native code that calls a logging class written in Ruby. To
pass the message string to the Ruby class, I am creating a string with
rb_str_new2 and then passing its VALUE to rb_funcall. I am wondering if I
need to do any clean-up for the string, or will Ruby handle this for me?

Also, if anyone can suggest an awesome doc on writing Ruby native
extensions, that would be appreciated. At the moment, I am mostly using the
Pickaxe online book.

Here is the code in question:

    void log_warning(const char *fmt, ...)
    {
        char message[BUFFER_LEN]; // Temporary buffer to hold the generated
message

        // Evaluate the format string and store it in the temporary buffer
        va_list ap;
        va_start(ap, fmt);
            vsnprintf(message, BUFFER_LEN, fmt, ap);
        va_end(ap);

        // Find the ID's to call tho Log.warning Ruby class method
        rb_require("log");
        ID log_class = rb_path2class("Log");
        ID log_warning_method = rb_intern("warning");

        // Create a Ruby string containing a copy of the formatted message
        VALUE message_value = rb_str_new2(message);

        // Call Log.warning, with the formatted message as an argument
        rb_funcall(log_class, log_warning_method, 1, message_value);

        // Do I need to do anything here to tell Ruby to clean up the
string?
    }

Thanks!

-Steven

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