threads
threads
NAMESYNOPSIS
DESCRIPTION
RETURN VALUE
NOTES
PORTABILITY
SEE ALSO
NAME
use_screen, use_window − curses thread support
SYNOPSIS
#include <ncurses/curses.h>
typedef int
(*NCURSES_WINDOW_CB)(WINDOW *, void *);
typedef int (*NCURSES_SCREEN_CB)(SCREEN *, void *);
int get_escdelay(void);
int set_escdelay(int size);
int set_tabsize(int size);
int use_screen(SCREEN *scr, NCURSES_SCREEN_CB func, void
*data);
int use_window(WINDOW *win, NCURSES_WINDOW_CB func, void
*data);
DESCRIPTION
This implementation can be configured to provide rudimentary support for multi-threaded applications. This makes a different set of libraries, e.g., libncursest since the binary interfaces are different.
Rather than modify the interfaces to pass a thread specifier to each function, it adds a few functions which can be used in any configuration which hide the mutex’s needed to prevent concurrent use of the global variables when configured for threading.
In addition to forcing access to members of the WINDOW structure to be via functions (see curs_opaque(3x)), it makes functions of the common global variables, e.g., COLORS, COLOR_PAIRS, COLS, ESCDELAY, LINES, TABSIZE curscr, newscr and ttytype. Those variables are maintained as read-only values, stored in the SCREEN structure.
Even this is not enough to make a thread-safe application using curses. A multi-threaded application would be expected to have threads updating separate windows (within the same device), or updating on separate screens (on different devices). Also, a few of the global variables are considered writable by some applications. The functions described here address these special situations.
The ESCDELAY and TABSIZE global variables are modified by some applications. To modify them in any configuration, use the set_escdelay or set_tabsize functions. Other global variables are not modifiable.
The get_escdelay function returns the value for ESCDELAY.
The use_window and use_screen functions provide coarse granularity mutexes for their respective WINDOW and SCREEN parameters, and call a user-supplied function, passing it a data parameter, and returning the value from the user-supplied function to the application.
USAGE
All of the ncurses library functions assume that the locale
is not altered during operation. In addition, they use data
which is maintained within a hierarchy of scopes.
|
• |
global data, e.g., used in the low-level terminfo or termcap interfaces. | ||
|
• |
terminal data, e.g., associated with a call to set_curterm. The terminal data are initialized when screens are created. | ||
|
• |
screen data, e.g., associated with a call to newterm or initscr. | ||
|
• |
window data, e.g., associated with a call to newwin or subwin. Windows are associated with screens. Pads are not necessarily associated with a particular screen. |
Most curses applications operate on one or more windows within a single screen.
|
• |
reentrant, i.e., it uses only the data passed as parameters. |
This table lists the scope of data used for each symbol in the ncurses library when it is configured to support threading:
RETURN VALUE
These functions all return TRUE or FALSE, except as noted.
NOTES
Both a macro and a function are provided for each name.
PORTABILITY
These routines are specific to ncurses. They were not supported on Version 7, BSD or System V implementations. It is recommended that any code depending on ncurses extensions be conditioned using NCURSES_VERSION.
SEE ALSO
ncurses(3NCURSES), opaque(3NCURSES), curses_variables(3NCURSES).
Opportunity
Personal Opportunity - Free software gives you access to billions of dollars of software at no cost. Use this software for your business, personal use or to develop a profitable skill. Access to source code provides access to a level of capabilities/information that companies protect though copyrights. Open source is a core component of the Internet and it is available to you. Leverage the billions of dollars in resources and capabilities to build a career, establish a business or change the world. The potential is endless for those who understand the opportunity.
Business Opportunity - Goldman Sachs, IBM and countless large corporations are leveraging open source to reduce costs, develop products and increase their bottom lines. Learn what these companies know about open source and how open source can give you the advantage.
Free Software
Free Software provides computer programs and capabilities at no cost but more importantly, it provides the freedom to run, edit, contribute to, and share the software. The importance of free software is a matter of access, not price. Software at no cost is a benefit but ownership rights to the software and source code is far more significant.
Free Office Software - The Libre Office suite provides top desktop productivity tools for free. This includes, a word processor, spreadsheet, presentation engine, drawing and flowcharting, database and math applications. Libre Office is available for Linux or Windows.
Free Books
The Free Books Library is a collection of thousands of the most popular public domain books in an online readable format. The collection includes great classical literature and more recent works where the U.S. copyright has expired. These books are yours to read and use without restrictions.
Source Code - Want to change a program or know how it works? Open Source provides the source code for its programs so that anyone can use, modify or learn how to write those programs themselves. Visit the GNU source code repositories to download the source.
Education
Study at Harvard, Stanford or MIT - Open edX provides free online courses from Harvard, MIT, Columbia, UC Berkeley and other top Universities. Hundreds of courses for almost all major subjects and course levels. Open edx also offers some paid courses and selected certifications.
Linux Manual Pages - A man or manual page is a form of software documentation found on Linux/Unix operating systems. Topics covered include computer programs (including library and system calls), formal standards and conventions, and even abstract concepts.
