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124 lines
4.2 KiB
Plaintext
124 lines
4.2 KiB
Plaintext
NS -- the Cocoa interface for macOS and compatible systems
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----------------------------------------------------------
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This directory contains files needed to build Emacs on system based on
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NextStep (NS), including macOS and GNUstep, using the Cocoa API.
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HISTORY
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The Nextstep (NS) interface of GNU Emacs was originally written in
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1994 for NeXTSTEP systems running Emacs 19 and subsequently ported to
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OpenStep and then Rhapsody, which became Mac OS X. In 2004 it was
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adapted to GNUstep, a free OpenStep implementation, and in 2008 it was
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merged to the GNU Emacs trunk and released with Emacs 23. Around the
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same time a separate Mac-only port using the Carbon APIs and
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descending from a 2001 Mac OS 8/9 port of Emacs 21 was removed. (It
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remains available externally under the name "mac".)
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OVERVIEW OF COCOA AND OBJECTIVE-C
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Cocoa is an API for the Objective-C language, an objective oriented
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superset of C. Anybody with experience with iOS or modern macOS
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application development should feel at home.
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A method call in Objective-C differs from most other languages in the
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fact that it doesn't have a normal name. Instead, the method name is
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made up of the name of each parameter. An exception to this rule are
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methods without parameters.
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The following calls a method in the object 'anObject'.
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[anObject alpha:1 beta:2 gamma:3];
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Classes are declared like the following:
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@interface AClassName
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{
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// A class method.
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+ (TYPE)name1:(TYPE)param1
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// An object method.
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- (TYPE)name1:(TYPE)param1 name2:(TYPE)param2;
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}
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@end
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GUIDELINES
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* Adhere the to the FSF philosophy that a feature in GNU software
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should not only be available on non-free systems.
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* People with varying Cocoa and Objective-C skills will read and
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modify the NS code over a long period of time. Keep the code simple
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and avoid language constructs that makes the code hard to maintain.
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* Don't use macros and types intended for the XCode Interface Builder,
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like 'IBAction'.
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* The NS interface should work on all version of macOS from Mac OS X
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10.6.8 (Snow Leopard) to the latest official release.
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* Under macOS, it is possible to build Emacs using NS, X11, or console
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only. A new macOS feature should work in all appropriate builds.
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TRACING SUPPORT
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The NS interface features a printf-based trace package that prints the
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call tree of selected functions in the Cocoa interface, plus various
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extra information. It can be enabled by uncommenting the line
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defining 'NSTRACE_ENABLED' in "nsterm.h". To enable more output,
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uncomment the lines defining symbols starting with 'NSTRACE_GROUP'.
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GNUSTEP AND OTHER COMPATIBLE SYSTEMS
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The NS interface works on systems compatible with macOS, for example
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GNUstep. Even though they are less frequently used, this is important
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for a number of reasons:
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* It supports the GNUstep project and provides an Emacs with the same
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look-and-feel as the rest of the system.
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* This allows other Emacs developers to test their changes on the NS
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interface without having access to a macOS machine.
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* If a feature in the NS interface work on free systems like GNUstep,
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this meets the FSF requirement that features in GNU software should
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not only be available on non-free systems.
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SEE ALSO
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The src/ns... files contains the C and Objective-C parts.
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The lisp/term/ns-win.el file contains the lisp part of the NS
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interface.
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The INSTALL file in this directory for compilation instructions.
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The Nextstep section in the etc/TODO file for a list of ideas for
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future development.
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----------------------------------------------------------------------
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Copyright 2008-2020 Free Software Foundation, Inc.
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This file is part of GNU Emacs.
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GNU Emacs is free software: you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation, either version 3 of the License, or
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(at your option) any later version.
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GNU Emacs is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with GNU Emacs. If not, see <https://www.gnu.org/licenses/>.
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